Micro Ch 9 Part 2
A ____ mutation changes an amino-acid-producing codon into a stop codon, leading to premature termination of a protein.
nonsense
The enzyme ____ ____ synthesizes a single strand DNA from the viral RNA template.
reverse transcriptase
A ____ mutation results in early termination of the protein.
nonsense
In bacterial conjugation, a donor cell with a F (fertility) ____ located in the cytoplasm is considered F+.
plasmid
Which type of plasmids confer the ability of an organism to survive treatment by antibiotics?
R factors
How do an Hfr cell and an F+ cell differ?
The plasmid is integrated into the chromosome of an Hfr cell but not in an F+ cell.
True or false: A cell with an integrated F factor transmits its genes at lower frequency than does a cell with a free plasmid in the cytoplasm.
False
True or false: Bacterial conjugation is a sexual process.
False
Which type of mutation is generally most harmful to cells?
Frameshift mutation
Which is an agent that induces changes in DNA?
Mutagen
Which process repairs DNA that has been damaged by ultraviolet radiation using visible light?
Photoactivation
____ refers to the transfer of genes from donor to recipient microorganisms.
Recombination
____ involves the transfer of DNA via bacteriophages.
Transduction
Which gene transfer method involves the uptake of free DNA by competent bacterial cells?
Transformation
A bacterial cell described as ____ can accept soluble DNA from the surrounding environment.
competent
Proteins that remove incorrect bases and replace them with correct ones are termed ____ repair enzymes.
excision
Plasmids are found in which type(s) of organisms?
fungi, bacteria
A ____ mutation results in a different amino acid being incorporated into a protein, with varying results.
missense
Donor and recipient bacterial cells are connected by the sex ____ during conjugation.
pilus
"Jumping genes" are known as ____.
transposons
In bacterial conjugation, which term refers to a recipient cell that does not have a fertility plasmid?
F-
True or false: Mutations are always harmful to cells.
False
Which of the following are true of RNA viruses compared to DNA viruses?
Smaller genomes, enter host cell in RNA form, virus cycle occurs in cytoplasm.
____ mutations in DNA are caused by random mistakes in replication and not known to be influenced by any mutagenic agent.
Spontaneous
True or false: A mutation is an alteration in the DNA sequence or content of a cell that is passed on when the cell divides.
True
An organism that has a mutation is called a ____.
mutant
Mutations that involve the addition, deletion, or substitution of a single base are referred to as ____ mutations.
point
Gram-____ cells conjugate and transfer genetic material through pores in their cell walls instead of pili.
positive
A(n) ____ mutation results from an insertion or deletion of nucleotides, leading to a shift of the triplet sequence from the point of mutation downstream.
frameshift
Any alteration in DNA that occurs as a consequence of exposure to chemical or physical mutagens is a(n) ____ mutation.
induced
Several DNA viruses are known to be initiators of cancers and are thus termed ____.
oncogenic
What is the main effect of ultraviolet radiation on DNA?
Abnormal bonding between adjacent pyrimidines
The ____ test is used to determine the carcinogenic potential of a chemical.
Ames
During which method of gene transfer are bacterial cells in direct contact?
Conjugation
____ is bacteria refers to horizontal gene exchange via pili.
Conjugation
The native or ____ type strain describes cells that carry nonmutated DNA.
wild
In bacterial conjugation, F+ donor cells are high frequency recombinant (Hfr) cells when the ____ is integrated into the chromosome.
F factor, plasmid
In bacterial conjugation, which term refers to a donor cell with a fertility plasmid located in the cytoplasm?
F+
Which viruses insert their DNA into the host genome increasing the risk of cancer?
Hepatitis B virus, Herpesvirus
What is a small circular segment of DNA found in the cytoplasm of prokaryotes that is capable of independent replication and usually contains nonessential genes?
Plasmid
Which defines a chemical or physical agent that induces a change in DNA?
Mutagen
____ of positive-strand ssRNA requires the synthesis of a negative strand which becomes a master template to create new daughter strands.
Replication
Which of the following is the genetic pattern of viral genomes?
Single or double stranded DNA or RNA
Transduction occurs through:
a bacteriophage
Griffith's experiment using Streptococcus pneumoniae demonstrated the process of ____.
transformation
The ssRNA of positive-strand viruses come ready to be ____ into proteins.
translated
