chapter 17
Refer to the table. Which of the triplets below is a possible anticodon in a tRNA that transports proline to a ribosome?
3'-GGC-5'
RNA processing converts the RNA transcript into ____
mRna
In eukaryotic cells, transcription cannot begin until
several transcription factors have bound to the promoter
Which of the following terms associated with transcription describe regions of nucleic acid?
terminator, promoter, gene
Use the scheme to answer the question. I −→−−−−enzymeX→enzymeX II −→−−−−enzymeY→enzymeY III The figure shows a simple metabolic pathway. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?
2
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 intron2. deletion of 3 bases crossing an intron-exon border3. substitution mutation at the third position of a codon4. substitution mutation at the second position of a codon
2, 3, 4, 1
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.
The anticodon of a particular tRNA molecule is
complementary to the corresponding mRNA codon
Translation occurs in the _____.
cytoplasm
Jennifer Doudna discovered CRISPR-Cas9 due to its role in which of the following?
defending bacteria against bacteriophage infection
Which of the following processes occurs in prokaryotes but not in eukaryotes?
simultaneous transcription and translation of the same mRNA
Which of the following molecules directly participates in the process of translation?
mRNA, tRNA, and rRNA
Which one of the following statements is true of tRNAs?
None of the listed answers are correct.
How is translation initiated?
all of the above
A particular triplet of bases in the coding sequence of DNA is 5'-AAA-3'. The anticodon on the tRNA that binds the mRNA codon is ________.
3'-AAA-5'
A codon consists of __________ bases and specifies which __________ will be inserted into the polypeptide chain.
three...amino acid
What is the process called that converts the genetic information stored in DNA to an RNA copy?
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 in eukaryotes requires which of the following molecules in addition to RNA polymerase?
transcription factors
What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?
translation
What is a ribozyme?
a biological catalyst made of RNA
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 shows the flow of genetic information?
DNA to RNA to protein
What does a mutagen cause?
a change in the sequence of DNA
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'
Given a DNA molecule with the sequence of bases 5'-ATTGCA-3', what would be the sequence of the complementary strand? (It will be helpful to draw the DNA molecule when answering the question.)
3'-TAACGT-5'
A particular triplet of bases in the template strand of DNA is 5'-AGT-3'. What would be the corresponding codon for the mRNA that is transcribed?
3'-UCA-5'
Use this model of a eukaryotic primary transcript to answer the following question.E = exon and I = intron5'-UTR E1 I1 E2 I2 E3 I3 E4 UTR-3'If the primary transcript is processed and transported to the cytosol, which of the following molecules best represents the mRNA that will be produced?
5'-UTR E1 E2 E3 E4 UTR-3'
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following statements to be true?
A gene from an organism can theoretically be expressed by any other organism.
Which of the following statements about ribozymes is/are correct?
A ribosome can be regarded as one large ribozyme, Ribozymes are RNA molecules that function as enzymes, In some genes, intron RNA functions as a ribozyme and catalyzes its own excision.
Which of the following describes the most likely effect that a single base substitution in the middle of gene's sequence will have on the protein the gene encodes?
A single amino acid would change because pairing of mRNA and tRNA in the ribosome would change.
During the elongation phase of translation, which site in the ribosome represents the first location where a codon pairs with an anticodon?
A site
Transcription begins at a promoter. What is a promoter?
A site in DNA that recruits the RNA Polymerase
Which of the following processes will occur at the exposed 3' end of a tRNA molecule?
An amino acid will bind covalently.
The RNA segments joined to one another by spliceosomes are _____.
EXONS
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 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.
Which of the following statements correctly describes the function of a signal peptide?
It helps target a protein to the ER.
Which of the following statements describes the effect of a nonsense mutation on a gene?
It introduces a premature stop codon into the mRNA.
Which of the following statements correctly describes a ribozyme?
It is an RNA with catalytic activity.
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 statements best describes the significance of the TATA box in the promoters of eukaryotes?
It is the recognition site for the binding of a specific transcription factor.
Which of the following statements about the function of RNA polymerase is correct?
It unwinds the double helix and adds nucleotides to a growing strand of RNA
Which of the following characteristics allows the CRISPR Cas9 enzyme to be an effective way to generate mutations that block the function of a specific protein (knock out)?
It's function is regulated by a complementary guide RNA
Which of the following properties is associated with a protein that will be secreted from a eukaryotic cell?
Its signal sequence must target it to the ER.
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 molecules are produced by transcription?
Messenger RNA, Ribozymes
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 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
Which answer correctly compares prokaryotic and eukaryotic codons?
Organisms utilize codons that are nearly universal among all organisms.
If a bacteria contained a mutant aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNAs with the anticodon AAA which of the following would occur?
Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU
Which of the following processes occurs as part of transcription?
