chapter 14 bio
RNA polymerase moves in which direction along the DNA?
3' to 5' along the template strand
Which of the following statements about mutations is false?
A knock-out mutation results in a total absence of the mutated protein.
Which of these is currently considered the best definition of a gene?
A gene codes for either a polypeptide or an RNA molecule.
In the diagram below, the two blue strands represent
DNA
Which component is not directly involved in translation?
DNA
Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)?
One addition and one deletion mutation.
Which positions in the logo have the least predictable bases? How can you tell?
The 12 positions showing no bases have the lowest predictive power (-18, -17, -16, -12, -11, -6, -5, -4, -2, 5, 6, and 8).
the figure represents tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino acid?
UUC
What is a ribozyme?
a biological catalyst made of RNA
prior to DNA analysis, why were rape kits typically collected for biological analysis?
blood typing
Which nucleic acid is translated to make a protein?
mRNA
which of the following is most likely in a fetus lacking adequate amounts of the protein REST?
neurons will develop improperly
DNA does not store the information to synthesize which of the following?
organelles
Which of the following events in translation is the first to occur in eukaryotes?
the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA
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
What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?
translation
If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein?
two
Use the following information to answer the next few questions. 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) already in the ribosome. Where does tRNA #2 move to after this bonding of lysine to the polypeptide?
E site
What is the function of GTP in translation?
GTP provides the energy for the formation of the initiation complex, using initiation factors.
Which of these correctly illustrates the pairing of DNA and RNA nucleotides?
GTTACG CAAUGC
which of the following is NOT true of a codon?
It extends from one end of a tRNA molecule.
Which of the following is a function of a poly-A tail in mRNA?
It helps protect the mRNA from degradation by hydrolytic enzymes.
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.
In what way might a point mutation in DNA make a difference in the function of a protein?
It might substitute a different amino acid in the active site.
What is the function of RNA polymerase?
It unwinds the double helix and adds nucleotides to a growing strand of RNA.
Which of the following molecules are produced by transcription?
Messenger RNA Ribozymes
Which of the following processes is an example of a post-translational modification?
Phosphorylation
which of the following is true?
REST is found in a wide variety of animals
During splicing, which molecular component of the spliceosome catalyzes the excision reaction?
RNA
Which of the following molecules is/are produced by translation? Include molecules that are subject to further modification after initial synthesis.
RNA polymerase Aminoacyl-tRNA synthetase
In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA known as pre-mRNA?
RNA polymerase II
What name is given to the process in which pre-mRNA is edited into mRNA?
RNA processing
Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Suppose that an induced mutation removes most of the 5' end of the 5' UTR. What might be the result of this removal?
Removal of the 5' UTR also removes the 5' cap, so the mRNA may be quickly degraded by hydrolytic enzymes.
An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following statements correctly describes the most likely result of this change?
The amino acid methionine will not be covalently bound to the altered tRNA.
Which of the following statements is true about protein synthesis in prokaryotes?
Translation can begin while transcription is still in progress. Submit
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 and complete description of a gene?
a DNA sequence that is expressed to form a functional product: either RNA or polypeptide Submit
Which of the following types of mutation, resulting in an error in the mRNA just after the 3 AUG start codon, is likely to have the most serious effect on the polypeptide product?
a deletion of two nucleotides
Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene?
a frameshift deletion at the beginning of the gene
During RNA processing a(n) _____ is added to the 3' end of the RNA.
a long string of adenine nucleotides
When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by
a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane.
Which of the following mutations is most likely to cause a phenotypic change?
a single nucleotide deletion in an exon coding for an active site of a protein
What enzyme catalyzes the attachment of an amino acid to tRNA?
aminoacyl-tRNA synthetase
What is a ribozyme? (activity)
an RNA with enzymatic activity
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 sets of structures would you be able to isolate from the cell?
an assembled ribosome with a polypeptide attached to the tRNA in the P site
Accuracy in the translation of mRNA into the sequence of amino acids in a polypeptide depends on specificity in which of the following?
bonding of the anticodon to the codon and the attachment of amino acids to tRNAs
which of the following appears to be true?
both LDL and triglycerides play a role in heart disease
which of the following is the biggest reason so many rape kits are not analyzed in the US?
cost
If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?
deletion
RNA processing converts the RNA transcript into _____.
mRNA
if what is happening with rape kits in Detroit and Cleveland holds true around the country, which of the following will happen?
numerous people will be arrested and indicted after analysis of stored rape kits
Which two positions in the logo sequence have the most predictable bases, and which bases would you predict at those two positions in a newly sequenced gene?
position 1 (T) and position 2 (G)
The following information should be used for the next few questions. 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 shown in the figure (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form. tRNA anticodon Amino acid GGC Proline CGU Alanine UGC Threonine CCG Glycine ACG Cysteine CGG Alanine The dipeptide that will form will be
proline-threonine.
in eukaryotic cells, transcription CANNOT begin until
several transcription factors have found the to the promotor
Which of the following does not occur in prokaryotic gene expression, but does occur 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.
