DNA, RNA, and Proteins Flashcards
(108 cards)
1
Q
what did Friedrich Mieschner do?
A
discovered nuclein by isolating phosphate-rich chemicals from the nuclei of white blood cells in pus
2
Q
what 2 experiments proved DNA to be the hereditary material?
A
Avery’s transformed infectious bacteria, Hershey and Chase’s injection of DNA into a host cell to make new viruses
3
Q
what 3 experiments on bacterial transformation proved DNA to be the substance of genes?
A
- Griffith
- Avery, MacLeod, and McCarty
- Hershey and Chase
4
Q
describe the Griffith experiment
A
- took 2 types of bacteria; virulent (s) and nonvirulent (r)
- (s) kills mice, (r) does not
- (s) mutates to (r) form, does not kill mice anymore
- (s) heated, doesn’t kill
- heat-killed (s) revived by combining with (r), kills mice, and living (s) form found in autopsy
5
Q
describe the Avery, MacLeod, and McCarty experiment
A
took Griffith further
- took living (r) form, combined with heat-killed (s) form in a medium, over time found only living (s) form
- added protease, RNase, and used ultracentrifguation, but still found living (s) form
- added DNase, (s) not found, showing that DNA is dominant
6
Q
describe the Hershey and Chase experiment
A
provided convincing evidence that DNA is the genetic material
-bacteria injected with their phage would replicate only the changed phage DNA
7
Q
what is Chargaff’s rule?
A
the ratios of A and T are 1:1, and the ratios of G and C are 1:1
8
Q
when did Watson and Crick propose their double helix model?
A
1953
9
Q
what did Rosalind Franklin do?
A
photographed DNA molecule using X-ray crystallogrophy
10
Q
what did Franklin’s DNA picture show?
A
that DNA is a coil with a constant diameter of 2nm
11
Q
what is the blueprint for all life?
A
DNA, deoxyribonucleic acid
12
Q
and is a karyotype?
A
a picture of all an organisms’ chromosomes
13
Q
how many chromosomes does a human have?
A
46
14
Q
how many chromosomes does a dog have?
A
78
15
Q
how many chromosomes does a cat have?
A
38
16
Q
how many chromosomes do cattle have?
A
60
17
Q
how many chromosomes does a goat have?
A
60
18
Q
how many chromosomes does a sheep have?
A
54
19
Q
how many chromosomes does a horse?
A
64
20
Q
how many chromosomes does a donkey have?
A
62
21
Q
how many chromosomes does a chicken have?
A
78
22
Q
how many chromosomes does a turkey have?
A
80
23
Q
how many chromosomes do camels, alpaca, and llamas have?
A
74
24
Q
how many chromosomes does a rabbit have?
A
40
25
how many chromosomes does a rat have?
38
26
DNA is a polymer of?
nucleotides
27
each nucleotide is composed of?
1. 5-carbon sugar
2. phosphate
3. nitrogenous base
28
list the 4 nitrogenous bases?
1. adenine
2. thymine
3. guanine
4. cytosine
29
list the purine bases (double ringed)
1. adenine
| 2. guanine
30
list the pyrimidine bases (single ringed)
1. cytosine
| 2. thymine
31
adenine pairs with thymine in what kind of bond?
double
32
cytosine pairs with guanine in what kind of bond?
triple
33
in DNA replication, nucleotides come together to make a new strand that is ____ to the old strand?
complimentary
34
the new double strand formed in DNA replication is a ____ to the old double strand?
duplicate
35
how is DNA replicated?
semi-conservative replication
36
is there only one form of the DNA double helix?
no, it can assume alternative forms
37
in what 4 organisms are DNA molecules circular instead of linear?
1. prokaryotes
2. mitochondria
3. chloroplasts
4. viruses
38
what kind of viruses carry single-stranded DNA?
bacteriophages
39
what virus carries RNA?
AIDS
40
list the 4 requirements for DNA to be the genetic material
1. must carry information
2. must replicate
3. must allow for information to change, or mutate
4. must govern the expression of the phenotype
41
where does DNA replication take place?
in the nucleus
42
what produces semiconservative replication?
complimentary base pairing
43
in DNA replication, what happens to the double helix?
it unwinds and each strand acts as a template
44
what does complimentary base pairing ensure?
that T signals the addition of A on new strand, and G signals addition of C
45
how many daughter helices are produced after replication?
2
46
in replication, what does Pol III do?
produces new strands of complimentary DNA
47
in replication, what does Pol I do?
fills in gaps between newly synthesized Okazaki fragments
48
in replication, what does DNA helicase do?
unwinds double helix
49
in replication, what do single stranded binding proteins do?
keep helix open- the exact opposite of bind actually
50
in replication, what does primase do?
creates RNA primers to initiate synthesis
51
in replication, what does ligase do?
welds together Okazaki fragments
52
where does DNA replication begin?
at the origin of replication
53
how many origins of replication are there?
can be multiple, up to 100,000 in complex organisms, but most bacteria only have 1
54
what is the replication bubble?
the area where DNA helices are unwound and replication takes place
55
what is the replication fork?
the active area where replication takes place
56
what establishes the RNA primers in replication?
primase
57
what holds open the unwound strands of DNA during replication?
single-stranded binding proteins
58
what joins Okazaki fragments into a continuous strand after the removal of primers in replication?
