FINAL PRACTICE QUESTIONS Flashcards
The formation of disulfide bonds depends on which chemical environment?
Oxidizing
What are the four descriptors of a plasmid?
Small DNA, Extrachromosomal, Autonomously-replicating, Circular
What is the melting temperature of a primer with the sequence 5’-GATAGCACCATCGTCAG-3’
52 degrees C
Antibiotics are added to solid culture medium for plating bacteria transformed with recombinant plasmids to
prevent nontransformed bacteria from yielding colonies
What components are needed for the synthesis of cDNA?
Reverse transcriptase, Deoxynucleoside triphosphates, a poly-thymidine phosphate synthetic oligonucleotide
What is NOT a feature that is shared by both prokaryotes and eukaryotes?
Endoplasmic Reticulum
Which properties of tRNA contribute to the degeneracy of the code
-Structure of the anticodon loop
-Incorporation of inosine in tRNA
-Attachment of the same amino acid to different tRNAs
What is NOT an important element of an expression vector to be used in yeast cells following gene cloning by ligation?
A promoter compatible with E.Coli
(A selectable marker that is compatible with E.Coli, a promoter compatible with yeast, and an origin of replication compatible with yeast are needed)
In Mendel’s experiment, he demonstrated that a daughter plant could pass on either parent’s allele to its offspring (but not both parents) lends support to which principle?
Discrete particle model
The synonym for the + strand of DNA is
coding strand
What is a post-translational modification that might occur to a protein secreted from a eukaryotic cell?
Glycosylation
A major advantage of translation-level control of gene expression compared to transcription-level control is
Faster response is possible
What is an advantage of solid phase synthesis over solution phase synthesis?
Easy removal of reactants between steps
In prokaryotic cells, the small ribosomal subunit is positioned at the start codon largely due to
base pairing between the Shine-Dalgarno sequence and rRNA
In experiments performed by Avery. Macleod, and McCarty, depletion of which component in extracts from “smooth type” pneumonia-causing bacteria prevented the transformation of ‘rough-type’ bacteria?
Deoxyribonucleic acid
If the lac repressor binds to lactose with an equilibrium constant Ka = 1 x 10^7 (M^-1), the transcriptional state of the lac operon will most likely be ________________ when the lactose concentration is 1 x 10^-5
High transcription
Why would Asn-Val-Thr be a sequence that might signal N-linked carbohydrate attachment to a protein expressed in a eukaryote?
Must be Asparagine - ____________ - Serine or Threonine
Energy required for ribosomal translocation is supplied by
GTP bound to an elongation factor protein
What is the most likely phenotypic effect to be observed in response to a random mutation in the amino acid sequence of a protein?
function unaffected
Which of the following statements about the regulatory gene is NOT true? The regulatory gene…
A. encodes the repressor
B. is always transcribed
C. is always located adjacent to the promoter
D. All of the above are untrue
C. Is always located adjacent to the promoter
A restriction endonuclease recognizing the sequence 5’-ATGCAT-3’ cleaves to yield a 4 base sticky end with a 3’ overhang. What would a product look like?
A terminal phosphate group would be left on the 6th nucleotide 5’-ATGCA *T-3’)
Unequal sharing of electrons by two atoms sharing a covalent bond is important to…
Hydrogen bonds, Dipole-Diploe bonds, and Hydrophobic effect
One method to transfrom bacterial cells with plasmid DNA is
electroporation
Most amino acids are chiral because
they have an atomic center of asymmetry
The side chain of which amino acid will most likely engage in covalent bonds
C
A bacterial gene is cloned into an expression vector for use in mammalian cells, and the vector is used to express the protein product in a mammalian cell line. No product is found in the culture medium, instead the product is found to have accumulated in the cytoplasm of the expression host cells. What is a likely explanation for this?
The gene product did not include a secretory signal peptide.
An open reading frame is…
the codon sequence bounded by the first ATG and the first subsequent stop codon
What is one way that chemical synthesis of DNA differs from natural synthesis?
Chemical synthesis proceeds in the 3’ —> 5’ direction
What are inclusion bodies?
Dense particles of protein sometimes found in the cytoplasm of cells that have been engineered for recombinant expression.
Which of the following is NOT true of secondary structures in proteins?
A. Van der Waals attractions between side chains are important to their stability
B. Formation depends on H-bonds between the backbone groups
C. The primary types are A-helices and B-sheets
D. They usually form rapidly after the creation of the polypeptide by the ribosome
E. All of the above (i.e, none of the above are true)
A. Van der Waals attractions between side chains are important to their stability
What property of Taq polymerase is highly useful for PCR?
Thermostability
What is a short peptide sequence added to a protein in order to facilitate convenient detection and purification by monoclonal antibodies?
Epitope Tag
What is used as a protecting group for the 5’ -OH group of nucleotides during artificial DNA synthesis?
Dimethoxytrityl groups
Elements of structured proteins that can be isolated from the whole molecule but retain their structure are…
Domains
What is a motivation for performing cDNA synthesis?
To clone eukaryotic genes that contain introns
An operator is a
Repressor binding site
Gene regulatory regions in DNA found >1000 bp up- or downstream of the gene are called
Enhancers
A eukaryotic gene contains 1500 bp b/w ATG and the first stop codon. The protein encoded by this gene only contains 200 amino acids. The most likely explanation for this observation is…
the gene contains one or more introns
Which of the following is not a eukaryotic proximal promoter element
Operator
The ribosomal site where the tRNA with the attached protein chain is bound following the translocation step is the
P site
The following complex of macromolecules is found within a cell: DNA attached to RNA polymerase, attached to a growing chain of RNA, attached to a ribosome, attached to a growing chain of amino acids. This cell is…
Prokaryotic
Which of the following is a nucleotide?
A. adenosine triphosphate
B. Deoxythyidine phosphate
C. Deoxyguanosine monophosphate
D. All of the above
E. None of the above
D. all of the above
What isotopes were used to label cellular DNA
P32
The sequence within the 3’ UTR of mRNA can affect its…
Stability
Which of the following forms of DNA could serve as a suitable template for DNA polymerase in the absence of any other nucleic acid polymers or enzymes
A. Partially double-stranded, linear DNA
B. Circular single-stranded DNA
C. Circular double-stranded DNA
D. fully double-stranded, linear DNA
A. Partially double-stranded, linear DNA
What is a biological catalyst primarily of protein
An Enzyme
True or False
The trp repressor protein must be bound to the co-repressor tryptophan in order to inhibit translation
False (i think it should be transcription to be true)
True or False
G and C are pyrimidines, and A and T are purines
False
Replication of the ____________ strand of DNA is discontinuous
lagging
What is the experimental technique that enabled the observation that the structure of DNA involved a helix
x-ray crystallography