The nitrogenous base adenine is found in all members of which of the following groups of molecules?
ATP, RNA, and DNA
Transcription in eukaryotes requires which of the following in addition to RNA polymerase?
several transcription factors
Spliceosomes are composed of _____.
small RNAs and proteins
Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Where on a pre-mRNA transcript does a spliceosome bind?
to each end of an intron
DNA template strand 5'___________________________3' DNA complementary strand 3'___________________________5' In the transcription event of the DNA in the figure, where would the promoter be located?
to the right of the template strand
What is the name of the process shown in the diagram?
initiation (of translation)
Where does translation take place?
ribosome
You add polynucleotide phosphorylase to a solution of ATP, GTP, and UTP. How many artificial mRNA 3 nucleotide codons would be possible?
27
Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Which components of the previous molecule will also be found in mRNA in the cytosol?
5' UTR E1 E2 E3 E4 UTR 3'
The direction of synthesis of an RNA transcript is _____.
5' —> 3'
using the figure on the left, identify a 5' --> 3' sequence of nucleotides in DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys
5'-CTTCGGGAA-3'
You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. How many artificial mRNA 3 nucleotide codons would be possible?
8
Which of these is a tRNA?
B
What is meant by translocation?
The ribosome slides one codon down the mRNA.
Polypeptides are assembled from _____.
amino acids
In the sequence alignment (Figure 1), count the number of each base at position 1. Order them from most frequent to least frequent.
10 T, 0 A, 0 C, 0 G
The figure shows the simple metabolic pathway. Enzyme 1 catalyzes the transformation of A into B and enzyme 2 catalyzes the transformation of B into C. Examine the simple metabolic pathway in the figure. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?
2
The following information should be used for the next few questions. 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 shown in the figure (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form. tRNA anticodon Amino acid GGC Proline CGU Alanine UGC Threonine CCG Glycine ACG Cysteine CGG Alanine 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'.
Use the representation in the figure to answer the following question. DNA template strand 5'___________________________3' DNA complementary strand 3'___________________________5' Given the locally unwound double strand in the figure, in which direction does the RNA polymerase move?
3' → 5' along the template strand
Examine the table of codons in the figure. 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'.
Examine the table of codons in the figure. A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA could code for this peptide?
5'-TTT-CCC-AAA-GGG-TTT-CCC
In the sequence alignment (Figure 1), count the number of each base at position -9. Order them from most frequent to least frequent.
7 G, 2 A, 1 C, 0 T
In the sequence alignment (Figure 1), count the number of each base at position 0. Order them from most frequent to least frequent.
8 A, 1 G, 1 T, 0 C
The genetic code is essentially the same for all organisms. Based on this information, one can logically assume which of the following statements to be correct?
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
If a mutated DNA sequence produces a protein that differs in one central amino acid from the normal protein, which of the following kinds of mutations could have occurred?
An addition mutation and a deletion mutation.
A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?
Any mutation in the sequence is selected against.
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
The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.
CUG
Which of the following mutations would likely be most dangerous to a cell?
Deletion of one nucleotide Which of the following molecules is/are produced by translation? Include molecules that are subject to further modification after initial synthesis.
Which one of the following is true of tRNAs?
Each tRNA binds a particular amino acid.
which of the following if NOT true of RNA processing
Exons are cut out before mRNA leaves the nucleus
You work for the government agency in charge of Codis, helping to analyze rape kits. Who do you work for?
Federal Bureau of Investigation
Which of the following statements correctly describes the function of a signal peptide?
It assists in the translocation of polypeptides across the ER membrane.
What is the function of the release factor in translation?
It binds to the stop codon in the A site in place of a tRNA.
Which of the following statements correctly describes alternative RNA splicing?
It can allow the production of proteins of different sizes and functions from a single mRNA.
What is the effect of a nucleotide-pair substitution that results in a nonsense mutation in a gene?
