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Biology 1113 > Chapter 17 > Flashcards

Chapter 17 Flashcards

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1
Q

What is the link between genotypes and phenotypes?

A

proteins

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2
Q

Gene expression

A

the process by which DNA directs protein synthesis

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3
Q

2 stages of gene expression

A

transcription and translation

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4
Q

one gene-one enzyme hypothesis

A

each gene dictates production of a specific enzyme (from bread mold) [debunked for a better explanation]

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5
Q

one gene-one polypeptide

A

The correction of “one gene-one enzyme” because some proteins aren’t enzymes and many proteins are comprised of several polypeptides.

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6
Q

What bridges genes and proteins?

A

RNA

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7
Q

Transcription

A

the synthesis of RNA using info in DNA (produces mRNA)

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8
Q

Translation

A

the synthesis of a polypeptide using info from mRNA

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9
Q

central dogma

A

concept that cells are governed by a cellular chain of command (DNA -> RNA -> Protein)

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10
Q

When does translation begin in prokaryotes?

A

it can begin before transcription is over

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11
Q

When does translation begin in eukaryotes?

A

after transcription and after the mRNA leaves the nuclear envelope

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12
Q

What separates translation from transcription in eukaryotes?

A

the nuclear envelope

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13
Q

primary transcript

A

the initial RNA transcript from any gene prior to processing

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14
Q

RNA processing

A

the process that modifies the eukaryotic RNA transcripts to yield the finished mRNA

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15
Q

triplet code

A

a series of non-overlapping, three-nucleotide words (encode for DNA)

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16
Q

DNA goes from mRNA to ____

A

amino acids (form polypeptide)

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17
Q

template strand

A

one of the two DNA strands
provides a template for ordering the sequence of complementary nucleotides in an RNA transcript
(always the same strand for a given gene)

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18
Q

codons

A

mRNA base triplets

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19
Q

What direction are codons read in translation?

A

5’ -> 3’

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20
Q

How many amino acids are made by the codons?

A

20

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21
Q

How many triplets code for stop?

A

3 (UAA, UGA, UAG)

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22
Q

What does it mean when we say the code is “redundant”?

A

more than one codon may specify a particular amino acid

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23
Q

reading frame

A

grouping of codons (must be correct to get right polypeptide)

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24
Q

Can genes be transcribed and translated after being transplanted from one species to another?

