Flashcards in bio chap 14 Deck (23)
Generally speaking, a nucleotide substitution has less severe consequences than a nucleotide addition/deletion.
Any DNA "damage" is considered to be a mutation, even if it is immediately correct by the action of DNA polymerase.
Spontaneous mutations that occur in somatic cells will be transmitted to offspring.
When comparing DNA sequences of similar genes for proteins in related species, you see that some of the sequences are longer in one species compared to the other. Which of the following would most likely represent the extra number of bases that you would see?
Genetic risk factors:
can increase the likelihood of somatic mutations.
can increase the likelihood of germ-line mutations.
can work synergistically with environmental risk factors.
can be heritable.
Any deviation in normal gene dosage is lethal.
The amount of new mutations in living organisms following a round of genome replication:
generally increases with larger genomes.
Imagine that a researcher is studying a mouse that carries a mutation in Pax7 ―a gene that is involved in muscle development. To his surprise, these Pax7 mutant mice appear relatively "normal." What is a possible explanation for this?
Other members of the Pax gene family have redundant functions in muscle development (and can compensate for the Pax7 mutation).
The normal copy of Pax7 on the corresponding homologous chromosome is sufficient for mouse survival.
These Pax7 mutant mice may have a synonymous mutation.
The use of antibiotics is creating the mutations in bacteria that make them resistant to these antibiotics.
A trinucleotide of 5'CTC3' or 5'TTC3' is transcribed and then translated into the amino acid glutamic acid. A trinucleotide of 5'CAA3' or 5'TAC3' is transcribed and then translated into valine. In sickle-cell hemoglobin, valine is present instead of glutamic acid. Assuming a single base pair substitution has occurred, what is the mRNA code for valine in the affected mutant?
What is one reason that RNA viruses and retroviruses have such a high rate of mutation?
because RNA is more fragile than DNA and because viral polymerases lack a proofreading mechanism.
The fact that humans have a relatively large number of mutations per genome per generation when compared to other organisms can be explained by:
most of a human's DNA is noncoding, so most of the mutations are neutral.
Normally in corn, genes for waxy and virescent kernel appearance are linked. In a certain stock, however, it was found that these two genes assort independently. Which chromosomal aberration would explain this?
_____ is the process where new genes evolve from duplicates of old ones.
Duplication and divergence
Which of the following would best describe the results seen in a flower whose sectors have different pigmentation?
the result of transposable elements
Which of the following statements concerning cancer and mutations is correct?
Usually multiple mutations are required in different genes to cause cancer.
Mutation rates (of nucleotides):
are highest in viruses.
Which of the following would you expect to have the lowest nucleotide mutation rate?
The rates of evolutionary change in DNA:
are highly variable among different gene families.
Consider a polyploid plant that has several copies of each of its genes. This plant will likely die prematurely, given this high gene dosage.
A researcher has carried out Giesma staining on a set of human chromosomes, and has arranged these chromosomes into a karyotype. She notices that in a homologous pair, a band is missing from one of the chromosomes. This likely resulted from:
either a deletion or a reciprocal translocation.
Even though the chance of a mutation for one given nucleotide is rare, mutations are rather common when looking at the whole genome.