UNIT
Genetic Processes
2
Chapter 4: Heredity and Reproduction
Genetic information is passed from one generation to the next by the process of
reproduction. This genetic information is stored in DNA molecules, which are
organized into genes on chromosomes.
There are two types of reproduction. Asexual reproduction involves one parent,
producing offspring that are genetically identical to the parent. Sexual reproduction
involves two parents, producing genetically variable offspring. Each of these processes
has biological advantages and disadvantages.
Information about sexual and asexual reproduction, and how genetic information
is transmitted during these processes, has applications related to human health, to
agriculture, and to the environment.
BIG IDEAS
• Genetic and genomic research
can have social and environmental
implications.
• Variability and diversity of
organisms result from the
distribution of genetic materials
during the process of meiosis.
Chapter 5: Mendelian Genetics—Patterns
of Inheritance
Our understanding of how traits are transmitted during reproduction is due largely
to the work of Gregor Mendel, the “Father of Genetics.” He used the results of many
experiments to develop laws describing the inheritance of traits.
There are many patterns of inheritance beyond those studied by Mendel.
Patterns of inheritance include complete dominance, incomplete dominance, and
codominance. Some traits, such as human skin colour, are controlled by multiple
pairs of alleles, resulting in a great amount of variation. Genetic factors play a role in
many disorders, such as cystic fibrosis. Genetic screening and carrier testing can help
determine the risk of expressing or passing on a genetic disorder. However, there are
social and ethical implications in the use of genetic screening and carrier testing.
Chapter 6: Genetics beyond Mendel
Genetic information is stored in DNA molecules. DNA is a double helix consisting
of pentose sugars, phosphate groups, and nitrogenous bases. Mutations, which are
changes in the sequence of nitrogenous bases in DNA, can occur due to environmental
factors or errors in replication.
Genomes of different organisms contain different numbers of genes. The human
genome, which consists of about 20000 genes, has been sequenced, and this
information can be used in medical and forensic applications.
Genetic engineering uses a variety of techniques to manipulate genetic information.
Gene therapy applies genetic engineering to overcome the effects of defective genes.
Genetic engineering and gene therapy have social and environmental considerations.
Manipulation of the genome has environmental and social considerations.
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4.1
Textbook pp. 138–141
The Nature of Heredity
Vocabulary
heredity
deoxyribonucleic acid (DNA)
locus
polyploid
genetics
gene
sexual reproduction
asexual reproduction
MAIN IDEA: Chromosomes carry information for traits, and traits are passed from parents
to offspring in a process known as heredity.
1. Genetic material includes deoxyribonucleic acid (DNA), chromosomes, and
genes. Create a graphic organizer to show the relationship between these
terms. T / I C
chromosomes
contain
genes
which are
portions of
DNA
molecules
2. List three ways in which chromosomes may vary from species to species.
3. How are the terms gene, locus, and chromosomes related?
4. Each gene carries information related to a specific
K/U
T/I
.
K/U
MAIN IDEA: Each species has a characteristic number of chromosomes per body cell.
Body cells and gemmates (sex cells) have different numbers of chromosomes.
5. Explain the difference between haploid and diploid cells, in terms of
chromosomes. T / I
6. Using the values in Table 1, determine the following
(a) the number of chromosomes in a haploid dog cell.
T/I
(b) the number of pairs of chromosomes in each human body cell.
T/I
Table 1 Chromosome Numbers in Assorted Species
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Species
Chromosome number per body cell
human
46
dog
78
mosquito
6
banana
22
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MAIN IDEA: Asexual reproduction almost always involves cell division and results in
offspring that are genetically identical to their single parent.
7. Fill in Table 2 below to describe asexual reproduction. T / I
Table 2 Asexual Reproduction
Number of parents
Biological advantage(s)
Resulting offspring
8. What are some disadvantages of asexual reproduction?
T/I
MAIN IDEA: Sexual reproduction results in offspring that are genetically variable.
Offspring inherit half of their genetic information from each of two parents.
9. Fill in Table 3 to describe sexual reproduction. T / I
Table 3 Sexual Reproduction
Number of parents
STUDY TIP
Tables
You can use tables to organize
information about the two main types
of reproduction. After the tables are
completed, use them to compare
these processes.
Biological advantage(s)
Resulting offspring
10. Describe a possible scenario in which asexual reproduction might be more
advantageous than sexual reproduction. T / I A
11. How might an organism benefit from being able to reproduce both asexually
and sexually?
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4.1 The Nature of Heredity
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4.2
Asexual Reproduction:
Copies and Clones
Textbook pp. 142–151
Vocabulary
fragmentation
chromatin
cloning
mitosis
sister chromatid
biotechnology
interphase
cytokinesis
genetically modified
organism
MAIN IDEA: Asexual reproduction is the most common form of reproduction among
unicellular organisms and is also widespread among many multicellular organisms—
particularly plants and fungi.
1. Among which species is asexual reproduction relatively rare? Provide a
possible explanation for this. T / I
2. Complete Table 1 by writing a short description of how each organism
undergoes asexual reproduction. K/U
Table 1 Organisms that Undergo Asexual Reproduction
LEARNING TIP
Chromosome Composition
An unduplicated chromosome is
made up of a single DNA molecule
and its associated proteins.
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Type of organism
Mode of asexual reproduction
strawberry plants
(a)
hydrae
(b)
aphids
(c)
fungi
(d)
MAIN IDEA: Cells divide during mitosis and cytokinesis. Cell division produces two
daughter cells that are genetically identical to each other and to the original parent cell.
is the stage of the cell cycle during which the genetic material in
3.
the nucleus is divided equally into new cells. K/U
4.
is the stage of the cell cycle during which the cell cytoplasm is
divided. K/U
5. The mass of thread-like structures composed of DNA and proteins is called
. K/U
6. The replication of chromosomes during interphase results in pairs of
(a) chromatids
(b) chromosomes
(c) sister chromatids
(d) homologous chromosomes K/U
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7. Sister chromatids contain the same
, found at the same
, and are held together by the
. K/U
8. Place the following stages of mitosis in order: anaphase, telophase, metaphase,
and prophase. K/U
(i)
(ii)
(iii)
(iv)
9. Match the stages of mitosis to the sentence that best describes it. K/U
(a) prophase
(i) centromeres divide and chromosomes move to
opposite poles of the cell
(b) anaphase
(ii) the first phase, during which chromosomes shorten
and thicken
(c) telophase
(iii) spindle fibres move and align the chromosomes
(d) metaphase
(iv) chromosomes reach opposite poles of the cell and
begin to unwind
MAIN IDEA: Biotechnology has many applications that are used to benefit society, but
also has potentially negative implications.
. K/U
10. Clones have little or no genetic
11. Compare the genetic makeup of a clone to the genetic makeup of the parent
organism. T / I
12. Write a sentence that explains the role of each of the following organisms in
the cloning of an adult mammal. K/U C
(a) The surrogate mother:
STUDY TIP
Contrasting
Contrasting, or differentiating, two
processes can help you learn about
each of the processes. Use this skill
to learn about the stages of mitosis.
Differentiate each of the stages,
explaining how each differs from
the others.
LEARNING TIP
Differentiation Dead-End
An unfertilized egg cell grows and
differentiates into a specialized cell
with a specific function. Once the cell
has differentiated, it loses its ability
to change into a different kind of cell.
