B.6.E Identify and
Illustrate changes
in DNA and
evaluate the
significance of
these changes !
Learning About DNA
DNA damage from environmental agents such as
ultraviolet light (SUNSHINE), nuclear radiation or
certain chemicals.
Our cells have built in mechanisms that catch and
repair most of the changes that occur during DNA
replication or from environmental damage. As we
age, however, our DNA repair does not work
effectively and we accumulate changes in our
DNA.
Still Learning About DNA
Some of these changes occur in body cells such as
in skin cells as a result of sun exposure, but are
not passed on to children ! BUT other errors can
occur in the DNA of cells that produce the egg
and SPERM. These are called germ line
mutations and can be passed from parent to
child.
If a child inherits a germ line mutation from
their parents, every cell in their body will have
this error in their DNA. Germ line mutations are
what cause diseases to run in families, and
responsible for some hereditary diseases
What Kind of Mutations
Are There When DNA
Replicates?
• A gene is essentially a sentence made
up of the bases A, T, G, and C that
describe how to make a protein. Any
changes to those instructions can alter
the gene’s meaning and change the
protein that is made, or how or when a
cell makes a protein.
Point Mutation
A point mutation is a sample change
in one base of a gene sequence. This
is equivalent to change in one letter
in a sentence, such as this example,
where we change the ‘C’ in cat to ‘H’ :
Original
The fat cat ate the wee
rat.
Point Mutation The fat hat ate the
wee rat.
Frame-shift Mutation
• In a frame shift
mutation, one or more
bases are inserted or
deleted, the equivalent
of adding or removing
letters in a sentence.
But because our cells
read DNA in three
letter “ Words ,“ adding
or removing one letter
changes each
subsequence word.
This type of mutation
can make the DNA
meaningless and often
results in a shortened
protein.
Insertion
Original the fat cat ate the wee rat.
Insertion the fat cat xlw ate the wee
rat.
Protein that is supposed to be made
by the cell will not be made.
Deletion
• Mutations that result in missing DNA
are called deletions. These can be
small, such as the removal of just
one “word”, or longer deletions that
affect a large number to genes on
the chromosome.
Original The fat cat ate the wee rat.
Deletion The fat ate the wee rat.
Genetic Variety in
Species
• occasionally a mutation can improve an
organism’s chance of surviving and
passing the beneficial change on to it’s
descendants. The Gene Associated with
Sickle Cell Anemia is caused by a single
base change, a substitution of Thymine for
adenine in the DNA. Causes the mucus in
the lungs and digestive system to be very
thick (viscous) instead of watery. This
thick mucus to builds up in the lungs and
block the absorption of oxygen. It also
blocks some of the digestive enzymes
from getting to the intestines. A patient
suffers from the lack of oxygen and
malnutrition. However they are immune to
Malaria. A benefit!
Number 61
1) Mutations can be considered as one
of the raw materials of evolution
because they
A-contribute to new variations in
organisms
B-are usually related to the
environment in which they appear
C-are usually beneficial to the
organism in which they appear
D-usually cause species of organisms
to become extinct
Number 62
ATCAGCGCTGGC
The above sequence of DNA is part of a
gene. How many amino acids are coded for
by this segment?
A
B
C
D
4
8
12
20
Number 63
Which of these would most likely cause a
mutation?
A the placement of ribosomes on the
endoplasmic
reticulum.
B the insertion of a nucleotide into DNA
C the movement of transfer RNA out of the
nucleus
D the release of messenger RNA from DNA
64
65 A mutation that occurs in the
gametes of an organism will most likely
be transferred to which
of the following?
A The siblings of the organism
B The offspring of the organism
C The other organisms living nearby
D The mating partner of the organism
B.6.F
Predict possible outcome of
various genetic combinations
such as monohybrid crosses,
dihybrid crosses and Non
Mendelian inheritance
GREGOR JOHANN
MENDEL
• 1822 – 1884
• Father of genetics
• Augustinian monk
•
•
•
•
•
Austria, now Czech
Republic Studied
