Microbiology chapter 13 and 14
Two important sites recognized by the sigma subunit and used to direct RNA polymerase core enzyme to the transcription start site are the ___ and __ sites
-35; -10
Place the molecules related to the direction of the flow of genetic information into the correct order, beginning with the genetic information.
1) DNA 2) RNA 3) Protein
Place the steps of translation elongation in order, with the first step to occur at the top.
1) aminoacyl-tRNA binding 2) transpeptidation 3) translocation
The following steps are carried out by DNA polymerase III for lagging strand synthesis (specifically synthesis of a single fragment on the lagging strand). Place them in the correct order with the first event at the top.
1) synthesize an RNA primer 2) discard old beta clamp proteins 3) load new beta clamps to the next spot on the DNA to be replicated 4) tether the template to the core enzyme
A typical tRNA molecule is ______ bases long.
70-95
The Shine-Dalgarno sequence(s) is/are located on this polycistronic mRNA at position(s)
A and C
Because the oriC locus in E. coli cells is rich in ________ base pairs, it has fewer hydrogen bonds overall, making it easier for it to become single-stranded to initiate DNA replication.
AT
Which nitrogenous bases typically pair in DNA? Instructions
Adenine ~ thymine Guanine ~ cytosine
Which statement regarding translation elongation is correct?
An amino acid matching the mRNA codon is added to the C-terminus of the polypeptide as the ribosome moves down the mRNA in the 5' to 3' direction.
Which of the following is most likely to contain repressible enzymes?
Biosynthetic pathways
Which four of the following are components of an amino acid?
Carboxyl group, amino group, alpha carbon atom, and a R side chain
Fred Griffith's work with Streptococcus pneumoniae in the late 1920s provided early evidence that _____ is the genetic material of cells.
DNA
Which three of the following are true of a helicase?
It moves using energy obtained from ATP hydrolysis, It is responsible for denaturing the 2 template strands of parent DNA, and It works ahead of the DNA replication fork.
Which three of the following statements are true regarding the antiparallel nature of double-stranded DNA?
One strand is oriented in the 5' to 3' direction while the other strand is oriented in the 3' to 5' direction, Both strands possess a free phosphate group on their 5' ends, and Both strands possess a free hydroxyl group on their 3' ends.
Which three of the following properties are used to categorize amino acids?
Presence of a charged side chain, presence of a nonpolar side chain, and presence of a polar side chain
uses the sugar ribose instead of deoxyribose and the base uracil instead of thymine.
RNA
The enzyme that catalyzes transcription is
RNA polymerase
The function of the promoter is to align the
RNA polymerase on the gene for transcription
Which of the following statements is false regarding factor-dependent transcription termination?
Sigma factor is the polypeptide that is responsible for factor-dependent transcription termination.
The work of Fred Griffith in the late 1920s on the bacterium _______________ pneumoniae provided early evidence on the identity of the genetic material of cells.
Streptococcus
Which of these statements best summarizes the frequency of errors in DNA replication?
The frequency of errors is low to reduce the number of potentially damaging mutations introduced each time DNA is replicated.
Which statement regarding methionine tRNAs is false?
The initiator tRNA has a formyl group bound to the sulfur in the methionine side chain.
Which statement regarding the orientation of genes and moving polymerases on the chromosome is true?
The replisome (DNA polymerase and accessory proteins) always moves in a specific direction on the chromosome.
Amino acids can be differentiated based on
The structure of their side chain (R group)
During DNA replication, DNA polymerases require a primer (of either DNA or RNA) to begin synthesis of DNA. Why?
They need a 'starting point' free 3' hydroxyl group to attach nucleotides to.
Which of the following are steps where gene expression is commonly regulated in bacteria?
Transcription elongation, Initiation of translation, initiation of transcription
Which of the following best describes the localization of transcription and translation within a bacteria cell?
Transcription occurs in the nucleoid and RNA polymerase moves toward the cytoplasm to hand off the transcript to a 30S ribosomal subunit.
Which arrow points to the α carbon of the amino acid?
