Regulation of gene expression

According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?

2

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?

2

An extraterrestrial life form is discovered. It has a genetic code much like that of organisms on Earth except that there are five different DNA bases instead of four and the base sequences are translated as doublets instead of triplets. How many different amino acids could be accommodated by this genetic code?

25

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' → 5' along the template strand

Choose the answer that has these events of protein synthesis in the proper sequence.

4, 1, 2, 5, 3

The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. The resulting artificial mRNA molecule would have ____ possible different codons if the code involved two-base sequences and ____ possible different codons if the code involved three-base sequences.

4;8

A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA codes for this peptide?

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

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.

We now know that the one gene-one enzyme hypothesis is not entirely accurate because

A, B, and C

Which of the following components are present upon the completion of translation initiation?

A, B, and C

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

ATP, RNA, and DNA

Which of the following are transcribed from DNA?

B and C only

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.

All of the following are directly involved in translation except

DNA.

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

It introduces a premature stop codon into the mRNA.

Which of the following is (are) true about RNA?

Only A and C are true.

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.

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.

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.

Which of the above is analogous to a single substitution mutation?

THECATARETHERAT

Which of the above is analogous to a frameshift mutation?

THECATATTHERAT

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?

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?

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.

Which of the following is (are) true of snRNPs?

They join together to form a large structure called the spliceosome.

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is

UUU

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

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

What is a ribozyme?

an RNA with enzymatic activity

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

When does translation begin in prokaryotic cells?

as soon as transcription has begun

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

as soon as transcription has begun

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

both C and D

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

both C and D

What are ribosomes composed of?

both rRNA and protein

Alternative RNA splicing

can allow the production of proteins of different sizes from a single mRNA.

The function of the ribosome in polypeptide synthesis is to

catalyze the addition of amino acids from tRNAs to the growing polypeptide chain.

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

either UCA or TCA depending on wobble in the first base

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

Garrod hypothesized that inborn errors of metabolism such as alkptonuria occur because

genes dictate the production of specific enzymes and affected individuals have genetic defects that cause them to lack certain enzymes

What are polyribosomes?

groups of ribosomes reading a single mRNA simultaneously

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

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.

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

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" only

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 nutrient "B" only

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

nucleotides consisting of a phosphate, sugar, and nitrogenous base

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

Of the following types of mutations, which one is likely to be the most common?

point mutation

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.

proline-threonine.

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.

What is the most abundant type of RNA?

rRNA

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?

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

What is an anticodon part of?

tRNA

Where is eukaryotic ribosomal RNA transcribed?

the nucleolus

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that

the rules for base pairing between the third base of a codon and tRNA are flexible.

Introns are significant to biological evolution because

their presence allows exons to be shuffled.

What is one function of a signal peptide?

to translocate polypeptides across the ER membrane

Which of the following is least related to the other items?

translation