A

Yes

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25
Why is there a leading strand and a lagging strand?
One side is waiting on the helicase to open the strand, the other is already open
26
RNA polymerase
catalyzes the synthesis of RNA | Pries open the DNA strands and joins together RNA nucleotides
27
Does RNA polymerase need a primer? Why or why not?
No; it is going 5' -> 3'
28
3 Stages of Transcription
initiation elongation termination
29
What is the DNA sequence where RNA polymerase attaches called?
the promoter
30
In bacteria, what is the sequence signaling the end of transcription called?
terminator
31
transcription unit
the stretch of DNA that is transcribed
32
transcription factors
mediate the binding of RNA polymerase and initiation of transcription in EUKARYOTES
33
What do promoters do?
1) signal the transcription start point | 2) extend several dozen nucleotide pairs upstream from start point
34
transcription initiation complex
the completed assembly of transcription factors and RNA polymerase II bound to a promoter
35
TATA box
a promoter crucial in forming initiation complex
36
How much of the strand does RNA polymerase untwist at a time?
10-20 bases
37
How fast is transcription in eukaryotes?
40 nulceotides per second
38
When does transcription stop in prokaryotes?
after the terminator sequence
39
polyadenylation signal sequence
the sequence in eukaryotes that signals a stop in 10-15 nucleotides past
40
RNA process
(in euk) enzymes modifying pre-RNA after transcription before sending to cytoplasm
41
How many (0, 1, 2) of the ends are altered during RNA processing?
usually both
42
Can parts of the middle of the pre-RNA be cut out?
Yes
43
5' cap
ending received by 5' when it is modified
44
poly-A tail
ending given to 3' end when it is modified
45
Why are the ends of pre-RNA modified in eukaryotes?
They seem to facilitate the transport to cytoplasm Protect from hydrolytic enzymes Help ribosomes attach to 5' end
46
introns
(intervening sequences) places of noncoding
47
exons
sequences that are eventually expressed (usually as amino acid sequences)
48
RNA splicing
removes introns and joins exons (creates mRNA with continuous coding sequence)
49
spliceosomes
variety of proteins and several small nuclear ribonucleoproteins (snRNPs) that recognize the splice sites
50
ribozymes
catalytic RNA molecules that function as enzymes and can splice RNA
51
3 properties of RNA enable it to function as an enzyme
It can form a 3D structure because of its ability to base-pair with itself Some bases in RNA contain functional groups that may participate in catalysis RNA may H bond with other nucleic acid molecules
52
Some ____ contain sequences that may regulate gene expression
introns
53
alternative RNA splicing
some genes can encode more than one kind of polypeptide depending on which sections are treated as exons
54
An organism can produce (less/more) proteins than genes.
more
55
domains
discrete regions in the modular architecture of proteins
56
A possible result of exon shuffling is
the evolution of new proteins
57
translation
the process through which genetic info flows from mRNA to proteins
58
transfer RNA
helps translate an mRNA into a protein
59
ribosome function in translation
site of growth for polypeptide Facilitate specific coupling of tRNA anticodons with mRNA codons in protein synthesis
60
What makes up a tRNA?
a single RNA strand about 80 nucleotides long
61
What shape is a tRNA molecule? What about the whole thing itself?
clover leaf L shaped (H bonds)
62
Are molecules of tRNA identical? Why or why not?
No, each one has a specific amino acid on one end
63
anticodon
the other end of tRNA; base-pairs with a complementary codon on mRNA
64
2 steps for accurate translation
A correct match between a tRNA and an amino acid (enzyme = aminoacyl-tRNA synthetase) A correct match between the tRNA anticodon and an mRNA codon
65
wobble
flexible pairing at the third base of a codon (allows some tRNAs to bond to more than one codon)
66
ribosomal RNA
(along with proteins) make up ribosomal subunits
67
3 bonding sites for tRNA on ribosome
P site (holds the tRNA that carries growing polypeptide chain) A site (holds the tRNA that carries the next amino acid to be added to the chain) E site (is the exit site (discharged tRNA leaves)
68
3 stages of translation
initiation elongation termination
69
What do all 3 stages of translation require?
protein "factors" that aid in the process (also sometimes need energy)
70
What is brought together in initiation?
mRNA, a tRNA with the first amino acid, and 2 ribosomal subunits
71
What happens first in initiation?
A small ribosomal subunit binds with mRNA and a special initiator tRNA
72
What happens second in initiation?
the small subunit moves along the mRNA until it reaches the start codon (AUG)
73
What happens in the third and final step of initiation?
Proteins called initiation factors bring in the large subunit that completes the translation initiation complex
74
What happens during elongation?
amino acids are added one by one to the C-terminus of the growing chain
75
What are the 3 steps of each addition in elongation?
codon recognition (ENERGY) peptide bond formation translocation (ENERGY)
76
When does termination occur?
When a stop codon in the mRNA reaches the A site of the ribosome
77
release factor
A site accepts this protein to start termination Causes addition of H2O instead of amino acid
78
What determines a proteins shape?
the primary structure
79
post-translational modifications
(what it sounds like) may be required before a protein can begin its job
80
What type of proteins do free ribosomes mainly produce?
Those that function in the cytosol
81
What type of proteins do bound ribosomes mainly produce?
endomembrane system and those secreted
82
Can ribosomes switch from bound to free and vis versa?
Yes; they are identical
83
Where does polypeptide synthesis begin?
always in the cytosol
84
Synthesis finishes in the cytosol unless...
the polypeptide signals the ribosome to attach to the ER
85
signal peptide
mark polypeptides destined for the ER or secretion
86
signal-recognition particle (SRP)
binds to the signal peptide and brings it and its ribosome to the ER
87
polyribosome (polysome)
when multiple ribosomes translate a single mRNA
88
Why can bacteria cells produce proteins quicker?
transcription and translation are coupled
89
mutations
changes in the genetic material of a cell or virus
90
point mutations
chemical changes in just one base pair of a gene
91
2 categories for point mutations
nucleotide-pair substitutions | one or more nucleotide-pair insertions or deletions
92
Genetic disorder or hereditary disease
if a mutation has an adverse effect on the phenotype of the organism
93
nucleotide-pair substitution
replaces one nucleotide and its partner with another pair of nucleotides
94
silent mutations
no effect on the amino acid produced by a codon because of redundancy in the genetic code
95
missense mutations
still code for an amino acid, but not the right one
96
nonsense mutations
change an amino acid codon into a stop codon (usually make a nonfunctional protein)
97
insertions and deletions
additions or losses of nucleotide pairs in a gene | more disastrous than substitutions
98
frameshift mutation
when the reading frame is altered

Biology 1113 (7 decks)

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