DNA ligase
59
what kind of replication occurs on the leading strand?
continuous
60
what kind of replication occurs on the lagging strand?
discontinuous
61
what direction does replication move in?
bidirectional, the replication forks move in opposite directions
62
what do telomeres do in linear chromosomes during replication?
ensure the maintenance and accurate replication of chromosome ends
63
how many origins of replication are in circular chromosomes, such as E. coli?
only one
64
what can unwinding and replication do to circular chromosomes, and what problems may that cause?
supercoiling, which may impede replication
65
what is topoisomerase?
an enzyme that relaxes supercoils by nicking strands
66
what is the basis for repair of errors that occur during replication or storage?
redundancy, more than one codon can code for the same amino acid
67
are errors during replication common?
no, they're rare
68
what is recombination?
when homologs physically break, exchange parts, and rejoin, creating reciprocal products
69
where can recombination occur?
anywhere along the DNA molecule
70
what prevents mutations from occurring during the recombination process?
precision in the exchange of genetic information
71
what does the Watson-Crick model show?
that DNA is a double helix composed of 2 antiparallel strands of nucleotides
72
in what order does DNA carry information?
in the sequence of its bases
73
list the 5 steps of DNA replication, including enzyme function
1. helicases unwind the parental double helix
2. single-stranded binding proteins stabilize the unwound parental DNA
3. the leading strand in synthesized continuously in the 5' to 3' direction by DNA polymerase
4. the lagging strand is synthesized discontinuously. Primase synthesizes a short RNA primer, which is extended by DNA polymerase to form an Okazaki fragment
5. After the RNA primer is replaced by DNA, DNA ligase joins the Okazaki fragment to the growing strand
74
what does RNA stand for?
ribonucleic acid
75
how is RNA similar to DNA
it has repeating subunits, nucleotides
76
what are the 4 main differences between RNA and DNA?
1. RNA contains ribose instead of deoxyribose in its nucleotides
2. adenine pairs with uracil instead of thymine like DNA
3. RNA is single stranded and shorter
4. RNA is less stable than DNA, and doesn't persist in the cell for very long, whereas DNA can persist for the life of the cell
77
what is the central dogma of molecular biology?
DNA to RNA: transcription
| RNA to proteins: translation
78
what are the 3 different RNA molecules involved in protein synthesis?
1. mRNA
2. rRNA
3. tRNA
79
what is transcription?
RNA synthesis from DNA
80
where does transcription occur?
in the nucleus
81
where does mRNA carry the message about what type of protein to make?
from the DNA in the nucleus to the ribosome outside the nucleus
82
what is the only difference between the transcribed RNa sequence from the DNA sequence?
the RNA sequence contains uracil instead of thymine
83
how is mRNA synthesized from DNA?
base pairing
84
how does DNA unwind?
in sections
85
what does RNA polymerase do in transcription?
attaches at the promoter sequence of DNA and moves along the DNA, unzipping the strands, allowing for more mRNA molecules to be formed
86
what is formed during transcription as a complimentary copy of a region one on strand of the DNA molecule?
a molecule of messenger RNA
87
list and describe the 3 modifications that initial mRNA goes through before leaving the nucleus?
1. capping: addition of a 7 methylguanosine cap on the 5' end prevents mRNA from degradation outside the nucleus
2. poly-A tail: polyadenylation on the 3' end stabilized mRNA
3. intron splicing: removes the noncoding segments from the mRNA strand and leaves the exons, or coding segments to leave the nucleus
88
what is a codon?
each 3 consecutive bases on the mRNA is a code word, or codon, that specifies an amino acid
89
how many codons make up the genetic code?
64
90
what 3 codons act as signal terminators?
UGA, UAG, UAA
91
what codon codes for both methionine and is also the START signal for translation?
AUG (school starts in august)
92
how many amino acids are there in all life forms?
20
93
what are amino acids?
the bricks or building blocks that make all proteins
94
what is translation?
synthesizing a protein from amino acids according to the sequences of the nucleotides in mRNA
95
where does translation occur?
at the ribosome in the cytoplasm of the cell
96
what type of RNA is needed for protein synthesis?\ and what does it do?
rRNA, ribosomal RNA; helps mRNA bind to the SMALL subunit of the ribosome
97
what is tRNA?
transfer RNA; brings specific amino acids to the ribosome to be assembled as proteins, 80 nucleotides long
98
what does ribosomal RNA join with to make ribosomes?
a bunch of proteins
99
what is the site of protein synthesis?
ribosomes
100
what do ribosomes consist of?
a large subunit and a small subunit that mRNa binds to
101
list the 6 steps of translation
1. mRNA leaves the nucleus and migrates to the ribosome
2. mRNA binds to the SMALL ribosomal subunit
3. tRNA brings an amino acid to the ribosome, where the anticodon on the tRNA binds to the codon of the mRNA
4. the amino acid bonds to its adjoining amino acid to form a growing polypeptide molecule
5. the tRNA without the amino acid is released from the ribosome
6. other tRNA's bring amino acids to the ribosome to complete the protein molecule
102
where does protein synthesis occur?
in the cytoplasm of the cell
103
what are the repeating subunits of protein molecules?
amino acids
104
why is the order of amino acids important?
it determines the 3D shape of the molecule, and the protein function
105
what are mutations?
changes in the DNA sequence that may be passed along to future generations; not always bad
106
what are point mutations?
a single base substitution
107
what are frame-shift mutations?
modifications of the reading frame after a deletion or insertion, resulting in all codons downstream being different
108
what are the 2 types of frameshift mutations?
1. deletion: a small DNA segment is lost
2. insertion: a segment of DNA is added
both change the entire sequence
