Chapter 17 Biology

An mRNA molecule with the sequence 5'-CCG-ACG-3'is being read by a ribosome.During translation which of the following tRNA anticodons will be the first to productively bind with this mRNA?

3'-GGC-5'

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

RNA processing

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

a long string of adenine nucleotides

Identify a 5′→3′ sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys.

5′-CTTCGGGAA-3′

A codon consists of __________ bases and specifies which __________ will be inserted into the polypeptide chain.

three, amino acid

The number of nucleotide bases "read" together on the mRNA to designate each amino acid is __________; this unit is called a(n) __________.

three; codon

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

It can be assumed that a ribosome met a stop codon in an intron and translation stopped resulting in a shortened protein. In human cells introns are removed by RNA splicing before translation starts, but there is no RNA splicing in bacterial cells. Also, some part of amino acids in the resulting protein was incorrect because they had been translated from introns . This fact could cause the production of a nonfunctional protein.

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Rank the following mutations with respect to their likelihood of affecting the structure of the polypeptide (from most likely to affect structure to least likely). 1. insertion mutation in the middle of an intron 2. deletion of 3 bases crossing an intron-exon border 3. substitution mutation at the third position of a codon 4. substitution mutation at the second position of a codon

2, 3, 4, 1 Most to Least Likely to Affect Structure: deletion of 3 bases crossing an intron-exon border substitution mutation at the third position of a codon substitution mutation at the second position of a codon insertion mutation in the middle of an intron

What is their proper sequence for these steps? 1. translation 2. RNA processing 3. transcription 4. modification of protein

3, 2, 1, 4 (transcription, RNA processing, translation, modification of protein)

Which of the following structures is needed for the translation initiation complex to form in eukaryotes?

5' cap

Which of the following statements best supports the one gene-one enzyme hypothesis?

A mutation in a single gene can result in a defective protein.

Transcription begins at a promoter. What is a promoter?

A site in DNA that recruits the RNA Polymerase

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 accurately describes the usual process of eukaryotic transcription?

Both introns and exons are transcribed, but the RNA transcribed from introns does not leave the nucleus.

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?

Complementary

The understanding that genetic information flows in one direction, from DNA to RNA to protein, became known as the central dogma of biology. The replication-transcription-translation pathway is connected with the DNA→RNA→protein flow of information.

During replication, a faithful copy of a DNA molecule is made. During transcription, the DNA "message" is copied onto a molecule of mRNA. During translation, the information carried in the mRNA is transferred to molecules of tRNA to build a protein on the ribosomes.

Which statement is true?

Each amino acid in a protein is coded for by three bases in the DNA.

Which of the following statements correctly describes Archibald Garrod's hypothesis for how "inborn errors of metabolism" such as alkaptonuria occur?

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

Which statement correctly describes mRNA processing?

Introns are cut out of the primary transcript, and the resulting exons are spliced together.

What is the function of the release factor during translation in eukaryotes?

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

Which of the following processes correctly describes alternative RNA splicing?

It can allow the production of proteins of different sizes and functions from a single mRNA.

The P site of a ribosome does which of the following?

It holds the tRNA carrying the growing polypeptide chain.

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 summary of protein synthesis is correct?

Messenger RNA is made on a DNA template, and then amino-acid-bearing transfer RNAs bind to the mRNA through codon-anticodon pairing.

Once researchers identified DNA as the molecule responsible for transmitting heritable traits, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. Which of the following statements correctly describes the mechanism of information transfer that accomplishes this task in eukaryotes?

Messenger RNA is transcribed from a single gene and transfers information to the cytoplasm, where protein synthesis takes place.

Which of the following best describes the redundancy in the genetic code?

More than one codon can specify the addition of the same amino acid.

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.

DNA does not store the information to synthesize which of the following?

Organelles

The four levels of protein structure are primary, secondary, tertiary, and quaternary structure. Review the levels of protein structure by clicking the image below.Drag each label into the appropriate bin depending on whether it applies to primary, secondary, tertiary, or quaternary structure.

Primary Structure- amino acid sequence Secondary Structure- result from hydrogen bonding bestrewn the backbone constituens of the poly peptide, alpha helix, beta pleated sheet Tertiary Structure- the overall shape of a polypeptide, results from interactions between side chains (R groups) of amino acids Quaternary Structure- The aggregation of multiple polypeptide subunits

Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of __________.

RNA

What catalyzes the linkage between ribonucleotides to form RNA during gene expression?

RNA polymerase

During which step of the replication-transcription-translation process does each type of RNA first play a role?

Replication: none Transcription/RNA procesing: mRNA Translation: tRNA, rRNA

Which of the following characteristics of gene expression is shared by eukaryotic and prokaryotic cells?

Signal sequences are needed for the production of membrane proteins.

Two mRNAs (mRNA X and mRNA Y) are synthesized with the same exon sequences but poly-A tails of very different lengths. mRNA X is 7,500 bases long. mRNA Y is 6,900 bases long. The mRNA's are added to separate in vitro translation mixtures containing radioactive methionine and the reactions are allowed to proceed for 30 minutes. When the mixtures are analyzed which of the following outcomes will most likely occur?

The mRNA X mixture will contain more radioactive proteins than the mRNA Y mixture.

Which of the following statements best describes the promoter of a protein-coding gene?

The promoter is a nontranscribed region of a gene.

Which of the following best explains the observation that in bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs?

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

RNA is synthesized from DNA by what process?

Transcription

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

Transcription

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

Translation can begin while transcription is still in progress.

What is a ribozyme?

a biological catalyst made of RNA

A particular mutation had no effect on the polypeptide encoded by a gene. This mutation probably involves __________.

a silent or neutral mutation

Polypeptides are assembled from _____.

amino acids

Translation occurs in the _____.

cytoplasm

The function of tRNA during protein synthesis is to __________.

deliver amino acids to their proper site during protein synthesis

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

exons

RNA is single stranded, can hydrogen-bond with other nucleic acids, and has functional groups that can function in catalysis. These characteristics support that RNA could have which of the following cellular roles?

forming peptide bonds

The flow of information in a cell proceeds in what sequence?

from DNA to RNA to protein

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

RNA processing converts the RNA transcript into _____.

mRNA

Which of the following molecules carries information from DNA and directs incorporation of amino acids at the ribosome?

mRNA

In many cases, more than one codon codes for the same amino acid. Because of this, we say that the code is __________.

redundant

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

modified guanine nucleotide

One strand of a DNA molecule has the following sequence: 3′-AGTACAAACTATCCACCGTC-5′. In order for that strand to be transcribed, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated.

promoter

In eukaryotic cells, transcription cannot begin until

several transcription factors have bound to the promoter.

Spliceosomes are composed of _____.

small RNAs and proteins

Sort each description by the type of RNA it describes.

tRNA: contains an anticodon has amino acids covalently attached mRNA: contains exons specifies the amino acid sequence for a protein rRNA: is a component of ribosomes is the most abundant form of RNA

During translation, amino acid chain elongation occurs until __________.

the ribosome encounters a "stop" codon

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

translation