Ch. 7 Microbiology Assignment Questions

the subunits of the 70S ribosome are - 50S - 40S - 60S - 30S

- 50S - 30S

which proteins are involved in the initiation of DNA replication - DNA gyrase - template - helicases - primase - DNA polymerase

- DNA gyrase - helicases - primase

which of the following allow cells to control expression of certain genes or groups of genes - DNA-binding proteins - alternative sigma factors - two-component regulatory systems - constitutive enzymes

- DNA-binding proteins - alternative sigma factors

How does RNA differ from DNA? - RNA is usually single stranded - Ribose in RNA contains one less carbon than deoxyribose in DNA - in RNA, uracil replaces thymine - in RNA, thymine is replaced with adenine

- RNA is usually single stranded - in RNA, uracil replaces thymine

select the true statements about events that take place during the elongation phase of translation - a peptide bond is formed between amino acids on adjacent tRNAs - tRNAs carrying amino acids occupy the A-site and the P-site of the ribosome - empty tRNAs leave the ribosome via the E-site - elongation starts at the promotor sequence of the DNA - amino acids are joined together by the enzymes RNA polymerase

- a peptide bond is formed between amino acids on adjacent tRNAs - tRNAs carrying amino acids occupy the A-site and the P-site of the ribosome - empty tRNAs leave the ribosome via the E-site

select the enzymes that function in DNA replication - primase - reverse transcriptase - lipase - ligase - helicase - DNA polymerase

- primase - ligase - helicase - DNA polymerase

which of the following involve transmission of information from the environment to a cell, allowing the cell to react to changing conditions - environmental fluctuation - quorum sensing - two component regulatory systems - antigenic variation - phase variation

- quorum sensing - two component regulatory systems

two component regulatory systems that microorganisms use to monitor their environment consist of which two proteins - sensor protein - response regulator - quorum sensor - natural selector

- sensor protein - response regulator

Which of the following are post-translational modification events? - the start and stops codons are removed from the new protein - signal sequences are added, tagging the protein for transport - proteins are folded into functional shapes by chaperones - the ribosome involved in synthesis of that protein is degraded by proteases

- signal sequences are added, tagging the protein for transport - proteins are folded into functional shapes by chaperones

identify the three different types of RNA used in gene expression - tRNA - cRNA - mRNA - rRNa

- tRNA - mRNA - rRNa

RNA polymerase can only add nucleotides to the ___ end of a growing strand

3'

when analyzing a DNA sequence, the sequence ___ on the plus strand indicates the possible start codon AUG in an RNA transcript

ATG

The molecule that contains all the instructions needed to produce a cell's components is ___ a) protein b) RNA c) DNA

DNA

the eukaryotic ribosome is 80S, and its subunits are a) 60S b) 40S c) 30S d) 50S

a) 60S b) 40S

at transcription termination, RNA polymerase encounters which of the folowing? a) a terminator and the RNA falls off the DNA template b) DNA nucleobases, which join to form a polypeptide c) DNA and RNA nucleotides, which join to form a polypeptide d) a start codon, which initiaties another transcript

a) a terminator and the RNA falls off the DNA template

bacteria use two-component regulatory systems to detect and react to changes in the a) external environment b) internal environment

a) external environment

carbon catabolite repression is a regulatory mechanism that ensures that a cell a) imports and uses the sugar that allows fastest cell growth b) can mutuate so that it can use any carbon source for growth c) imports and uses lactose if it is present in the medium d) only imports and uses glucose from a medium

a) imports and uses the sugar that allows fastest cell growth

the ___ DNA strand is used as the template for RNA synthesis a) minus (-) b) plus (+)

a) minus (-)

DNA replication is described as being ___, because each new DNA molecule formed by the process has one original parent strand and one newly synthesized strand a) semiconservative b) synthetic c) conservative d) complementary

a) semiconservative

a(n) ___ is a regulatory protein that facilitates transcription by enhancing the ability of RNA polymerase to initiate transcription

activator

a tRNA has a(n) ___ which is complementary to the ___ of the mRNA

anticodon, codon

the two strands of the DNA helix are ___, meaning they are arranged in opposite directions

antiparallel

consider the lac operon: When ___ is not available, a repressor prevents transcription. When lactose is available, some of it is converted into ___, which is an inducer a) lactose; glucose b) lactose; allolactose c) allolactose; lactose d) glucose; lactose

b) lactose; allolactose

RNA polymerase binds to the ___ to begin transcription a) initiator b) promotor c) terminator d) primer

b) promotor

metagenomics is defined as which of the following a) large genes in a bacterial population b) study of the total microbial genomes in an environment c) study of microbial regulatory genes in an organism

b) study of the total microbial genomes in an environment

what regions of DNA signals the end of an RNA transcript a) operator b) terminator c) promotor

b) terminator

a new field, called ___, has emerged involved with the computer based analysis of nucleotide sequences

bioinformatics

The sequence of nucleotides in DNA dictates the sequence of a) nitrogenous bases in nucleotides b) nucleotides in DNA c) amino acids in a protein d) protein in amino acids

