Genetics
Genetics
Bell: What is Genetics?
Study of heredity
passing of traits from parents to offspring
Traits- Visible characteristics
Gregor Mendel
Watch video clips- DVD and “From the Gardent to
the Genome” YouTUBE- click for link
“Father of Genetics”
Austrian Monk
Conducted experiments with peas
Used numbers in the study of biology
Gregor Mendel
Experimented with
Self-pollination - fertilization within itself
Creation of pure-breed or true-breed
offspring identical to parents
Cross-pollination - fertilization of one by another
Offspring from both parents
Gregor Mendel
How many experiments were needed to determine
conclusive results?
Heads/Tails Activity
Round x Wrinkled =
7324 offspring
Yellow x Green =
8023 offspring
Axial x Terminal =
858 offspring
Purple x White =
929 offspring
Inflated x Constricted = 1181 offspring
Green x Yellow =
580 offspring
Tall x Dwarf =
1064 offspring
Mendel’s First
Experiment- Terminology
and
Crosses
Parental Generation - P
- Purebreds for each parent
1st Filial - F1 (first generation)
offspring of cross (children)
created hybrid - cross between 2 parents
2nd Filial - F2 (second generation)
Grandchildren
Mendel’s Conclusions
I. Traits are determined by a “factor”
Now termed GENES
Different forms of a gene are called ALLELE
II. Each “factor” is inherited separately
III. Each trait is determined by one of the “factors”
inherited from the parents
Principle of Dominance Dominant masks the expression of the
recessive
Bellringer - Genetics Day
2
What will be the fur color of the offspring of
Benjamin Bear and Elizabeth Bear?
Genetics Terminology
Purebred or True-breed
Dominant
Recessive
Genotype
Phenotype
Homozygous
Heterozygous
Practice with REEBOPS
How many show the
dominant phenotype for
body segments?
4
How many show the
recessive eye number?
1
What is the genotype of
those showing the
recessive eye number?
ee
What is the genotype of
those showing the
dominant phenotype for
eye number ?
EE or Ee
Are there any traits that
are not dominant or
recessive?
*Which of the traits shown are
heterozygous?
Orange Nose, 2 antennae,
Hump #, Nose Color, Antennae #
Teddy Bear Genetics
Law of Segregation = 2 forms of a gene/ allele are
separated during meiosis
(one to each gamete)
Complete the Teddy Bear Genetics
Probability
Likelihood that an event will happen
Ex) coin toss
1 coin flip = 1/2 chance or 50%
Heads 3 times in a row = 1/2 x 1/2 x 1/2 =
1/8
1/2 chance for each event (flip)
Principles of Probablility can be used to predict
genetic outcomes
Genetics and Probability
Ability to roll tongue = dominant trait
Can you determine your genotype?
With a partner:
John is heterozygous for tongue rolling and
Nancy cannot roll her tongue. What is the
chance that they will have children that cannot
roll their tongue?
How did you figure it out?
Genetics and Probability
Punnett Square - tool used to predict genetic
combinations
Tongue Rolling problem with punnett square
Closure problem: George and wife are both
heterozygous for widow’s peak. What percentage of
their children will have a Widow’s peak?
HW: Bikini Bottom Genetics
Genetics and Probability
Day 3
Bellringer: Mom and Dad both have free earlobes.
Junior also has free earlobes. His sister has
attached earlobes. What are Mom and Dad’s
genotypes in relation to earlobes? What is the
chance that they will have another child with
attached earlobes?
Check Bikini Bottom Genetics
Classwork: Genetics Worksheet
Genetic Crosses
Test Cross: used to determine genotype of dominant
phenotype
Cross an “unknown” dominant with a recessive
Why?
