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110 terms

Biology

STUDY
PLAY
Which of the following is NOT a criterion for an organism's genetic material?
The genetic material must be dynamic, changing rapidly in response to changes in the environment.
The protein of T2 bacteriophage is labeled with 35S and the DNA with 32P. Where would one detect most of the 32P if the T2 bacteriophage were allowed to infect the bacteria?
inside the infected bacteria
Which purine base forms 3 hydrogen bonds when binding its complementary nucleotide base?
guanine
How many replication forks are there at a replication origin?
2
This molecule catalyzes covalent bond formation between fragments of DNA.
ligase
All of the following are critical factors for DNA replication on the leading strand EXCEPT?
DNA ligase
Which molecule is responsible for separating double-stranded DNA into single strands?
DNA helicase
________ attaches DNA sequences at the ends of eukaryotic chromosomes
Telomerase
DNA is a double helix structure whose strands are held together by hydrogen bonds with A to T and C to G base pairing.
True
Okazaki fragments are sequences of DNA most often found on the lagging strand of DNA during DNA replication.
True
Who discovered that DNA was the genetic material or transforming factor that could convert nonvirulent R-type Streptococcus pneumoniae bacterium to the virulent S-type?
Avery, MacLeod, and McCarty
___________ are the building blocks of DNA.
nucleotides
In producing a strand of DNA the nucleotides combine to form what type of bond?
phosphodiester
The mechanism of DNA replication is
semiconservative.
Studies by Avery, MacLeod, and McCarty with different strains of bacteria and those by Hershey and Chase with T2 bacteriophage determined that proteins are highly complex molecules that form the genetic material for bacteria and viruses.
False
Which of the following would represent the "transformation principal" first proposed by Griffith through his studies on Streptococcus pneumoniae bacterium?
.DNA
The protein of T2 bacteriophage is labeled with 35S and the DNA with 32P. Where would one detect most of the 32P if the T2 bacteriophage were allowed to infect the bacteria
inside the infected bacteria
___________ are the building blocks of DNA.
nucleotides
All of the following nucleotide bases are pyrimidines EXCEPT
adenine
The mechanism of DNA replication is
semiconservative.
During DNA replication, all of the following proteins are important for separating the DNA strands and allowing movement of the replication fork EXCEPT
DNA polymerase
This molecule catalyzes covalent bond formation between fragments of DNA.
ligase
________ is directly produced from the transcription of a eukaryotic gene.
pre-mRNA
Which of the following statements about RNA processing in eukaryotes is INCORRECT?
Introns are simply excised out of pre-mRNA to produce the mature mRNA.
How many nucleotides are contained in a single codon?
3
Which of the following serves as the "translator" or intermediary between an mRNA codon and an amino acid?
tRNA
The most common eukaryotic ribosome carries out its function in the
cytosol.
How many distinct aminoacyl-tRNA synthetases does each cell make?
~20
What molecule provides the energy for translation?
GTP
RNA polymerase II of eukaryotes always requires more than one general transcription factor to initiate transcription.
True
DNA is used as a template to make mRNA, which contains the information to make a polypeptide.
True
tRNA contains the genetic code for producing a polypeptide.
False
The process that produces mRNA from DNA is called
transcription
Which of the following statements about RNA polymerase in bacteria is INCORRECT
It catalyzes the addition of nucleotides to the 5′ end of a growing RNA strand.
which of the following statements about the mRNA start codon is INCORRECT?
The start codon is usually GGA
Which factors are needed to recognize the stop codon and disassemble the translation machinery?
release factors
The most common eukaryotic ribosome carries out its function in the
cytosol.
A ________ bond holds the amino acids of a growing polypeptide chain together during the elongation stage of translation.
peptide
The term N-terminus refers to the presence of a(n) ________ at the 5′ end of a polypeptide.
amino group
A single gene always encodes for an enzyme
True
RNA polymerase II of eukaryotes always requires more than one general transcription factor to initiate transcription
True
A(n) ______ is an organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately results in the formation of a functional product
gene
Which protein influences the ability of RNA polymerase to transcribe genes?
transcription factors
________ enables a single gene to encode two or more polypeptides that are different in their amino acid sequence.
Alternative splicing
Because more than one codon can specify the same amino acid, the genetic code is said to be
degenerate.
The term N-terminus refers to the presence of a(n) ________ at the 5′ end of a polypeptide.
amino group
A single gene always encodes for an enzyme
True
DNA is used as a template to make mRNA, which contains the information to make a polypeptide
True
As part of the transcriptional unit, regulatory sequences are the sites where RNA polymerase and transcription factors bind to regulate transcription.
False
The cells of every organism make only a few different tRNA molecules encoded by the same gene.
False
In eukaryotes, 40S and 60S combine to form a 100S ribosome.
False
Some genes such as that for β-actin are expressed at relatively constant levels in tissues regardless of variations in the animal's condition. What do we call this type of gene?
constitutive gene
Once the lac repressor binds to the lac operator site, RNA polymerase is prevented from transcribing which genes?
galactosidase and galactoside transacetylase genes
The lac operator site within the lac operon is an example of which of the following?
cis-acting element
The ability of glucose to repress the lac operon depends on which of the following effector molecules?
cAMP
Which of the following occurs when the cAMP-CAP complex binds the CAP site near the lac promoter?
