5b : The central Dogma Flashcards
1
Q
Flow/process in central dogma
A
DNA-> Rna -> Protein
(From gene to protein)
2
Q
DNA -> mRNA
A
Transcription
3
Q
mRNA - > Protein
A
Translation
4
Q
The site where Transcription occurs
A
Nucleus
5
Q
Site where translation Occurs
A
Ribosome
6
Q
- semiconservative
- Synthesis in 5’ to 3’
direction - Primer is needed for initations
- complex process involving several enzymes and protein
A
DNA replication
7
Q
needed for initiation
A
Primer
8
Q
a complex process involving several enzymes and proteins
A
Replisome
9
Q
a large protein complex that carries out DNA replication, starting at the replication origin
A
Replisome
10
Q
base pairing allows each strand to serve as a template for a new strand
A
Replication of DNA
11
Q
Introduced semi-conservative replication
A
Meselson and Stahl (1958)
12
Q
- label “parent” nucleotides in DNA strands with heavy nitrogen = ^15N
- label new nucleotides with lighter isotope =^14N
A
Meselson & Stahl
13
Q
lighter isotope
A
^14N
14
Q
heavy nitrogen
A
^15N
15
Q
Mode of DNA replication process (experiment of Meselson & Stahl)
A
- Bacteria cultured in medium containing ^15N
- Bacteria transfered to medium containing ^14N
- DNA sample centrifuged after 20 min (First replication)
- DNA sample centrifuged after 40 min (Secon replication)
16
Q
Alternative models of DNA replication
A
- Conservative
- Semiconservative
- Dispersive
17
Q
The parental double helix remain intact and an all new copy is made
A
Conservative model
18
Q
The two parent strands of the parental molecule, seperates, and each function as a template for synthesis of a new complementary strand
A
Semiconvervative model
19
Q
Each strand of both daughter molecules contains a mixture of old and newly synthesized parts
A
- Dispersive model
20
Q
Types of DNA polymerases
A
- DNA Polymerase I
- DNA Polymerase II
- DNA Polymerase III
21
Q
Functions of DNA Polymerase I
A
-5’ to 3’ polymerization
-3’ to 5’ proof reading
-5’ to 3’ exonuclease activity
22
Q
Functions of DNA Polymerase II
A
DNA repair function
23
Q
DNA Polymerase III
A
Primary replication enzyme
24
Q
Proofreading during DNA replication
A
- Polymerase adds incorrect nucleotide
- Polymerase detects the mispaired bases
- Polymerase use 3’ to 5’ exonuclease activity to remove intact nucleotide
25
Replication fork components
-Helicase
-Single-strand binding protein
-Topoisomerase
-Primase
-DNA pol I and III
- DNA Ligase
26
unwinds parental double helix at replication forks
- helicase
27
Binds to and stabilizes single-stranded DNA until it can be used as a template
Single-strand binding protein
28
corrects 'overwinding' ahead of replication forks by breaking, swiveling and rejoining DNA strands
Topoisomerase
29
Synthesize a single RNA primer at 5' end of the leading strand
Primase
30
Synthesize an RNA primer at the 5' end of an okazaki fragments
Primase
31
Joins the 3' end of the DNA that replaces the primer to the rest of the leading strand
DNA Ligase
32
Joins the okazaki Fragments
DNA Ligase
33
- from DNA nucleic acid language
- to RNA nucleic acid language
Transcription
34
- transcribed DNA strand
- untranscribed DNA strand
- synthesis of complementary RNA strand
Making mRNA
35
transcribed DNA strand =
Template strand
36
untranscribed DNA strand =
coding strand
37
synthesis of complementary RNA strand
Making mRNA
38
synthesis of complementary RNA strand
Transcription bubble
39
Enzyme used in making mRNA
RNA Polymerase
40
Direction in which RNA polymerase build RNA
5' to 3'
41
Transcription in prokaryotes
1. Initiation
2. Elongation
3. Termination
42
RNA polymerase binds to promoter sequence on DNA
Initiation
43
Role of promoter (sequence on DNA)
- Starting point
- Template strand
- Direction on DNA
44
- where to start reading
- start of gene
Starting point
45
which strand to read
Template strand
46
- always read DNA 3'
to 5'
- build RNA 5' to 3'
Direction on DNA
47
RNA polymerase copies DNA as it unwinds
Elongation
48
Simple proofreading
- 1 error/105 bases
- make many mRNAs
- mRNA has short life
- not worth editing!
