bio.111 chapter 15-17

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?

DNA Contains phosphorus whereas protein does not

Which of the following proteins synthesizes DNA

DNA polymerase

Which of the following cells are affected most by telomere shortening?

Only eukaryotic cells

In what general way are regulons regulated?

Regulons can be under either positive or negative control.

A poly A sequence of nucleotides is added to the __ of eukaryotic mRNA

Tail

Which one of the following is TRUE? A codon ______.

is the basic unit of the genetic code

Of the following, which is the most current description of a gene?

A DNA sequence that is expressed to form a functional product: either RNA or polypeptide

During elongation, which site in the ribosome represents the location where a codon is being read?

A site

Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator?

B) inducer

Bacterial and eukaryotic cells primarily control gene expression at the level of transcription. If instead cells exerted control of gene expression primarily at the post-translational level, what would be different?

Cells would expend significantly more energy.

A promoter is___

Dna

What segments are removed from the primary mRNA?

Introns

How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes?

It catalyzes the lengthening of telomeres, compensating for the shortening that occurs during replication

The mutation resulting in sickle-cell disease changes one base pair of DNA so that a codon now codes for different amino acid so it is an example of__

Missense mutation

All three domains (Bacteria, Archaea, and Eukarya) follow the same genetic code. Therefore, which of the following statements would most likely be correct?

The genetic code evolved before the different domains diverged.

Researchers found E. coli that had mutation rates one hundred times higher than normal. Which of the following is the most likely cause of these results?

The proofreading mechanism of DNA polymerase was not working properly

In ecoli, if RNA polymerase is missing___, then transcription initiation would not occur at the appropriate initiation sites

The sigma factor

Why are the genes involved in lactose metabolism considered to be an operon?

They are all controlled by the same promoter.

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

a base-pair deletion

Ribosomes can attach to prokaryotic messenger RNA _____.

before transcription is complete

Although the expression of most genes is tightly regulated, some genes are expressed at roughly constant rates. Which of the following genes would you predict to be constitutively (constantly) expressed?

genes that code for regulatory proteins

The greatest expression of the lac operon occurs when lactose levels are _____.

high and glucose levels are low

According to the central dogma, what molecule should go in the blank? DNA → _____ → Proteins

mRNA

Semiconservative replication involves a template. What is the template?

one strand of the DNA molecule

Which of the following is an exception to the central dogma?

the discovery of RNA viruses that synthesize DNA using reverse transcriptase

How do the leading and the lagging strands differ

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction

In bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. Which of the following statements explains this fact?

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