bio chapter 13 questions

In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.

1', 5'

Nucleic acids are assembled in the _____ direction.

5' to 3'

The direction of synthesis of an RNA transcript is _____.

5' —> 3'

Considering the table of mRNA codons, how many unique tRNA molecules must there be to translate mRNA into protein?

61. (The three stop codons need no tRNA, but the rest of the 64 codons need their own unique tRNA.)

Which of the following events occurs during transcription?

A molecule of RNA is formed based on the sequence of nucleotides in DNA. (During transcription, RNA nucleotides line up with their complementary DNA partners, transcribing the information in DNA into RNA.)

Eukaryotes use mRNA to carry the sequence for a protein to the ribosomes outside of the nucleus. Why then don't prokaryotes translate DNA directly?

because control of transcription of mRNA is a major method of controlling gene expression

The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.

CUG

What prevents women from expressing genes on their two X chromosomes twice as much as men express their single X chromosome?

Cells in women have one X condensed. (Condensing the DNA of one X prevents expression from that chromosome.)

Which of these is a difference between a DNA and an RNA molecule?

DNA is double-stranded, whereas RNA is single-stranded.

Which one of the following does not play a role in translation?

DNA. (DNA contains the instructions for making proteins, but these instructions are transcribed to RNA before translation occurs.)

Bacteria simultaneously transcribe and translate mRNA. Why don't eukaryotes?

Eukaryotic mRNA must be taken outside the nucleus before it can be translated. (The protein production occurs in the cytoplasm or on the endoplasmic reticulum, entirely different locations than the nucleus)

Which of these correctly illustrates the pairing of DNA and RNA nucleotides?

GTTACG CAAUGC

What does it mean if a gene is "expressed"?

It is transcribed and translated. (A gene can have little effect if it is not transcribed into RNA and translated into protein.)

What is the primary job of DNA?

It provides blueprints for proteins.

The genetic code is often described as redundant. What feature of the genetic code does this reference?

Most amino acids have more than one codon.

What was the conclusion of Beadle and Tatum's experiment?

One gene carries the information for one enzyme.

The initiator tRNA attaches at the ribosome's _____ site.

P

The enzyme ______ synthesizes an RNA strand by first unwinding a DNA molecule and then stringing together a series of RNA nucleotides complementary to it.

RNA polymerase

How does RNA polymerase know where to start transcribing a gene?

RNA polymerase binds to the promoter of the gene.

What name is given to the process in which pre-mRNA is edited into mRNA?

RNA processing. (RNA processing edits the RNA transcript that has been assembled along a DNA template.)

Which of the following statements about ribosomes is correct?

Ribosomes are made from RNA and protein. They are used to synthesize protein.

If the sequence for a eukaryotic gene is placed directly into a bacterial chromosome, what will occur?

The bacterium will produce mRNA, but it will contain extra sequences not found in the eukaryotic mRNA due to transcription of both introns and exons by the bacterium. (Eukaryotes process out introns while making mRNA. The bacterium will not have this machinery and will therefore create an mRNA with the introns still in it.)

A mutation deletes the regulator gene of the lac operon. What effect will this have on the expression of the lac operon?

The genes of the lac operon will always be expressed.

What is the relationship between the template strand and the mRNA transcribed from it?

The mRNA is complementary and runs in the reverse direction relative to 5' and 3'.

The protein pepsin is produced in the cells lining the stomach, but not in cheek cells. Why is this?

There are no transcription factors for pepsin in cheek cells. (The gene is identical in every cell in the body, so the transcription factors to express the gene must be missing.)

What is the function of the cap and tail on eukaryotic mRNA?

They are involved in transporting the mRNA outside of the nucleus. (The cap and tail act as signals to take the mRNA to a ribosome.)

If transcription and translation were applied to a book, which statement would correctly describe the process of each?

Transcription is making a copy and translation is changing the language.

Which anticodon would match the codon AAG?

UUC

Polypeptides are assembled from _____.

amino acids

The sequence of nitrogen-containing bases on one strand of DNA most directly determines the sequence of

amino acids in a protein molecule.

Which of the following changes will have the least impact on a gene?

an inversion mutation that inverts the gene and promoter

A(n) _____ is a sequence of three bases on a molecule of transfer RNA (tRNA) that is complementary to a coding triplet of messenger RNA (mRNA) bases.

anticodon

Which of the following is a good reason for mRNA to be single-stranded, instead of double-stranded like DNA?

because a complementary strand of RNA would prevent the binding of tRNA anticodons to the codon

Which of the following mutations will have the largest effect on the expression of this gene? 1 2 3 4 5 ATG GTC GCA TGT TAG.

deleting the A in position 1. (This will disrupt the start codon, preventing translation of the entire mRNA.)

In eukaryote genes, nucleotide segments that code for proteins, called _____, are interrupted by noncoding segments, called _____.

exons, introns

What would cause a region of DNA to have no expressed genes?

if the DNA was condensed

What type of mutation is caused by adding one nucleotide into the middle of a sequence?

insertion. (This mutation changes the groupings of three during translation, otherwise known as the reading frame.)

Which of the following does not occur during RNA processing?

mRNA attaches to the small subunit of a ribosome. (mRNA attaches to the small subunit of a ribosome at the beginning of translation.)

Which of the following is a correct statement about mRNA?

mRNA moves from the nucleus to the cytoplasm following RNA processing.

RNA processing converts the RNA transcript into _____.

mRNA. (The editing of the RNA transcript produces mRNA.)

Use the genetic code (Table 13-3) to translate the following strand of DNA: TACACCTAA.

methionine, tryptophan, isoleucine

What would you expect to see inside the cells of a woman with Turner's syndrome (XO)?

no Barr bodies. (Because the woman only has one X chromosome, there is no need to inactivate one.)

Amino acids are added one at a time to the growing protein chain, or _____, on a ribosome.

polypeptide

Which of the following is the most energy-efficient mechanism to prevent a protein from taking action?

prevent transcription of the mRNA. (If a protein is not to be used, the energy of transcription and translation can be saved at this stage.)

The site of translation is

ribosomes in the cell cytoplasm.

Consider the DNA base sequences represented here. Which hypothetical substitution is most likely to be neutral? 1 2 3 4 5 ATG ACT TAT ACC TGA.

substitution at the T labeled "2"

During translation, which component is directly responsible for reading the sequence of nucleotides so it may be translated into a sequence of amino acids?

tRNA. (The anticodon of tRNA is the only component of the translation machinery that can "read" the mRNA)

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine, cytosine

What is the ultimate purpose of the three structural genes of the lac operon?

to break down lactose

The process by which the genetic information encoded in DNA is copied into messenger RNA (mRNA) is called ______.

transcription

What is another name for RNA synthesis?

transcription

What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA?

transcription. (Transcription is the process by which a DNA template is used for the manufacture of several different types of RNA.)

In eukaryotic cells the first step in protein synthesis is the _____.

transferring of information from DNA to messenger RNA

The process by which information encoded in messenger RNA (mRNA) is used to assemble a protein is called _____.

translation

What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?

translation. (Translation is the process by which information encoded in RNA is used to manufacture a polypeptide.)