Bio Topic 17 SQ

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

3' CCA 5'

During translation (polypeptide elongation), charged tRNAs enter the ribosome at the

A site

Which of the following statements is TRUE?

All of these statements are true. Many eukaryotic primary mRNA molecules have "intervening" sequences, or introns, that do not code for proteins. Many eukaryotic genes have "intervening" sequences, or introns, that do not code for proteins. 5' and 3' untranslated regions (UTRs) are parts of exons, but do not code for proteins.

What is meant by the statement that "the genetic code is not ambiguous"?

Each codon specifies just one amino acid.

Which of the following statements about RNA processing is FALSE?

Exons are cut out before mRNA leaves the nucleus.

What is the function of the release factor?

It binds to the stop codon in the A site in place of a tRNA.

Which of the following statements about a codon is FALSE?

It extends from one end of a tRNA molecule.

Which of the following statements is TRUE?

Many prokaryotic genes have "intervening" sequences, or introns, that do not code for proteins. All of these statements are true. 5' and 3' untranslated regions (UTRs) are parts of exons, but do not code for proteins. Many prokaryotic primary mRNA molecules have "intervening" sequences, or introns, that do not code for proteins.

Which of the following statements about the genetic code is TRUE?

Mitochondrial genes use a slightly different genetic code than nuclear genes.

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

Translation can begin while transcription is still in progress.

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

Ribosomal RNAs, or rRNAs

are not translated to form proteins

The "polyA" tail that is added to the 3' end of eukaryotic mRNA molecules

consists of a string of adenosine ribonucleotides

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

hydrogen bonding between base pairs

Which of the following statements about translation is TRUE?

mRNA molecules are read by the translation machinery in the 5' to 3' direction. The 5' and 3' UTRs of an mRNA molecule are not translated. Translation of an mRNA begins at an AUG codon All of these statements are true.

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that

many noncoding stretches of nucleotides are present in mRNA.

A mutant bacterial cell has a defective aminoacyl 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

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

In eukaryotic cells, transcription cannot begin until

several transcription factors have bound to the promoter.

During translation, after the ribosome breaks the bond between the growing polypeptide chain and the tRNA in the P site and then forms a covalent (peptide) bond between the growing polypeptide chain and the amino acid attached to the tRNA in the A site

the tRNA that was in the P site is now in the E site and leaves the ribosome

The proteins that help RNA polymerase bind the DNA at the promoter site are known as

transcription factors

How many different amino acids could be specified if codons were two nucleotides in length?

16

How many different amino acids could be specified if codons were four nucleotides in length?

256

The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of ATP, GTP, and UTP. How many artificial mRNA 3 nucleotide codons could possibly be made?

27

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'

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The anticodon loop of the first tRNA that will complement this mRNA is

3' GGC 5'

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'

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

3' UUA 5'

Given the locally unwound double strand below, in which direction does the RNA polymerase move?

3' → 5' along the template strand

The nucleotide sequence of the template strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' ATGCGTA 3'

5' AAUUCGGG 3'

The nucleotide sequence of the coding strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' ATGCGTA 3'

5' AUGCGUA 3'

The nucleotide sequence of the template strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' AATTCGGG 3'

5' CCCGAAUU 3'

Which of the following statements is TRUE?

5' UTRs are part of exons coding regions are part of exons 3' UTRs are part of exons

The figure below represents a tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino acid?

5' UUC 3'

The nucleotide sequence of the template strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA?

5'UACGCAU 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. How many different artificial mRNA 3 nucleotide codons could possibly be made?

8

Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression?

A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.

A particular triplet of bases in the coding strand of a gene is TTT. If an mRNA is made from this gene, the anticodon on the tRNA that will bind the codon on the mRNA is

AAA

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

ATP, RNA, and DNA

A particular triplet of bases in the coding strand of a gene is GGG. If an mRNA is made from this gene, the anticodon on the tRNA that will bind the codon on the mRNA is

CCC

Which of the following statements is TRUE?

DNA is transcribed and RNA is translated

Which of the following correctly shows the flow of information in a cell?

DNA to RNA to protein

A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already. Where does tRNA #2 move to after this bonding of lysine to the polypeptide?

E site

A particular triplet of bases in the template strand of a gene is GGG. If an mRNA is made from this gene, the anticodon on the tRNA that will bind the codon on the mRNA is

GGG

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

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

What is meant by the statement that "the genetic code is redundant"?

