How Genes Direct the Production of Proteins Flashcards
(96 cards)
1
Q
A strand of DNA copied fully linearly is called a ____.
A
heteronuclear (hn)/agent RNA
2
Q
When can the splicing and post-transcriptional modifications occur on the hnRNA after emergence from RNA polymerase II?
A
immediately
3
Q
snoRNAs serve as a guide to direct specific ____ of the rRNAs.
A
modifications (post-transcriptional)
4
Q
DNA is ___ into RNA.
A
transcribed
5
Q
What type of RNA regulates gene expression at the post-transcriptional level?
A
microRNA
6
Q
The third base “U” COULD pair with:
A
A, G, or I
7
Q
Most protein coding genes are transcribed by ____.
A
RNA Polymerase II
8
Q
The third base “C” COULD pair with:
A
G or I
9
Q
This antibiotic blocks initiation to elongation.
A
Streptomycin
10
Q
mRNA is ___ into protein.
A
translated
11
Q
TFIID situates on the gene to create the start site for transcription. What factor does its placement attract?
A
TFIIB
12
Q
What kind of bond is formed between the Met-tRNA and the new aminoacyl-tRNA in the A site?
A
peptide bond
13
Q
____ process and chemically modify rRNAs.
A
sno/snRNA
14
Q
After meeting at the AUG codon, ____ and ____ bind.
A
the Met-tRNA; the large ribosomal subunit
15
Q
tRNA transfers ____ to the growing peptide chain.
A
amino acids
16
Q
Where would you find free ribosomes?
A
anywhere in the cytosol
17
Q
Where are ribosomes assembled?
A
nucleolus (not a membrane-bound structure)
18
Q
How many STOP codons must be encountered for translation to halt?
A
2 consecutive STOP codons
19
Q
How is the translation of proteins regulated using base pairs?
A
- base pairing between mRNA codon
- triplet complimentary sequence in tRNA called the anticodon
20
Q
Why don’t we use tetracycline in children?
A
because tetracycline loves to bind to mineralized surfaces
21
Q
Is the genetic code universal for all organisms?
A
YES
22
Q
What structure does the small ribosomal subunit recognize and attach to on mRNA?
A
5’-cap structure
23
Q
Which antibiotic blocks A-site binding of aminoacyl-tRNA?
A
Tetracycline
24
Q
What type of structure does miRNA form to block protein synthesis? What enzyme does it utilize?
A
a hairpin structure (complementary base pairs folded in on itself); “Dicer” enzyme
25
An Argonaute, facilitated by Dicer, is a mature _____.
miRNA
26
What is it called when more than one codon can make the same amino acid?
degenerate
27
How many RNA Polymerase II molecules can work on copying a gene simultaneously?
A BUNCH!
28
Which nucleic acid would be more useful when sequencing the genome of an ant fossilized in amber?
DNA - more stable than RNA due to deoxyribose properties
29
A 3 base sequence is a ____.
codon
30
Can gene transcription proceed in opposite directions?
YES - since template for genes is always 3'-to-5' the strand can just flip flop since it's DNA
31
What is the role of transcription factors?
to park RNA polymerase II appropriately on the DNA strand in order to initiate and complete transcription starting at base 1
32
Which antibiotic blocks the peptidyl transferase reaction, thereby preventing elongation?
Chloramphenicol
33
rRNA comes from a ____.
gene
34
____ directs the proper cleavage of introns and allows the ligation of exons.
snRNA
35
What are the three STOP codons?
UAA, UAG, UGA
36
What types of RNA processing must wait until the primary strand is complete?
capping, polyadenylation
37
What happens after the initiation of helicase activity by TFIIH in DNA transcription?
ATP is expended; phosphorylation of the C-terminal RNA polymerase II occurs; TF disassembled; polymerase opens into active conformation; transcription occurs
38
If you were to put DNA and RNA into a solution with a pH of 10, which would degrade first and more quickly?
RNA - very unstable in alkaline conditions
39
Synthesis of new DNA (aka RNA strand) is always ____; the template (DNA) runs ____.
5'-to-3'; 3'-to-5'
40
What would likely be the cause of closely similar or analogous genes being located in totally separate regions of the body?
alternative splicing of mRNA at some point in development (driven by developmental cells signals hormones, environmental signals, etc.)
41
A number of antibiotics we use to treat infections target ____ and ____.
transcription; translation
42
What happens in the elongation step of translation?
synthesis of the peptide chain
43
What gets pushed out of the A site and P site by the ribosome? What gets pushed into the P site?
A site - dipeptide
P site - "empty" tRNA
*P site - peptide
44
Do UTRs or non-translated regions get translated?
NO; but they do get transcribed
45
At which codon and amino acid does translation start?
AUG; methionine
46
rRNA encodes _____.
ribosomal proteins
47
Of these components, which is/are used to synthesize the sequential protein?
