7.E: Molecular Biology (Exercises)
- Page ID
- 117825
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
7.1: The Structure of DNA
Multiple Choice
Which of the following does cytosine pair with?
A. guanine
B. thymine
C. adenine
D. a pyrimidine
- Answer
-
A
Prokaryotes contain a ________chromosome, and eukaryotes contain ________ chromosomes.
A. single-stranded circular; single-stranded linear
B. single-stranded linear; single-stranded circular
C. double-stranded circular; double-stranded linear
D. double-stranded linear; double-stranded circular
- Answer
-
C
Free Response
Describe the organization of the eukaryotic chromosome.
- Answer
-
The DNA is wound around proteins called histones. The histones then stack together in a compact form that creates a fiber that is 30-nm thick. The fiber is further coiled for greater compactness. During metaphase of mitosis, the chromosome is at its most compact to facilitate chromosome movement. During interphase, there are denser areas of chromatin, called heterochromatin, that contain DNA that is not expressed, and less dense euchromatin that contains DNA that is expressed.
Describe the structure and complementary base pairing of DNA.
- Answer
-
A single strand of DNA is a polymer of nucleic acids joined covalently between the phosphate group of one and the deoxyribose sugar of the next to form a “backbone” from which the nitrogenous bases stick out. In its natural state, DNA has two strands wound around each other in a double helix. The bases on each strand are bonded to each other with hydrogen bonds. Only specific bases bond with each other; adenine bonds with thymine, and cytosine bonds with guanine.
7.2: DNA Replication
Multiple Choice
DNA replicates by which of the following models?
A. conservative
B. semiconservative
C. dispersive
D. none of the above
- Answer
-
B
The initial mechanism for repairing nucleotide errors in DNA is ________.
A. mismatch repair
B. DNA polymerase proofreading
C. nucleotide excision repair
D. thymine dimers
- Answer
-
B
Free Response
How do the linear chromosomes in eukaryotes ensure that its ends are replicated completely?
- Answer
-
Telomerase has an inbuilt RNA template that extends the 3' end, so a primer is synthesized and extended. Thus, the ends are protected.
7.3: Transcription
Multiple Choice
A promoter is ________.
A. a specific sequence of DNA nucleotides
B. a specific sequence of RNA nucleotides
C. a protein that binds to DNA
D. an enzyme that synthesizes RNA
- Answer
-
A
Portions of eukaryotic mRNA sequence that are removed during RNA processing are ________.
A. exons
B. caps
C. poly-A tails
D. introns
- Answer
-
D
7.4: Translation
Multiple Choice
The RNA components of ribosomes are synthesized in the ________.
A. cytoplasm
B. nucleus
C. nucleolus
D. endoplasmic reticulum
- Answer
-
C
How long would the peptide be that is translated from this MRNA sequence: 5'-AUGGGCUACCGA-3'?
A. 0
B. 2
C. 3
D. 4
- Answer
-
D
Free Response
Transcribe and translate the following DNA sequence (nontemplate strand): 5'-ATGGCCGGTTATTAAGCA-3'
- Answer
-
The mRNA would be: 5'-AUGGCCGGUUAUUAAGCA-3'. The protein would be: MAGY. Even though there are six codons, the fifth codon corresponds to a stop, so the sixth codon would not be translated.
7.5: How Genes Are Regulated
Multiple Choice
Control of gene expression in eukaryotic cells occurs at which level(s)?
A. only the transcriptional level
B. epigenetic and transcriptional levels
C. epigenetic, transcriptional, and translational levels
D. epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels
- Answer
-
D
Post-translational control refers to:
A. regulation of gene expression after transcription
B. regulation of gene expression after translation
C. control of epigenetic activation
D. period between transcription and translation
- Answer
-
B
Free Response
Describe how controlling gene expression will alter the overall protein levels in the cell.