Most amino acids are specified by more than one codon.

Which of the following statements about pre-mRNAs (primary mRNAs) is correct?

PolyA tails are added to primary mRNAs Introns are removed from primary mRNAs by splicing Primary mRNAs may contain both exons and introns all of these answers are correct

Which of the following is NOT a major difference between transcription in prokaryotes versus eukaryotes?

Prokaryotic mRNA molecules are synthesized by RNA polymerase catalyzing the formation of phosphodiester bonds between ribonucleotides that are base paired with the DNA template strand; eukaryotic mRNA molecules are synthesized by RNA polymerase catalyzing the formation of phosphodiester bonds between ribonucleotides that are base paired with the DNA coding strand

In comparing DNA replication with transcription, which of the following is true only of DNA replication?

The entire template molecule is represented in the product.

When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply?

There are also genes for RNAs other than mRNA.

A particular triplet of bases in the template strand of DNA is TTT. The anticodon on the tRNA that binds the mRNA codon is

UUU

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 LEAST serious effect on the polypeptide product?

a deletion of three nucleotides

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?

a deletion of two nucleotides

When a ribosome reaches the end of the coding region of an mRNA molecule, so that a stop codon is in the A site of the ribosome,

a release factor binds the stop codon at the A site and the polypeptide is freed from the tRNA in the P site

Which of the following mutations would be most likely to have a harmful effect on an organism?

a single nucleotide insertion downstream of, and close to, the start of the coding sequence

Translation of mRNA

almost always begins at an AUG codon, which specifies methionine

When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation reaction were to be experimentally stopped at this point, which of the following would you be able to isolate?

an assembled ribosome with a polypeptide attached to the tRNA in the P site

Transfer RNAs, or tRNAs

are translated to form short polypeptides that are part of ribosomes. None of these answers is correct. form 3-dimensional shapes as a result of ionic bonds between different parts of the molecule. are important components of ribosomes

Transfer RNAs, or tRNAs

bind only a specific amino acid All of these answers are correct. have 3-dimensional shapes that are formed by hydrogen bonding between the nitrogenous bases of some of the ribonucleotides comprising the tRNA contain an anticodon that base pairs with an appropriate codon on a mRNA molecule

During translation, the role of release factors is to

bind rRNAs, allowing their release from the ribosome bind the mRNA stop codon in the A site of the ribosome, causing release of the completed polypeptide release amino acids from charged tRNAs bind tRNAs, allowing their release from the ribosome

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.

Aminoacyl tRNA synthetases

catalyze the formation of a covalent bond between an amino acid and an appropriate tRNA molecule

Which of the following types of RNA molecules have polyA tails?

eukaryotic mRNA molecules

A single aminoacyl tRNA synthetase can typically recognize

just one amino acid, but several tRNAs

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3'

met-ser-ser-leu-ser-leu

Which of the following is NOT a typical modification of a eukaryotic primary (or precursor) mRNA?

phosphorylation

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The charged transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) shown in the table below are available. Two of them can correctly match the mRNA so that a dipeptide can form. The dipeptide that will form will be

proline-threonine.

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

several transcription factors (TFs)

The final product of an expressed gene can be which of the following?

tRNA, rRNA or polypeptide

The DNA strand to which ribonucleotides hydrogen bond during transcription is known as the

template strand

The sequence of an RNA molecule will be complementary to the sequence of the

template strand from which that RNA molecule was made

During translation, tRNAs leave the ribosome from

the E site

During translation,

the growing polypeptide chain is transferred from the tRNA in the P ribosome site to the amino acid attached to the tRNA in the A ribosome site.

During translation, after the ribosome breaks the bond between the growing polypeptide chain and the tRNA in the P site and then forms a covalent (peptide) bond between the growing polypeptide chain and the amino acid attached to the tRNA in the A site,

the position of the ribosome on the mRNA shifts and a new, charged tRNA enters the A site of the ribosome OR the ribosome shifts over one codon on the mRNA, such that the codon specifying the next amino acid is now lined up with the A site

For the DNA molecule shown below, where would the promoter be located?

to the right of the template strand

Which of the following are needed for the initiation of transcription?

transcription factors a promoter sequence all of these answers are correct RNA polymerase

Which of the following help form a transcription complex at a promoter?

transcription factors and RNA polymerase