(cap : 5' UTR : coding sequence : 3' UTR : polyA tail)
coding sequence
48
Which type of RNA turns off gene expression by directing the degradation of mRNAs?
siRNA
49
What happens after the binding of TFIID and TFIIB?
TFIIH binds, which has helicase activity
50
What disassembles from the RNA polymerase II transcriptional complex after phosphorylation of RNA pol II?
transcription factors (TFIID, TFIID, TFIIH)
51
Why are bacterial cells able to replicate so much faster than eukaryotic cells?
because mRNA can be translated to proteins SIMULTANEOUSLY with transcription of DNA to RNA
52
In individuals affected with Roberts Syndrome, there is ____ rDNA to rRNA transcription, which leads to decreased ____.
decreased; protein synthesis
53
What is mRNA translated into?
proteins
54
Which part of the DNA sequence get translated into the amino acid sequence of the protein.
exons
55
Genes that are essentially the same but found in different regions of the body are ____.
isoform genes
56
What transcription facto recognizes the TATA box, specifically its subunit?
TFIID; TBP
57
The RNA polymerase II has to be properly ____ on the start site of transcription.
phased
58
What molecule is created by the "charging" of tRNA with the specific mRNA codon? What enzyme catalyzes this?
aminoacyl-tRNA; aminoacyl-tRNA synthetase
59
TFIIH does what in the initiation of transcription?
acts with helicase activity to unwind DNA at transcription start point; phosphorylation of RNA polymerase II
60
What is the role of TFIIB?
to position RNA polymerase II on the DNA strand correctly
61
___ do get translated; ___ get transcribed, but not translated.
Exons; introns
62
Does splicing occur simultaneously with transcription?
YES
63
Mature mRNA is exported to the ____ or ____ via nuclear bound proteins.
cytoplasm; cytoplasmic ER
64
miRNA binds to the RISC complex (RNA-inducing silencing complex), which suppresses ____ and promotes ____.
protein synthesis; mRNA degradation
65
RNA splicing is performed by the ____, a complex made up of snRNAs and proteins in a SNP complex.
spliceosome
66
Where does transcription occur?
nucleus of eukaryotes
67
What factor binds first to the TATA box?
TFIID (w/ subunit called the TBP - TATA box binding protein)
68
mRNA is transcribed from a ___.
gene
69
At which point of transcription and translation does export to the cytoplasm occur?
post-translationally **after DNA has been transcribed into mRNA (after polyadenylation at 3' end - AAAA)
70
Do all proteins contain methionine in their sequence?
NO, because post-translational modifications occur and may take methionine out or cleave bits off
71
When does splicing take place?
before the maturation of mRNA
72
How do cells achieve their specialized functions?
based on:
expression of specific genes
post-translational modifications (glycosylation, phosphorylation) of resulting proteins
73
What does RNA Polymerase II transcribe?
mRNA
74
Where would you find membrane-bound ribosomes?
rough ER (associated with membrane proteins and may be secreted out of the cell)
75
A strand of unprocessed RNA containing introns an exons is referred to as ____.
hnRNA
76
Where are proteins synthesized? Where does translation take place?
cytoplasm of cell in eukaryotes
77
mRNA is read by the ribosomal machine as a ___.
codon
78
miRNA is a _____ repressor.
translational
79
Which antibiotic prevents RNA synthesis?
Rifamycin
80
Response elements are ___ when referring to their structure.
promoter regions
81
What happens in the termination step of translation?
synthesis stops and protein is released from the ribosome
82
Gene expression can be regulated by transcription factors that bind to:
promoter elements in DNA and/or
| proteins that are bound to these promoter elements
83
Translation starts at the ___ end of mRNA.
5'
84
What is the purpose of polyadenylation (addition of polyA tail)?
stabilizes the RNA since it is more easily degraded than DNA
85
Which is the most abundant RNA in a cell?
rRNA (mRNA is only 3%!)
86
What are the 4 steps of translation?
Activation
Initiation
Elongation
Termination
87
What kind of RNA regulates gene expression by blocking the translation of specific mRNAs?
microRNA
88
What happens in the initiation step of translation?
binding of ribosome to 5'-end of mRNA
| subsequent binding of initiator Met-tRNA (AUG)
89
This antibiotic blocks the ribosome exit channel and inhibits elongation.
Erythromycin
90
_____ are sequences in the DNA that direct or promote the transcription of a gene.
Promoters
91
What happens in the activation step of translation?
the formation of aminoacyl-tRNAs
92
Where would you find the TATA box on a strand of DNA?
about 25 base pairs before the start site of transcription
93
Is at the translational level the same as at the post-transcriptional level?
YES
94
What is the obligatory first step in the initiation of TBP/TFIID and RNA polymerase II binding?
the presence or absence of specific transcription factors
95
In both prokaryotes and eukaryotes, how many strands of DNA are transcribed into RNA?
1
96
Which base in the triplet codon is the LEAST specific?
the third base (allows "wobble")