inheritance in garden
peas
Video
Law of Segregation
• Each individual has a pair of
factors (alleles) for each trait.
Dominant/Recessive
• The factors (alleles) segregate
(separate) during gamete (sperm
& egg) formation
• Each gamete contains only one
factor (allele) from each pair
• Fertilization gives the offspring
two factors for each trait one
from each parent
MENDEL’S
EXPERIMENTS
Modern Genetics View
• Each trait in a pea plant is
controlled by two alleles
(alternate forms of a gene)
• Dominant allele (capital letter)
masks the expression of the
recessive allele (lowercase)
• Homozygous=identical alleles
TT or tt
• Heterozygous=different alleles
Tt
Relationship between
Gene and Allele
• Gene - a
segment of
DNA that
controls a
specific trait.
• Allele - the
alternate (or
contrasting)
form of a
gene.
Difference between
Genotype and Phenotype
• Genotype - genetic
makeup of an
organism; refers to
the alleles for a trait.
TT or Tt
• Phenotype - physical
or outward
expression of the
alleles for that trait.
(What it looks like)
Tall or short
Punnett Square
• A diagram used to
predict the
probability of
certain traits by
offspring.
• The following
examples will
illustrate the
outcome of
different types of
crosses.
DIHYBRID CROSS
• Mendel obtained
similar results with
other pairs of traits
• e.g., TtYy x TtYy
dihybrid cross
• 9:3:3:1 ratio in F2
generation
• Independent
Assortment Not all
the plants that were
tall, also inherited
the yellow trait
Incomplete Dominance
• In Incomplete Dominance, One allele not
completely dominant over the other, so
blending of the parental traits occurs. (2
alleles produce 3 phenotypes.)
Result: Heterozygous phenotype somewhere
in between homozygous phenotype.
Examples:
• Trait: Flower Color
Expressions: Red x White  Pink
RR= Red; RW= pink; WW= white
Codominance
In codominance, neither allele are
dominant; both are expressed. A
cross between organisms with two
different phenotypes produces
offspring that has both phenotypes
of the parental traits
shown. Always spotted or striped
2. Codominance
• Both alleles contribute to the
phenotype.
• Example: In some chickens
Black Chicken x White  Speckled
Chicken
YOU tell me which type
of dominance…
Codominance!
Type of
Dominance?
Incomplete
Dominance!
Type of Dominance?
Incomplete Dominance!
Sex Linked Traits
• The genes for these traits are
on X chromosomes
• Because only males receive one
X chromosome, they are more
likely to inherit disorders
passed on
• Examples are Hemophilia and
colorblindness.
66. In a cross of a round hybrid
pea with a true breeding round
parent (Ww x WW), what
genotypic proportions would be
observed in the offspring?
• A. Half heterozygous, half
homozygous dominant
• B. Half round, half wrinkled
• C. All heterozygous
• D. All round
67. A cat that was born with
black spots and a white coat
is an example of
•
•
•
•
A.
B.
C.
D.
Codominance
Incomplete Dominance
Sex Linked Trait
Mendel inheritance
68. Which of the following is
heterozygous dominant
•
•
•
•
A.
B.
C.
D.
Tt
TT
Tt
None
• 69 In cocker spaniels the allele
for a black coat color (B) is
dominant over the allele for a
brown coat color (b). If a brown
cocker spaniel is crossed with a
heterozygous black cocker
spaniel, which of the following
genotypic ratios can be
expected?
• F 0 BB: 2 Bb: 2 bb
• G 1 BB: 2 Bb: 1 bb
• H 2 BB: 0 Bb: 2 bb
• J 2 BB: 1 Bb: 0 bb
70 If several pea plants with the genotype T
TYy are crossed with pea plants with the
genotype Ttyy, what percentage of the
offspring will be expected to have the T TYy
allele combination?
A 25%
B 40%
C 50%
D 75%
B.6.G
Recognize the significance
of meiosis to sexual
reproduction
Clip
Meiosis in the Cell
• The process results in 4
daughter cells (Count the
vowels)
• Daughter cells are haploid (N) ½
the number of chromosomes
• Daughter cells are genetically
different, provides diversity
• Make sex cells (gametes) sperm
and
egg
Crossing OverInterchanging of
Chromosomes
• XX=female
• XY=male
DNA Exchanges creating DIVERSITY
Diploid VS. Haploid
• Body cells that
have the full set
of chromosomes
are DIPLOID
• (46)
• PERFORMS
MITOSIS
• Sex cells that
have half a set
of chromosomes
are HAPLOID
• (23)
• PERFORMS
MEIOSIS
71 Crossing-over between nonsister
chromatids during meiosis is significant in
