Gene to Protein Flashcards
(190 cards)
1
Q
Genes specify ____
A
proteins
2
Q
how do genes specify proteins
A
transcription and translation
3
Q
transcription
A
DNA directed synthesis of RNA
4
Q
eukaryotic cels modify RNA _____ transcription
A
AFTER
5
Q
translation
A
RNA directed synthesis of a polypeptide
6
Q
what can affect protein structure and function
A
mutations of one or a few nucleotides
7
Q
information content of genes
A
specific nucleotide sequences
8
Q
DNA inherited by an organism leads to a specific trait by
A
dictating the synthesis of proteins
9
Q
the link between genotype and phenotype
A
proteins
10
Q
gene expression
A
process by which DNA directs protein synthesis
11
Q
two stages in gene expression
A
transcription and translation
12
Q
how do genes depict phenotype
A
through enzymes
13
Q
one-gene one-enzyme hypothesis
A
gene dictates production of a specific enzyme
14
Q
are all proteins enzymes
A
NO
15
Q
many proteins are composed of ______ polypeptides with ______
A
several AND own gene
16
Q
what did the one-gene one-enzyme hypothesis become
A
one-gene one-polypeptide
17
Q
in prokaryotic cells, transcription and translation are
A
not separated
18
Q
in eukaryotic cells, where is transcription
A
nucleus
19
Q
where is a translation in eukaryotic cells
A
ribosomes in cytoplasm
20
Q
how does polymerase add nucleotides
A
pairing with DNA template
21
Q
nucleotides are added to the ____ end
A
3’
22
Q
sense strand
A
defined by the promoter
23
Q
sense strand runs from
A
5’ to 3’
24
Q
template strand runs
A
3’ to 5’
25
thetemplate strand is also known as
anti-sense strand
26
transcription produces
mRNA
27
mRNA is a message to
produce a protein
28
site of translation
ribosome
29
why can translation begin before transcription is done in prokaryotes
not separated
30
what separates transcription from translation in eukaryotes
nuclear enevlope
31
how are eukaryotic RNA modified to finished mRNA
RNA processing
32
primary transcript
initial RNA transcript from any gene prior to processing
33
central dogma
concept that cells are governed by cellular chain of command
34
what steps are the central dogma
DNA to RNA to PROTEIN
35
how many nucleotides correspond to an amino acid
3 nucleotides per amino acid
36
triplet code
series of nonoverlapping, three nucleotide "words"
37
the flow of information from gene to protein is based on
triplet code
38
what does the template strand provide
a template for ordering the sequences of complementary nucleotides in RNA transcript
39
codons
specifies an amino acid placed at the corresponding position along the polypeptide
40
codons are read in
5' to 3'
41
61 of the codons are for
amino acids
42
3 codons are for
stop signals
43
start codon
AUG
44
stop codons
UAA
UAG
UGA
45
genetic code is
redundant
46
redundant
more than ONE codon may specify a particular amino acid
47
the genetic code is not
ambiguous
48
ambiguous
no codon specifies more than ONE amino acid
49
what must codons do to specify polypeptides being produced
read in the correct reading frame
50
reading frame
defined by the start codon and the terminating codon
51
by being redundant, what does the genetic code prevent
potential mutations by having no change in amino acid despite change in codon
52
the genetic code is nearly
universal
53
genes can be what after one species to another
transcribed and translated
54
first step in gene expression
transcription
55
three steps in transcription
1. initiation
2. elongation
3. terminantion
56
initiation
after RNA polymerase binds to the promoter the DNA strand unwinds
57
what does polymerase do in the initiation
initiates RNA synthesis to the start point on the template strand
58
direction of polymerase in elongation
downstream
59
elongation
unwinds the DNA and elongates the RNA transcript 5' to 3'
60
termination
RNA transcript is released
61
what stage does the polymerase detach from the DNA
termination
62
RNA synthesis is catalyzed by
RNA polymerase
63
RNA polymerase
separates DNA strands and joins together RNA nucelotides
64
the sequence of the resulting RNA is complementary to
the DNA template
65
RNA polymerase does not need
a primer
66
RNA synthesis follows the same base-pairing rule as
DNA
67
promoter
DNA sequence where RNA polymerase attaches
68
in bacteria the sequence signalling the end of transcription is
terminator
69
transcription unit
stretch of DNA that is transcribed
70
promoters signal the
transcriptional start point
71
promoters usually extend
several dozen nucleotide pairs upstream of the start point
72
transcription factors
mediate binding of RNA polymerase and the initiation of transcripton
73
transcription-initiation complex
assembly of transcription factors and RNA polymerase II bound to a promoter
74
TATA box