Genetic Crosses - 2 traits
Principle of Independent Assortment genes segregate independently during meiosis
cause of different genetic combinations in gametes
Dihybrid cross
both parents are hybrid for 2 traits
Genetic Crosses - 2 traits
Dihybrid worksheet practice
Mendel’s peas activity
Dihybrid Crosses
Beyond Dominant and
Recessive
Incomplete Dominance -
neither allele is dominant over the other
Purebreds phenotypes are 2 extremes
Hybrid phenotype is in the middle
Incomplete Dominance
4 o’clock Flowers
X
Beyond Dominant and Recessive
Codominance
Both alleles are dominant
Hybrid shows both traits
CodominanceRoan Cattle
Bell: Day 5
How are codominant and incomplete dominant
alleles different than dominant and recessive alleles?
AGENDA
Incomplete Dominance Practice
Multiple Alleles
Blood Typing Lab
Blood Type Problems
Multiple Alleles
Humans have ______ blood types
Alleles:
Type
A=
B=
AB =
O=
Human Heredity: Day 6
Bell: What is the genotype of the possible children if
a heterozygote for Widow’s peak marries a
homozygous recessive (straight hairline)?
What is/are the possible phenotype(s)?
AGENDA
1. Independent
Projects
2. Blood Typing
3. Pedigrees
4. Sex-linked traits
*Quiz NEXT time*
Human Heredity
Human Chromosomes
Human cell =
46 chromosomes (23 pairs)
1 set from Mom (egg) : 1 set from Dad (sperm)
2 of those are known as sex chromosome
Female = XX
Male = XY
Remaining 44 chromosomes = autosome
Pedigree
Chart that shows the relationships within a family
Often used to determine the mode of inheritance
Pedigree (cont.)
Female =
Affected Female =
Male =
Affected Male =
If a heterozygote is known then half
of the shape is shaded
Pedigree Practice Worksheet
Pedigree Practice:
Autosomal Dominant?
A.
B.
C.
Draw each pedigree
Assume that the affected trait is dominant. Write the
genotypes beside each recessive individual
Is it possible for this trait to be autosomal dominant?
-Circle if possible
or
X if not possible
Can two affected individuals
have unaffected children?
Pedigree Practice
Autosomal Recessive?
A.
B.
C.
Assume the trait is recessive.
Draw the pedigree and write the genotype beside
each person.
Is it possible for the trait to be recessive?
- Circle if possible or X if not possible
If the trait is autosomal recessive, what can you
conclude the children will be of two affected parents?
Pedigree Practice
Carrier Heterozygote that
“carries” the
affected allele, but
does not express
the allele (Allele
remains hidden.)
** Who are the
carriers?
Is the affected trait autosomal dominant or
recessive? Why?
Day 7
Bell:
Fifty
wavy-haired
couples
decide
to form
a cool.
commune,
because
they
think
wavy
hair
is
Each
couple
has
twoofchildren.
Out of
the“uncool”
100
children,
how
many
them
should
have
straight
hair? (Of course,
they
willcurly-haired
have to be
excommunicated,
along
with
their
siblings, once they reach adulthood.)
AGENDA
Quiz
Pedigree
Sex-linked Traits
Sex-Linked Genes
Pattern of inheritance is located on the Xchromosome or the Y- chromosome
Y is much smaller
Therefore, there are more X-linked disorders/traits
What numbers to you
See?
Ex. Colorblindness
X-linked disorder
Most common in ?
Males (1/10)
Females (1/100)
Allele Definition -
Colorblind Problem
Marian’s father is colorblind. Marian herself has
normal color vision. Marian and her husband, Martin,
who is also colorblind, have just had their first child; a
son they have named Mickey. (Write the genotypes of
Marian and Martin.)
a. What is the probability that their son is colorblind?
b. If Martin were not colorblind, how would this affect
the prediction about Mickey?
c. If Marian and Martin were to have a girl, who they
would name Minnie, what is the probability that she
would be colorblind?
X-linked BELL
Hemophelia is a hereditary disease in which the blood
does not clot. The allele for normal blood clotting is
carried on the X chromosome.
1. A carrier female marries a hemophilic man. How many
male children will have hemophilia? How many female
children?
2. A normal woman whose father had hemophilia marries
a normal man. What is the chance that their children will
have hemophilia?
3. Todd is not colorblind. He is married to Ann whose
father was red-green colorblind. Todd and Ann have 2
children, Ed is colorblind and lisa is not. What are the
genotypes of Todd, Ann, Ed, and Lisa?