c) amino acids in a protein

Why is regulation of gene expression important? a) a cell can only express certain genes at any one time b) the cell needs a "rest period" when making protein c) not all cell proteins are needed all of the time

c) not all cell proteins are needed all of the time

The ___ sequence of DNA encodes the ___ ___ of protein a) amino acids; protein b) protein; amino acid c) nucleotide; amino acids d) codons; nucleobases e) nucleobases; amino acids

c) nucleotide; amino acids

to initiate replication of a DNA molecule, specific proteins must bind to a specific DNA sequence called which of the following a) beginning point b) start sequence c) origin of replication

c) origin of replication

all DNA nucleotides contain which of the following a) the same nucleobase and phosphate, but different sugars b) the same sugar, but different phosphates and nucleobases c) the same sugar and phosphate, but different nucleobases d) the same nucleobases, but different phosphates and sugars

c) the same sugar and phosphate, but different nucleobases

CAP must be bound to the inducer ___ in order to be function in the cell

cAMP

post transcriptional modification: methylated guanine derivative at the 5' end is called

cap

what is it called when an enzyme is constantly synthesized

constitutive

a repressor protein can only bind to the operator if the repressor forms a complex with a ___ molecule

corepressor

translation occurs in the ___ of eukaryotic protozoa and the ___ of bacterial cells

cytoplasm, cytoplasm

transcription occurs in the ___ of bacteria and the ___ of yeast cells

cytoplasm, nucleus

which enzyme completes the final sealing of okazaki fragments in a newly synthesized DNA strand a) RNA polymerase b) helicase c) DNA polymerase d) DNA ligase

d) DNA ligase

what enzyme binds to the DNA promotor region to initiate transcription a) DNA gyrase b) primase c) DNA polymerase d) RNA polymerase e) RNA synthase

d) RNA polymerase

some microorganisms can alter characteristics of certain surface proteins, allowing them to avoid detection by the host's immune system. This phenomenon is called ___ a) phase variation b) natural selection c) quorum sensing d) antigenic variation

d) antigenic variation

the lac operon only functions when ___ is present in the medium but ___ is absent from the medium a) glucose; lactose b) glucose; allolactose c) lactose; altose d) lactose; glucose

d) lactose; glucose

during elongation, RNA polymerase synthesizes a single-stranded RNA molecule using the ___ stand of the DNA template a) plus (+) b) protein c) RNA d) minus (-)

d) minus (-)

in the presence of lactose, the repressor no longer binds to the ___ and transcription ___ a) promoter; proceeds b) operator; stops c) promotor; stops d) operator; proceeds

d) operator; proceeds

a ___, which is a characteristic series of amino acids at one end of a protein, tags that protein for transport a) transport factor b) sigma factor c) start codon d) signal sequence

d) signal sequence

microorganisms must adapt rapidly to changes in their environment in order to do which of the following a) infect b) die c) communicate d) survive

d) survive

high temperatures break the hydrogen bonds between the two strands of DNA, causing the double stranded molecule to ___

denature

T/F: DNA binding proteins that bind to DNA always inhibit transcription

false

T/F: repressible enzymes are essential enzymes that are constantly synthesized and are involved in processes such as glycolysis

false

the functional unit of a genome that codes for a product is a(n)

gene

what is it called when an enzyme is synthesized only when needed

inducible

repressor proteins block transcription. If the shape of the repressor is changed so that it cannot bind to the operator, ___ occurs and transcription progresses a) repression b) induction c) translation d) splicing

induction

which is the correct order of events in transcription - elongation - initiation - termination

initiation, elongation, termination

___ is a copy of the DNA template that is translated during protein synthesis

mRNA

computer analysis of nucleotide sequences looks for ___ ___ ___, which are stretches of DNA that potentially encode a protein

open reading frames

an operator, a promotor, and a regulatory protein are components of an

operon

post transcriptional modification: adenine derivatives at the 3' end is called

polyadenylation

the translation "machinery" reads the mRNA in groups of 3 nucleotides; as a consequence, any given sequence has three possible ___ ___

reading frames

duplication of the genome is called

replication

the ___ ___ is a Y-shaped point on a replicating DNA molecule where the DNA polymerase is synthesizing new strands of DNA

replication fork

what is it called when enzyme synthesis is turned off when not needed

repressible

DNA binding proteins control transcription. A binding protein that blocks transcription is called a(n) ___, while one that facilitates transcription is called a(n) ___

repressor, activator

protein synthesis involves ___ which align amino acids and catalyze peptide bond formation between them

ribosomes

RNA is produced when a region of DNA known as the ___ is copied. The newly synthesized strand of RNA is called the ___.

template, transcript

copying DNA into RNA is called

transcription

information is passed from the environment into the cell by a process known as a signal ____

transduction

decoding RNA to synthesize protein is called

translation

T/F: quorum sensing allows bacteria to detect population density; facilitating coordinated activities such as biofilm formation

true

T/F: the lac operon is an inducible operon

true

T/F: when a repressor is bound to the operator of an operon, transcription is blocked

true

the nucleobase thymine in DNA is replaced by ___ in RNA

uracil