(b) The egg cell donor:
(c) The adult mammal to be cloned:
13. List two problems that tend to develop in mammals produced by cloning.
(i)
K/U
(ii)
14. List three applications of biotechnology.
K/U
15. Identify and describe an advantage of using cloning to produce livestock and
crop plants. K/U
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4.2 Asexual Reproduction: Copies and Clones
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16. Why are cloned plants and animals more vulnerable to changes in the
environment and new diseases than populations that exhibit genetic
variability? T / I A
17. Describe a situation in which the genetic consistency of cloned livestock
organisms is a risk rather than a benefit. Explain your response. T / I A
18. Identify one reason why cloning is used instead of captive breeding in some
situations to increase the population of endangered species. K/U T / I
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4.3
Sexual Reproduction:
Adding Variety
Textbook pp. 152–159
Vocabulary
gamete
meiosis
crossing over
karyotype
fertilization
homologous chromosome
gametogenesis
sex chromosomes
zygote
tetrad
spermatogenesis
autosomes
ova
synapsis
oogenesis
MAIN IDEA: Sexual reproduction produces genetically variable offspring by combining
the genetic information from two parents.
1. Identify and describe the two key processes that occur in sexual reproduction. T / I
2. Fill in Table 1 with what you know about human sex cells.
K/U
Table 1 Human Sex Cells
Reproductive organs that
produce sex cells
Name of sex cell
female
male
MAIN IDEA: During meiosis, diploid cells undergo two cell divisions, resulting in haploid cells.
3. Compare the number of chromosomes in daughter cells produced by mitosis
to the number of daughter cells produced by meiosis. T / I
4. Use a diagram to explain the difference between sister chromatids and
homologous chromosomes. T / I
homologous
chromosomes
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sister
chromatids
4.3 Sexual Reproduction: Adding Variety
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5. Explain why the term “independent assortment” is appropriate to describe
how homologous chromosomes are sorted during meiosis I. T / I
MAIN IDEA: Meiosis I divides homologous chromosomes. Homologous chromosomes
are assorted independently of other pairs.
6. Define the following terms related to meiosis I: K/U
(a) Tetrad:
STUDY TIP
Defining Terms
Defining terms related to a process
can increase your understanding of
the process as a whole. Work with
a partner to review the definition
of each of the vocabulary terms for
this lesson.
(b) Synapsis:
(c) Crossing over:
7. The exchange of chromosomes’ genetic information is known as
, and occurs during
. K/U
8. How does crossing over contribute to genetic diversity? K/U
MAIN IDEA: Meiosis II divides sister chromatids.
9. The formation of genetically variable sex cells in meiosis II is called
. K/U
10. Add the following labels to Figure 1: first meiotic division, first polar body,
oogenesis, ovum, three polar bodies, second meiotic division, spermatogenesis,
sperm cells. K/U
(a)
(b)
chromosome
number
46
23
(c)
23
23
23
23
46
23
23
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(g)
(d)
23
(e)
23
(f)
23
23
23
(h)
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MAIN IDEA: Mammals have X and Y sex chromosomes and use an XX/XY system for
female/male sex determination; however, there are many different sex-determination
systems in living things.
11. Contrast the sex-determination mechanism of mammals with the sexdetermination mechanism of turtles and crocodiles. T / I
12. Figure 1 below represents the sex chromosomes of two individual mammals.
(a) Under each diagram, write the term XX or XY.
K/U
(b) Circle the diagram that represents a male mammal.
Figure 1 Sex chromosomes
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4.3 Sexual Reproduction: Adding Variety
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4.4
Abnormal Meiosis and/or
Fertilization
Textbook pp. 161–166
Vocabulary
non-disjunction
monosomy
Down syndrome
prenatal testing
trisomy
MAIN IDEA: Errors in meiosis can result in abnormal numbers of chromosomes and can
cause serious genetic disorders.
1. When homologous chromosomes fail to separate during meiosis the result is
in daughter cells. K/U
an abnormal number of
2. Fill in Table 1 below by identifying the non-disjunction disorder associated
with each chromosome abnormality. K/U
Table 1 Nondisjunction Disorders
Non-disjunction disorder
Chromosome abnormality
(a)
One X chromosome, no Y chromosome
(b)
Trisomy 21
(c)
Two X chromosomes and one Y chromosome
MAIN IDEA: Karyotypes can be used to evaluate chromosome numbers and diagnose
genetic disorders.
3. What evidence in a karyotype would lead to a diagnosis of Patau
syndrome? K/U
4. Explain why karyotypes are an effective way to diagnose non-disjunction
disorders. T / I
MAIN IDEA: Prenatal testing can be used to determine the likelihood of certain genetic
disorders.
and
are types of prenatal
5.
K/U
testing in which fetal cells are collected and analysed.
6.
is a type of prenatal screening that tests hormone
K/U
levels.
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MAIN IDEA: Assisted reproductive technologies (ARTs) are technologies used to enhance
the chances of reproductive success.
7. Fill in the concept map below to show the relationship between these terms:
artificial insemination, in vitro fertilization, assisted reproductive technologies,
intracytoplasmic sperm injection, and laser-assisted hatching. T / I
Assisted reproductive technologies
include
(a)
STUDY TIP
Concept Maps
You can use a concept map to show
the relationship between concepts
or ideas. In this section, you can
use a concept map to show the
relationship between various assisted
reproductive technologies. Try
making one other concept map that
shows the relationship between other
concepts in this lesson.
(b)
which can be made more successful using
(c)
(d)
MAIN IDEA: There are many applications of reproductive technologies in agriculture,
industry, and wildlife conservation.
8. The use of artificial insemination in wildlife conservation has benefits and
costs. List two benefits and a cost below. K/U
(a) Benefits:
(b) Cost:
MAIN IDEA: The use of many reproductive technologies is highly controversial.
9. Write one or two sentences to support the following statement: “Regardless of
an individual’s position on the moral and ethical implications of reproductive
technologies, it is important to understand the science behind these
technologies.” T / I C A
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4.4 Abnormal Meiosis and/or Fertilization
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4.5
Textbook pp. 167–170
Cytoplasmic Inheritance
Vocabulary
maternal inheritance
paternal inheritance
horizontal gene transfer
MAIN IDEA: Mitochondria and chloroplasts contain genetic material and are able to
reproduce independently within the cytoplasm of the cell.
1. The DNA found in mitochondria and chloroplasts contains the
. K/U
necessary for the proper functioning of the
2. The genes in mitochondria contain information related to the process of
. K/U
3. The genes in chloroplasts contain information related to the process of
. K/U
4. Mitochondria originated as
organisms. K/U
5. Chloroplasts originated as
organisms. K/U
STUDY TIP
Comparing and Contrasting
Comparing and contrasting can help
you learn about the characteristics
of objects and processes. Work with
a partner to compare and contrast
chloroplasts and mitochondria.
MAIN IDEA: The DNA in mitochondria and chloroplasts is usually inherited maternally.
6. Compare and contrast the inheritance of mitochondrial DNA to that of
nuclear DNA. T / I C
7. Define the following terms:
(a) Maternal inheritance:
K/U
(b) Paternal inheritance:
MAIN IDEA: The combination of genetic variation within organelles and the random
assortment of organelles into daughter cells can produce genetic variation within the cells
of individuals.
