Mastering BIO 17

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

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following? Different organisms have different numbers of different types of amino acids. DNA was the first genetic material. The same codons in different organisms translate into the different amino acids. A gene from an organism can theoretically be expressed by any other organism. All organisms have experienced convergent evolution.

A gene from an organism can theoretically be expressed by any other organism.

Transcription begins at a promoter. What is a promoter?

A site in DNA that recruits the RNA Polymerase

At which site do new aminoacyl tRNAs enter the ribosome during elongation?

A-site

All proteins start with what?

AUG - (methionine)

What determines which base is to be added to an RNA strand during transcription?

Base pairing between the DNA template strand and the RNA nucleotides

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand? Covalently bound Permanently base-paired Complementary Identical

Complementary

Which one of the following is true of tRNAs? tRNAs are double-stranded. There are four types of tRNA. Each tRNA binds a particular amino acid. tRNAs carry special sequences known as codons. All of the above.

Each tRNA binds a particular amino acid.

True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.

False

The "universal" genetic code is now known to have exceptions. Evidence for this can be found if which of the following is true? If several codons are found to translate to the same amino acid, such as serine. If UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only). If prokaryotic organisms are able to translate a eukaryotic mRNA and produce the same polypeptide. If one stop codon, such as UGA, is found to have a different effect on translation than another stop codon, such as UAA. If a single mRNA molecule is found to translate to more than one polypeptide when there are two or more AUG sites.

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

What happens to RNA polymerase II after it has completed transcription of a gene?

It is free to bind to another promoter and begin transcription.

Which of the following best describes the significance of the TATA box in eukaryotic promoters? It prevents supercoiling of the DNA near the start site. Its significance has not yet been determined. It is the recognition site for a specific transcription factor. It sets the reading frame of the mRNA. It is the recognition site for ribosomal binding.

It is the recognition site for a specific transcription factor.

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

It might substitute a different amino acid in the active site.

The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an averaged-sized protein is about 400 amino acids long. What is the best explanation for this fact?

Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated.

Suppose that an error in transcription alters the formation of a single tRNA molecule in a cell. The altered tRNA still attaches to the same amino acid (Phe), but its anticodon loop has the sequence AAU, which binds to the mRNA codon UUA (usually specifying leucine, Leu). What will be the effect on translation in this cell? The altered tRNA will be so unstable that it will not participate in translation. One altered tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones. The altered tRNA will cause this mRNA to make only nonfunctioning product. The tRNA-Leu will not be able to enter the ribosome to bind to the UUA codon. The altered tRNA will result in an amino acid variant in all copies of the protein.

One altered tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones.

DNA does not store the information to synthesize which of the following? DNA Proteins Messenger RNA Organelles

Organelles

Which of the following processes is an example of a post-translational modification?

Phosphorylation

Where does translation take place?

Ribosome

Which of the following steps occurs last in the initiation phase of translation?

The large ribosomal subunit joins the complex.

Which of the following statements best describes the promoter of a protein-coding gene? The promoter is a site at which only RNA polymerase will bind. The promoter is a site found on RNA polymerase. The promoter is a nontranscribed region of a gene. The promoter is part of the RNA molecule itself.

The promoter is a nontranscribed region of a gene.

What is meant by translocation?

The ribosome slides one codon down the mRNA.

What is the process called that converts the genetic information stored in DNA to an RNA copy?

Transcription

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.

Of the following, which is the most current description of a gene? a discrete unit of hereditary information that consists of a sequence of amino acids a DNARNA sequence combination that results in an enzymatic product a DNA sequence that is expressed to form a functional product: either RNA or polypeptide a unit of heredity that causes formation of a phenotypic characteristic a DNA subunit that codes for a single complete protein

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

What is a ribozyme?

a biological catalyst made of RNA

Which of the following types 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? an insertion of a codon a substitution of the third nucleotide in an ACC codon a deletion of a codon a deletion of two nucleotides a substitution of the first nucleotide of a GGG codon

a deletion of two nucleotides

During RNA processing a(n) _____ is added to the 3' end of the RNA.

a long string of adenine nucleotides

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in a frameshift mutation. a base-pair substitution. a polypeptide missing an amino acid. a nucleotide mismatch. a nonsense mutation.

a polypeptide missing an amino acid.

Which of the following mutations is most likely to cause a phenotypic change? a duplication of all or most introns a nucleotide substitution in an exon coding for a transmembrane domain a frameshift mutation one codon away from the 3' end of the nontemplate strand a single nucleotide deletion in an exon coding for an active site a large inversion whose ends are each in the same region between genes

a single nucleotide deletion in an exon coding for an active site

Which of the following nucleotide triplets best represents a codon? a triplet at the opposite end of tRNA from the attachment site of the amino acid a triplet separated spatially from other triplets a sequence in tRNA at the 3' end a triplet that has no corresponding amino acid a triplet in the same reading frame as an upstream AUG

a triplet in the same reading frame as an upstream AUG

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

bonding of the anticodon to the codon and the attachment of amino acids to tRNAs.

Translation occurs in the _____.

cytoplasm

The RNA segments joined to one another by spliceosomes are _____.

exons

After an RNA molecule is transcribed from a eukaryotic gene, what are removed and what are spliced together to produce an mRNA molecule with a continuous coding sequence?

introns ... exons

Which nucleic acid is translated to make a protein?

mRNA

During RNA processing a(n) _____ is added to the 5' end of the RNA.

modified guanine nucleotide

A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that none of the options will occur; the cell will recognize the error and destroy the tRNA. the ribosome will skip a codon every time a UUU is encountered. proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU. none of the proteins in the cell will contain phenylalanine. the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons.

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

Transcription in eukaryotes requires which of the following in addition to RNA polymerase? the protein product of the promoter ribosomes and tRNA aminoacyl-tRNA synthetase several transcription factors start and stop codons

several transcription factors

In eukaryotic cells, transcription cannot begin until the DNA introns are removed from the template. several transcription factors have bound to the promoter. the 5' caps are removed from the mRNA. DNA nucleases have isolated the transcription unit. the two DNA strands have completely separated and exposed the promoter.

several transcription factors have bound to the promoter.

Spliceosomes are composed of _____.

snRNPs and other proteins

DNA template strand 5'____________________________ 3' DNA complementary strand 3'____________________________ 5' In the transcription event of the previous DNA, where would the promoter be located? to the right of the template strand to the left of the non-template strand to the left of the template strand to the right of the non-template strand at the 3' end of the newly made RNA

to the right of the template strand