ch. 9: microbial genetics

DNA polymerase ____ is the main enzyme involved in the building of the new DNA chain, whereas DNA polymerase ____ is involved mostly with removing the primers and repairing damaged DNA.

III/I

Proteins that remove incorrect bases and replace them with correct ones are termed ______ repair enzymes.

excision

Several DNA viruses are known to be initiators of cancers and are thus termed

oncogenic

The mechanisms of ______ transformation involve genes that can regulate cellular genomes and control the onset of cell division.

oncogenic

In bacterial conjugation, a donor cell with a F (fertility) _____ located in the cytoplasm is considered F+.

plasmid

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

The complete set of chromosomes and genes in an organism is referred to as the

genome

A small number of ______ are considered beneficial in that they provide the cell with a useful change in structure or physiology.

mutations

Which type of mutation is due to random mistakes in replication?

spontaneous mutation

The term _____, or codon, is a sequence of 3 nucleotides in DNA that encodes an amino acid.

triplet

During semiconservative _____ the DNA is replicated prior to binary fission.

replication

In bacterial conjugation, which term refers to a recipient cell that does not have a fertility plasmid?

F-

True or false: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.

False; b/c Hfr donors have the F factor integrated into the chromosome

True or false: Viral genomes are always composed of either single or double stranded DNA.

False; b/c they can be composed of single or double stranded DNA or RNA

Which of the following are functions of RNA polymerase?

Unwinds DNA so that transcription can take place Synthesizes an RNA molecule from DNA template

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

Which is the correct order of events when a protein is made in the process of translation?

initiation, elongation, termination

Donor and recipient bacterial cells are connected by the sex pilus during

conjugation

phenotype

expression of inherited genes

True or false: Bacterial conjugation is a sexual process.

false

True or false: Mutations are always harmful to cells.

false

what are the types of RNA?

mRNA, tRNA, rRNA

a permanent inheritable alteration in the DNA sequence of a cell is a(n)

mutation

Which term represents all of the genetic information within a cell?

genome

The first three events of translation in the correct order are _____, _____, _____, followed by protein folding and processing.

initiation, elongation, termination

F- cell has no

plasmid

______ mutations in DNA are caused by random mistakes in replication and not known to be influenced by any mutagenic agent

spontaneous

anticodon

trinucleotide sequence in tRNA

Ames Test

used to determine the carcinogenic potential of a chemical

Two components of an operon include the _____ that acts as an on/off switch, and the _____ gene sequences.

operator; structural

Donor and recipient bacterial cells are connected by the sex ______ during conjugation.

pilus

Mutations that involve the addition, deletion, or substitution of no more than a few bases are referred to as

point mutations

The enzymes responsible for building the DNA strand, proofreading newly produced DNA strands, and removing the RNA primer are DNA _____ I and III.

polymerase

repressor

protein product of a repressor gene that combines with the operator and arrests the transcription and translation of structural genes

Which term refers to the transfer of genes from donor to recipient microorganisms?

recombination

recombination

refers to the transfer of genes from donor to recipient microorganisms, where the recipient strain shows a change in genetic makeup at the end.

What is the name of the specialized plasmid that directs conjugation in gram-negative cells?

F factor

The flow of genetic information in a cell is a process starting with _____ which encodes _____ which encodes protein.

DNA; RNA

The main enzyme responsible for transcription is

RNA polymerase

mutation

a change in genes and is not due to heredity

DNA polymerases are responsible for:

building the DNA chain proofreading/repair

The DNA of a chromosome is _____-stranded.

double

what is another term for genetics--the study of inheritance in living things?

heredity

In bacterial conjugation, which type of donor has the fertility factor integrated into the chromosome?

Hfr

Genetic inheritance in microorganisms is best defined by which term?

heredity

Genetic transfer of ______ to a methicillin-resistant Staphylococcus aureus (MRSA) strain produces vancomycin resistant enterococci (VRE).

a transposon containing the vanA operon

_____ in bacteria refers to horizontal gene transmission via pili

conjugation

The _____ protein is capable of repressing an operon.

repressor

The protein product of a repressor gene is the _____ which binds the operator to stop transcription.

repressor

In a chromosome, the DNA is composed of ______ strands.

2

Which best describes the flow of genetic information in a cell?

DNA encodes RNA which encodes protein

DNA polymerase I

Removing the RNA primers, replacing gaps between Okazaki fragments with correct nucleotides, repairing mismatched bases

Regulatory RNA

may exert control on several levels in both prokaryotes and eukaryotes

Which are components of an operon in a sequence of DNA?

operator and structural genes

DNA that has been damaged by ultraviolet radiation can be restored by what?

photoactivation or light repair

Which term, synonymous with codon, describes a trinucleotide sequence coding an amino acid in DNA?

triplet

Which nitrogenous base is found in RNA but not found in DNA?

uracil

Vancomycin-resistant enterococci (VRE) arise when, through genetic transfer, a MRSA strain acquires the ______ operon located within a _____.

vanA; transposon

What binds with an inactive repressor to make an active repressor?

corepressor

What must occur prior to cell division to ensure that each new cell has a complete set of DNA chromosome(s)?

(DNA) replication

introns

are DNA sequences found within a gene that do not encode the protein corresponding to the gene

Conjugation in gram-negative cells is directed by a plasmid called the

F factor

Which of the following is the genetic pattern of viral genomes?

Single or double stranded DNA or RNA

recombination

acquisition of new genes through mechanisms other than heredity

DNA polymerase III

adding bases to the new DNA chain, proofreading the chain for mistakes

In eukaryotic cells, gene expression is regulated in response to _____ stimuli such as nutrient and toxin levels, and also during growth and _____.

environmental; development

Which DNA sequences are found within a gene but do not encode the protein specified by that gene?

introns

inversion

the flipping of a DNA segment