8. Write a short paragraph that explains genetic variation within organelles, using
plants with variegated leaves as an example. K/U C
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MAIN IDEA: Some observable characteristics and genetic disorders are inherited through
mitochondrial DNA.
9. A genetic disorder related to energy metabolism is likely due to changes in the
. K/U
DNA of the
10. Describe the process of DNA egg swapping, as it relates to mitochondrial
diseases. T / I C
MAIN IDEA: Horizontal gene transfer can result in one organism exhibiting a characteristic
of an entirely different organism.
11. Define the term horizontal gene transfer and give an example. K/U
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4.5 Cytoplasmic Inheritance
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CHAPTER
4
SUMMARY
Heredity and Reproduction
Genetic information is passed from one generation to the next in the process of
reproduction. Information about the processes involved can be used to benefit society
and human health.
Genetic information
is contained in DNA, in
the form of
genes
which are found on
chromosomes
that are passed to of
spring during
reproduction
which can be
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sexual
asexual
which produces
which produces
variable of spring
identical of spring
and requires the
process of
and requires the
process of
which can also
be produced by
meiosis
cell division
(mitosis and
cytokinesis)
biotechnology
(artificial clones)
called
natural clones
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CHAPTER
4
QUESTIONS
For each question, select the best answer from the four alternatives.
1. Which best summarizes the source of genetic information in offspring
produced in the process of sexual reproduction? (4.1) K/U
(a) Genetic information from both parents is present in the offspring.
(b) Genetic information from only the father is present in the offspring.
(c) Completely new genetic information is generated in the offspring.
(d) Genetic information from only the mother is present in the offspring.
2. Cells formed by the process of gametogenesis are (4.3) K/U
(a) diploid
(b) haploid
(c) polyploid
(d) homologous
K/U
T/I
C
A
Knowledge/Understanding
Thinking/Investigation
Communication
Application
Indicate whether each of the statements is true or false. If you think the statement is
false, rewrite it to make it true.
3. A karyotype can be used to determine how many genes an organism has. (4.4)
K/U
4. Multiple marker screening is one type of prenatal testing. (4.5)
K/U
Respond to each statement or answer each question below.
5. Do you think cloning will ever completely replace sexual reproduction as a
means of producing farm animals? Explain why or why not. (4.2) T / I A
6. Explain what would happen if crossing over stopped occurring in a particular
species. (4.3) T / I
7. Define the term non-disjunction, and infer why non-disjunction disorders
typically have drastic effects on phenotype. (4.4) T / I
8. Contrast the inheritance of nuclear genetic material and cytoplasmic genetic
material during human reproduction, and explain why this difference is
significant. (4.4, 4.5) T / I
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Chapter 4 Questions
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Complete the following graphic organizers.
9. Complete the following comparison matrix to compare asexual reproduction
and sexual reproduction. (4.1, 4.2, 4.3) T / I C A
Asexual reproduction
Sexual reproduction
Number of parents
Key cellular process
Result
Biological advantage
Biological disadvantage
10. Sequence and describe the phases of mitosis in the following flow chart. (4.2)
T/I
C
A
(a)
(b)
S
(c)
S
(d)
S
11. In the space below, make a Venn diagram below that compares the processes
of meiosis and mitosis. (4.1, 4.2, 4.3) T / I C A
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5.1
Mendelian Inheritance
Vocabulary
trait
F1 generation
allele
dominant allele
true-breeding organism
monohybrid
homozygous
recessive allele
hybrid
monohybrid cross
heterozygous
Punnett square
cross
F2 generation
genotype
probability
P generation
law of segregation
phenotype
test cross
MAIN IDEA: Gregor Mendel was the first person to record and quantify the inheritance
of traits in an organism over many generations. He did this through the selective crossbreeding of common pea plants (Pisum sativum). His experiments laid the groundwork for
modern day genetics.
1. Why did Mendel select the pea plant for his experiments? Give three
characteristics of the pea plant that make it ideal for crosses.
2. Explain the significance of Mendel’s use of true-breeding plants in his
experiments.
Textbook pp. 184–193
LEARNING TIP
Characteristic or Trait
Do not confuse the terms
“characteristic” and “trait.” Traits
represent the variation within a
characteristic. For example, height is
a characteristic, while short and tall
are traits; sight is a characteristic,
while normal vision, nearsightedness, and far-sightedness
are traits.
3. Explain how the characteristics that Mendel chose to study aided his study of
the inheritance of traits.
4. Define “monohybrid cross” and explain its significance in experiments that
study the inheritance of traits.
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5.1 Mendelian Inheritance
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MAIN IDEA: Mendel’s data revealed patterns of inheritance.
Table 1 Mendel’s Data
Characteristics
P
F1
F2
Ratio
seed shape
round × wrinkled
all round
5474 round
1850 wrinkled
2.96 : 1
seed colour
yellow × green
all yellow
6022 yellow
2001 green
3.01 : 1
pod shape
inflated × constricted
all inflated
882 inflated
299 constricted
2.95 : 1
pod colour
green × yellow
all green
428 green
152 yellow
2.82 : 1
flower colour
purple × white
all purple
705 purple
224 white
3.15 : 1
flower position
axial × terminal
all axial
651 axial
207 terminal
3.14 : 1
stem length
tall × dwarf
all tall
787 tall
277 dwarf
2.84 : 1
5. (a) Write a sentence that summarizes the mathematical pattern in Mendel’s
data for the F1 generation (Table 1).
(b) Write a sentence that summarizes the mathematical pattern in Mendel’s
data for the F2 generation (Table 1). T / I C
6. (a) What were Mendel’s two main conclusions about how traits are passed
from one generation to the next?
(b) What is the formal name used to describe Mendel’s two conclusions?
LEARNING TIP
Dominance
In genetics, dominance refers only
to which gene is expressed in an
organism. It does not mean that
the dominant allele is stronger,
better, or more common than the
recessive allele.
K/U
MAIN IDEA: Genes have alternate forms called alleles.
is any of the alternate forms of a gene that may occur at a
7. A(n)
specific locus. K/U
8. Cells have two alleles for each gene, one from each parent. If the two alleles
for that
for a particular gene are the same, the individual is
allele. If the two alleles for a particular gene are different, the individual is
for that allele. K/U
MAIN IDEA: Genes influence traits.
9. The set of alleles an individual has, or its genetic makeup, is known as its
. K/U
10. An individual’s outward appearance with respect to a specific characteristic is
. K/U
its
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11. Some alleles are dominant, while others are recessive.
are always expressed in the phenotype, whereas
show up unless they are the only allele present in the genotype.
alleles
alleles do not
K/U
Use Figure 1 to answer questions 12 and 13.
TT
Tt
tt
Figure 1
12. Based on the information in Figure 1, which allele for plant height is
dominant? T / I
13. Circle any plant or plants shown in Figure 1 that are homozygous. Cross out
any plant or plants that are heterozygous. K/U
14. Explain how two different genotypes may result in the same phenotype.
K/U
MAIN IDEA: A Punnett square is a diagram used to predict the proportions of genotypes
in the offspring resulting from a cross between two individuals.
