Chapter 4: DNA- The Molecular Basis of Life Flashcards
(117 cards)
1
Q
Deoxyribonucleic Acid (DNA)
A
A double-stranded polymer of nucleotides (each consisting of a deoxyribose sugar, a phosphate, and four nitrogenous bases) that carries the genetic information of an organism.
2
Q
Bacteriophage
A
Any bacteria-infecting virus
3
Q
Isotope
A
Different atoms of the same element containing the same number of protons but a different number of neutrons.
4
Q
Radioisotopes
A
Unstable isotopes that decay spontaneously by emitting radiation.
5
Q
Deoxyribose Sugar
A
Sugar molecule containing five carbons that as lost the -OH (hydroxyl group) on its 2’ (2 prime) carbon.
6
Q
Phosphate Group
A
Group of four oxygen atoms surrounding a central phosphorous atom found in the backbone of DNA.
7
Q
Nucleotides
A
Molecules that consist of a five-carbon sugar (deoxyribose or ribose) with a nitrogenous base attached to their 1’ carbon and a phosphate group attached to their 5’ carbon.
8
Q
Nitrogenous Base
A
An alkaline, cyclic molecule containing nitrogen.
9
Q
Glycosyl Bond
A
A bond between a sugar and another organic molecule by way of an intervening nitrogen or oxygen atom.
10
Q
Antiparallel
A
Parallel but running in opposite directions; the 5’ end of one strand of DNA aligns with the 3’ end of the other strand in a double helix.
11
Q
Complementary Base Pairing
A
The pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand; adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).
12
Q
Mitosis
A
Division of the nucleus of a eukaryotic cell into two daughter nuclei with identical sets of chromosomes.
13
Q
Cytokinesis
A
Division of cytoplasm and organelles of a cell into two daughter cells.
14
Q
Template
A
a single-stranded DNA sequence that acts as the guiding pattern for producing a complementary DNA strand.
15
Q
Semiconservative
A
The process of replication in which each DNA molecule is composed of one parent strand and one newly synthesized strand.
16
Q
DNA Helicase
A
The enzyme that unwinds double- helical DNA by disrupting hydrogen bonds.
17
Q
Anneal
A
The pairing of complementary strands of DNA through hydrogen bonding.
18
Q
Single- stranded binding proteins (SSBs)
A
A protein that keeps separated strands of DNA apart.
19
Q
DNA Gyrase
A
The bacterial enzyme that relieves the tension produced by the unwinding of DNA during replication.
20
Q
Replication Fork
A
The region where the enzymes replicating a DNA molecule are bound to untwisted, single stranded DNA.
21
Q
Replication Bubble
A
The region where two replication forks are in close proximity to each other, producing a bubble in the replicating DNA.
22
Q
DNA Polymerase III
A
The enzyme responsible for synthesizing complementary strands of DNA during DNA replication.
23
Q
Deoxyribonucleoside Triphosphates
A
Molecules composed of a deoxyribose bonded to three phosphate groups and a nitrogenous base.
24
Q
RNA (ribonucleic acid) Primer
A
A sequence of 10 to 60 RNA bases that is annealed to a region of single-stranded …………… not done
25
Adenine and guanine are pyrimidines
False; Adenine and guanine are purines.
26
The DNA double helix makes a complete turn every 3.4 nm along its length.
True
27
DNA’s backbone is held together by hydrogen bonds while the complementary bases are held together by phosphodiester bonds.
Flase; Phosphodiester bonds hold DNA’s backbone together while the complementary bases are held together by hydrogen bonds.
28
If the deoxynucleotide sequence in one strand of a short stretch of DNA double helix is 5'–CTGGAT–3', then the complementary sequence in the opposite strand is 3'–GACCTG–5'.
False; If the deoxynucleotide sequence in one strand of a short stretch of DNA double helix is 5'–CTGGAT–3', then the complementary sequence in the opposite strand is 3'–GACCTA–5'.
29
DNA helicase is an enzyme that ensures that the appropriate complementary base pairs have been added to the growing daughter strands during DNA replication.
False; DNA polymerase III is an enzyme that ensures that the appropriate complementary base pairs have been added to the growing daughter strands during DNA replication.
