Chapter 9 Microbial Genetics

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

excision

The lactose repressor protein binds to the ... ...of the lac operon.

operator

The process of bacteria turning on or off a group of genes that changes its phenotype in a heritable manner is called......

phase variation

A mutation that affects only a single pair in DNA is termed a ... mutation

point

... mutations are generally most harmful to cells because they cause the greatest change in the amino acid sequence of a protein.

frameshift

Control of enzymes at the level of gene expression ensures that

genes are active only when their enzyme products are required

The .... is the genetic makeup of an organism that is ultimately responsible for an organism's expressed characteristics.

genotype

The corepressor of the histidine biosynthetic operon is

histidine

Viral mRNA is translated into viral protein on ... ribosomes using ...tRNA

host; host

The final sealing of nicks in a newly synthesized DNA strand is catalyzed by the enzyme...

ligase

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

mutation

Genes are made up of building blocks called... ...

nucleic acids

The process of replication of the DNA molecule is described as being ... because the parent strands serve as templates for the production of two daughter strands of DNA.

semiconservative replication

What is the function of mRNA?

serves as a transcript of a gene sequence of template DNA

rRNA composes ... subunits together with protein

ribosomal

True or False: A RNA template is a strand of RNA made from DNA

False

True or false: A point mutation results from an insertion or deletion of nucleotides, and always leads to a shift of the triplet sequence from the point of mutation downstream.

False

Induced mutations are caused by

2-amino purine, and ultraviolet light

A codon contains how many nucleotides?

3

Which sequence of DNA nucleotides is complementary to the DNA triplet 5'-ATG-3'?

3'-TAC-5'

Which is the main event of transcription termination?

RNA polymerase reaches a terminator region

During transcription, RNA polymerase synthesizes ... from a(n) ... template

RNA; DNA

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

Recombination

Which kind of gene encodes a protein?

Structural

The lactose repressor protein is allosteric, meaning that it has two binding sites, on for ... and another for ...

The operator DNA sequence, and lactose

.... involves the transfer of DNA via bacteriophages.

Transduction

... RNA is transcribed and then plays a role in translation by carrying amino acids to the ribosome

Transfer

Which gene transfer method involves the uptake of free DNA by competent bacterial cells?

Transformation

... is the process of decoding the mRNA into a polypeptide.

Translation

"Jumping genes" or _____, can lead to changes in genotype within a cell or between cells.

Transposons

True or false: Eukaryotic DNA is linear whereas bacterial DNA is circular.

True

A nitrogen-containing molecule found in DNA and RNA that provides the basis for the genetic code is a nitrogenous....

base

Binding of arginine to the arginine repressor protein causes the repressor to

bind to the operator sequence

DNA transfer between bacterial cells typically involves DNA in the form of ...

chromosomal fragments or plasmids

A ... is a discrete cellular structure composed of a neatly packaged DNA molecule

chromosome

A ... is a discrete cellular structure composed of a neatly packaged molecule

chromosome

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

conjugation

During conjugation, the donor cell generally retains a copy of the genetic material being transferred. This is termed a ... process.

conservative

Biosynthesis of DNA, RNA, and protein ... energy.

consumes

A recombinant is defined as an organism that...

contains and expresses genes that originated in another organism.

Most DNA damage is resolved by...

enzymes

...are DNA sequences which encode for functional proteins.

exons

In Eukaryotes, which DNA sequences encode functional protein?

exons

The ability of Neisseria gonorrhoeae strains to produce attachment ... is an example of phase variation

fimbriae

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

introns

The newly forming DNA strand that is discontinuously replicated in segments (Okazaki fragments) is called the ... strand

lagging

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

mutations

A ... mutation results in early termination of the protein

nonsense

Building blocks of DNA, called .... , contain the same sugar and phosphate, but different nitrogenous bases.

nucleotides

In a protozoal or fungal cell, chromosomes are located in the...

