CH 17 Gene Expression Flashcards
(77 cards)
1
Q
Gene expression
A
- The process by which information encoded in DNA directs the synthesis of proteins, or, in some cases, RNAs that are not translated into proteins, and instead function as RNAs
-Transcription
-Translation
2
Q
Transcrition
A
- the synthesis of RNA using a DNA template
-RNA polymerase - Consists of three stages
- Initiation
- Promoter-start point
- “Upstream” of actual start of transcription (before actual start point)
- TATA box (eukaryotes)
- All different sequences/lengths w/ TATA repeat
- Transcription Factors
- Bound to RNA polymerase=transcription
- Initiation complex
- Promoter-start point
- Elongation
- RNA polymerase unwinds double helix
- Nucleotides added to 3’ end of growing RNA
- Genes can be transcribed simultaneously
- Amplification of gene expression
- Termination
- RNA polymerase transcribes polyadenylation signal sequence
- The RNA transcript is release 10-35 nucleotides later
- RNA polymerase transcribes polyadenylation signal sequence
- Initiation
- “rewritten”
3
Q
Messenger RNA (mRNA)
A
- a type of RNA, synthesized using a DNA template that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein (in eukaryotes, the primary RNA transcript must undergo RNA processing to become mRNA)
- carries a genetic message from the DNA to the protein synthesizing machinery of the cell
4
Q
Translation
A
- the synthesis of a polypeptide using the genetic information encoded in an mRNA molecule
- there is a change of “language” from nucleotides to amino acids
-occurs in the ribosomes
5
Q
Triplet Code
A
- a genetic information system in which a series of three nucleotide-long words specifies a sequence of amino acids for a polypeptide chain
6
Q
Template Strand
A
- the DNA strand that provides the pattern, or template, for ordering, by complementary base pairing, the sequence of nucleotides in an RNA transcript
-for any given gene, the same strand is used as the template every time that gene is transcribed- further along on the same chromosomal DNA molecule, the opposite strand may function as the template for a different gene
7
Q
Codon
A
- a three nucleotide sequence of DNA or RNA that specifies a particular amino acid or termination signal
- the basic unit of the genetic code
8
Q
Coding Strand
A
- nontemplate strand of DNA, which has the same sequence as the mRNA except it has Thymine (T) instead of Uracil (U)
9
Q
Reading Frame
A
- on an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis (translation)
10
Q
RNA polymerase
A
- an enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complementary binding to nucleotides on a DNA template strand
- assemble a polynucleotide only in 5’ to 3’ direction (adding to its 3’ end)
- able to start a chain from scratch; doesn’t need to add the first nucleotide onto a pre-existing primer (DNA polymerase cannot do this)
11
Q
Promoter
A
- a specific nucleotide sequence in the DNA of a gene that bind RNA polymerase, positioning it to start transcribing RNA at the appropriate place
- initiate transcrption
12
Q
Terminator
A
- in bacteria, a sequence of nucleotides that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detach from the DNA
13
Q
Transcription Unit
A
- a region of DNA that is transcribed into and RNA molecule
14
Q
Start Point
A
- in transcription, the nucleotide position on the promoter where RNA polymerase begins synthesis of RNA
15
Q
Transcrption Factors
A
- a regulatory protein that bind to DNA and affect transcription of specific genes
- help guide the binding of RNA polymerase and the initiation of transcription
16
Q
Transcription Initiation Complex
A
- the completed assembly of transcription factors and RNA polymerase bound to a promoter
17
Q
TATA Box
A
- a DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
18
Q
RNA Processing
A
- modification of RNA in primary transcripts including splicing out of introns, joining together of exons, and alteration of the 5’ and 3’ ends
19
Q
5’ Cap
A
- a modified form of guanine nucleotide added onto the 5’ end of a pre-mRNA nucleotide
20
Q
Poly-A-Tail
A
- a sequence of 50-250 adenine nucleotides added onto the 5’end of a pre-mRNA molecule
21
Q
RNA Splicing
A
- after synthesis of a eukaryotic primary RNA transcript, the removal of portions of the transcript (introns) that will not be included in the mRNA and the joining together of the remaining portions (exons)
22
Q
Introns
A
- a noncoding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing; which also refers to the region of DNA from which this sequence was transcribed
23
Q
Exons
A
- a sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed
24
Q
Spliceosome
A
- a large complex made up of proteins and RNA molecules that splices up RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons
25
Ribozyme
- an RNA molecule that functions as an enzyme, such as an intron that catalyzed its own removal during RNA splicing
26
Alternative RNA Splicing
- a type of eukaryotic gene regulation at the RNA processing level in which different mRNA molecules are produces from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
27
Transfer RNA (tRNA)
- an RNA molecule that functions as a translator between nucleic acid and protein languages by picking up a specific amino acid and carrying it to the ribosome, where the tRNA recognizes that appropriate codon in the mRNA
28
anticodon
- a nucleotide triplet molecule that base pairs with a particular complementary codon on an mRNA molecule
29
point mutation
- a change in a single nucleotide pair of a gene
30
nucleotide substitution
- a type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced by another pair of nucleotides
31
silent mutation
- a nucleotide pair substitution that has no observable effect on the phenotype; for example, within a gene, a mutation that results in a codon that codes for the same amino acid
32
missense mutations
- a nucleotide pair substitution that results in a codon that codes for a different amino acid
33
missense mutation
- a mutation that changes an amino acid codon to one of three stop codons, resulting in a shorter and usually nonfunctional protein
34
frameshift mutation
- a mutation occurring when nucleotides are inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons
35
Insetions
- a mutation involving the addition of one or more nucleotide pairs to a gene
36
Deletions
- a deficiency n a chromosome resulting from the loss of a fragment through breakage
- a mutational loss of one or more nucleotide pairs from a gene
37
mutagen
- a chemical or physical agent that interacts with DNA and can cause a mutation
- ex. x-rays, UV light
38
Stop codons are unique because they...