heredity. This
process most likely leads to an increase in
which of the following?
F The expression of dominant traits
G Number of gametes
H The occurrence of polyploidy
J Genetic variation
B.6.H
Fingerprinting, Genetic
modifications, and
Chromosomal Analysis
The Human Genome
Project
• The project identifies all the
approximant genes in DNA
• No two organisms have the
same genome.
• Developed to discover where
our diseases are on
chromosomes
DNA Fingerprinting
DNA Fingerprinting or
chromosome painting
• Allows us to compare the
genomes of different species to
compare how similar they are.
Karyotyping
Questions
• 72. What is crossing over?
• A. Exchanging of the
Chromosomes
• B. Dividing of the cells
• C. Chromosomes are
doubled
• D. Walking across the street
Questions
• 73. How many Chromosomes
are in a human diploid cell?
• A. 16
• B. 26
• C. 46
• D. 69
Questions
• 74. True or
False this
person is a
female?
• A. true
• B. false
75 The technique known as chromosome painting
is the result of scientific research. Scientists
use chromosome painting to mark the locations of
genes on human chromosomes with
fluorescent tags. It is also possible to apply this
technique to the chromosomes of many
different species. Chromosome painting allows for
which of the following?
F A comparison of the genomes of different
species
G The sequencing of proteins from many species
H An increase in mutations in many species
J The extraction of amino acids from different
species
7.4
Analyze and evaluate how
evidence of common ancestry
among groups is provided by the
fossils record, biogeography, and
homologies, including
anatomical, molecular, and
developmental
Darwin’s theory
 Variation exist among individuals in a
species.
Individuals will compete for resources
(food and space)
Some competition would lead to death
of some individuals while others would
survive.
Natural selection is the process to
survive and reproduce. The favorable
variations of this are called
adaptations.
Evolution
Fossils
Fossils provide the only direct
evidence of history of evolution.
The uppermost rock layers are
our most current forms of life.
Fossils from the deeper layers
are the common ancestors of
modern forms.
Homologous structures
Darwin pointed out the forelimbs of such
animals as humans, whales, bats, and other
creatures are strikingly similar, even though
the forelimbs are used in different ways.
 Darwin also proposed that the similar
forelimbs all relate to a common ancestor.
 He also observed that animals have
structures they do not use. These useless
organs are called vestigial organs. In humans
it’s the appendix, the fused tail vertebrae, and
the wisdom teeth, and muscles that move the
ears and nose.
Homologous Structure
Analogous structures
Analogous structures
are
structures in different organisms that look
similar or perform similar functions, but
are not derived from the same ancestral
source.
 Some examples are bats wings and birds
wings, through looking similar and
performing similar function evolved
separately.
Analogous Structure
Embryology
Darwin noted the striking
similarity among embryos of
complex animals, such as
humans, chickens, frogs,
reptiles, and fish. Common
ancestor.
DNA and Amino acid
comparisons
The less number of amino acid
differences between organisms
the more closely related they
are. Common ancestor.
76. Which
layer of
rock is the
oldest?
a. Red layer
b. Green layer
c. Yellow
layer
77. Which of the following is
not a key piece of evidence
in finding a common
ancestor?
a. Fossils
b. Embryology
c. Similar looks
d. Homologous structures
78. Which of
the
following is
the most
closely
related to
humans?
a. The mouse
b. The gorilla
c. The frog
d. The
lamprey
Species
Gorilla
Rhesus
Monkey
Mouse
Chicken
Frog
Lamprey
Amino Acid
Differences
from Human
Hemoglobin
Protein
1
8
27
45
67
125
79.
80.
Analyze and evaluate how
natural selection produces
change in populations, not
individuals
Natural Selection
Overproduction
Species produce more young than will
survive to reproduce age (Ex. Cats have
huge litters)
 Variation
Individuals vary from one another in
many characteristics (even siblings
differ) “Oh Deer Game”
 Competition
There is competition among offspring for
resources