- Answer
-
The cell controls which protein is expressed, and to what level that protein is expressed, in the cell. Prokaryotic cells alter the transcription rate to turn genes on or off. This method will increase or decrease protein levels in response to what is needed by the cell. Eukaryotic cells change the accessibility (epigenetic), transcription, or translation of a gene. This will alter the amount of RNA, and the lifespan of the RNA, to alter the amount of protein that exists. Eukaryotic cells also change the protein’s translation to increase or decrease its overall levels. Eukaryotic organisms are much more complex and can manipulate protein levels by changing many stages in the process.
7.6: Cloning and Genetic Engineering
Multiple Choice
In gel electrophoresis of DNA, the different bands in the final gel form because the DNA molecules ________.
- are from different organisms
- have different lengths
- have different nucleotide compositions
- have different genes
- Answer
-
B
In the reproductive cloning of an animal, the genome of the cloned individual comes from ________.
A. a sperm cell
B. an egg cell
C. any gamete cell
D. a body cell
- Answer
-
D
What carries a gene from one organism into a bacteria cell?
A. a plasmid
B. an electrophoresis gel
C. a restriction enzyme
D. polymerase chain reaction
- Answer
-
A
Free Response
What is the purpose and benefit of the polymerase chain reaction?
- Answer
-
The polymerase chain reaction is used to quickly produce many copies of a specific segment of DNA when only one or a very few copies are originally present. The benefit of PCR is that there are many instances in which we would like to know something about a sample of DNA when only very small amounts are available. PCR allows us to increase the number of DNA molecules so that other tests, such as sequencing, can be performed with it.
7.7: Biotechnology in Medicine and Agriculture
Multiple Choice
What is a genetically modified organism (GMO)?
A. a plant with certain genes removed
B. an organism with an artificially altered genome
C. a hybrid organism
D. any agricultural organism produced by breeding or biotechnology
- Answer
-
B
What is the role of Agrobacterium tumefaciens in the production of transgenic plants?
A. Genes from A. tumefaciens are inserted into plant DNA to give the plant different traits.
B. Transgenic plants have been given resistance to the pest A. tumefaciens.
C. A. tumefaciens is used as a vector to move genes into plant cells.
D. Plant genes are incorporated into the genome of Agrobacterium tumefaciens.
- Answer
-
C
Free Response
Today, it is possible for a diabetic patient to purchase human insulin from a pharmacist. What technology makes this possible and why is it a benefit over how things used to be?
- Answer
-
The human insulin comes from the gene that produces insulin in humans, which has been spliced into a bacterial genome using recombinant DNA technology. The bacterium produces the insulin, which is then purified for human use. Before there was genetically engineered human insulin, diabetics were given insulin extracted from pig pancreases, which was similar to, but not exactly like, human insulin. Because it was not exactly like human insulin, the pig insulin caused complications in some diabetic patients.
7.8: Genomics and Proteomics
Multiple Choice
What is the most challenging issue facing genome sequencing?
A. the inability to develop fast and accurate sequencing techniques
B. the ethics of using information from genomes at the individual level
C. the availability and stability of DNA
D. all of the above
- Answer
-
B
Genomics can be used in agriculture to:
A. generate new hybrid strains
B. improve disease resistance
C. improve yield
D. all of the above
- Answer
-
D
What kind of diseases are studied using genome-wide association studies?
A. viral diseases
B. single-gene inherited diseases
C. diseases caused by multiple genes
D. diseases caused by environmental factors
- Answer
-
C
Free Response
Describe two of the applications for genome mapping.
- Answer
-
Genome mapping helps researchers to study disease-causing genes in humans. It also helps to identify traits of organisms that can be used in applications such as cleaning up pollution.
Identify a possible advantage and a possible disadvantage of a genetic test that would identify genes in individuals that increase their probability of having Alzheimer's disease later in life.
- Answer
-
The benefit of such a test is that the individual can make preparations for having the disease including taking treatments that slow the disease. The disadvantage of the test is that it might be used by insurance companies to deny coverage to the person.