Module 6 Regulating Gene Expression
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167 Terms
Compare translation to writing a sentence. What does each letter represent?
an amino acid.
Compare translation to writing a sentence. What does the completed sentence represent?
a protein
What would happen if the amino acids were in the incorrect order?
The protein may fold differently, perform a different function, or have no function.
Define the term mutation.
A change in the nucleotide sequence of DNA.
Mutation _________ affect the phenotype.
may or may not
Which of the following is true about silent mutations?
They have no impact on the protein coded by the gene.
Somatic mutations occur in the ______.
body cells
_____ cell mutations are passed on by _____.
Somatic; mitosis
Germ line mutations occur in the germ line cells that give rise to _______ and are passed on by ________.
gametes (meiosis); reproduction
The change a mutation causes to DNA is:
permanent
What is a point mutation?
A change involving a single nucleotide or a small number of nucleotides.
Point mutations _____.
may result in proteins that are less efficient
What is a substitution mutation?
One nucleotide is replaced by another.
What is an insertion mutation?
One or more nucleotides are added to a DNA sequence.
What is a deletion mutation?
One or more nucleotides are removed from a DNA sequence.
What is a frameshift mutation?
When nucleotides are inserted or deleted, shifting the reading frame of the codons.
What is a silent mutation?
A mutation that changes a DNA codon without changing the amino acid encoded by that codon.
What is the final product of a strand of DNA that has undergone a mutation?
The resulting protein may be unchanged, altered, shortened, misfolded, or not produced, depending on the mutation.
Changing one nucleotide in a DNA sequence can change ________ in a protein.
All are correct
How can a mutation in DNA affect the function of the resulting protein?
It can change the protein’s amino acid sequence, three-dimensional shape, and stability, therefore affecting its function.
Why can a DNA mutation fail to change the amino acid sequence?
The genetic code is redundant, meaning multiple codons can code for the same amino acid.
Using AAA TTT GGG AAA as an example, which of the following would be an example of a substitution mutation?
ATA TTT GGG AAA
Using AAA TTT GGG AAA as an example, which of the following would be an example of a frame-shift mutation?
AAA ATT TGG GAA A
What is a mutagen?
A physical or chemical agent that can change the DNA of an organism and thus increases the frequency of mutations.
Examples of mutagens are:
Ultraviolet radiation, X-rays, tobacco smoke, benzene, and certain viruses.
How do mutagens lead to mutations?
Mutagens damage DNA or interfere with its replication and repair, producing changes in its nucleotide sequence.
All mutations are caused by mutagens.
False
How can mutations occur without a mutagen?
Spontaneous mutations can result from errors during DNA replication, repair, or recombination.
Are mutations always harmful to an organism?
No, mutations may be harmful, neutral, or beneficial.
What is a neutral mutation?
It does not significantly affect an organism’s survival or reproduction.
What is a beneficial mutation?
It increases an organism’s ability to survive or reproduce in a particular environment.
An example of a beneficial mutation:
A mutation that produces antibiotic resistance can help bacteria survive exposure to a particular antibiotic.
An example of a harmful mutation:
A single nucleotide change affecting hemoglobin structure that causes sickle cell disease
How does a mutation affect the processes associated with the central dogma of biology?
A mutation can affect transcription and translation, leading to altered or nonfunctional proteins. This affects gene expression and cellular processes governed by those proteins.
Prokaryotes regulate gene expression during _____, and eukaryotes regulate gene expression during _____.
transcription only; transcription and translation
Which of the following are the parts of an operon?
I promoter
II operator
III structural gene
IV regulatory gene
I, II, III
The lac operon is an example of a(n) _____.
inducible operon
The trp operon is an example of a(n) _____.
repressible operon
In the presence of tryptophan, _____.
the trp operon is not used
In the presence of lactose ______.
the lac operon is turned on
mRNA molecules can last for _____ in the cytoplasm.
hours to weeks
What causes the degradation of mRNA in the cytoplasm?
Both are correct
What is the function of the nuclear pores in the nuclear membrane?
Only mRNA molecules with proper caps and tails are passed through to the cytoplasm
Which of the following shows the correct order of where eukaryotic gene expression is regulated?
unpacking DNA - transcription - mRNA processing - translation - protein processing
Which process can cause a permanent inactivation of a gene?
methylation
Which process loosens DNA from the histones, allowing transcription to take place?
acetylation
_____ attach to the promoter region of a gene, while _____ can be thousands of nucleotides away from the gene. Both factors allow RNA polymerase to attach to the promoter.
Transcription factors; activators
Why does the functionality of proteins decrease over time?
The shape of the protein changes, which decreases their functionality.
What function do interfering RNAs (iRNA) perform in gene expression?
They prevent the translation from mRNA to proteins by binding to mRNA molecules.