crucial for forming the initiation complex in eukaryotes
75
as RNA polymerase moves along DNA it
untwists the double helix
76
a gene can transcribe simultaneously by
several RNA polymerases
77
mechanism of termination are _____ in bacteria and eukaryotes
different
78
in bacteria, the termination
polymerase stops transcription at the end of terminator
79
in bacteria, the mRNA can be translated
without further modification
80
in eukaryotes, termination
RNA polymerase II transcribes a polyadenylation signal sequence
81
pre-mRNA signals that it is what cell
eukaryotic
82
how do enzymes in the nucleus of eukaryotes modify pre-mRNA
RNA processing
83
when does RNA processing take place
BEFORE it is released to cyoplasm
84
during RNA processing both ends of the primary transcript
are altered
85
primary transcript
pre-mRNA
86
5' end of pre-mRNA receives
5'cap of guanine nucleotides
87
the 3' end of pre-mRNA receives
poly-A-tail with adenine nucleotides
88
functions of the alterations of mRNA ends
1. facilitate the export of mRNA to the cytoplasm
2. protect mRNA from hydrolytic enyzmes
3. help ribosomes attach to 5' end
89
where do noncoding stretches of nucleotides lie in eukaryotes
between coding regions
90
noncoding regions are called
intervening sequences or introns
91
exons
regions that are eventually expressed and translated into amino acids
92
RNA splicing
removes introns and joins exons
93
RNA splicing creates
an mRNA molecule with a continuous coding sequence
94
spliceosomes consist of
variety of proteins and several small nuclear ribonucleoproteins
95
spliceosomes recognize
splice sites
96
RNA splicing can be carried out by
spliceosomes
97
the RNA of spliceosomes does what
catalyze the splicing reaction
98
ribozymes
catalytic RNA molecules
99
function of ribozymes
as enzymes
100
what rendered obsolete the belief that all biological catalysts were proteins
ribozymes
101
what three properties of RNA enable it to function as an enzyme
1. RNA can form a 3D structure
2. some bases in RNA contain functional groups
3. RNA may hydrogen bond with other nucleic acid
102
why can RNA form a 3D structure
its ability to base pair with itself
103
what can some functional groups of RNA do
participate in catalysis
104
some _____ contain sequences that may regulate gene expression
introns
105
genes can code _______ polypeptide
more than one
106
alternative RNA splicing
genes encoding more than one polypeptide depending on which segments are treated as exons during splicing
107
the number of proteins an organism can produce is _______ than its number of genes
much greater
108
domains
proteins often have modular architecture consisting of discrete regions
109
many _____ code for different _____ in a protein
exons AND domains
110
exon shuffling may result in
the evolution of new proteins
111
translation is a process where genetic information flows from _____ to _____
mRNA to protein
112
cell translates mRNA messages into proteins with the help of
tRNA
113
tRNA
transfer of amino acids to growing polypeptide in a ribosome
114
molecules of tRNA _____ identical
aren't
115
each tRNA molecule carries
a specific amino acid on one end
116
each tRNA molecule has an
anticodon on the other end
117
anticodon
base-pairs with a complementary codon on mRNA
118
what does a tRNA molecule look like
a clover
119
why can a tRNA molecule fold into a 3D conformation
hydrogen bonds
120
tRNA has a rough ____ 3D shape
L
121
what are the two steps needed for accurate translation
1. a correct match between a tRNA and amino acid
2. correct match between tRNA anticodon and mRNA codon
122
what catalyzes the match between tRNA and amino acid in translation
aminoacyl-tRNA synthetase
123
what allows some tRNAs to bind to more than one codon
flexible pairing at the third base of a codon
124
wobble
flexible pairing at the third base of a codon
125
what facilitates specific coupling of tRNA anticodons with mRNA condons
ribosomes
126
what are the two ribosomal units made from
proteins and ribosomal RNA
127
how many subunits are on a ribosome
two (large and small)
128
are the ribosomes of bacteria and eukaryotes similar
YES
129
three binding sites for tRNA in a ribosome
P site
A site
E site
130
E site of a ribosome is the
exit site
131
p site of a ribosome is the
peptidyl-tRNA biding site
132
A site of a ribosome is the
aminoacyl-tRNA binding site
133
three stages of translation
initiation, elongation, terminantion
134
what do all three stages of translation require
protein "factors" that aid in the translation process
135
do some steps in translation require energy
YES
136
what does initiation bring together in translation
mRNA, tRNA with the first amino acid and two ribosomal subunits
137
what happens to the small ribosomal subunit in initiation during translation
