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IB Biology
Gene Regulation
Post-translational + mutations
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Cards (39)
What occurs to the ribosome after termination?
The small and large
subunits
separate
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What is the wobble effect in genetics?
Redundancy in the
genetic code
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How many amino acids are coded by the genetic code?
20
amino acids
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How many codons code for amino acids?
61 of the
64
possible codons
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What is the significance of the first two nucleotides in a codon?
They are always identical for each
amino acid
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What does the third nucleotide in a codon do?
It can change without affecting the
amino acid
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Why do cells not need 61 different tRNA molecules?
The third
nucleotide
can wobble
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What is the role of inosine in tRNA anticodons?
It can bind with A,
C
, and
U
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How does the wobble effect protect against mutations?
It can turn mutations into
silent ones
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What must happen to a polypeptide chain after translation?
It must be
folded
into a functional shape
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Where does most protein folding occur?
In the
endoplasmic reticulum
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What are chaperonins?
Proteins
that assist in folding
polypeptides
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What are the types of post-translation modifications?
Glycosylation: Addition of
carbohydrates
Lipidation: Addition of lipids
Phosphorylation: Addition of
phosphate groups
Ubiquitination: Addition of
ubiquitin
for degradation
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What are mutations?
Changes in the
nucleotide
sequence
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What can cause mutations?
Errors in
DNA
replication
or
mutagens
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What are mutagens?
Factors that change
nucleotide
sequences
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Give examples of mutagens.
Ultraviolet
radiation,
cigarette
smoke
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What are point mutations also known as?
Substitutions
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What happens in silent point mutations?
No change in the
amino acid
sequence
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What are missense point mutations?
They replace one
amino acid
with another
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What disease is caused by a missense mutation?
Sickle Cell Anemia
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What is a nonsense point mutation?
It creates a
stop codon
prematurely
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What are frameshift mutations?
Insertions
or
deletions
not in multiples of
three
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What is Tay Sachs Disease caused by?
A
frameshift mutation
in the
HEXA gene
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What happens due to the frameshift mutation in Tay Sachs Disease?
The enzyme
hexosaminidase A
becomes nonfunctional
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What are gametic mutations?
Mutations in
germ cells
passed to offspring
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What are somatic cell mutations?
Mutations in
normal
body cells not passed on
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How do mutations relate to natural selection?
They can lead to changes in
phenotype
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What is an example of natural selection in rock pocket mice?
Dark mice survive better on
dark lava
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What causes antibiotic resistance in bacteria?
Mutations
that provide survival advantages
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How do pesticides lead to resistance in insects?
Individuals with resistance
genes
survive and
reproduce
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What are the mechanisms that can change genotype or phenotype?
Errors in
mitosis
or
meiosis
Horizontal gene transfers
Transformation
Transduction
Conjugation
Transposition
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What can errors in meiosis lead to in humans?
Conditions like
Down Syndrome
or
triploidy
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What is horizontal gene transfer?
Transfer of
genetic information
outside
reproduction
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What is transformation in horizontal gene transfer?
Uptake of
naked DNA
from the environment
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What is transduction in horizontal gene transfer?
Viral transmission of
genetic information
between
bacteria
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What is conjugation in horizontal gene transfer?
Direct transfer of DNA between
prokaryotes
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What is transposition in horizontal gene transfer?
Movement of
DNA segments
within
DNA molecules
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How can related viruses increase genetic variation?
By combining
genetic information
in
host cells
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