30
DNA replication is conservative.
False; DNA replication is semi- conservative.
31
Joachim Hammerling’s experiment using Acetabularia revealed that the hereditary information is found in the foot of the alga where the nucleus resides.
True
32
DNA polymerase III builds a complementary DNA strand during DNA replication in the 3' to 5' direction.
False; DNA polymerase III builds a complementary DNA strand during DNA replication in the 5' to 3' direction.
33
After one replication of double-stranded DNA, some of the daughter DNA molecules contain no parental material.
False; After one replication of double-stranded DNA, the daughter DNA molecules are comprised of 50% parental material.
34
Erwin Chargaff’s rules state that adenine bonds with thymine, and cytosine bonds with guanine.
True
35
Which of the following best describes deoxyribonucleic acid (DNA)?
It consists of a linear backbone of the sugar deoxyribose and phosphates, with nitrogenous bases attached to the sugar residues.
36
Which of the following is associated with only the lagging strand during DNA replication?
Okazaki fragments
37
The percent composition of adenine in a DNA molecule is found to be 35%. Therefore, which of the following is the percent composition of guanine?
15%
38
DNA replication occurs in which of the following ways?
in the 5' to 3' direction only
39
Which of the following did Matthew Meselson and Franklin Stahl’s experiment illustrate?
DNA replicates semiconservatively.
40
In eukaryotes, transcription occurs in the cytoplasm and translation occurs in the nucleus.
False; In eukaryotes, transcription occurs in the nucleus and translation occurs in the cytoplasm.
41
During transcription, RNA polymerase uses the template strand of DNA as a template to synthesize the complementary mRNA.
True
42
RNA comprises a ribose sugar, a phosphate, and a nitrogenous base. The nitrogenous base may be adenine, uracil, guanine, or cytosine.
True
43
Beadle and Tatum’s investigation of metabolism in the organism Neurospora crassa led to the one gene–one polypeptide hypothesis.
True
44
When a bacteria’s environment is high in lactose, the LacI protein is bound tightly to the operator of the lac operon.
False; When a bacteria’s environment is high in lactose, the LacI protein is bound to a lactose molecule.
45
A missense mutation results in the substitution of one or more amino acids in the protein chain.
False; A missense mutation results in the substitution of one amino acid in the protein chain.
46
Telomeres are examples of positive variable number tandem repeats that protect the chromosome.
True
47
The role of ribosomal RNA is to deliver amino acids to the ribosome to undergo protein synthesis.
False; The role of tRNA is to deliver amino acids to the ribosome to undergo protein synthesis.
48
The complementary mRNA sequence to the DNA sequence ATGGGCCATAC is UACCCGGUAUG.
True
49
Which of the following best describes ribonucleic acid (RNA)?
similar to DNA but it contains ribose in place of deoxyribose and uracil instead of thymine
50
What does the central dogma specify?
A DNA sequence encodes an RNA sequence that encodes protein.
51
The anticodons of arginine, serine, and tyrosine are GCA, UCA, and AUA, respectively. If a segment of DNA codes for these three amino acids in the sequence listed (arginine, serine, tyrosine), which of the following would be the sequence of deoxyribonucleotides of the strand of the DNA molecule that coded for these amino acids?
GCATCAATA
52
Which of the following are the enzymes involved in posttranscriptional modification?
poly-A polymerase and spliceosomes
53
Base-pair substitutions involving the third base of a codon may not result in an error in the polypeptide. What is partly responsible for this avoidance of error?
Most tRNAs bind tightly to a codon with only the first two bases of the anticodon.
54
What does the base sequence AAU GGC code for?
two specific amino acids
55
What does an operon typically consist of?
an operator, a promoter, and a cluster of genes
56
Restriction endonucleases recognize, bind, and cut specific four to eight nucleotide palindromic sequences of DNA.
True
57
To produce blunt ends, restriction endonucleases must disrupt both phosphodiester and hydrogen bonds.
False; To produce blunt ends, restriction endonucleases must disrupt only phosphodiester bonds.
58
Methylases add a methyl group to a specific recognition site, preventing the binding of the respective restriction enzyme.