RNA is synthesized
In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein?
RNA polymerase II
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.
Which of the following statements about RNA processing is correct?
Ribozymes may function in RNA splicing.
Which of the following is true of RNA processing?
Ribozymes may function in the addition of a 5′5′ cap.
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 is most likely to occur if a researcher removes the 5' cap and poly-A tail of an mRNA and inserts the mRNA molecule into a eukaryotic cell?
The molecule will be degraded by enzymes
Your body contains tens of thousands of different proteins, each with a specific structure and function. The unique three-dimensional shape of each of these diverse proteins is based on several superimposed levels of structure. Which of the following is an accurate statement about proteins?
The primary structure of a protein is the order of amino acids in a polypeptide, as coded for by the DNA of a gene.
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.
Which of the following statements is true about protein synthesis in prokaryotes?
Translation can begin while transcription is still in progress.
What is the function of the release factor during translation in eukaryotes?
What is the function of the release factor during translation in eukaryotes?
Which of the following statements is the most current description of a gene?
a DNA sequence that is expressed to form a functional RNA or polypeptide product
Which of the following changes in an exon is most likely to result in a nonfunctional protein product?
a base-pair deletion
A single base substitution mutation is likely to have a less harmful effect when the base change results in which of the following?
a codon that specifies the same amino acid as the original codon
While characterizing an error-prone organism, researchers found that each of the following types of mutations occurred immediately downstream of the translation start site. Which type of mutation is likely to have the most serious effect on the function of the polypeptide product?
a deletion of two nucleotides
Which of these is currently considered the best definition of a gene?
a gene codes for either a polypeptide or an RNA molecule
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. What is the result of this type of mutation?
a polypeptide missing an amino acid
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 termination occurs when a ribosome interacts with which of the following structures?
a stop codon
Post-translational modifications of proteins may include which of the following processes?
addition of carbohydrates to form a glycoprotein
Using the CRISPR-Cas9 system to correct a genetic defect in a mouse brings with it which of the following risks?
altering non-target mouse genes needed for cell function
Polypeptides are assembled from _____.
amino acids
Accuracy in translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________.
attachment of amino acids to tRNAs
Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?
complementary
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
A section of DNA has the base sequence shown in #1. A mutation in this DNA strand results in the base sequence shown in #2. What type of mutation does this change represent?#1 5' - AGCGTTACCGT-3'#2 5'-AGGCGTTACCGT-3'
frameshift mutation
The flow of information in a cell proceeds in what sequence?
from DNA to RNA to protein
What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure?
hydrogen bonding between base pairs
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 of the following is true of a codon?
it can be in either DNA or RNA
Where does RNA polymerase begin transcribing a gene into mRNA?
it starts after a certain nucleotide sequence called a promoter
According to the central dogma, which of the following intermediate molecules correctly completes the flow chart describing the flow of information in a cell blank? DNA - ________ - Proteins
mRNA
Which of the following molecular structures contains codons?
mRNA
Which of the following molecules carries information from DNA and directs incorporation of amino acids at the ribosome?
mRNA
During RNA processing a(n) _____ is added to the 5' end of the RNA.
modified guanine nucleotide
Use the scheme to answer the question. I −→−−−−enzymeX→enzymeX II −→−−−−enzymeY→enzymeY III −→−−−−enzymeZ→enzymeZ IV Refer to the metabolic pathway illustrated. If I, II, III, and IV are all required for growth, a bacterial strain that does not make enzyme X would be able to grow on medium supplemented with which of the following nutrient(s)?
nutrients A and B only
Use the scheme to answer the question. I −→−−−−enzymeX→enzymeX II −→−−−−enzymeY→enzymeY III −→−−−−enzymeZ→enzymeZ IV Refer to the metabolic pathway illustrated. If I, II, III and IV are all required for growth, a bacterial strain that does not make enzyme Y would be able to grow on medium supplemented with which of the following compounds?
nutrients A and C only
DNA does not store the information to synthesize which of the following?
organelles
Where does translation take place?
ribosome
Which component is directly involved in translation?
ribosome
What name is given to the process in which pre-mRNA is edited into mRNA?
rna processing
Spliceosomes are composed of _____.
small RNAs and proteins
Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA?
the primary transcript is larger than the mRNA
Which answer correctly compares the primary transcript in a prokaryotic cell with the functional mRNA?
the primary transcript is the same size as the mRNA
In eukaryotes which of the following is the first step in translation?
the small subunit of the ribosome recognizes and attaches near the 5' cap of mRNA
Which of the following characteristics is directly related to the coding of a single amino acid during the process of translation?
the three-base sequence of mRNA
In the structure of many eukaryotic genes, individual exons parallel which of the following?
the various domains of the protein product
Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?
whether or not the cell is compartmentalized by internal membranes