It introduces a premature stop codon into the mRNA.
Which of the following best describes the significance of the TATA box in eukaryotic promoters?
It is the recognition site for a specific transcription factor.
RNA polymerase in a prokaryote is composed of several subunits. Most of these subunits are the same for the transcription of any gene, but one, known as sigma, varies considerably. Which of the following is the most probable advantage for the organism in having such variability in RNA polymerase?
It might allow the polymerase to recognize different promoters under certain environmental conditions.
Where does RNA polymerase begin transcribing a gene into mRNA?
It starts after a certain nucleotide sequence called a promoter.
Garrod's information about the enzyme alteration resulting in alkaptonuria led to further understanding of these types of metabolic pathways in humans. Phenylketonuria (PKU) occurs when another enzyme in the pathway is altered or missing, resulting in a failure of phenylalanine (phe) to be metabolized to another amino acid: tyrosine. Tyrosine is an earlier substrate in the pathway altered in alkaptonuria. How might PKU affect the presence or absence of alkaptonuria?
It would have no effect because tyrosine is also available from the diet.
What must happen to a newly made polypeptide before it can be secreted from a cell?
Its signal sequence must target it to the ER, after which it goes to the Golgi.
which of the following is true?
LDL is a type of cholesterol
During translation, nucleotide base triplets (codons) in mRNA are read in sequence in the 5' → 3' direction along the mRNA. Amino acids are specified by the string of codons. What amino acid sequence does the following mRNA nucleotide sequence specify? 5′−AUGGCAAGAAAA−3′
Met-Ala-Arg-Lys
What amino acid sequence does the following DNA nucleotide sequence specify? 3′−TACAGAACGGTA−5′
Met-Ser-Cys-His
The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an average-ized 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 the amino acid leucine, Leu). What will be the effect on the translation of polypeptides in this cell?
One altered tRNA molecule will have little effect because it will compete with many "normal" ones.
The initiator tRNA attaches at the ribosome's _____ site.
P
Based on the logo, what five adjacent base positions in the 5' UTR region (the untranslated region at the 5' end of the mRNA) are most likely involved in ribosome binding? Explain.
Positions -12 to -8 have the tallest stacks in the 5' UTR region; therefore, they represent the most likely sequence for the ribosome binding site.
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. What would be a potential consequence for a cell in which this happens? Remember that phenylalanine may be encoded by multiple codons.
Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
In the diagram below, the gray unit represents _____.
RNA polymerase
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.
Part A - Understanding the genetic codePart complete Use the table to sort the following ten codons into one of the three bins, according to whether they code for a start codon, an in-sequence amino acid, or a stop codon. Drag each item to the appropriate bin.
Start/Methionine AUG Stop codon UAG, UAA, UGA Amino acid AAA, UGC, AUC, CAC, GCA, ACU
The tRNA shown in the figure has its 3' end projecting beyond its 5' end. What will occur at this 3' end?
The amino acid will bind covalently.
In comparing DNA replication with RNA transcription in the same cell, which of the following is true only of replication?
The entire template molecule is represented in the product.
Which of the following steps occurs last in the initiation phase of translation?
The large ribosomal subunit joins the complex.
In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly-A tail. Which of the following would you expect him to find?
The molecule is degraded by hydrolytic enzymes because it is no longer protected at the 5' end and the 3' end.
Which of the following statements best describes the promoter of a protein-coding gene?
The promoter is a nontranscribed region of a gene.
When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply?
There are also additional genes for RNAs other than mRNA.
What is the process called that converts the genetic information stored in DNA to an RNA copy?
Transcription
In the 1920s, Hermann Muller discovered that X-rays caused genetic changes in Drosophila. In a related series of experiments in the 1940s, other scientists discovered that other types of chemicals have a similar effect. A new chemical food additive is developed by a cereal manufacturer. Why is it necessary to test for its ability to cause mutation?