X
Which two of the following does DNA polymerase require to catalyze the synthesis of DNA?
a primer (DNA or RNA) to provide a free 3' hydroxyl group, and template DNA
The trailer region of a gene produces
a region on the mRNA after the stop codon that is transcribed but not translated
The amino acid is added to the ___ of a tRNA
acceptor stem
Binding of an effector to one domain of a transcriptional regulatory protein changes the conformation of its DNA-binding domain. This is an example of
allosteric control
DNA polymerase catalyzes the formation of a phosphodiester bond between an existing DNA strand and
an incoming nucleoside triphosphate
The term _____________ describes the situation where one strand of DNA is oriented in the 5' to 3' direction while its complementary strand is oriented in the reverse 3' to 5' direction.
antiparallel
In translation elongation, each new amino acid is added to the ______ terminus of the polypeptide.
carboxyl
Which of the following is most likely to contain inducible enzymes?
catabolic pathways
After DNA replication, the two daughter chromosomes may be topologically linked, like two links in a chain. These linked chromosomes are called
catenanes
During translation, a triplet _____ corresponds to a 'word' being 'read' from the mRNA to be translated into a particular amino acid in the polypeptide
codon
Which two of the following descriptors apply to RNA?
contains the sugar ribose instead of deoxyribose, uses the base uracil instead of deoxyribose
Topoisomerase resolves catenated daughter chromosomes by
creating a double-stranded break in one chromosome, then rejoining the strands after the chromosomes are separated
The sugar molecule found in DNA is ______, while the sugar molecule used in RNA is ______.
deoxyribose; ribose
The unusual amino acid selenocysteine is inserted into proteins via recognition with a specific ______ factor. This is followed by incorporation when a UGA stop codon is encountered in association with nucleotide sequences called cis-acting selenocysteine insertion sequence elements (SECIS).
elongation
True or false: All genes code for proteins.
false
True or false: Most enzymes in biosynthetic pathways are inducible enzymes.
false
The large amount of energy required to synthesize proteins is to ensure the _____ of the protein synthesis process.
fidelity
During DNA replication, the holoenzyme must discard old clamps, load new clamps, and tether the template to the core enzyme
for each okazaki fragment
The addition of one amino acid to a polypeptide is an energy-intensive process. For each amino acid added, _____ GTPs are hydrolyzed and _____ ATPs are required for amino acid activation.
four; two
The enzyme responsible for denaturing DNA in front of the replication fork is
helicase
The rho factor binds to a site on the mRNA and uses its ______ activity to dissociate the RNA from the DNA template.
helicase
Some genes are oriented to be transcribed in the same direction that the replisome (DNA polymerase and accessory proteins) moves. The genes generally encode
highly expressed proteins
The level of some enzymes, such as β-galactosidase, increase significantly in the presence of a small effector molecule called a(n)
inducer
Small effector molecules whose presence increases the level of specific enzymes are called
inducers
Transcription involves three separate processes: ___, elongation, and termination
initiation
The coding region of a gene
is between the start and stop codons
The Shine-Dalgarno sequence
is located in mRNA and is important in the initiation of translation and is found in bacteria
This mRNA can be identified as a polycistronic mRNA because
it has more than one coding region
A gene promoter functions to position the RNA polymerase so that
it is at the exact DNA template for the RNA to be synthesized
In E. coli, the oriC locus is a good point for the initiation of DNA replication because
it is rich in AT base pairs
The protein factor NusG interacts with both the RNA polymerase and the 30S ribosomal subunit and is believed to act to
keep the mRNA single-stranded
During DNA replication, the ______ strand is replicated in the direction opposite to the movement of the replication fork.
