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