nucleus

A(n) ... is a sequence of DNA nucleotides that codes for one functional protein or RNA.

gene

When a cell is actively growing, the arg operon is ...., and the arginine is ....

on; actively synthesized

When E. coli is grown in a medium containing both glucose and lactose, it will first consume the

glucose

The purine nitrogenous bases found in RNA are adenine and

guanine

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

plasmid

The protein bridge between two bacteria during conjugation is called the

pilus

The ... of the lac operon is a gene that encodes a repressor protein

regulator

Ensuring that the DNA code will be maintained during cell growth and cell ... is one of the two essential effects of the structure of DNA

replication

DNA ... are enzymes responsible for the replication of DNA.

polymerases

The ... is a particle composed of two subunits of rRNA that is the site of protein synthesis

ribosome

Mutations that occur because of errors in DNA replication are termed...

spontaneous

The mRNA sequence AUG, specifying the first amino acid in protein sequences, is called the .... codon

start

The ... of lac operon is comprised of three genes, each encoding a different enzyme needed to catabolize lactose

structural locus

Which RNA carries amino acids to the ribosome during protein synthesis?

tRNA

The process of transcription ... results in the release of a completed RNA transcript

termination

True or false: Several codons code for the same amino acid, which is called redundancy of the code.

true

True or false: The expression of the genotype creates traits referred to as the phenotype

true

The pyramidine nitrogenous bases found in RNA are cytosine and...

uracil

The native or ... type strain exhibits nonmutated characteristics

wild type

The two versions of transduction are...

specialized and generalized

Which is true regarding bacterial chromosomes?

Located in the nucleoid region of the cytoplasm.

The pyrimidine nitrogenous bases found in DNA are thymine and ...

Cytosine

An insertion sequence consists of only two genetic elements:

DNA encoding enzymes for transposition and tandem repeats

Which is the main event of translation?

mRNA binds to the ribosome

During semiconservative ... the DNA is duplicated prior to binary fission.

replication

When E. coli is grown in a medium containing both glucose and lactose, the lac operon will be

repressed until the glucose is consumed

Which is the main event of translation termination?

A nonsense codon is reached and the peptide is released from the ribosome

Which is the main event of translation elongation?

Amino acids are joined by peptide bonds.

What is the main event of transcription termination

RNA polymerase reaches a terminator region

Transposable elements are capable of moving from

The chromosome to a plasmid, one site in the chromosome to another site in the chromosome, and a plasmid to the chromosome.

Transposable elements are capable of moving from ...

The chromosome to a plasmid, one site in the chromosome to another site in the chromosome, and a plasmid to the chromosome.

... involves the uptake of free DNA by competent bacterial cells

Transformation

True or false: Topoisomerases relieve the superhelical tension as DNA is replicated.

True

.... , .... , and .... are the three stop codons within the genetic code.

UAG, UAA, UGA

The structure of DNA was discovered in 1953 by

Watson and Crick

True or false: The phenotype is the sum of all the genes constituting an organism's distinct genetic makeup.

false

The binding of lactose to the lactose repressor protein causes the repressor to leave the operator region. This happens because lactose...

induces a conformation change in the protein.

The ... DNA strand is the strand that is not directly used for transcription into mRNA during protein synthesis.

nontemplate

The DNA genome of DNA animal viruses is replicated in the ... ; the genome of RNA viruses is replicated in the ....

nucleus; cytoplasm

During ... DNA replication, the newly made double helices are composed of one parent template and one newly synthesized strand.

semiconservative

The 3' end of a eukaryotic chromosome that cannot be copied is called the ...

telomere

The parent strands in a DNA molecule are used as a ... to synthesize a complementary strand of DNA

template

Conjugation is a conservative process, meaning that...

the donor retains a copy of the genetic material being transferred

The antibiotic rifamycin can be used to treat tuberculosis because

the drug is more active against bacterial RNA polymerase than the human enzyme.