lagging
An initially transcribed portion of the gene that does not code for amino acids is the _____ region
leader
During DNA replication, one strand of DNA is replicated as the replisome moves in the same direction as the replication fork. This strand is called the _____ strand
leading
Match each type of RNA with its function. Instructions
mRNA ~ specifies the sequence of amino acids for protein synthesis tRNA ~ carries amino acids during protein synthesis rRNA ~ structural components of ribosomes
The Shine-Dalgarno sequence is located on ________ molecules and is important in the initiation of
mRNA; translation
Code degeneracy and wobble in the genetic code means that
multiple codons can bind with the same anticodon on a tRNA molecule
The term 'operon' describes
multiple genes transcribed from a single promoter
Translation termination occurs when
one of three stop codons is reached by the ribosome
A set of genes transcribed from a single promoter is termed a(n)
operon
DNA polymerase catalyzes the formation of a(n) ______ bond between an existing DNA strand and an incoming nucleoside triphosphate.
phosphodiester
Bacterial RNA polymerase contains five different types of
polypeptides
The enzyme RNA polymerase is composed of six subunits, two α, β, β', δ, and σ. The complete functional enzyme is said to exhibit ____ structure
quaternary
In the ribosome's translational domain, the A site
receives tRNAs carrying the next amino acid to be added
The sigma factor of bacterial RNA polymerase enables the enzyme to
recognize the promoter
The complex of twelve or more proteins that replicates the DNA is called the
replisome
A corepressor, a small effector molecule, is typically found in systems that use ______ enzymes.
repressible
Proteins that inhibit transcription initiation by binding to operator DNA are called
repressor proteins
Ribose in RNA is different from deoxyribose in DNA because
ribose has a hydroxyl group attached to the 2' carbon
DNA replication could be categorized as a(n) ______ and ______ process.
semiconservative and extremely accurate
The unusual amino acid selenocysteine is synthesized from ______ after it has been attached to certain tRNA molecules by the enzyme
serine; selenocysteine synthase
The _____ factor subunit of bacterial RNA polymerase recognizes two sequences of six bases each about 35 base pairs and about 10 base pairs before the transcription start point.
sigma
The component of RNA polymerase holoenzyme that recognizes a promoter is called
sigma factor
The process of translation continues until a(n) ___ codon is reached.
stop
The terminator sequence of a gene will
stop transcription by RNA polymerase
Not all genes code for proteins - some code for __ RNA or __ RNA.
t ; r
The enzyme DNA polymerase is composed of a single polypeptide that folds into its active configuration. The complete functional enzyme is said to exhibit ____ structure
tertiary
The three sites in the translational domain of the ribosome are
the A,P and E sites
The replisome is best defined as
the complex of at least twelve proteins that performs DNA synthesis at a replication fork
The fMet-tRNA differs from the Met-tRNA in that
the fMet-tRNA has a formyl group covalently bound to the amino group of the methionine
The coding region of a gene typically begins with
the start codon
The reading frame of an mRNA molecule is
the way triplets of bases are read to code for individual amino acids
Guanine pairs with cytosine using ______ hydrogen bonds, while adenine pairs with thymidine using ______ hydrogen bonds.
three; two
The leader region ______ in a messenger RNA is not actually ______ into amino acid sequence later
transcribed; translated
The three stages of the mRNA synthesis are initiation, elongation, and termination, and they are often referred to collectively as the ___ cycle
transcription
Regulation of gene expression at the level of RNA polymerase binding to the promoter occurs through the action of proteins termed
transcription factors
_____ is a process which generates three kinds of RNA. ____ carries amino acids during protein synthesis. ____ molecules are components of ribosomes. ____ bears the message for protein synthesis.
transcription; transfer RNA, ribosomal rna, messenger RNA
The process of synthesizing a messenger RNA molecule using DNA as a template is ______, while the process of synthesizing a polypeptide from the messenger RNA is ______.
transcription; translation
Match the level of control with its definition
transcriptional control ~ control of mRNA synthesis Translational control ~ control of protein synthesis Protein activity control ~ control of posttranslational modification
There are three phases of the translation elongation cycle. They include aminoacyl-tRNA binding, the ______ reaction, and translocation.
transpeptidation
True or false: Most enzymes in biosynthetic pathways are repressible enzymes.
true
Although there are 61 sense codons, there are not 61 different tRNA molecules. Code degeneracy and ___ in the genetic code allows several codons to pair with the same anticodon on a tRNA molecule.
wobble