Natural Selection
 Survival
of the Fittest Phenotype
The individuals best suited to there
environment will survive and pass
on their traits
 Favorable Combinations Increase
Population will change to all
favorable traits
Population
Variations. Which
will be eaten first?
Population trait of beak
size and shape shifted
due to the type of food
sources available.
Gene Flow and Genetic Drift
Can be caused by land barriers
 Migration
 Mutations
 Sexual Reproduction
 ALL INCREAS GENETIC DIVERSITY
 Video on Gene Flow

81.
82 After examining the fossil record, scientists have
determined that scorpions today are much
smaller than their extinct ancestors. For example,
Jaekelopterus rhenaniae, a giant scorpion species that lived
255 million to 460 million years ago, was 2.5 meters long.
Which of the following conclusions is supported by this
information?
F Scorpions living today have increased their numbers
since they first appeared.
G Scorpions in the fossil record are smaller than their
descendants are.
H Scorpions have changed as a result of natural
selection.
J Scorpions do not appear in their original state in the
fossil record.
83 The concept of gene flow is
demonstrated when a cow is driven off from
its herd, joins another herd, and reproduces.
When the cow contributes to the gene pool of
the new herd, which of these most likely
increases?
A Natural selection
B Genetic variation
C Environmental fitness
D Reproductive mutations
84 Some organisms have genes that improve their
ability to survive and reproduce. If the genes
also help their offspring survive and reproduce, then
which of the following will most likely
increase?
F The frequency of the genes in one individual
G The frequency of the genes in the population
H The number of genes in one chromosome
J The number of genes in the species
B.7.G
Analyze and evaluate
scientific explanations
concerning the complexity of
the cell Endosybiosis
Evolution of Eukaryotes
Origin of mitochondria
 Engulfed aerobic bacteria, but did not
digest them
 Mutually beneficial relationship natural
selection
 Clip

B.8.B
Categorize organisms using
a hierarchical classification
system based on similarities
and differences shared
among groups
Phylogeny and Taxonomy

The evolutionary history of a group of
related species is called phylogeny
A
scientific discipline called taxonomy is the
study of naming living things. We use the
same system to name so that there is no
mistaking which organisms we are looking at.
Memory devise
King
 Phillip
 Came
 Over
 For
 Good
 Soup

least specific
Most specific
85. Dogs (Canus familiaris) are
most closely related genetically to
which of the following organisms?
A.
B.
C.
D.
African hunting dog (Lycaon pictus)
Grey wolf (Canus lupus)
Grizzly bear (Ursus arctos)
Domestic cat (Felis catus)
86. How Did the Eukaryotic Cell Evolve?
A. It gained nutrients from the environment
 B. It mutated
 C. It engulfed an aerobic bacteria
 D. None of the above

87. Which of the following share
the most recent common ancestor?




A. mosses and ferns
B. Mosses and pine
trees
C. Ferns and flowering
plants
D. pine trees and
flowering plants.
88. How do Finches adapt to their
environment?
A. By migrating
 B. Color change of feathers
 C. Beak size depends on food source
 D. None of the above