True
59
DNA ligase is able to join both sticky- and blunt-end fragments together by reconstituting a phosphodiester bond using a condensation reaction.
True
60
Gel electrophoresis separates DNA fragments according to charge. The larger the fragment, the larger the charge it will carry because of the presence of more phosphate groups.
False; Gel electrophoresis separates DNA fragments according to size. The larger the fragment, the the slower the fragment will be able to navigate through the gel.
61
The introduction of a foreign gene into a living cell is known as transformation.
True
62
Plasmids are single-stranded circular pieces of DNA that are found in eukaryotic cells.
False; Plasmids are double-stranded circular pieces of DNA.
63
The Flavr Savr tomato was developed using antisense technology.
True
64
Restriction fragment length polymorphism is highly discriminating because it targets polymorphic regions of DNA.
True
65
The polymerase chain reaction makes a large number of copies of the entire genome.
False; The polymerase chain reaction makes a large number of copies of target regions of DNA.
66
Agarose gel electrophoresis of DNA involves the movement of DNA in an electric field through the pores of a rectangular slab of agarose. Since DNA has a pronounced negative charge, it naturally moves toward positive electrodes when an electric current is applied to the gel. How do large pieces of DNA move relative to small pieces in such a system?
slower, because they meet more resistance from the gel matrix
67
Which of the following primers, used with PCR, would allow copying of the single-stranded DNA sequence 5'-ATGCCTAGGTC-3'?
5'-GACCT-3'
68
Which of the following tools of recombinant DNA technology is incorrectly paired with its use?
DNA ligase: an enzyme that cuts DNA, creating sticky ends
69
Which of the following best describes Southern blotting?
the detection of DNA fragments on membranes by a radioactive DNA probe
70
The restriction enzyme BamHI was purified from which of the following?
Bacillus amyloliquefens
71
Which of the following best describes antisense oligonucleotides?
They hybridize to mRNA and prevent ribosomes from translating the mRNA into protein.
72
DNA Replication is described as semi-conservative because one of the strands of the new double helix is an old strand from the parental DNA molecule, while the other has been newly sunthesized using the new strand as a template
False; Using the old strand
73
All the hydrogen bonds in DNA may be formed between nitrogen and hydrogen atoms and oxygen and hydrogen atoms.
True
74
The anticodon for the mRNA codon CGA is GCT
False; GCU
75
Ribosomes move along mRNA in a 5'--> 3' direction
True
76
The genetic change responsible for the disease sickle cell anemia is a point mutation.
True
77
The mRNA transcript for a gene is made up of the same bases, in the same proportion, as the strand of DNA complementray to the template strand, excpet the uracil will be replaced by thymine.
False; thymine will be replaced with uracil.
78
Gene expression order
```
DNA (genotype)
Pre mRNA
mRNA
1 protein
2,3,4 protein
Trait (phenotype)
```
79
The fact that the genetic code is very different in almost all organisms indicates that it evolved early in the history of life on earth.
F; very similar in almost all organisms
80
Some restriction endonucleases make zigzag cuts in double-stranded DNA leaving blunt ends.
F; leaving sticky ends
81
Gel electrophoresis separates DNA fragments on the basis of their size.
T
82
The paired basis of a DNA molecule are best described as
complementary
83
DNA replication
results in each cell produced by mitosis and cytokinesis having a complete set of genetic instructions
84
Which of the following is a correct representation of a segment of DNA?
1. 5'ATTC3', 3'ATTC5'
2. 5'AUUC3', 3'UAAG5'
3. 5'CCGG3', 5'GGCC3'
4. '5ATAG3', 3'TATC5'
5. 5'ACGA3',3'TGCT5'
4 and 5
85
DNA replication
occurs before cytokinesis
86
The nucleotide at the end of one strand of a fragment of double-stranded DNA has a free phosphate attached to the 5' carbon of its deoxyribose sugar. The complementary nucleotide has
a hydroxyl group (-OH) attached to the 3' carbon of its deoxyribose sugar
87
The model for DNA structure proposed by Watson and Crick, by its very nature, suggests a way in which the DNA molecule can replicate itself, because
each base is capable of specifying the base opposite to it in the double helix
88
If the percentage composition of thymine in a DNA molecule is 22%, what is the percentage composition of cytosine?
