Biology Unit 5 - Protein Synthesis

enzyme A, enzyme B A -> B, -> C According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?

2

[Codon table] A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be

3' AAA-GAA-TAA-CAA 5'

RNA polymerase moves along the template strand of DNA in the ____ direction, and adds nucleotides to the ____ end of the growing transcript.

3' to 5'; 3'

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.

4, 1, 2, 5, 3

[Codon table] A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand (DNA strand that is complementary to the template strand) of the DNA codes for this peptide?

5' TTT-CCC-AAA-GGG-TTT-CCC

Which of the following helps to stabilize mRNA by inhibiting its degradation?

5' cap and poly-A tail (C and D)

A particular eukaryotic protein is 300 amino acids long. Which of the following could be the maximum number of nucleotides in the DNA that codes for the amino acids in this protein?

900

During translation, chain elongation continues until what happens?

A stop codon is encountered

Which of the following does not occur during the termination phase of translation?

A tRNA with the next amino acid enters the P site

A particular triplet of bases in the template strand of DNA is AGT. The corresponding codon for the mRNA transcribed is

ACU

The nitrogenous base adenine is found in all members of which group?

ATP, RNA, and DNA

Allolactose induces the synthesis of the enzyme lactase. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?

Allolactose binds to the repressor protein

The genetic code is essentially the same for all organisms. From this, one can logically assume all of the following except

DNA was the first genetic material

What is the effect of a nonsense mutation in a gene?

It introduces a stop codon into the mRNA

What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis

During splicing, which molecular component of the spliceosome catalyzes the excision reaction?

RNA

Using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because

RNA acts as an expendable copy of the genetic material, allowing the DNA to serve as a permanent, pristine repository of the genetic material, many mRNA molecules can be transcribed from a single gene, increasing the potential rate of gene expression (B and C)

Which of the following is true for both prokaryotic and eukaryotic gene expression?

RNA polymerase binds to the promoter region to begin transcription

RNA polymerase and DNA polymerase differ in that

RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis

For a repressible operon to be transcribed, which of the following must be true?

RNA polymerase must bind to the promoter, and the repressor must be inactive

Which of the following statements best describes the termination of transcription in prokaryotes?

RNA polymerase transcribes through the terminator sequence, causing the polymerase to fall off the DNA and release the transcript.

Each of the following is a modification of the sentence THECATATETHERAT. A.THERATATETHECAT B. THETACATETHERAT C. THECATARETHERAT D. THECATATTHERAT E. CATATETHERAT Which of the above is analogous to a single substitution mutation?

THECATARETHERAT

Each of the following is a modification of the sentence THECATATETHERAT. A.THERATATETHECAT B. THETACATETHERAT C. THECATARETHERAT D. THECATATTHERAT E. CATATETHERAT Which of the above is analogous to a frameshift mutation?

THECATATTHERAT

As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs?

The tRNA that was in the A site moves into the P site, The tRNA that was in the P site moves to the E site and is released (A and C)

Which of the following statements are true about protein synthesis in prokaryotes?

Translation can begin while transcription is still in progress

The figure below represents tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino acid?

UUC

Which point mutation would be most likely to have a catastrophic effect on the functioning of a protein?

a base deletion near the start of a gene

Which of the following DNA mutations is the most likely to be damaging to the protein it specifies?

a base-pair deletion

Which of the following is a characteristic of all viruses?

a nucleic acid genome, a protein capsid (A and B)

When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by

a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane

enzyme A, enzyme B A -> B, -> C A mutation results in a defective enzyme A. Which of the following would be a consequence of that mutation?

an accumulation of A and no production of B and C

What is a ribozyme?

an enzyme made up of RNA

From the following list, which is the first event in translation in eukaryotes?

base pairing of activated methionine-tRNA to AUG of the messenger RNA

Accuracy in the translation of mRNA into the primary structure of a protein depends on specificity in the

bonding of the anticodon to the codon, attachment of amino acids to tRNAs (C and D)

What are ribosomes made of?

both rRNA and protein

Alternative RNA splicing

can allow the production of proteins of dramatically different sizes from a single mRNA, can allow the production of proteins of dramatically different amino acid sequences from a single mRNA (B and C)

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in

continuous transcription of the structural gene controlled by that regulator

A. operon B. inducer C. promoter D. repressor E. corepressor A lack of this nonprotein molecule would result in the inability of the cell to "turn off" genes

corepressor

When does translation begin in prokaryotic cells?