do not code for amino acids but instead allow a releasing factor to bind to the A site of the ribosome
39
Which of the following catalyzes the linkage between ribonucleotides to form RNA during gene expression?
RNA polymerase
40
In order for transcription to occur in the stand, there would have to be a specific recognition sequence, called a(n) (BLANK) to the left of the DNA sequence.
promoter
41
The function of tRNA during protein synthesis is to...
deliver amino acids to their proper site during protein synthesis
42
Gene expression is...
the process by which DNA directs the synthesis of proteins
43
What is a key difference in gene expression between eukaryotic and prokaryotic cells?
In prokaryotic cells, the mRNA transcript is immediately available as mRNA without processing.
44
The "triplet code" refers to the fact that...
three nucleotides code for a single amino acid
45
Insertions and deletions are called...
frameshift mutations
46
The TATA box is a sequence with a (BLANK) that allows for the binding of (BLANK) and (BLANK).
eukaryotic promoter; transcription factors, RNA polymerase II
47
Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of...
RNA
48
The bonds that hold tRNA molecules in the correct three-dimensional state are...
hydrogen bonds
49
A type of point mutation that results in a premature stop codon is called a (BLANK) mutation
nonsense
50
When RNA is being made, the RNA base (BLANK) always pair with the base (BLANK) in DNA
U; A
51
(BLANK) is the synthesis of a polypeptide using information in the mRNA.
Translation
52
(BLANK) is the synthesis of RNA using information in the DNA.
Transcription
53
Eukaryotic processing of the primary transcript includes...
the addition of a 5' cap, a 3' Poly-A-Tail, and the splicing out of introns
54
What is the proper order of the following events in the expression of a eukaryotic gene?
1. translation
2. RNA processing
3. Transcription
4. modification of protein
3,2,1,4
55
Which statement is true?
Each amino acid is coded for by three bases in DNA
56
Generally speaking, how many genetic codes are there?
One
57
The number of nucleotide bases "read" together on the mRNA to designate each amino acid is (BLANK); this unit is call a(n) (BLANK).
three; codon
58
In many cases, more than one codon codes for the same amino acid. Because of this, we say that the code is...
redundant
59
Bacteria can transcribe and translate human genes to produce functional human proteins because...
the genetic code is nearly universal
60
In a eukaryotic cell, transcription takes place...
in the nucleus
61
What catalyzes the linkage between ribonucleotides to form RNA during gene expression?
RNA polymerase
62
In transcription...
All of the answer choices are correct
-only one of the DNA strands is used as the template
-the RNA nucleotides used are produced by the cell
-the promoter region acts as an initial binding site for RNA polymerase
63
In eukaryotes, which mechanism operates after transcription, but before translation of mRNA into protein?
RNA splicing
64
Which accurately describes the usual process of eukaryotic transcription?
Both introns and exons are transcribed, but the RNA transcribed from introns does not leave the nucleus
65
Which statement correctly describes mRNA processing?
introns are cut out of the primary transcript, and the resulting exons are spliced together
66
Two different proteins with mostly different structures are translated from two different mRNAs. These mRNAs, however were transcribed from the same gene. What mechanism could best account for this?
Exons from the same gene could be spliced in different ways to make different mRNA's
67
At one point, as a cell carried out is day to day activities, the nucleotides GAT were paired with the nucleotides CUA. This pairing occurred...
during transcrption
68
At one point as a cell carried out its day to day activities, the nucleotides GAT were pained with the nucleotide CUA. This pairing occurred
during transcription
69
Which summary of protein synthesis is correct? (Translation)
Messenger RNA is made on a DNA template, and then amino acid bearing transfer RNAs bind to the mRNA through codon anti-codon pairing
70
During translation in a eukaryotic cell...
polypeptides are synthesized at ribosomes, according to instructions carried by mRNA
71
The P site of a ribosome does which of the following?
It hold the tRNA carrying the growing polypeptide chain
72
The first amino acid inserted into a new polypeptide is usually...
methionine
73
Which is a post translational modification of a polypeptide?
cleavage of a polypeptide into two or more chains
74
During translation, amino acid chain elongation occurs until...
the ribosome encounters a "stop" codon
75
Polysomes may be defined as...
groups of ribosomes translating the same mRNA
76
Cells are able to distinguish proteins destines for secretion or for segregation to specific intracellular compartments from those that will remain in the cytoplasm because...
Some proteins, as the begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide chain to attach to the ER and translocate the polypeptide into the lumen (space) of the ER
77
A particular mutation had no effect on the polypeptide encoded by a gene. This mutation probably involves
a silent or neutral mutation