15. (a) What does the information on each axis of a Punnett square represent?
(b) What does the information inside a Punnett square represent?
K/U
16. In pea plants, the trait of axial flowers, A, is dominant, and the trait of terminal
flowers, a, is recessive. Draw a Punnett square in the space below that shows a
cross between two pea plants heterozygous for the trait of flower position. The
genotype of each parent plant is Aa. T / I C
A
a
A
AA
Aa
a
Aa
aa
STUDY TIP
Punnett Square
A Punnet square can be used to
predict the inheritance of alleles.
Use a Punnett square when you are
asked to find the possible genotypes
of offspring that result from a cross.
Explain how a test cross can be used to determine the genotype of an unknown
parent. K/U
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5.1 Mendelian Inheritance
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5.2
Textbook pp. 194–196
LEARNING TIP
Notation of Alleles
Notation of alleles for a specific
gene can be represented using
superscripts. For example, consider
the alleles for colour in snapdragons.
The gene is C for colour. The alleles
are red (R ) and white (W ). When you
combine the notations for genes and
alleles, the result is CR for the red
allele and CW for the white allele.
LEARNING TIP
Notation of Alleles in Incomplete
Dominance
In incomplete dominance, alleles are
neither dominant nor recessive. In
this situation, uppercase letters with
superscripts are used to represent
different alleles.
Variations in Heredity
Vocabulary
complete dominance
incomplete dominance
codominance
MAIN IDEA: Alleles that determine the phenotype regardless of the presence of other
alleles follow a pattern of inheritance called complete dominance.
1. Mendel’s experiments involved crossing homozygous dominant plants with
homozygous recessive plants. In these crosses, only one allele is expressed
in the phenotype despite the presence of the other allele. This pattern of
. K/U
inheritance called
2. Use your knowledge of complete dominance to explain why individuals who
are heterozygous and those that are homozygous for the dominant allele can
have different genotypes but the same phenotype. T / I A
MAIN IDEA: Not all traits are inherited in simple patterns such as complete dominance.
Variations in the patterns of heredity exist, and dominance is not always complete.
occurs when neither allele dominates the
3.
other and both exercise an influence on the phenotype, resulting in partial
expression of both traits. K/U
4. The snapdragon is an organism that displays incomplete dominance for
flower colour. Complete Table 1 by recording the flower colour, or phenotype,
associated with each genotype. K/U
Table 1 Snapdragon Genotypes and Phenotypes
Genotype
Phenotype
CRCR
CRCw
CwCw
5. Consider a cross between two pink-flowering snapdragons. What percentage
T/I
of the offspring will have pink flowers?
6. Consider a cross between a red snapdragon and a white snapdragon. What
T/I
percentage of the offspring will have pink flowers?
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MAIN IDEA: Codominance occurs when both alleles are fully expressed, producing
offspring with a third genotype.
7. Type AB blood is an example of codominance. Draw a Punnett square to
show a cross between an individual with type A blood (genotype IAi) and an
individual with type B blood (genotype IBi). Circle any offspring that will have
type AB blood. T / I A
IA
i
I Bi
IB
I Ai
i
ii
MAIN IDEA: Blood type is an example of a gene with multiple alleles. The three blood
type alleles are I A, I B, and i. Different combinations of the three alleles produce type A,
type B, type AB, and type O blood.
8. (a) Fill in the missing information in Table 2 below to reinforce what you
know about human blood types. T / I
Table 2 Human Blood Types
Genotype
Blood type
IAIA
A
IAi
Able to receive blood from
Able to donate blood to
STUDY TIP
Charts and Tables
Charts and tables are an effective
way to organize information. Create
a graphic organizer to differentiate
between complete dominance,
incomplete dominance, and
codominance.
A, AB
A
IBIB
IBi
IAIB
B
AB
ii
(b) Which blood type is known as the universal donor? Why?
(c) Which blood type is known as the universal recipient? Why?
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K/U
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5.2 Variations in Heredity
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5.3
Pedigrees−Tracking Inheritance
Vocabulary
Textbook pp. 197–201
pedigree
sex-linked
X-linked
Y-linked
autosomal inheritance
STUDY TIP
Pedigree Chart Symbols
You can use a pedigree chart to
track the inheritance of traits through
generations of a family. With a
partner, use flashcards to review the
symbols used on pedigree charts.
MAIN IDEA: A pedigree chart traces the inheritance of a trait among members of a family.
It shows the connections between parents and offspring, the sex of individuals in each
generation, and the presence or absence of a trait.
1. Use the terms in the box below to label the pedigree symbols below. K/U
affected female
affected male
fraternal twins
identical twins
normal female
normal male
mating
siblings
(a)
(c)
(e)
(g)
(b)
(d)
(f)
(h)
2. Draw a pedigree chart for the following: A man and a woman are both
heterozygous for a recessive genetic disorder. They have three children: an
unaffected female, an unaffected male, and an affected female. The affected
female and a man who is heterozygous for the disorder have male fraternal
twins who are both affected. T / I A
3. Describe how phenotypes can be used to predict genotypes in a pedigree.
MAIN IDEA: The expression of genes on the sex chromosomes differs from the expression
of autosomal genes.
4. If an allele is located on an autosome, or a non-sex chromosome, it is
inheritance. K/U
transmitted through
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5. In autosomal inheritance, males and females are affected at
rates. K/U
6. Identify the two human chromosomes on which an autosomal allele could not
be located. K/U
7. Sex-linked inheritance occurs when a
allele on the X or Y
chromosome of the parent is passed on to the offspring. K/U
8. Red-green colour blindness is an example of X-linked inheritance. A woman
who is an unaffected carrier of red-green colour blindness and a man who
has normal vision are expecting a child. Draw a Punnett square to show the
possible genotypes of their offspring. Use XR to represent the normal allele and
Xr to represent the allele for red-green colour blindness. T / I
XR
Xr
XR
XRXR
XRXr
Y
XRY
XrY
9. Use the information in the completed Punnett square from question 8 to
answer the following questions. T / I A
(a) In what percentage of male offspring would you expect to have red-green
colour blindness?
(b) What percentage of female offspring would you expect to be unaffected
carriers of red-green colour blindness?
(c) How does the expression of the red-green colour blindness trait differ
between male offspring and female offspring?
10. Can a male be an unaffected carrier of a recessive X-linked trait? Explain.
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T/I
A
5.3 Pedigrees−Tracking Inheritance
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5.4
Textbook pp. 202–203
STUDY TIP
Mind Maps
You can use a mind map to organize
information found in a reading
passage. In this case, the mind map
helps collect and organize the main
ideas found throughout the reading
selection.
Biology Journal: The Gene Hunters
MAIN IDEA: The gene for Huntington’s disease has been located through extensive
research. Research continues as scientists seek a way to prevent or cure this disease.
1. Use the mind map below to take notes about Huntington’s disease and the
search for the Huntington’s disease gene. K/U C
Symptoms:
Tools and Techniques Used
in Research:
Huntington’s disease
Mode of Inheritance:
Location of Marker:
2. People from all walks of life can make contributions to science. Explain why
the hunt for the gene that causes Huntington’s disease is an example of this
fact. T / I A
3. Scientific inquiry involves questioning, researching, identifying and controlling
variables, hypothesizing, predicting, planning, performing and recording,
observing, analyzing, evaluating, and communicating. How did Dr. Nancy
Wexler’s work fit this pattern? Use examples to justify your answer. T / I A
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5.5
Genetic Disorders
Vocabulary
mutation
carrier testing
genetic screening
phenylketonuria (PKU)
Textbook pp. 204–207
MAIN IDEA: Many human disorders have a genetic component.
