Transcription and Translation

Which of the following numbered terms represents the correct order of sequences in a prokaryotic mRNA molecule as it was synthesized? 1)3′ trailing sequences2)coding sequences3)leader sequences4)termination signals

3 → 2 → 4 → 1

One of the mRNA codons specifying the amino acid leucine is 5′-CUA-3′. Its corresponding anticodon is:

3′-GAU-5′.

The total number of different three-base combinations of the four nucleic acid bases is:

64

Why was it important in the studies of Beadle and Tatum that Neurospora is haploid?

Because a mutation that arises is not masked by a normal allele on a homologous chromosome.

Why is only one strand of DNA transcribed into mRNA?

Because transcribing both DNA strands would produce different amino acid sequences.

Beadle and Tatum irradiated Neurospora and initially grew the mutant strains on complete medium. How were they able to determine what type of mutation each strain had?

By growing the mold on minimal media supplemented with different combinations of amino acids, vitamins, etc.

The transcript in Figure 13-3 is labeled:

E

What conclusions did Beadle and Tatum reach with their studies of Neurospora?

Each mutant gene affected only one enzyme.

A nonsense mutation is a base-pair substitution that results in the replacement of one amino acid with another.

False

In eukaryotes, the initiator tRNA carries the amino acid leucine.

False

Molecular chaperones assist in the folding of newly synthesized mRNAs.

False

The nucleotide sequence in RNA to which RNA polymerase binds is called the promoter.

False

The template DNA strand is described as being parallel to the complementary RNA strand.

False

Which of the following is not a reason why Neurospora is an ideal organism to study the effects of genetic mutations?

Neurospora contains homologous chromosomes that are easily viewed with a light microscope.

RNA differs from DNA in all of the following except:

RNA contains cytosine.

Refer to Figure 13-3. The component labeled B is:

RNA polymerase.

Which of the following is a characteristic of uracil?

The ability to bond with adenine.

How does the first nucleotide at the 5′ end of a new mRNA chain differ from the other nucleotides in the chain?

The first nucleotide retains its triphosphate group, while the others do not.

Which is most directly responsible for the sequence of amino acids in a protein?

The sequence of codons in mRNA

Which of the following is not a nucleotide found in RNA?

Thymine

A transposon is a DNA sequence that "jumps" into the middle of a gene.

True

A gene can now be defined as:

a DNA sequence that carries information to produce a specific RNA or protein product.

Beadle and Tatum began their studies with wild-type Neurospora, which is:

a normal phenotype that will grow on minimal medium.

Initiation of transcription requires:

a promoter sequence.

Leader sequences contain signals that:

allow the ribosomes to be properly positioned to translate the message.

Ribose differs from deoxyribose by having:

an extra hydroxyl group

During protein synthesis, ribosomes:

attach to the mRNA molecule and travel along its length.

Substitution of one base pair for another can result in a __________ mutation that results in the conversion of an amino acid specifying codon to a termination codon.

nonsense

Translocation is the process whereby the __________ moves in order to place the tRNA bound to the growing polypeptide chain in the __________ site, thereby freeing the __________ site for a new aminoacyl-tRNA.

ribosome; P; A

Refer to Figure 13-2. The portion of the molecule labeled 5 is:

the attached amino acid.

In essentially all organisms, the AUG codon codes for:

the initiation of translation.

Frameshift mutations result from:

the insertion or deletion of one or two base pairs.

The experimental design in Figure 13-1 was used to examine:

the relationship between genetic changes and metabolic enzymes.

Linus Pauling demonstrated that:

the structure of hemoglobin was altered by a mutation of a single gene.

RNA synthesis is also known as:

transcription

If a human gene mRNA were placed into a cell of yeast, it would be:

translated into the protein that is found in humans.

The conclusion associated with mutant strain III in Figure 13-1 was that it:

was missing an enzyme for metabolism and could not synthesize arginine.

The wobble hypothesis states that:

certain tRNA anticodons can pair with more than one codon sequence.

Interrupted coding sequences include long sequences of bases that do not code for amino acids. These noncoding sequences, called __________, are found in __________ cells.

introns; only eukaryotic

The codon is found in the:

mRNA

Which of the following numbered events represents the correct sequence of events of prokaryotic translation initiation? 1)large ribosomal subunit binds to initiation complex2)initiation tRNA binds small ribosomal subunit3)initiation complex binds to ribosome recognition sequence on mRNA

2 → 3 → 1

The portion of the molecule in Figure 13-2 that contains the anticodon is:

3

Which of the following is made from DNA?

mRNA, tRNA, and rRNA

A mutation that replaces one amino acid in a protein with another is called a __________ mutation.

missense

Following peptide bond formation between the amino acid in the A site on the ribosome and the growing polypeptide chain, the tRNA in the A site:

moves to the P site of the ribosome.