AP BiYOO

Eukaryotic cells can control gene expression by which of the following mechanisms? a. histone acetylation of nucleosomes b. DNA acetylation c. RNA induced modification of chromatin structure d. repression of operons e. induction of operators in the promoter

A

In both eukaryotes and prokaryotes, gene expression is primarily regulated at the level of a. transcription. b. translation. c. mRNA stability. d. mRNA splicing. e. protein stability

A

When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation reaction were to be experimentally stopped at this point, which of the following would you be able to isolate? a. an assembled ribosome with a polypeptide attached to the tRNA in the P site b. separated ribosomal subunits, a polypeptide, and free tRNA c. an assembled ribosome with a separated polypeptide d. separated ribosomal subunits with a polypeptide attached to the tRNA e. a cell with fewer ribosomes

A

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following charged transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form. The dipeptide that will form will be, the picture is in the answer a. cysteine-alanine. b. proline-threonine. c. glycine-cysteine. d. alanine-alanine. e. threonine-glycine

B

Choose the answer that has these events of protein synthesis in the proper sequence. 1. An aminoacyl-tRNA binds to the A site. 2. A peptide bond forms between the new amino acid and a polypeptide chain. 3. tRNA leaves the P site, and the P site remains vacant. 4. A small ribosomal subunit binds with mRNA. 5. tRNA translocates to the P site. a. 1, 3, 2, 4, 5 b. 4, 1, 2, 5, 3 c. 5, 4, 3, 2, 1 d. 4, 1, 3, 2, 5 e. 2, 4, 5, 1, 3

B

When this is taken up by the cell, it binds to the repressor so that the repressor no longer binds to the operator: a. operon b. inducer c. promoter d. repressor e. corepressor

B

Which of the following statements are true about protein synthesis in prokaryotes? a. Extensive RNA processing is required before prokaryotic transcripts can be translated. b. Translation can begin while transcription is still in progress. c. Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles. d. Translation requires antibiotic activity. e. Unlike eukaryotes, prokaryotes require no initiation or elongation factors.

B

The process of translation, whether in prokaryotes or eukaryotes, requires tRNAs, amino acids, ribosomal subunits, and which of the following? a. polypeptide factors plus ATP b. polypeptide factors plus GTP c. polymerases plus GTP d. SRP plus chaperones e. signal peptides plus release factor

B (Its a weird question, but because it says polymerasES, it implies multiple which is wrong)

Of the following, which is the most current description of a gene? a. a unit of heredity that causes formation of a phenotypic characteristic b. a DNA subunit that codes for a single complete protein c. a DNA sequence that is expressed to form a functional product: either RNA or polypeptide d. a DNA—RNA sequence combination that results in an enzymatic product e. a discrete unit of hereditary information that consists of a sequence of amino acids

C

This binds to a site in the DNA far from the promoter to stimulate transcription: a. enhancer b. promoter c. activator d. repressor e. terminator

C

This can inhibit transcription by blocking the binding of positively acting transcription factors to the DNA: a. enhancer b. promoter c. activator d. repressor e. terminator

D

This protein is produced by a regulatory gene: a. operon b. inducer c. promoter d. repressor e. corepressor

D

This is the site in the DNA located near the end of the final exon, encoding an RNA sequence that determines the 3' end of the transcript: a. enhancer b. promoter c. activator d. repressor e. terminator

E

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is a. 3' UCA 5'. b. 3' UGA 5'. c. 5' TCA 3'. d. 3'ACU 5'. e. either UCA or TCA, depending on wobble in the first base.

a

RNA polymerase moves in which direction along the DNA? a. 3' 5' along the template strand b. 3' 5' along the coding (sense) strand c. 5' 3' along the template strand d. 3' 5' along the coding strand e. 5' 3' along the double-stranded DNA

a

If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides? a. 1 b. 2 c. 3 d. 4 e. 12

b

What are the coding segments of a stretch of eukaryotic DNA called? a. introns b. exons c. codons d. replicons e. transposons

b

What is a ribozyme? a. an enzyme that uses RNA as a substrate b. an RNA with enzymatic activity c. an enzyme that catalyzes the association between the large and small ribosomal subunits d. an enzyme that synthesizes RNA as part of the transcription process e. an enzyme that synthesizes RNA primers during DNA replication

b

Which of these is the function of a poly (A) signal sequence? a. It adds the poly (A) tail to the 3' end of the mRNA. b. It codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage ~10—35 nucleotides away. c. It allows the 3' end of the mRNA to attach to the ribosome. d. It is a sequence that codes for the hydrolysis of the RNA polymerase. e. It adds a 7-methylguanosine cap to the 3' end of the mRNA.

b

A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which might this illustrate? a. The sequence evolves very rapidly. b. The sequence does not mutate. c. Any mutation in the sequence is selected against. d. The sequence is found in many but not all promoters. e. The sequence is transcribed at the start of every gene

c

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is a. TTT. b. UUA. c. UUU. d. AAA. e. either UAA or TAA, depending on first base wobble.

c

The nitrogenous base adenine is found in all members of which group? a. proteins, triglycerides, and testosterone b. proteins, ATP, and DNA c. ATP, RNA, and DNA d. alpha glucose, ATP, and DNA e. proteins, carbohydrates, and ATP

c

What is the most abundant type of RNA? a. mRNA b. tRNA c. rRNA d. pre-mRNA e. hnRNA

c

Which of the following help(s) to stabilize mRNA by inhibiting its degradation? a. TATA box b. spliceosomes c. 5' cap and poly (A) tail d. introns e. RNA polymerase

c

Which of the following is (are) true of snRNPs? a. They are made up of both DNA and RNA. b. They bind to splice sites at each end of the exon. c. They join together to form a large structure called the spliceosome. d. They act only in the cytosol. e. They attach introns to exons in the correct order.

c

Introns are significant to biological evolution because a. their presence allows exons to be shuffled. b. they protect the mRNA from degeneration. c. they are translated into essential amino acids. d. they maintain the genetic code by preventing incorrect DNA base pairings. e. they correct enzymatic alterations of DNA bases.

d

Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes a. union with ribosomes. b. fusion into circular forms known as plasmids. c. linkage to histone molecules. d. excision of introns. e. fusion with other newly transcribed mRNA.

d

Transcription in eukaryotes requires which of the following in addition to RNA polymerase? a. the protein product of the promoter b. start and stop codons c. ribosomes and tRNA d. several transcription factors (TFs) e. aminoacyl synthetase

d