Bio quiz review Flashcards
The Meselson-Stahl experiment made clear predictions regarding experimental outcomes if dispersive, conservative, or semiconservative DNA replication was occurring in their Escherichia coli cells. This experiment enables the detection of “new” and “old” DNA by assessing the _______________ of DNA molecules in the cells.
density
A scientist is studying alien microorganisms discovered in a meteorite. He determines that these organisms contain DNA, and when DNA replicates, the resulting daughter strand only consists of newly synthesized DNA. DNA replication in these microorganisms is
Conservative
The following data were obtained from three organisms : an RNA virus, a DNA virus, and a wombat (an Australian mammal). Which is likely the sample from the RNA virus?
Sample
Adenine
Cytosine
Guanine
Thymine
Uracil
(a)
28.0
22.0
22.0
0.0
28.0
(b)
21.0
29.0
29.0
21.0
0.0
(c)
27.0
24.0
26.0
23.0
0.0
a
Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus) and bacterial cells. In these experiments, they used radioactivity to label nucleic acids (in this case DNA) and proteins. What do radioactive sulfur and phosphate specifically label?
Sulfur labels protein and phosphate labels DNA
Topoisomerase and helicase have distinct functions that include which of the following?
- Helicase relieves supercoiling that occurs in front of the replication fork
- Topoisomerase is responsible for unwinding the double helix (separating strands).
- The enzymes have nearly identical activities but are located at different sites during DNA replication
- Helicase is responsible for unwinding the double helix (separating strands).
Helicase is responsible for unwinding the double helix (separating strands).
When RNA polymerase adds a nucleotide to the growing RNA strand,
- the reaction is rho-dependent, and the nucleotide is added directly to a “rut” site.
- the incoming nucleotide is added to the 5′ end of the growing strand, and never to the 3′ end.
- the energy needed for this reaction is derived from breaking a phosphate bond.
- the reaction is catalyzed by the s subunit of RNA polymerase.
The energy needed for this reaction is derived from breaking a phosphate bond
In humans, exons and introns are best distinguished by the fact that exons are ______________ and introns are ______________.
- 300 nucleotides in average size; 6000 nucleotides in average size (and larger than exons)
- found in genes encoding proteins and functional RNAs; found only in genes encoding proteins
- more prevalent and constitute the majority of a mammalian genome; less prevalent and constitute a small portion of a mammalian genome.
- considered to be “noncoding”; considered to “encode” a protein
- always removed from the mature mRNA; always part of the mature mRNA
- 300 nucleotides in average size; 6000 nucleotides in average size (and larger than exons)
Consider the sequence, in which the dots represent any nucleotide sequence of unspecified length. The highlighted sequence is transcribed but is not present in mature mRNA, and likely corresponds to
5’ …AGGUAAGU……………………A…………UUUCCCAGG…
An intron
Which of these is important for the assembly and function of the spliceosome?
A. protein-snRNA interactions
B. snRNP-RNA interactions
C. DNA-DNA interactions
D. DNA-snRNP interactions
E. Both A and B
E. Both A and B
The secondary alpha-helix structure in a protein is stabalized by:
hydrogen bonds along the peptide backbone
Refer to the codon table given. In vitro (in a test tube) translation of a synthetic RNA with the repeating sequence (AGA)20 would produce which of the following?
1.no translation product because the translation start site was not included in the RNA
- polypeptides containing arginine, polypeptides containing glutamic acid, and polypeptides containing lysine
- polypeptides starting with methionine followed by arginine additions
- polypeptides containing a mixture of amino acids (mostly arginine, glutamic acid and lysine)
- polypeptides containing arginine
- polypeptides containing arginine, polypeptides containing glutamic acid, and polypeptides containing lysine
Sixty-one codons specify 20 different amino acids. Therefore, some amino acids are specified by more than one codon. Which of these also is TRUE?
A) Most amino acids can be brought to the ribosome by more than one type of tRNA.
B) A single tRNA can only ever recognize a single codon.
C) Every amino acid is encoded by at least three codons.
D) Wobble demonstrated by tRNAs can result from the presence of inosine, a “rare base.”
E) Both A) and D)
Both A and D
The first stage of protein translation occurs when Met-tRNAiMet base pairs with the mRNA being translated in the ribosomal:
The P site
A tRNA with the anticodon 3′-ACC-5′ would carry the amino acid. Use the table
Tryptophan
All of the following techniques exploit the ability of nucleic acids with complementary nucleotide sequences to find and base pair with each other EXCEPT for:
PCR
Northern Blot
Western Blot
Sanger Sequencing
All require nucleic acid hybridization
Western blot
