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Which is the correct sequence of events in eukaryotic gene expression?
1 ‐ RNA processing
2 ‐ transcription
3 ‐ translation
4 ‐ export of the mRNA out of the nucleus
Garrod hypothesized that ʺinborn errors of metabolismʺ such as phenylketonuria occur because...
genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.
The amino acid sequence of a protein...
-determines its function.
-is determined by the mRNA nucleotide sequence that “encodes” it.
In the process of transcription...
a strand of mRNA is formed with nucleotide sequences complementary to those of DNA.
In the process of translation,...
a polypeptide is formed as dictated by the nucleotide sequence in mRNA.
New amino acids (other than the initial start Met) enter at which site?
At the E site...
the “uncharged” tRNA is released.
During translation, the growing polypeptide may be found attached to a tRNA in which position(s)?
As the ribosome shifts down the mRNA by a distance of three nucleotides, the tRNA that was in the...
P site moves into the E site.
Translation is terminated when a stop codon is presented at the ________ site.
The complimentary messenger RNA strand that would be synthesized from the DNA base sequence of CTGAC would be
Splicing joins together...
Which of the following statements about eukaryotic mRNA is TRUE?
-A “cap” is added to their 5ʹ end.
-A “poly‐A tail” is added to their 3ʹ end.
-Each mRNA transcript usually specifies only a single protein.
If a frameshift mutation causes a stop codon to be inserted into the DNA sequence...
the resulting protein will be too short and non‐functional.
A nucleotide deletion in the coding region of a DNA sequence...
causes the amino acids inserted AFTER the deletion to be incorrect.
A mutation in which of the following parts of a gene is likely to be LEAST damaging to a cell?
intron (gets cut out)
correct sequence of events in translation...
1 ‐ A release factor enters the A site.
2 ‐ A charged tRNA enters the A site.
3 ‐ The ribosome translocates.
4 ‐ A peptide bond is formed between the polypeptide chain on the tRNA in the P site and the amino acid on the tRNA in the A site.
5 ‐ The small and large ribosome subunits assemble at the start codon of the mRNA transcript.
6 ‐ Translation terminates.
-are read in nonoverlapping units.
-specify either the particular amino acid that should be incorporated during translation or indicate the point at which translation should be terminated.
The genetic code is...
Which enzyme is incorrectly matched to its function?
a. RNA polymerase ‐ transcription
b. aminoacyl‐tRNA synthetase ‐ attaches an amino acid to a tRNA b. peptidyl transferase ‐ translation
d. DNA ligase ‐ joins Okazaki fragments
Which of the following RNAs is INCORRECTLY paired with its function?
pre‐mRNA ‐ mRNA that has had its introns removed by splicing
RNA molecule that carries information specifying the sequence of amino acids of a protein from DNA to ribosomes
small RNA molecule that transfers an amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation
is an important catalytic and structural component of the ribosome.
is an important catalytic and structural component of the spliceosome.
Endocrine signaling involves the release of ligands (signaling molecules) into the blood stream and affects neighboring cells only.
one cell releases ligands (signaling molecules) that act on membrane‐receptors on that nearby cells.
one cell releases ligands (signaling molecules) that act on membrane‐receptors on that same cell.
________ ligands (signaling molecules) bind to membrane‐bound receptors on adjacent cells in the process of contact‐dependent signaling.
Which event best describes “reception” of a signal?
The conformational change of a receptor as it binds a signaling molecule.
ligands (signaling molecules) pass through a cell junction from on cell to adjacent cells via the cytosol.
During exposure to elevated glucose, a yeast cellʹs membrane glucose transporters will rapidly increase so the cell can import glucose. Which would represent the signal (primary messenger) for the yeast cell in this signal transduction pathway?
Which is the correct sequence of events in a receptor‐mediated cell signaling event?
1 – signal transduction
2 – receptor activation
3 – ligand (signal molecule) binding 4 – signal termination
5 – cellular response
3, 2, 1, 5, 4
A ligand is a...
small molecule that binds to a membrane‐bound receptor.
Which statement best describes the advantage of second messengers?
In general, kinases _________ target proteins, whereas, phosphatases _________ target proteins.
In general, a signal transmitted via phosphorylation of a protein...
brings a conformational change that often activates that protein.
Which is the correct sequence of activation of the proteins involved in a G‐protein coupled receptor‐ mediated cell signaling pathway?
1 ‐ G‐protein
2 ‐ G‐protein coupled receptor 3 – intracellular target protein 4 ‐ adenylyl cyclase
5 ‐ protein kinase A
2, 1, 4, 5, 3
The second messenger cAMP is synthesized by the enzyme...
As a result of ligand binding to the G‐protein coupled receptor, the G‐protein changes conformation and ultimately...
GTP replaces the GDP on the alpha subunit.
the alpha subunit rejoins the beta and gamma subunits.
Which of the following events does NOT occur as part of G‐protein coupled receptor‐mediated cell signaling...
a. Proteins undergo conformational changes.
b. GTP is hydrolyzed to GDP.
c. The (ligand) signaling molecule is transported across the membrane. d. Enzymes are activated.
The (ligand) signaling molecule is transported across the membrane.
cGMP is synthesized and hydrolyzed similarly to cAMP. One function of cGMP is to provide a signal that leads to dilation of blood vessels and increased blood flow to target organs. Viagra, a prescription drug used to treat erectile dysfunction (as well as pulmonary arterial hypertension), facilitates an erection by prolonging cGMP signaling. Viagra most likely works by
Which of the following might be responses of a cell due to activation of a particular cell signaling pathway?
a. altered metabolism (either catabolism or anabolism)
b. altered cell shape
c. altered gene expression
d. cell movement
In Sutherland’s experiments investigating the ability of epinephrine to stimulate the liver to convert glycogen to glucose‐6‐phosphate in liver cells,...
a. the primary messenger is epinephrine.
b. the secondary messenger is cAMP.
c. the target protein is glycogen phosphorylase, an enzyme that catalyzes the conversion of glycogen to glucose‐6‐phosphate.
In eukaryotes, cell cycle checkpoints...
a. verify that the processes at each phase of the cell cycle have been accurately completed before progression into the next phase.
b. act at G1, G2, and mitosis.
c. rely on a special class of kinases and regulatory proteins.
d. are important to insure DNA mutations or chromosomal abnormalities are not propagated (passed on) to daughter cells.
Which is the period between cell divisions?
The cell cycle is controlled in most cells by...
a series of checkpoints.
If mammalian cells receive a “go‐ahead” signal at the G1 checkpoint, they will most likely...
complete the cycle and divide.
Which of the following is the protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?
cyclin‐dependent kinase (cdk)
a. are a family of proteins that help control the progression of cells through the cell cycle.
b. show concentrations that vary in a cyclical fashion during the cell cycle.
c. have no enzymatic activity themselves.
When a replication error occurs, the process by which the DNA polymerase repairs the damage is known as ____.
nucleotide excision repair
Which of the following is TRUE regarding thymine dimers?
a. Thymine dimers are covalent linkages between adjacent thymine bases in DNA.
b. Thymine dimers can be repaired by the cell.
c. Thymine dimers can induce mutations during DNA replication.
d. Thymine dimers are often induced by UV light.
p53 or protein 53 has been described as ʺthe guardian of the genomeʺ and responds to diverse cellular stresses to regulate target genes that induce cell cycle arrest, apoptosis, senescence, DNA repair, or changes in metabolism. Given this description, p53 is most likely a
tumor suppressor gene.
The myc protein regulates transcription of diverse sets of genes, many of which induce cell proliferation. Given this description, myc is most likely a
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