28%
89
When DNA helicase is active, the result is
separation of the two strands of the double helix
90
During DNA replication, the function of RNA primers is to
serve as starting points for DNA strand elongation by DNA polymerase in prokaryotes
91
During DNA replication, one of the new strands of DNA is synthesized continuously, while the other is synthesized as a number of separate fragments of DNA that are subsequently linked by DNA ligase. This is because
DNA polymerase only synthesizes DNA in the 5'-3' direction
92
```
A DNA nucleotide contains
1. a cyclic nitrogen-containing part
2. a single ring containing five carbons
3. a part which contains four oxygen atoms surrounding a central atom
In order, 1, 2 and 3 are
```
a base, a sugar, a phosphate group
93
The main support to the DNA molecule is provided by two backbones which run along the two sides of the double helix. These backbones consist of
sugars and phosphates linked together
94
5' GGCATA (X)
(Z) CCGTAT (Y)
If the above is a representation of a piece of double-stranded DNA, what symbols should occupy the positions (X), (Y) and (Z)?
3',5',3'
95
In what order do the following molecules become involved in DNA replication?
1. single-stranded binding proteins
2. DNA polymerase
3. primase
4. helicase
4,1,3,2
96
An enzyme, which excises a mismatched base in a newly synthesized strand of DNA, is called
exonuclease or 'check and edit' enzyme
97
The number of protein-encoding genes in the human genome is approximately
30 000
98
Complementary base pairing is the result of
hydrogen bonding
99
The genetic code is
very similar in antelopes, pine trees and bacteria
100
Which of the following correctly describes the order in which cell components become involved in protein synthesis?
RNA polymerase, mRNA, ribosome, tRNA
101
Line A below shows the peptide synthesized after transcription and translation of a piece of DNA. Line B shows the peptide synthesized after a mutation in this piece of DNA.
A. proline - arginine - aspartic acid - lysine - glycine
B. proline - glutamine - aspartic acid - lysine - glycine
The type of change in the DNA most likely to be responsible for the difference between the peptides is
a base substitution
102
A section of mRNA 9 codons long would most likely result in the addition of how many amino acids to a growing polypeptide (the stop codon is absent from the section of mRNA)?
9
103
DNA acts as a template for transcription. Which of the following statements regarding the DNA of a gene being expressed is true?
after unwinding, only one of the DNA strands acts as a template
104
The temperatures at which two segments of DNA unwind has been established. Segment A unwinds at 71.6 degrees C, while segment B unwinds at 80.7 degrees C. The difference is due to the fact that
B is richer in cytosine-guanine pairs than A
105
In eukaryotes, introns are removed before mRNA leaves the nucleus because
they do not code for protein
106
RNA polymerase participates in
DNA transcription
107
Base pairing due to hydrogen bonding is fundamental to
both processes
108
If transcription could proceed in both directions along both DNA strands of a gene, how many different polypeptides could be coded for a single gene?
4
109
A piece of double-stranded DNA consisting of 18 nucleotides would likely create a first-formed mRNA transcript having
3 condons
110
Which of the following is true with respect to the lac operon?
the repressor is bound to the operator, except when it is bound to the inducer
111
Compare the two mRNA sequences below:
AUAUUCGGCAAUCCG
AUAUUCCGCAAUCCG
This change could be a result of
point mutation
112
Mutations can be inheritable if they effect cells in the
testes
113
The 'Central Dogma' states that the flow of genetic information is in the direction
DNA, mRNA, protein
114
The function of the polyadenine tail that is added to mRNA in eukaryotic cells is to
prevent degradation of the mRNA
115
The discovery of restriction endonucleases (=restriction enzymes) was crucial to the development of recombinant DNA technology because these enzymes
cut DNA at specific and predictable sequences of bases
116
When recombinant DNA is formed, it is necessary to join the sugar-phosphate backbones of the plasmid DNA and the introduced DNA that contains the 'gene of interest'. Which of the following is used to do this
ligase
117
Restriction endonucleases can break
covalent bonds and hydrogen bonds