. K/U
1. A change in the genetic code of an allele is called a
2. Which of the following disorders is not caused by a gene mutation? K/U
(a) Huntington’s disease
(b) phenylketonuria
(c) asthma
(d) hemophilia
3. Indicate whether the following statement is true or false. If you think the
statement is false, rewrite it to make it true: Cystic fibrosis is passed on
through a dominant mutated gene. K/U
4. Complete the Punnett square below to show the possible offspring of an
unaffected male carrier of cystic fibrosis and a female with two normal alleles.
Use F for the normal allele and f for the cystic fibrosis allele. T / I
F
F
F
STUDY TIP
Punnett Squares
You can use a Punnett square to
predict the proportions of genotypes
in the offspring resulting from a cross
between two individuals. Practise
using a Punnett square for various
crosses, including the one shown in
question 4.
f
(a) What percentage of the possible offspring do not carry an allele for cystic
fibrosis?
(b) What percentage of the possible offspring are unaffected carriers of a cystic
fibrosis allele?
(c) What percentage of the possible offspring will have cystic fibrosis?
5. Would your answers to question 4 differ if the female was a healthy carrier
of the cystic fibrosis allele and the male had two normal alleles? Explain your
response. T / I A
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5.5 Genetic Disorders
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MAIN IDEA: Genetic screening is used to detect mutated genes that cause genetic
disorders.
6. Genetic screening is used to identify the presence of a defective allele that
leads to a genetic disorder. Explain how a genetic counsellor might use a
pedigree chart in addition to DNA testing in order to diagnose a genetic
disorder. T / I
7. Explain how genetic screening can be used to predict the severity of cystic
fibrosis symptoms an affected individual will have. T / I
8. Explain how a mutation in BRCA1 or BRCA2 can lead to the development of
cancer. T / I A
MAIN IDEA: Newborn genetic screening is now used to identify the presence or absence
of defective genes in many countries, including Canada.
List three specific disorders that are part of Ontario’s newborn screening program. K/U
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5.6
Explore an Issue
in Genetic Screening
Textbook pp.208–209
MAIN IDEA: Genetic testing has many benefits, but the use and ownership of the results
has raised many ethical and legal issues.
1. Legal access to and ownership of genetic information are topics that will
become increasingly important as the ability to test for specific genes and
disorders increases. In the chart below, add facts and opinions related to each
of the listed questions. When you have completed the chart, you can review
the information you have recorded to help you form guidelines about these
important issues. C A
Question
Who makes
decisions about
access to genetic
information?
Who should have
access to an
individual’s genetic
information?
Facts and opinions
STUDY TIP
Organizing Facts and Opinions for
Discussion
Charts can be used to organize
information related to complex
issues. In this chart, you should
record your thoughts and opinions
about each of the questions listed.
Then, you can use this information in
group discussions.
LEARNING TIP
Making Decisions as a Group
Before you come to a decision as
a group, make a list on chart paper
of pros and cons for the question at
hand. Place the chart paper where
all group members can see and have
access to it. This can be helpful in
forming new thoughts and ideas
about the discussion at hand. During
a brainstorming session like this one,
take an accepting attitude of all the
ideas presented to the group. Wait until
the page is full to critique the ideas.
Should an individual
ever be required by
law to share genetic
information?
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5.6 Explore an Issue in Genetic Screening
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5.7
Textbook pp. 210–214
LEARNING TIP
Gene Order
When completing the Punnett square
for a dihybrid cross, keep the genes
in alphabetical order and write the
dominant alleles (capital letters) first,
for example, TtPp.
Multi-trait Inheritance
Vocabulary
dihybrid cross
product law
law of independent
assortment
discontinuous
variation
continuous
variation
additive allele
MAIN IDEA: A dihybrid cross involves two traits.
1. A dihybrid cross involves a cross between two individuals who differ in two
.
pairs of
2. Mendel performed dihybrid crosses in plants that were true-breeding for two
traits. For example, a plant that had yellow seed colour and round seed shape
was crossed with a plant that had green seed colour and wrinkled pod shape.
In this cross, the traits for yellow seed colour (YY) and round pod shape
(RR) are dominant. Green seed colour (yy) and wrinkled pod shape (rr) are
recessive. T / I C
(a) Draw a Punnett square to show the genotypes of the resulting offspring.
RY
Ry
rY
ry
RY
RrYy
RrYy
RrYy
RrYy
Ry
RrYy
RrYy
RrYy
RrYy
rY
RrYy
RrYy
RrYy
RrYy
ry
RrYy
RrYy
RrYy
RrYy
(b) If the F1 generation was then crossed, what would be the resulting
genotype ratio of the F2 generation?
3. Mendel crossed numerous heterozygous F1 generation plants. What did
his experiments reveal to him about the inheritance of traits? Explain your
reasoning. T / I
STUDY TIP
Developing Explanations
Diagrams can be used to visualize
concepts and ideas. In this case, a
Punnett square is used to show how
alleles assort independently. Using
your completed diagram, explain this
concept to a friend.
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Unit 2 • Genetic Processes
Bio11SG_U2Ch05_P01.indd 28
MAIN IDEA: Mendel’s law of independent assortment states that alleles of different
genes separate into gametes independently of one another.
4. In pea plants, the allele for the trait of tall plants (T) is dominant; the allele for
dwarf plants is recessive (t). The allele for purple flowers (P) is dominant; the
allele for white flowers (p) is recessive. Complete the Punnett square below
(Figure 1) to show the dihybrid cross between two pea plants, both of which
are heterozygous for these traits. T / I
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TP
Tp
tP
tp
TP
Tp
tP
tp
Figure 1
5. Fill in Table 1 below to show the ratio of the phenotypes of the offspring in the
dihybrid cross in question 4. A
Table 1 Phenotypic Ratios
Number of
offspring
(a)
9
tall plants, white flowers
(b)
(c)
Phenotype
3
LEARNING TIP
Sample Size
Note that Mendel observed these
ratios only because of his large
sample size. He crossed hundreds
of plants, producing thousands of
offspring. As sample size increases,
the closer the experimental (actual)
probability gets to theoretical
probability.
(d)
6. An individual is heterozygous for two traits. His genotype for those traits is
BbGg. In Figure 2 below, show the four possible gametes this individual can
produce. T / I A
BbGg
Figure 2
MAIN IDEA: Genetic ratios are probabilities.