We want to prevent any chance that it might cause mutations.
assuming all other numbers of interest fall into the normal range, which of the following is most likely to be successfully treated with the statin drug Lipitor?
a 57 year old man with high LDL
In order for a eukaryotic gene to be engineered into a bacterial colony to be expressed, what must be included in addition to the coding exons of the gene?
a bacterial promoter sequence
Which small-scale mutation would be most likely to have the greatest negative effect on the functioning of a protein?
a base deletion near the start of a gene
Which of the following DNA mutations is likely to have the most negative effect on the protein it specifies?
a base-pair deletion
What does a mutagen cause?
a change in the sequence of DNA
which of the following people is most likely to have the highest levels of REST?
a healthy 91 year old man
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. What is the most likely result of this mutation in the protein product?
a polypeptide missing an amino acid
you are a neurologist doing research on Parkinson's disease. you discover something very similar to REST that impacts people with Parkinson's. What have you discovered?
a protein
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 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
Which of the following descriptions of nucleotide triplets best represents a codon?
a triplet in the same reading frame as an upstream AUG
The figure shows the simple metabolic pathway. Enzyme 1 catalyzes the transformation of A into B and enzyme 2 catalyzes the transformation of B into C. Examine the simple metabolic pathway in the figure. A mutation results in a defective enzyme 1. Which of the following results would be a consequence of that mutation
an accumulation of A and no production of B and C
When the spliceosome binds to a pre-mRNA transcript, where does it typically attach?
at certain sequences along an intron
Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?
complementary
the anticodon of a particular tRNA molecule is
complementary to the corresponding mRNA codon
Translation occurs in the _____.
cytoplasm
Which of the following types of mutations could result in a frameshift mutation?
either an insertion or a deletion of a base
The RNA segments joined to one another by spliceosomes are _____.
exons
True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.
false
True or false? A codon is a group of three bases that can specify more than one amino acid.
false
The flow of information in a cell proceeds in what sequence?
from DNA to RNA to protein
Garrod hypothesized that inherited diseases such as alkaptonuria, the inability to metabolize the chemical alkapton, occur because
genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.
What type of bonding is responsible for maintaining the shape of the tRNA molecule in the figure?
hydrogen bonding between base pairs
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)
Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I1). Which of the following results might occur?
inclusion of I1 in the mRNA
After an RNA molecule is transcribed from a eukaryotic gene, what is removed and what is spliced together to produce an mRNA molecule with a continuous coding sequence?
introns ... exons
A eukaryotic 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 eukaryotic DNA.
Examine the table of codons in the figure. What amino acid sequence will be produced based on the following mRNA codon sequence?
met-ser-ser-leu-ser-leu
The figure shows the simple metabolic pathway. Enzyme 1 catalyzes the transformation of A into B and enzyme 2 catalyzes the transformation of B into C. Examine the simple metabolic pathway in the figure. If A, B, and C are all required for growth, a strain mutant for the gene-encoding enzyme 2 would be capable of growing on which of the following media?
minimal medium supplemented with C only
The figure shows the simple metabolic pathway. Enzyme 1 catalyzes the transformation of A into B and enzyme 2 catalyzes the transformation of B into C. Examine the simple metabolic pathway in the figure. If A, B, and C are all required for growth, a strain that is mutant for the gene-encoding enzyme 1 would be able to grow on which of the following media?
minimal medium supplemented with nutrient B only
During RNA processing a(n) _____ is added to the 5' end of the RNA.
modified guanine nucleotide
Use the following information to answer the next few questions. 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) already in the ribosome. Which component of the complex described enters the exit tunnel through the large subunit of the ribosome?
newly formed polypeptide
Which three positions in the sequence logo in Figure 3 have the most predictable bases? Name the most frequent base at each position.
position 0 (A); position 1 (T); position 2 (G)
The process of translation in both prokaryotes and eukaryotes requires tRNAs, amino acids, and ribosomal subunits. Which of the following components must also be present for translation to proceed?
protein factors and GTP
Which of the following experimental procedures is most likely to speed up mRNA degradation in a eukaryotic cell?
removal of the 5' cap
the template strand of a gene contains this sequence: 3'- TAC TAG GCT AGT TGA -5'. A mutation occurs that changes the gene sequence to 3'- TAC TAG ACT AGT TGA -5'. How does this mutation affect the resulting amino acid sequence?
the mutation introduces a stop codon
you are a neurologist. a patient presents to you with amyloid plaques. which of the following is true?
the patient may or may not exhibit symptoms of Alzheimer's
In the diagram below, the green unit represents _____.
the promotor
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that
the rules for base pairing between the third base of a codon and tRNA are flexible.
What gene feature is represented by the bases in positions 0-2?
the translation start codon AUG
A codon consists of __________ bases and specifies which __________ will be inserted into the polypeptide chain.
three ... amino acid
you have a blood panel done and your triglyceride level is 107. Which of the following is true?
your level is below that of the average American
you have a normal APOC3 gene. you eat a very fatty meal. which of the following is most likely to happen?
your triglycerides will spike