49
RNA polymerase stops at termination sequence
Termination
50
Components of RNA Polymerase Holoenzyme
- 2 αββ’
- (2 αββ’) δ
51
2 αββ’
Core enzyme
52
(2 αββ’) δ
RNA Polymerase holoenzyme
53
Prokaryotic Termination of Transcription
- Rho-independent termination
- Rho-dependent termination
54
palindromic GC-rich region (hairpin loop) followed by a stretch of
9A's (AAA....) in the DNA being transcribed
Rho-independent termination
55
the Rho protein is responsible for termination
Rho-dependent termination
56
noncoding (inbetween) sequence
Intron
57
coding (expressed) sequence
Exon
58
Transcription in Eukaryotes
- 3 RNA polymerase enzymes
- Initiation complex
59
- only transcribes rRNA genes
- makes ribosomes
RNA polymerase I
60
Transcribes genes into mRNA
RNA polymerase 2
61
only transcribes tRNA genes
RNA polymerase 3
62
- transcription factors bind to promoter regionupstream of gene
- transcription factors
trigger the binding of RNA
polymerase to DNA
Initiation complex
63
______ bind to ____ upstream of gene
Transcription factors; promoter region
64
recognition site for transcription factors
TATA box binding site
65
3 steps of eukaryotic transcription
- Initiation
- Elongation
- Termination
66
Post-transcriptional processing
- Primary transcript
- mRNA processing
67
eukaryotic mRNA needs work after transcription
Primary transcript
68
making mature mRNA
mRNA Processing
69
- addition of a methylated G nucleotide to the 5’ end of the transcript
Capping
70
Addition of 100-200 residues of poly A’s to the 3’ end even before termination of transcription has completed
Tailing
71
Purpose of Tailing
1. aids in export of mature mRNA from nucleus stability,
2. prevents degradation from 3’ end
3. serves as recognition signal for ribosome
72
Introns are cut out of immature RNA transcripts
Splicing
73
RNA is ____
Ribozyme
74
catalytically active RNA molecules or RNA- protein complexes, in which solely the RNA provides catalytic activity
Ribozyme
75
Who discovered ribozyme
- Sidney Altman
- Thomas Cech
76
Components of translation machinery
1. Ribosomes
2. Messenger RNA
3. Transfer RNA
4. amino acyl synthetase
5. Proteins factors
77
- protein factory composed of aggregates of RNA and protein 70S in prokaryotes and 80S in eukaryotes
Ribosome
78
RNA protein for prokaryotes
70s
79
RNA protein for Eukaryotes
80S
80
Facilitate coupling of tRNA anticodon to mRNA codon
Ribosome
81
Structure of ribosome
- ribosomal RNA (rRNA) & proteins
- 2 subunits (Large and Small)
82
Different ribosomes sites
- A site
- P site
- E site
83
A site
aminoacyl-tRNA site
84
P site
peptidyl-tRNA site
85
E site
Exit site
86
holds tRNA carrying next amino acid to
be added to chain
A site (aminoacyl-tRNA site)
87
holds tRNA carrying growing polypeptide chain
P site (peptidyl-tRNA site)
88
empty tRNA leaves ribosome from exit site
E site (exit site)
89
bears amino acid sequence
mRNA
90
Structure of Transfer RNA
- "Clover leaf" structure
91
What can be found on the clover leaf end?
Anticodon
92
What can be found attached on the 3' of the clover leaf structure
amino acid
93