7. The probability of two independent events both occurring may be calculated
.
using the
8. To calculate the probability of two independent events both occurring,
.
multiply their individual
9. In a dihybrid cross, either a Punnett square or the probability law can be used
to determine the likelihood of a particular outcome. Compare the predicted
probabilities using each of these methods. T / I
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5.7 Multi-trait Inheritance
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MAIN IDEA: Variation in the expression of genes can be described as either continuous
or discontinuous.
variation occurs when a trait is either expressed or is not
10.
variation occurs
expressed (i.e. there is no in-between trait).
in nature when the expression of a characteristic is a sum of the expression of
all alleles involved. K/U
11. Classify the pea plant traits studied by Mendel as continuous or discontinuous.
Write a sentence to justify your classification. T / I
12. Identify a human trait that exhibits continuous variation.
13. Define the term “additive allele.”
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K/U
K/U
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CHAPTER
5
SUMMARY
Mendelian Genetics—Patterns of Inheritance
Gregor Mendel
is known as the “Father of Genetics” because of his study of the inheritance of certain tratis in pea plants.
Mendel showed that the inheritance of these traits follows particular laws.
law of segregation
law of independent assortment
based on the conclusions that
which states
for each characteristic,
an organism carries two genes:
one from each parent
parent organisms donate only one copy
of each gene in their gametes.
During meiosis, the two copies of each
gene separate, or segregate
if genes are located on separate
chromosomes, they will be inherited
independently of one another
Punnett squares
Patterns of inheritance
can be tracked and
predicted using tools
such as
include
complete
dominance
incomplete
dominance
codominance
which occurs
when
which occurs
when
which occurs
when
one allele determines
the phenotype,
regardless of the
presence of another
allele
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pedigree charts
neither allele dominates
the other; both exercise
an influence on the
individual, resulting in
partial expression of
both traits
both alleles are
expressed fully,
resulting in offspring
with a third phenotype
Chapter 5 Summary
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CHAPTER
K/U
T/I
C
A
5
QUESTIONS
Knowledge/Understanding
Thinking/Investigation
Communication
Application
For each question, select the best answer from the four alternatives.
1. Which of the following statements is one of the conclusions that forms the law
of segregation? (5.1) K/U
(a) Each parent passes on only one of its two alleles for each gene.
(b) Dominant alleles, if present, are always passed on.
(c) The frequency of genotypes among offspring is random and cannot be
predicted.
(d) Individuals have a single, segregated allele for each gene.
2. An individual with the genotype IAi has type A blood. What do this particular
genotype and phenotype demonstrate? (5.2) K/U
(a) compatible dominance
(b) codominance
(c) complete dominance
(d) incomplete dominance
Indicate whether each of the statements is true or false. If you think the statement
is false, rewrite it to make it true.
3. A diagram used to show the inheritance of a trait through generations of a
family is called a Punnett square. (5.3) K/U
4. Nancy Wexler is a scientist who investigated the cause of phenylketonuria. (5.4)
K/U
Respond to each statement or answer each question below.
5. An individual with type AB blood marries an individual with type O blood.
Is it possible for their offspring to have the same blood type as either parent?
Explain your response. (5.2) T / I A
6. Describe the symptoms of cystic fibrosis. Then, classify the allele that causes
the disorder as dominant or recessive and state whether it is autosomal or
X-linked. (5.5) K/U T / I
7. Identify one ethical issue related to genetic screening. Then, write a sentence
that summarizes your opinion on this issue. (5.6) T / I A
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8. Compare and contrast discontinuous and continuous variation. Identify one
way they are similar and one way they are different. (5.7) T / I
9. In humans, the allele M codes for melanin, and the allele m does not.
Individuals with the genotype mm have albinism. Draw a Punnett square to
show a cross between two individuals who are heterozygous for this trait and
circle any possible offspring who will have albinism. (5.1) T / I C
M
m
M
MM
Mm
m
Mm
mm
10. Fill in Table 1 below to compare codominance, complete dominance, and
incomplete dominance. (5.2) T / I C
Table 1
Codominance
Complete dominance
Incomplete dominance
Number of
alleles present
Number of
alleles that
affect phenotype
Phenotype of
heterozygote
11. Draw a pedigree chart to show the following: A man with an autosomal
recessive disorder and a woman who does not carry the allele for this disorder
have three children: a son, a daughter, and another son. None of the children
have the disorder. The youngest son and a woman who is an unaffected
carrier of this disorder have two daughters. Both of their daughters have the
disorder. (5.3) T / I C A
I
1
2
II
1
2
3
4
5
6
III
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Chapter 5 Questions
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6.1
DNA and the Code of Life
Vocabulary
nuclein
X-ray crystallography
scientific model
complementary base pairing
Textbook pp. 228–233
nucleotide
MAIN IDEA: Many scientists have contributed to the discovery of deoxyribonucleic acid
(DNA) as the molecule that stores and transmits genetic information from parent(s) to
offspring.
1. Fill in Table 1 to keep track of the experiments discussed in this section.
Explain how each experiment contributed to the discovery of DNA as genetic
material. K/U
Table 1
Scientist
Contribution
Miesher
(a)
Hammerling
(b)
Hershey and Chase
(c)
Levene
(d)
Watson and Crick
(e)
2. What evidence was there that genetic material is contained in the nucleus?
3. How did Hershey and Chase prove that DNA was hereditary material?
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6.1 DNA and the Code of Life
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STUDY TIP
Diagrams
You can use diagrams to learn about
the structure of biological molecules.
Start a visual glossary for terms in
this chapter that can be diagrammed.
For each, write the term and draw a
diagram. At the end of the chapter,
use your visual glossary for review.
MAIN IDEA: DNA is composed of four types of nucleotides. Each nucleotide consists of a
sugar, a phosphate group, and a nitrogenous base.
4. Figure 1 below shows a nucleotide. Label the following components:
deoxyribose sugar, nitrogenous base, and phosphate group K/U
(c)
O
(a)
HN
O
O–
LEARNING TIP
DNA Twist
DNA exists as a right-handed double
helix as a well as a left-handed
double helix. The two types of helix
are mirror images of each other.
Watson and Crick built a model of a
right-handed helix.
O
P
O
O
–
C
C
N
C
CH3
CH
CH2OH O
HC
CH
CH
CH
OH
H
(b)
Figure 1
5. What is the only difference among the four nucleotides?
K/U
6. List the four possible nitrogenous bases that are found in the nucleotides of
DNA. K/U
7. Describe the relationship among the nitrogenous bases in DNA that was
discovered by Chargaff. K/U
MAIN IDEA: James Watson and Francis Crick determined the structure of the DNA
molecule.
8. DNA consists of
strands that run in
directions. Each strand is made up of alternating
and
molecules with nitrogenous bases attached to the
backbone.
9. Define the term X-ray crystallography, and describe the role this
technique played in the development of Watson and Crick’s model of DNA
structure. T/I C
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10. Identify at least one discovery by other scientists that Watson and Crick
accounted for when developing their own model of DNA. T/I
MAIN IDEA: Nucleotides always pair in the same way.
11. Define the term complementary base pairing. K/U
12. Identify the complementary base pairs in DNA.
K/U
13. The sequence of a piece of DNA is GATCTCGA. What is the complementary
base sequence? T/I A
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6.1 DNA and the Code of Life
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6.2
Textbook pp. 234–239
Mutations
Vocabulary
point mutation
chromosome
mutation
spontaneous
mutation
antibiotic resistant
transposition
transposon
microarray
induced mutation
MAIN IDEA: A mutation is a change in the genetic code of an allele. Some mutations
affect sequences of DNA in a gene, whereas others affect an entire chromosome.
1. Compare and contrast point mutations and chromosomal mutations. T/I
2. (a) In Table 1, describe what happens in each type of point mutation.
