AP Biology - Chapter 17 - Practice Test

Once transcribed, eukaryotic mRNA typically undergoes, substantial alteration, that includes...

Excision of introns

What is FALSE of RNA processing?

Exons are cut out before mRNA leaves the nucleus

The universal genetic code is now known to have exceptions. Evidence for this could be found if which one of the following is true?

If UGA, usually a stop code on, is found to code for an amino acid such as tryptophan (usually coded for by UGG only)

What is true about a codon?

It consists of three nucleotides, and a code for the same amino acid as another coat on, it never codes for more than one amino acid, it is the basic unit of the genetic code

What is FALSE about a codon?

It extends from one end of a tRNA molecule

Why might a point mutation in DNA make a difference in the level of a protein's activity

It might substitute an amino acid in the active site

A transcription unit that is 8000 nucleotides long may use 1200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that...

Many non-coding stretches of nucleotides are present in mRNA

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

Minimal medium supplemented with nutrient "B" only

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 genes expression?

RNA polymerase binds to the promoter region to begin transcription.

Which of the following is true of snRPs?

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

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 type of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?

a deletion of two nucleotides

A site (translation)

accepts an incoming tRNA bound to an amino acid.

The anti-codon of a particular tRNA molecule is

complementary to the corresponding mRNA codon

A frameshift mutation could result from

either an insertion or a deletion of a base

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

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

hydrogen bonding between base pairs

What bonds hold nucleotides together?

hydrogen bonds

The TATA sequence is found only several nucleotides away from the start site of transcription. This most probably relates to which of the following.?

the number of hydrogen bonds between A and T in DNA

Introns are significant to biological evolution because

their presence allows exons to be shuffled

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 4 nueclotides

2

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

3' UCA 5'

RNA polymerase moves in which direction along the DNA?

3' to 5' along the template strand

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

5' cap and poly A tail

The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. How many artificial mRNA 3 nucleotide codons would be possible?

8

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

A gene from an organism could theoretically be expressed by any other organism, all organisms have a common ancestor, the same codons in different organisms usually translate into the same amino acids, different organisms have the same number of different types of amino acids

Which of the following nucleotide triplets best represents a codon?

A triplet in the same reading frame as an upstream AUG

What are the sites of translation?

A, P, E

Particular triplet of bases in the coding sequence of DNA is AAA. The anti-codon on the tRNA that binds the mRNA codon is...

AAA

The nitrogenous base adenine is found in all me,bees of which group?

ATP, RNA, and DNA

A part of the promoter called the TATA box is said to be highly conserved in evolution, which might this illustrate?

Any mutation in the sequence is selected against.

Which of these is the function of a poly (a) signal sequence?

It codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage, 10-35 nucleotides away

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

It introduces a premature stop codon into the mRNA.

What is true of RNA processing

Nucleotides may be added at both ends of the RNA, ribozymes may function in RNA splicing, RNA spicing can be catalyzed by spliceosome, a primary transcript is often much longer than the final RNA molecule that leaves the nucleus

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

RNA

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?

RNA polymerase II

In which of the following actions does RNA polymerase differ from DNA polymerase?

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 separate from the DNA and release the transcript.

And eukaryotic cells transcription cannot begin until...

Several transcription factors have bound to the promoter

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell. After he has removed it's 5' cap and poly(a) tail which of the following would you expect him to find?

The molecule is digested by exonucleases because it is no longer protected at the 5' end

Each eukaryotic mRNA, even after post-transcriptional modification, includes 5' and 3' UTRs. What are they?

The untranslated region at either end of the coding sequence

What is true about proteins synthesis in prokaryotes?

Translation can begin while transcription is still in progress

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

Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because

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

P site (translation)

holds the tRNA carrying the growing polypeptide chain

What bonds hold together amino acids

peptide bonds

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

point mutation

Transcription in eukaryotes requires, which of the following in addition to RNA polymerase

several transcription factors

E site (translation)

the exit site, where discharged tRNAs leave the ribosome