LearnSmart Chapter 8 Microbiology Assignment
In bacteria, _________ refers to DNA transfer requiring cell to cell contact.
Conjugation
_______ sometimes incorporates the incorrect nucleotide when generating a new strand of DNA during DNA ______; this leads to a detectable distortion in the DNA helix.
DNA polymerase; replication
Which type of DNA repair is shown in this figure?
Excision repair
In bacterial conjugation, the term _______ designates a donor cell with an F plasmid.
F+
T/F: Alkylating agents cause frameshift mutations.
False
T/F: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.
False
Which of the following terms describes the sequence of nucleotides (genetic makeup) of an organism or a cell?
Genotype
Which type of DNA damage repair is shown I this figure?
Modified nucleobase repair
Which of the following are replicons?
Plasmid Chromosome
A bacteriophage consists of what two major components?
Protein coat DNA or RNA genome
Extensively damaged DNA activates the ______ repair mechanism, which cannot always determine the correct nucleotide sequence, thus introducing mutations resulting from the repair process itself.
SOS
________ repair is activated by extensive DNA damage and uses a polymerase that lacks proofreading ability, ultimately resulting in mutations.
SOS
Modified nucleobases can result in ______ if they are not repaired before DNA replication occurs.
base substitutions
Chemical mutagens can cause two types of mutations: ______ substitutions and _______ mutations.
base; frameshift
The consequences of not repairing damaged DNA in cells include ______.
cancer (in animals) cell death
A bacterial cell described as _________ can take up DNA from the surrounding environment.
competent
The F or Fertility plasmid contains genes that are required for bacterial ________.
conjugation
This image is showing a step required for bacterial ________.
conjugation
Plasmids with a _____ copy number occur in only one copy per cell, while those with a ______ copy number are present in many copies per cell.
low; high
The easiest way to defect if streptomycin sensitive (Str5) cells are transformed with DNA from streptomycin resistant cells (Str8) is by growing the cells on ________.
medium containing streptomycin
The enzymes of the mismatch DNA repair mechanism distinguish between the template strand and the newly synthesized strand by the presence of an ______ group on certain nucleobases of the template strand.
methyl
Mutations are rare because _______.
most damage is repaired before it is passed on to progeny
DNA in the environment that is not contained within a cell or virus is called _______ DNA.
naked
Chemical mutagens that modify _______ increase the odds of incorrect nucleotide incorporation during DNA replication.
nucleobases
Repair of nucleotide incorporation errors during the process of DNA replication is accomplished by _________ by DNA polymerase and by _________ repair.
proofreading; mismatch
Once donor DNA is in a recipient cell, it integrates into that cell's chromosome by ________.
homologous recombination
Genetic change in bacteria occurs through which two mechanisms?
horizontal gene transfer mutation
After new virus particles have assembled in the bacterial host cell, they are usually _________.
released as a result of host cell lysis
When some species of bacteria reach a certain density or when nutrients are in short supply, they _______.
turn on genes required for competence
Examples of conditions where bacteria can become naturally competent in the environment include _________.
when certain nutrients are scarce when there is a high density of bacteria
Which mechanism of gene transfer involves the uptake of "naked" DNA by competent bacterial recipient cells?
Transformation
Which of the following are methods of gene transfer in bacteria?
Transformation Transduction Conjugation
The common consequence of a ________ mutation is the appearance of an early stop codon that produces a shortened and thus non-functional protein.
frameshift
During conjugation, the F plasmid nucleic acid that transfers is ________.
single-stranded DNA
Many DNA polymerases have the ability to detect and repair their own errors in nucleotide incorporation. This ability is called _______.
proofreading
Which of the following are sources of "naked" DNA?
secreted into the environment by bacteria lysed (burst) bacterial cell
"Jumping genes", or _________, can lead to changes in genotype within a cell or between cells.
transporons
T/F: When an Hfr cell transfers chromosomal DNA to a recipient cell, it does not need to produce an F pilus.
False
What are some of the disadvantages of the SOS DNA polymerase?
It can result in a lot of mutations in the DNA It has no proofreading ability
In transformation, only one daughter cell inherits donor DNA. This is because ________.
only a single strand of donor DNA integrates into the recipient chromosome
In an experiment, donor DNA, recipient cells, and DNase are added to a mixture. The recipient cells are not transformed. This tells us what about the donor DNA?
It is naked.
________ is used to fix nucleotide incorporation errors that are missed by the proofreading function of DNA polymerase.
Mismatch repair
________ are DNA segments that increase the rate of mutations by inserting themselves into genes and inactivating them.
Transporons
Which of the following types of radiation are mutagenic?
X-rays Ultraviolet rays
When DNA is transferred from an Hfr cell to a recipient cell, the recipient becomes _________.
an F cell
Base ______ structurally resemble nucleobases and can be mistakenly incorporated into nucleotides and then into DNA.
analogs
The repair of thymine dimers by enzymes that make single-stranded cuts that flank both sides of the thymine diner is called _______ repair.
excision
Chromosomal DNA that is transferred from an Hfr cell but does not integrate into the recipient's chromosome _______.
is degraded
Chromosomal DNA that is transferred from an Hfr cell but does not integrate into the recipient's chromosome __________.
is degraded
In bacterial conjugation, F+ donor cells are high frequency recombinant (Hfr) cells when the F plasmid _______.
is integrated into the chromosome
In bacterial conjugation, F+ donor cells are high frequency recombinant (Hfr) cells when the F plasmid _________.
is integrated into the chromosome
The transfer of bacterial DNA from a donor to recipient via a bacteriophage is called _________.
transduction
Place the steps of F plasmid transfer in the correct order.
F pilus makes contact with recipient cell One strand of F plasmid is cut in origin of transfer Single strand of F plasmid is transferred to the recipient cell Complement of transferred strand is synthesized
During DNA replication, the template strand can be distinguished from the newly synthesized strand by the presence of _____ groups on certain nucleobases. This is very important for mismatch repair.
methyl
Bacteriophages can consist of ___________.
RNA genome DNA genome Protein coat (capsid)