K/U
Table 1 Point Mutations
Type of point mutation
Description
base-pair substitution
insertion
deletion
(b) What are the similarities and differences among the three types of point
mutations? T/I
3. A sequence of DNA is shown below. Show how each of the following types of
mutations would affect the sequence by rewriting a sequence to include the
mutation. For each answer, use an arrow to point out the mutation. T/I A
GCGTTACGGC
(a) Base-pair substitution:
(b) Insertion:
(c) Deletion:
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4. All the mutations you modelled in Question 3 changed the sequence of
bases read by ribosomes in the cell. What is the effect of changing the DNA
sequence that the ribosomes read? T/I
5. Why aren’t mutations in body cells passed on to offspring?
T/I
A
MAIN IDEA: Mutations are caused by several factors.
6. A mutation that occurs randomly and is not due to any outside factors is called
mutation. K/U
a(n)
7. A mutation that is the result of exposure to a physical or chemical agent is
mutation. K/U
called a(n)
8. What are two chemical or physical factors that can cause mutations? K/U
MAIN IDEA: Mutations can be helpful, harmful, or have no effect on organisms.
9. Explain why lactose tolerance can be described as a beneficial mutation.
T/I
10. Identify a factor that can cause the proportion of lactose tolerant and
intolerant individuals in a population to vary from one location to another.
T/I
MAIN IDEA: Bacteria have developed antibiotic resistance due to mutations, including
those in the gene that directs the shapes of cell wall building-block molecules.
11. Explain why a mutation that affects a bacterium’s cell wall structure might
confer antibiotic resistance to the bacterium. T/I
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STUDY TIP
Main Idea Webs
You can use a main idea web to
organize facts about a topic. After you
have completed the main idea web
for question 12, choose another topic
in the chapter, and create another
main idea web for that topic.
6.2 Mutations
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MAIN IDEA: Transposons are sequences of DNA that can move along and between
chromosomes, possibly causing a change in an organism’s phenotype.
12. Fill in the main idea web with information about transposons. K/U T/I
Are defined as:
(a)
Move in a process called:
(b)
Transposons
Were studied by:
(c)
Can cause diseases such as:
(d)
13. What characteristic makes corn an ideal organism in which to study
transposons? T/I A
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6.3
Genomes
Vocabulary
Human Genome
Project (HGP)
coding DNA
functional genomics
DNA bank
non-coding DNA
model organism
DNA fingerprinting
Textbook pp. 240–244
human genome
MAIN IDEA: The Human Genome Project has successfully sequenced the 3 billion base
pairs in the human genome. Different genomes contain different numbers of genes. The
human genome contains approximately 20 000 genes.
1. (a) When the Human Genome Project was launched in 1990, what was its
goal? K/U
(b) When was this goal achieved?
K/U
2. Compare and contrast coding DNA and non-coding DNA. Identify one way
they are similar and one way they are different. T/I
3. Sort the following organisms into Table 1 below: mouse, E.coli bacterium, fruit
fly, Asian rice, yeast. K/U
Table 1 Number of Genes Present in Different Genomes
Organisms with fewer genes than
humans have
Organisms with more genes than
humans have
(a)
(b)
STUDY TIP
Tables
A table can be used to organize
information into categories. Try using
a table to organize other information
presented in this lesson.
MAIN IDEA: Information gathered about genes and their functions is known as functional
genomics.
4. Explain why mice are good model organisms for studies of human genetic s.
Use an example to illustrate your reasoning.
5. Define the term model organism:
K/U
MAIN IDEA: DNA fingerprinting and DNA banks allow DNA to be used for identification
and other purposes.
6. Explain the reasoning behind the storage of the DNA of extinct species, even
though current technology does not allow extinct species to be restored using
this DNA. T/I A
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6.3 Genomes
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7. Using the information in Figure 1 below, explain why police would eliminate
suspect 2 from suspicion for this crime. T/I A
1:
DNA PROFILE OF THE TECHNICIAN PREPARING THE DNA
FINGERPRINT, ADDED AS ANOTHER INTERNAL REFERENCE
2:
DNA PROFILE OF THE VICTIM
3:
DNA PROFILE OF SUSPECT 1
4:
DNA PROFILE OF SUSPECT 2
5:
DNA PROFILE OF FORENSIC SAMPLE TAKEN FROM
THE VICTIM
Figure 1
8. Describe one way in which DNA evidence is used in fish and wildlife
enforcement. T/I A
9. List four ways that the information in Canada’s DNA data bank can be used by
law enforcement officials. K/U
(i)
(ii)
(iii)
(iv)
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Manipulating the Genome
Vocabulary
restriction enzyme
Textbook pp. 245–248
recombinant DNA
MAIN IDEA: Restriction enzymes are used to cut DNA so that genomes can be
manipulated.
1. Fill in the flow chart below with the following sentences to give an overview of
the process of moving a gene from the genome of one organism to the genome
of another organism. K/U
• Bacteria containing the plasmid are added to the same environment as the
target organism.
• The gene for the desired trait is inserted into the plasmid.
• The plasmid containing the inserted gene enters bacteria cells in culture.
A gene for a desired
trait is cut from an
organisms genome.
6.4
A plasmid is cut
with a restriction
enzyme.
STUDY TIP
Flow Charts
You can use a flow chart to learn
about the steps in a process. After
you have completed this flow chart,
review the steps of this process with
a partner.
(a)
(b)
(c)
The plasmid in the bacteria enters the target
organism and the gene for the desired trait is
incorporated into its genome.
2. In the DNA sequence below, draw lines to show how BamH1 will cut the
DNA. A
AGAGTTCTGGTACAGGATCCGATCTGTCA
TCTCAAGACCATGTCCTAGGCTAGACAGT
MAIN IDEA: New genes can be added to an organism’s DNA.
3. What are plasmids, and how are they used in manipulating genomes?
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6.4 Manipulating the Genome
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4. In the process of genetic engineering, why is the ability to enter and exit
bacterial cells a useful property of plasmids? T/I A
5. A fragment of DNA consisting of nucleotide sequences from at least two
. K/U
different sources is called
MAIN IDEA: The agriculture, health, and manufacturing industries use recombinant DNA
technology to increase disease resistance in crops, to improve nutrition in foods, and to
develop useful products.
6. The goals of using recombinant DNA technology in food production are to
enhance nutritional value, make food less susceptible to rotting, and to make
crops resistant to pests and herbicides.
(a) Do these goals differ from the goals of food production in the past? K/U
(b) How does recombinant DNA technology change the time frame needed to
achieve these goals? Explain. K/U
7. List two potential applications of spider silk protein produced using
recombinant DNA technology. K/U
8. Explain how the use of Bt corn can affect the amount pollution related to corn
production. T/I
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6.5
Gene Therapy
Vocabulary
gene therapy
target cell
Textbook pp. 249–251
vector
MAIN IDEA: Gene therapy is the replacement of a defective or missing gene, or the addition of a new gene into a person’s genome.
1. Explain the role of target cells, vectors, and viruses in gene therapy. T/I
2. (a) Explain why plasmids cannot be used in gene therapy in humans.
(b) Explain why viruses are good vectors for gene therapy.