RNA polymerase binds to the promoter and transcription rate increases.
What is the effect of DNA methylation?
It inhibits transcription
Which of the following does NOT occur during transcriptional regulation in eukaryotes?
Chromatin is converted to the closed conformation
Small effector molecules directly bind the DNA they regulate.
False
RNA polymerase can bind to the promoter region of the DNA even when the lac repressor is bound to the operator site.
True
Unmethylated CpG islands are correlated with inactive genes
False
The ability of cells to control their level of gene expression is called
gene regulation
Liver cells, mammary cells, and skin cells all contain the same genome; however, their respective proteomes vary drastically. This observation is best explained by what phenomenon?
cell differentiation
Why is the operon arrangement of genes beneficial to certain bacteria?
It allows the coordinated regulation of a group of genes that encode proteins with a common function
The lacA gene found within the lac operon encodes for galactosidase transacetylase. This enzyme attaches a(n) ________ group to lactose and lactose analogs
acetyl
The lacP site lies within the lac operon and is upstream of the genes that encode for proteins involved in lactose uptake and metabolism. Which of the following statements is TRUE of the lacP site?
It is the lac promoter site where RNA polymerase binds.
Where is the response element found in eukaryotic genes?
50 to 100 base pairs upstream from the transcriptional start site
of the following does NOT occur during transcriptional regulation in eukaryotes?
Chromatin is converted to the closed conformation.
Eukaryotic DNA methylation occurs on which base
cytosine
Different globin polypeptides are expressed at similar levels during the embryonic and fetal stages of mammalian development.
False
Liver cells, mammary cells, and skin cells all contain the same genome; however, their respective proteomes vary drastically. This observation is best explained by what phenomenon?
cell differentiation
Which of the following are points of control for gene expression in eukaryotes?
All of the choices are correct
Why is the operon arrangement of genes beneficial to certain bacteria?
It allows the coordinated regulation of a group of genes that encode proteins with a common function
The lac operator site within the lac operon is an example of which of the following?
cis-acting element
The ability of glucose to repress the lac operon depends on which of the following effector molecules?
cAMP
What is the effect of DNA methylation
It inhibits transcription
Where is the response element found in eukaryotic genes?
50 to 100 base pairs upstream from the transcriptional start site
Which of the following does NOT occur during transcriptional regulation in eukaryotes?
Chromatin is converted to the closed conformation
Bacteria can regulate gene expression by controlling the rate at which mRNA is translated into protein
True
Both eukaryotes and prokaryotes require a promoter region for gene transcription.
True
All of the following are chemical mutations EXCEPT
X-rays
Ionizing radiation can produce which of the following
free radicals
Which of the following LEAST belongs with the others
nucleotide excision repair
Which of the following base pairs would be targeted and repaired by a mismatch repair system?
A-G
What is the function of the MutS protein in methyl-directed mismatch repair
To find mismatches.
________can convert proto-oncogenes into oncogenes
Nonsense mutations
Which of the following viruses can cause cancer
All of the choices are correct
At what phase of the cell cycle does p53 halt cell division if it senses DNA damage?
G1
Mutations can produce a polypeptide with increased function
True
Certain types of cancer are caused by viruses
True
Which of the following CANNOT be repaired by nucleotide excision repair (NER)?
mismatched bases
Which of the following base pairs would be targeted and repaired by a mismatch repair system
A-G
________can convert proto-oncogenes into oncogenes
Nonsense mutations
A physician discovered a cancerous tumor in the cartilage of a patient. What type of tumor is this?
sarcoma
Which of the following viruses can cause cancer
All of the choices are correct
Should a genetic abnormality arise, ________ prevent a cell from progressing uncontrollably through the cell cycle
checkpoint proteins
The timing of a mutation during development has negligible effects on the severity of the genetic defect
False
The movement of DNA polymerase continues unimpeded if a thymine dimer is present in the DNA double helix.
False
Most oncogenes encode proteins that function in cell growth signaling pathways.
True
Myc genes tend to be overexpressed in only a few forms of cancer
False
which of the following types of physical mutagens produces thymine dimer mutations?
ultraviolet light
A repair enzyme recognizes an incorrect structure in the DNA and directly converts it back to a correct structure. Which of the following DNA repair systems is responsible for the correction?
direct repair
When cancer cells have the ability to migrate to other parts of the body, they are said to be
metastatic.
Which of the following cellular proteins is NOT a part of the epidermal growth factor (EGF)/EGF receptor signaling pathway that leads to cell division?
MutS
MAPK and MEK are intracellular signaling proteins that mediate cell division induced by growth factors. When mutations in the normal MAPK and MEK genes result in an abnormally high level of MAPK and MEK activity and increases in the rate of cell division, then the mutated gene is called a(n)
oncogene.
All of the following tumor-suppressor genes inhibit cell division EXCEPT
BRCA1.
Which protein directs apoptosis?
caspase
Most oncogenes encode proteins that function in cell growth signaling pathways
True
Myc genes tend to be overexpressed in only a few forms of cancer
False
Certain types of cancer are caused by viruses
True