Pedigree Practice
A
B
C
Draw the pedigree and write the genotypes beside
each individual. Assume X-linked recessive.
Is it possible for it to be x-linked recessive?
What can you conclude about children whose mother
is affected by an x-linked recessive trait?
X-linked Conclusions
What can you conclude about children if only the
mother is affected by an X-linked recessive trait?
Why is it possible for females to be carriers of Xlinked traits, but not males to be carriers?
BELL: PEDIGREE
One last time!
BELL - Pedigree (one last time). Using the
markers, solve the 1, 2, and 3 pedigrees
Erase when finished.
AGENDA
1. Turn in Alcaptunuria Lab.
2. Karyotype Internet Activity
3. Karyotype notes
4. Genetic Disorders/Disease
Project
Karyotype
Organized profile of a human’s chromosomes
Chromosomes are paired by
centromere location
banding pattern
Size
Analyzing Karyotypes
What can you tell by this karyotype?
Analyzing Karyotypes
What can you tell by this karyotype?
Analyzing Karyotypes
What can you tell by analyzing this karyotype?
Analyzing Karyotypes
What can you tell by analyzing this karyotype?
Analyzing Karyotypes
What can you tell by this karyotype?
Analyzing Karyotypes
What can you tell by analyzing this karyotype?
Karyotype Analysis:
Chromosomal Disorders
Nondisjunction- occurs when either homologous
chromosome fails to separate during meiosis
Results abnormal # of chromosomes in gametes
Trisomy = 1 extra homologous chromosome (3)
Polysomy = more than 1 extra
Monosomy = only 1 chromosome
Karyotype Analysis:
Chromosomal Disorders
High frequency of Nondisjunction in humans
Results usually so devastating that it results in
miscarriage
Only 3 trisomies that result in babies
Down’s syndrome - 21
Edward’s syndrome - 13
Patau Syndrome - 18
Nondisjunction:
Sex Chromosomes
Monosomy (X only) = Turner’s Syndrome
Trisomy (XXY or XXXY) = Klinefelter’s Syndrome
Trisomy (XXX) - cannot be distinguished from normal
females / no affect
When would the effect show up?
Chromosomal Alterations
Deletion
Portion of Chromosome lost during cell division
(genes lost = usually lethal)
Duplication
A fragment joins the chromosome and is then
repeated
Translocation
A fragment is moved from one
chromosome to another
Wrap-Up
Bell:
What is a karyotype?
How is a karyotype created?
Human Genetic
Disorders Assignment
Go to website for assignment
Human
Disorders/Diseases
BELL:
What is a karyotype and how is it made?
Describe the 3 type of chromosomal
alterations. Why do they affect an individual?
AGENDA
Human Disorders Project
(Presentations)
Genes and the environment
Perfect Baby
AGENDA
Genetics Quiz #2
Perfect Baby Video
Discussion
Genes and the Environment
Human Genome and
Ethics
AGENDA
Human Genome - gene patenting
DNA databases
Designer Babies?
Video Discussion
What are some of the strange and unexpected
discoveries made from analyzing the human
genome?
Why is sequencing the human genome considered
such an important and historic event
• Video - 7. Who Owns the Genome?
What effects might patenting genes have on current
research efforts?
Do you think genes should be patented? Why or
Group Work
why not?
With your group, read and answer the questions to the case stud
“Patenting Genes.” Elect a spokesperson to share your answers.
DNA Databases
13. DNA Databases - link
What are some ethical issues surrounding the
creation of DNA databases?
What are some implications of creating DNA chips
that would allow doctors to screen newborns for
many diseases?
Case Study
Newborn screening or Genetic Discrimination: read
the case study with your group - appoint a
spokesperson to share your answers
Should we create babies
by design?
Can we do it now? - link to 15. Genetic Modification
Should We Create Babies by Design? - Internet
Activity
with a partner complete the web based activity
through Mr. Lauver’s website (class
assignments)
What is your position on “Babies by Design”? Why?