during transcription

A frameshift mutation could result from

either an insertion or a deletion of a base

Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes

excision of introns

A mutation in which of the following parts of a gene is likely to be most damaging to a cell?

exon

What are the coding segments of a stretch of eukaryotic DNA called?

exons

Which of the following are transcribed from DNA?

exons and rNA (B and C)

What are polyribosomes?

groups of ribosomes reading a single mRNA simultaneously

Viral genomes can consist of any of the following except

helical capsomeres

The function of the ribosome in polypeptide synthesis is to

hold mRNA and tRNAs together, catalyze the addition of amino acids from tRNAs to the growing polypeptide chain, move along the mRNA and eject tRNAs during the translocation process (A, B, and C)

What type of bonding is responsible for maintaining the shape of the tRNA molecule?

hydrogen bonding between base pairs

All of the following are found in prokaryotic mRNA except

introns

Which of the following is not directly involved in the process of translation?

ligase

enzyme A, enzyme B A -> B, -> C We now know that the one gene-one enzyme hypothesis is not entirely accurate because

many genes code for proteins that are not enzymes, a single gene codes for a single polypeptide chain, and many enzymes are made up of more than one polypeptide chain, and many genes code for RNA molecules that have no enzymatic activity (A, B, and C)

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of 400 amino acids. This is best explained by the fact that

many noncoding nucleotides are present in mRNA

A codon

may code for the same amino acid as another codon

[Codon table] What amino acid sequence will be generated, based on the following mRNA codon sequence? 5'AUG-UCU-UCG-UUA-UCC-UUG

met-ser-ser-leu-ser-leu

enzyme A, enzyme B A -> B, -> C If A, B, and C are all required for growth, a strain mutant for the gene encoding enzyme B would be capable of growing on which of the following media?

minimal medium supplemented with "C"

enzyme A, enzyme B A -> B, -> C If A, B, and C are all required for growth, a strain that is mutant for the gene encoding enzyme A would be able to grow on which of the following media?

minimal medium supplemented with nutrients "B" and "C" (C and D)

Which of the following represents a similarity between RNA and DNA?

nucleotides consisting of a phosphate, sugar, and nitrogenous base

[Codon table] What is the sequence of a peptide based on the mRNA sequence 5' UUUUCUUAUUGUCUU 3' ?

phe-ser-tyr-cys-leu

Sickle-cell disease is probably the result of which kind of mutation?

point

If the triplet CCC codes for the amino acid proline in bacteria, then in plants CCC should code for

proline

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following activated 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. tRNA Anticodon: Amino acid GGC: proline CGU: alanine UGC: threonine CCG: glycine ACG: cysteine CGG: alanine The dipeptide that will form will be

proline-threonine

A. operon B. inducer C. promoter D. repressor E. corepressor A mutation in this section of DNA could influence the binding of RNA polymerase to the DNA

promoter

A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of a phenylalanine. The consequence of this for the cell will be that

proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU

RNA viruses appear to have higher rates of mutation because

replication of their genomes does not involve the proofreading steps of DNA replication

A. operon B. inducer C. promoter D. repressor E. corepressor This protein is produced by a regulatory gene

repressor

Viruses with single-stranded RNA that acts as a template for DNA synthesis are known as

retroviruses

[Codon table] Suppose the following DNA sequence was mutated from 3' AGAGAGAGAGAGAGAGAG 5' to 3' AGAAGAGAGATCGAGAGA 5'. What amino acid sequence will be generated based on this mutated DNA?

ser-ser-leu

Which of the following is least related to the other items? a. wobble b. anticodon c. tRNA d. snRNPThis is the correct answer. e. triplet code

snRNP

Which of the following is not a part of the eukaryotic transcription initiation complex?

snRNP

Which of the following is not related to ribosomal activity?

spliceosome

Transcription of the structural genes in an inducible operon

starts when the pathway's substrate is present

What is an anticodon part of?

tRNA

Where is eukaryotic ribosomal RNA transcribed?

the nucleolus

Introns are significant to biological evolution because

their presence allows exons to be moved around more easily, creating proteins with new combinations of functional domains

The lactose operon is likely to be transcribed when

there is lactose but no glucose in the cell, the cyclic AMP and lactose levels are both high within the cell (C and D)

Viruses are referred to as obligate parasites because

they cannot reproduce outside of a host cell

Which of the following is least related to the other items? a. transcription b. TATA box c. template strand d. RNA polymerase II e. translation

translation