Download Mutations - stephen fleenor

Warm-Up (1/19)
On the piece of white paper from the back, answer
the following question.
Describe three
mechanisms by which
sexual reproduction
increases genetic
variation.
Name
Date
Period
3C.1a: Alterations in DNA sequence can lead to changes in the type or
amount of protein produced and the consequent phenotype.
3C.1a.1: DNA mutations can be positive, negative or neutral based on
the effect or the lack of effect they have on the resulting nucleic acid or
protein and the phenotypes that are conferred by the protein.
3C.1b: Errors in DNA replication or DNA repair mechanisms, and external
factors, including radiation and reactive chemicals, can cause random
changes, e.g., mutations in DNA.
3C.1b.1: Whether or not a mutation is detrimental, beneficial or neutral
depends on the environmental context. Mutations are the primary
source of genetic variation.
3C.2a: The imperfect nature of DNA replication and repair increases
variation.
1A.1c: Genetic variation and mutation play roles in natural selection. A
diverse gene pool is important for the survival of a species in a changing
environment.
1A.2b: Phenotypic variations are not directed by the environment but occur
through random changes in the DNA and through new gene combinations.
3C.2c: Sexual reproduction in eukaryotes involving gamete formation,
including crossing-over during meiosis and the random assortment of
chromosomes during meiosis, and fertilization serve to increase variation.
Reproduction processes that increase genetic variation are evolutionarily
conserved and are shared by various organisms.
The Central Dogma, Revisited
His
Met
DNA code
makes RNA
code makes
polypeptide
code.
GUA
ribosome
nucleus
G
G
A
C
A T G C A T G C AG
AUGCAUGCA
T A C G T A CG T C
The Molecular Nature of Mutation
Mutation =
change in the
DNA sequence…
ribosome
nucleus
G
G
A T G C A T G C AG
A
C
T A C C T A CG T C
The Molecular Nature of Mutation
Mutation =
change in the
DNA sequence…
…resulting in
change in RNA
sequence…
ribosome
nucleus
G
G
A
C
A T G C A T G C AG
AUGGAUGCA
T A C C T A CG T C
The Molecular Nature of Mutation
Leu
Mutation =
change in the
DNA sequence…
…resulting in
change in RNA
sequence…
Met
CUA
AUGGAUGCA
ribosome
…resulting in
change in the
polypeptide
sequence…
nucleus
G
G
A
C
A T G C A T G C AG
AUGGAUGCA
T A C C T A CG T C
The Molecular Nature of Mutation
Mutations can affect
sequence of protein OR
amount of protein.
protein
(high levels)
repressor
activator
promoter
before mutation
coding
sequence
RNA
(high levels)
The Molecular Nature of Mutation
Mutations can affect
sequence of protein OR
amount of protein.
repressor
protein
(low levels)
activator
X
promoter
after mutation
coding
sequence
RNA
(low levels)
The Molecular Nature of Mutation
Mutations occur…
1. During DNA
replication
(DNA polymerase
makes a mistake)
2. During DNA
repair
3. By exposure
to radiation
or chemicals
Critical Thinking Question #1
Discuss this question with your partner and write or
represent it. I will call on three people to share their
partners’ answers.
Explain three mechanisms by which
genetic variation can be introduced in
somatic cells.
3C.1a: Alterations in DNA sequence can lead to changes in the type or
amount of protein produced and the consequent phenotype.
3C.1a.1: DNA mutations can be positive, negative or neutral based on
the effect or the lack of effect they have on the resulting nucleic acid or
protein and the phenotypes that are conferred by the protein.
3C.1b: Errors in DNA replication or DNA repair mechanisms, and external
factors, including radiation and reactive chemicals, can cause random
changes, e.g., mutations in DNA.
3C.1b.1: Whether or not a mutation is detrimental, beneficial or neutral
depends on the environmental context. Mutations are the primary
source of genetic variation.
3C.2a: The imperfect nature of DNA replication and repair increases
variation.
1A.1c: Genetic variation and mutation play roles in natural selection. A
diverse gene pool is important for the survival of a species in a changing
environment.
1A.2b: Phenotypic variations are not directed by the environment but occur
through random changes in the DNA and through new gene combinations.
3C.2c: Sexual reproduction in eukaryotes involving gamete formation,
including crossing-over during meiosis and the random assortment of
chromosomes during meiosis, and fertilization serve to increase variation.
Reproduction processes that increase genetic variation are evolutionarily
conserved and are shared by various organisms.
From Mutation to Variation
The effect of a
mutation depends
on its context.
Apoptosis
Activating
Protein
AEP mRNA
promoter
AEP gene
From Mutation to Variation
Deleterious mutation
messes it up.
The effect of a
mutation depends
on its context.
Apoptosis
Activating
Protein
X
AEP mRNA
X
promoter
AEP gene
From Mutation to Variation
Deleterious mutation
messes it up.
The effect of a
mutation depends
on its context.
Apoptosis
Activating Protein
(low levels)
AEP mRNA
(low levels)
X
promoter
AEP gene
From Mutation to Variation
The effect of a
mutation depends
on its context.
Beneficial mutation
makes it better.
Apoptosis
Activating
Protein
(high levels)
AEP mRNA
(high levels)
X
promoter
AEP gene
From Mutation to Variation
The effect of a
mutation depends
on its context.
Messed-Up Apoptosis Protein
• Negative for embryos.
• Positive for neurons.
From Mutation to Variation
The effect of a
mutation depends
on its context.
Messed-Up Lactase Protein
• Negative for dairy farmers.
• Neutral for islanders.
From Mutation to Variation
Populations are
genetically
diverse because
of mutations.
From Mutation to Variation
A diverse gene pool is
important for the survival of a
species in a changing
environment.
Ice Age
Critical Thinking Question #2
The transcription factor CTIP2 represses
genes responsible for differentiating
epithelial cells into hair follicle cells;
therefore, CTIP2 represses the hair follicle
cell fate. Vulpes lagopus is a species of
snow fox which lives in the extremely cold
conditions of the arctic tundra. Predict the
effects of a deleterious mutation in the ctip2
gene occurring in the ovaries of a female
arctic fox on the Vulpes lagopus population.
Closure
On the piece of white paper from the
back, answer the following question:
Explain how a mutation can be
detrimental in one environmental
context and beneficial in
another.
Name
Date
Period
Scale
1 – 10