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

The term ... is a sequence of 3 consecutive nucleotide bases in DNA that encodes an amino acid.

triplet

True or false: Within a nucleotide, the phosphate group is linked to the 5' carbon of the pentose sugar.

true

Which template DNA sequence encodes the peptide sequence Phenylalanine-Leucine-Aspartic Acide-Valine?

3'-AAAAACCTACAT-5'

A DNA triplet encodes ... mRNA codon(s) and ... amino acid(s).

1;1

Which type of RNA is transcribed from a DNA template?

All types of RNA

The ... test is a method of detecting mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritionally defective bacteria.

Ames

The genes of which microorganisms are arranged as operons?

Bacteria

What is the function of tRNA?

Brings amnio acids to ribososmes to make proteins

Which two of the following statements regarding DNA packaging are correct?

DNA is thousands of times longer than the cell, and the intricate coiling of DNA is required to package it inside the cell.

Which is the main enzyme in elongation of a DNA strand during replication?

DNA polymerase

... is the pentose sugar in DNA

Deoxyribose

In bacterial conjugation, a recipient cell having no ... plasmid is considered F-

F

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

Genome

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

Hfr

What is the result of a point mutation that changes a template gene sequence from 3'-TACGCCATATAT-5' to 3'-TACGCCATCTAT-5'?

Nonsense mutation

the central dogma, DNA encodes ... which encodes protein.

RNA

Which enzyme transcribes DNA into RNA?

RNA polymerase

Which two of the following statements regarding tRNA charging with amino acids are correct?

The anticodon in tRNA specifies which amino acid it carries, and "Charging" refers to the process of adding an amino acid to a tRNA.

The pyrimidine nitrogenous bases found in DNA are cytosine and ...

Thymine

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

Triplet

The biosynthesis of the amino acid histidine requires enzymes whose genes are organized in the his operon. The his operon would be expected to be active when the cell is growing in a medium containing

a low concentration of amino acids

The regulator of the lac operon is a gene that encodes

a repressor protein

The purine nitrogenous bases found in RNA are guanine and ...

adenine

Which two of the following operons in E. Coli would be repressible?

an operon encoding amino acid biosynthetic enzymes, an operon encoding vitamin biosynthetic enzymes.

The enzyme beta-galactosidase, encoded in the lac operon has an enzymatic activity to

hydrolyze lactose

Mutations that occur because of exposure to know mutagens are termed

induced

Because lactose is ultimately responsible for stimulating protein synthesis from the lac operon it is called the

inducer

Many catabolic operons are ... , while those that encode anabolic enzymes are ...

inducible; repressible

A mutation that leads to the insertion of a different amino acid in the encoded protein is termed a ... mutation

missense

A mutation that leads to the insertion of a different amino acid in the encoded protein is termed a ... mutation.

missense

In bacteria, a regulatory gene, a control region, and structural genes collectively are referred to as a(n)...

operon

During replication initiation, the enzyme ... synthesizes primer sequences.

primase

RNA ... are structures that provide DNA polymerase with the 3' end needed for synthesis during DNA

primers

RNA polymerase binds to the ...region of the DNA to initiate transcription.

promoter

The ... of the lac operon is a region of DNA that is recognized by RNA polymerase.

promoter

During protein synthesis, many copies of a specific...can be synthesized from a single mRNA transcript.

protein

... and proteins compose ribosome subunits.

rRNA

In general, a strand of RNA made from DNA is called an RNA...

transcript

One reason protein synthesis is more efficient in bacteria than in eukaryotes is because bacterial ... and ... are simultaneous

transcription, translation

The process of introducing foreign genes to a plant cell by adding the DNA directly to the cell medium us termed

transfection

The process of shifting the ribosome down the nRNA to read new codons is termed...

translocation

What did Griffith's experiment using Streptococcus pneumoniae demonstrate?

That DNA released from a dead cell can be transferred to live cell

The genes of the lac operon in E.coli encode enzymes that

catabolize lactose


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