T/I
3. Draw a flow chart that summarizes the basic process of gene therapy in three
steps. K/U
(a)
(b)
(c)
MAIN IDEA: There are both minor and major drawbacks to gene therapy.
5. In your own words, identify and describe five obstacles that gene therapy must
overcome to be an effective treatment for human disease. K/U
(i)
(ii)
(iii)
STUDY TIP
Restating in Your Own Words
Restating concepts in your own
words is a good way to test your
understanding of the concepts. Try
restating several of the concepts
from this lesson in your own words.
Any that you cannot restate might
require additional study.
(iv)
(v)
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6.5 Gene Therapy
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MAIN IDEA: Genetics provides new alternatives for the medical treatment of genetic
disorders.
6. Gene therapy has shown promise in the treatment of which of the following? K/U
(a) inherited blindness
(b) Duchenne muscular dystrophy
(c) deafness
(d) all of the above
7. Explain the role and significance of each as it relates to gene therapy.
(a) restriction enzymes
T/I
(b) recombinant DNA
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6.6
Explore Applications in Genetics
MAIN IDEA: Advances in our understanding of genetics and related genetic engineering
technologies are providing entirely new tools for the diagnosis, treatment, and prevention
of diseases.
1. Choose two of the four technologies listed below. For each of your chosen
technologies, create a fishbone diagram to show the potential applications and
risks associated with the technology, as well as the current status and media
status of the technology. T/I
• transgenic model organisms
• gene therapy
• therapeutic cloning
• animal and plant “pharming”
potential
applications
potential risks
current status
media status
Technology:
Textbook pp.252–253
STUDY TIP
Fishbone Diagrams
You can use a fishbone diagram to
organize important ideas about a
topic. When you make a fishbone
diagram, identify four categories into
which your ideas can be organized.
What other categories could be
used on the fishbone diagram on
this page?
2. What two questions do you feel are most important in deciding whether the
government should spend money researching a genetic technology? Explain
your choices. T/I A C
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6.6 Explore Applications in Genetics
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CHAPTER
6
SUMMARY
Genetics Beyond Mendel
Genetic information
is stored and transmitted in
Errors that occur in the
sequence of DNA can affect
DNA
Consists of repeating units
called nucleotides, which are
each made up of
a nitrogenous
base
a pentose
sugar
sequences of DNA
in a gene, and are
called point
mutations
a phosphate
group
DNA
14
both of which can cause
can be used for identification
in the process of
can be manipulated
in the process of
DNA
fingerprinting
genetic
engineering
Unit 2 • Genetic Processes
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an entire
chromosome,
and are called
chromosomal
mutations
genetic disorders
that may or may not
affect phenotype
in
which
restriction
enzymes
are used
to make
recombinant
DNA
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CHAPTER
6
QUESTIONS
For each question, select the best answer from the four alternatives.
1. In a sample of double-stranded chimpanzee DNA, 36% of the bases are
thymine. What percentage of the bases in this sample are cytosine? (6.1)
(a) 14%
(b) 28%
(c) 36%
(d) 72%
K/U
T/I
C
K/U
A
Knowledge/Understanding
Thinking/Investigation
Communication
Application
2. A sequence of DNA is GACCTGAA. Which of the following could represent
what the sequence would be after undergoing a base-pair substitution? (6.2) K/U
(a) GACCGAA
(b) GACGTGAA
(c) GACCTTGAA
(d) AAGTCCAG
Indicate whether each of the following statements is true or false. If you think the
statement is false, rewrite it to make it true.
3. Most of the DNA in the human genome is “coding DNA.” (6.3)
4. Restriction enzymes cut DNA at specific sites. (6.4)
K/U
K/U
Respond to each statement or answer each question below.
5. Identify a human disease that is caused by an induced mutation, explain why
the mutation is classified as induced, and name the physical or chemical agent
that induces the mutation. (6.2) T/I
6.
Explain how the type of virus used as a vector for human gene therapy for a
particular disease is selected. (6.5) T/I
7.
Identify and describe one current or next-generation genetic technology that is
used in medical treatments. (6.6) T/I
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Chapter 6 Questions
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Complete the following graphic organizers.
8.
Fill in the main idea web to describe DNA. (6.1)
Has the following three
components:
(a)
T/I
Has a structure known as:
(b)
DNA
Was modelled by:
(c)
9.
Functions in living things:
(d)
In the space below, create a Venn diagram that compares point mutations
and chromosomal mutations. Add the following phrases to the correct
sections of your Venn diagram: large-scale change, small-scale change, can
cause disorders, caused by non-disjunction. Include at least one example for
each. (6.2) T/I C
10. Complete the following comparison matrix to compare mutations in
autosomes to mutations in gametes. (6.2) T/I C
Mutations in
Autosomes
Mutations in
Gametes
Passed to offspring?
Can be induced by chemical or physical agents?
Can occur in non-coding DNA?
Might be corrected immediately during copying?
Might cause disease in future generations?
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UNIT
2
QUESTIONS
For each question, select the best answer from the four alternatives.
1. Which of the following statements about DNA is correct? (4.1, 6.1, 6.2, 6.3) K/U
(a) All DNA is part of one or more genes, which are found on chromosomes.
(b) DNA stores and transmits genetic information.
(c) DNA sequences are unchanging; they cannot be altered in any way.
(d) Living organisms all contain the same amount of DNA.
2. Which of the following would best help a doctor diagnose a disorder caused by
non-disjunction? (4.4, 5.1, 6.1, 6.3) K/U
(a) X-ray crystallography
(b) a test cross
(c) DNA fingerprinting
(d) a karyotype
Indicate whether each of the statements is true or false. If you think the
statement is false, rewrite it to make it true.
3. Sex-linked traits are coded for by genes on either the X chromosome or the Y
chromosome. (5.3) K/U
4. For each trait, individuals carry one allele. (5.1) K/U
Respond to each statement or answer each question below.
5. A friend states: “I inherited my brown eyes from my dad.î (4.1)
(a) Rewrite this statement, using your knowledge of genetics.
T/I
C
A
(b) Explain how your friendís brown eyes were inherited.
6. The terms gene and genome look very similar. Write a sentence that clearly
indicates the relationship between the terms gene and genome. (4.1, 6.3) T / I
C
A
7. Compare and contrast genetic screening and gene therapy. Identify one way
they are similar and one way they are different. (5.5, 6.5) T / I A
8. Use your knowledge of genomes to state whether there is a relationship
between the number of genes in an organism’s genome and the relative
complexity of the organism. Explain your response. (6.3) K/U
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Unit 2 Questions
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Complete the following graphic organizers.
9. Complete the following graphic organizer describing meiosis. (4.3)
T/I
A
C
Diploid (2n) parent
cell
undergoes
(a)
producing
two haploid
cell
which undergo
(b)
producing
(c)
10. Draw a Punnett square to show a cross between two individuals who are
heterozygous for a trait. The dominant allele for the trait is G; the recessive allele
is g. Circle any offspring that will have the dominant phenotype. (5.1) T / I C
G
g
G
g
11. Complete the following comparison matrix to compare pedigree charts and
Punnett squares. (5.1, 5.3) T / I A C
Force
Pedigree Chart
Punnett Square
Predicts all possible genotypes of
offspring?
Shows the individuals in several
generations of a family?
Tool used by genetic counsellors?
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