microbiology ch.8 Flashcards
A sequence of nucleotides in DNA that codes for a functional product is a(n)
a. genetic code.
Which process results in a new double-
stranded DNA molecule that contains one
original strand and one new strand?
c. semiconservative replication
In DNA replication, the newly added nucleotide is joined to the growing DNA strand by
a. DNA polymerase.
b. RNA polymerase.
c. DNA ligase.
d. DNA gyrase.
DNA polymerase adds new nucleotides to the _____ end only on a DNA strand.
Which of the following enzymes joins DNA strands and joins Okazaki fragments and new segments in excision by forming covalent bonds?
a. RNA polymerase
b. DNA polymerase
c. DNA ligase
d. DNA gyrase
What carries the coded information for making specific proteins from DNA to ribosomes?
d. RNA polymerase
Which molecules recognize specific codons and transport amino acids?
A group of three nucleotides is called a(n)
Transcription begins when RNA polymerase binds to the DNA at the
Of the 64 codons, how many are sense
Perhaps 60–80% of genes are NOT regulated, but are
What is the process that turns on the
transcription of a gene or genes?
d. catabolite repression
A set of operator and promoter sites and the structural genes they control defines
a. a corepressor.
b. an operon.
c. an inducer.
Inhibition of the metabolism of alternative
carbon sources by glucose is called
d. catabolite repression.
Epigenetic inheritance is
a. a process that turns on the transcription of a gene (or genes).
b. the semiconservative replication of DNA to be passed on to offspring.
c. turning genes off by methylation of certain nucleotides.
d. a process that inhibits gene expression.
Ionizing radiation causes
a. DNA to break.
b. bonding between adjacent thymines.
c. nitrogenous base substitutions.
d. the formation of highly reactive ions.
Ultraviolet light is a form of mutagenic radiation, which causes cellular damage that can be
a. repaired by DNA replication.
b. repaired during transcription.
c. repaired during translation.
d. cut out and replaced.
What is the most common type of mutation involving single base pairs?
a. frameshift mutation
b. nonsense mutation
c. missense mutation
d. base substitution
Mutations in which one or a few nucleotide pairs are deleted or inserted in the DNA are called
a. nonsense mutations.
b. frameshift mutations.
c. point mutations.
d. base-pair mutations.
Approximately what percentage of substances found by the Ames test to be mutagenic have been found to be carcinogenic in animals?
Which of the following is defined as the
“exchange of genes between two DNA
molecules to form new combinations of genes on a chromosome”?
c. genetic recombination
d. crossing over
Transformation is the transfer of DNA from a donor to a recipient cell
a. by a bacteriophage.
b. as naked DNA in solution.
c. by sexual reproduction.
d. by crossing over.
The process in which bacterial DNA is transferred from a donor cell to a recipient cell inside a bacteriophage is called
c. specialized transduction.
The process in which genetic material is transferred from one bacterium to another is called
d. specialized transduction.
Which type of plasmid carries genes for sex pili and for the transfer of the plasmid to another cell?
a. resistance factors
b. bacteriocin plasmids
c. conjugative plasmids
What provides a natural mechanism for the movement of genes from one region of a DNA molecule to another?
d. R factors