binds with mRNA and a special initiator tRNA and moves along the mRNA until reaching the start codon
138
initiation factors in translation
proteins that bring in the large subunit that completes the translation initiation complex
139
what completes the translation initiation complex
the arrival of a large ribosomal subunit
140
what happens during the elongation of translation
amino acids are added one by one to the preceding amino acid
141
where are amino acids added during the elongation of translation
at the C terminus of the growing chain
142
what does each addition of amino acids require in translation
elongation factors
143
elongation factors occur in three steps
1. codon recognition
2. peptide bond formation
3. translocation
144
what direction does translation proceed along the mRNA
5' to 3'
145
what steps are the energy used in translation
1st (codon recognition) and 3rd (translocation) steps
146
when does termination occur in translation
when a stop codon in the mRNA reaches the A site of the ribosome
147
what does the site accept in translation termination
release factor
148
release factor causes
the addition of WATER molecule instead of an amino acid
149
what releases the polypeptide and causes the translation assembly to come apart
the addition of water instead of an amino acid (release factor)
150
is translation sufficient to make a functional protein
NO
151
what happens to polypeptide chains after translation
1. modified
2. targeted to a specific site in the cell
152
what does a polypeptide do during and after synthesis
begins to coil and foil into its 3D shape
153
what dictates primary structure
gene
154
what does primary structure dictate
shape
155
what might be needed for proteins to be fully functional
post-translation modifications
156
two populations of ribosomes in cells
free and bound ribosomes
157
free ribosomes are in the
cytosol
158
bound ribosomes are
attached to the ER
159
free ribosomes synthesize
proteins that function in the cytosol
160
bound ribosomes make
proteins of the endomembrane system and those secreted by the cell
161
ribosomes are _______
identical
162
because ribosomes are identical they can do what
switch from free to bound ribosomes
163
where does polypeptide synthesis begin
in the cytosol
164
synthesis of a polypeptide will finish in the _____ UNLESS a polypeptide signals ribosome to _______
cytosol OR attach to ER
165
what are polypeptides destined for ER or secretion marked by
signal peptide at amino terminus
166
signal-recognition particle
binds to the signal peptide and brings it and its ribosome to the ER
167
polyribosome or polysome
multiple ribosomes can translate a single mRNA simultaneously
168
what does forming a polysome enable cells to do
make many polypeptides very quickly
169
how do bacteria ensure a streamlined process
coupling transcription and translation
170
with bacteria, the newly made protein can
quickly diffuse to its site of function
171
with eukaryotes what separates transcription and translation
nuclear envelope
172
mutations
changes in the genetic material of a cell or virus
173
point mutations
changes in just ONE base pair of a gene
174
what mutation can lead to the production of an abnormal protein
point mutation
175
a genetic disorder or hereditary disease
mutation has effect on the phenotype of the organism
176
two categories of point mutations
1. nucelotide-pair substitutions
2. one or more nucleotide-pair insertions or deletions
177
nucleotide-pair substitution
replaces one nucleotide and its partner with another pair of nucelotides
178
what are three possible outcomes from a nucleotide-pair substitution
1. silent mutation
2. missense mutation
3. nonsense mutation
179
silent mutation
no effect on amino acid produced by codon
180
why do silent mutations have no effect on amino acid
genetic code redundancy
181
missense mutations
still code for an amino acid but not the correct amino acid
182
nonsense mutations
change an amino acid codon into a stop codon
183
what does a nonsense mutation lead to
nonfunctional protein
184
insertions and deletions are the ______ in a gene
additions or losses of nucleotide pairs
185
what mutations have disastrous effects on the protein more often than substitutions
insertions and deletions
186
what can insertions or deletions alter
the reading frame
187
what can produce a frameshift mutation
insertion or deletion
188
when can spontaneous mutations occur
during DNA replication, recombination or repair
189
mutagens
physical or chemical agents that cause mutations
190
what have we considered a gene as
1. discrete unit of inheritance
2. specific nucleotide sequence in a chromosome
3. DNA sequence that codes for specific polypeptide chain
