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Biochemistry 304 > CH4 DNA, RNA, Flow of Genetic Info P2 > Flashcards

CH4 DNA, RNA, Flow of Genetic Info P2 Flashcards

(62 cards)

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1
Q

During which phases must the 2 strands of DNA double helix be sep’d?

A

replication

transcription

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2
Q

Denaturation (Melting)

A

when the double helix is reversibly melted.

DNA strand separation via heating soln.

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3
Q

Hypocrhomism

A

how DNA melting is observed.

bases stacked in double helix absorb less UV light than those in single-stranded molecule.

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4
Q

Reannealing

A

process when cooling two strands bind to e/o, reform double helix.

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5
Q

Polymerase

A

replicate DNA.
catalyze phosphodiester-bridge formation.
instructions from templates.

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6
Q

(DNA)n + dNTP (DNA)n+1 + PPi

A

DNA replication.

rxn catalyzed by DNA polymerase.

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7
Q

What are the key characteristics of DNA synthesis?

A
  1. 4 Deoxynucleoside triphosphates and Mg2+
  2. template strand
  3. primer
  4. DNA polymerase w/ nuclease activity
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8
Q

Deoxynucleoside Triphosphates

A

activate precursors

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9
Q

Template Strand

A

directs DNA synthesis

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10
Q

Primer

A

what the new strand grows from

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11
Q

Nuclease Activity (of DNA polymerase)

A

allows for removal of mismatched bases

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12
Q

The polymerization reaction is catalyzed by?

A

DNA polymerases

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13
Q

dNTPs

A

incorporates a phosphate
activated precursors
subsequent breakdown of released pyrophosphate helps drive phosphodiester bond formation

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14
Q

Pyrophosphate Hydrolysis

A

drive strand elongation

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15
Q

Tobacco Mosaic Virus

A

RNA genomes replicated by RNA-directed RNA polymerases

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16
Q

Retroviruses (ex HIV-1)

A

single-stranded RNA genomes converted to DNA double helices via reverse transcriptase

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17
Q

Flow of Info

RNA to DNA in Retroviruses

A

Each step uses Reverse Transcriptase

  1. Viral DNA
    - Synthesis of DNA complementary to RNA
  2. DNA-RNA Hybrid
    - RNA digestion
  3. DNA Transcript of Viral RNA
    - Synthesis of 2nd Strand of DNA
  4. Double-Helical Viral DNA
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18
Q

Reverse Transcriptase

A

enzyme that converts RNA genome of retrovirus into DNA.

catalyzes synthesis of complementary DNA strand, digests RNA, subsequent synthesis of DNA strand.

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19
Q

Gene Expression

A

transformation of DNA Info into functional molecules

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20
Q

What are the most abundant types of RNA?

A

tRNA
mRNA
rRNA

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21
Q

RNA polymerase

A

catalyzes transcription (synthesis of RNA from DNA template)
initiates and elongates RNA product w/ chain growing 3’ to 5’
no primer needed
3’ OH of growing chain attacks innermost phosphoryl alpha group of incoming nucleoside triphosphate

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22
Q

What are the 3 requirements of RNA polymerase?

A
  1. DNA template
  2. activated precursors in form of 4 ribonucleoside triphosphates
  3. Divalent metal ions (ex Mg2+, Mn2+)
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23
Q

DNA Template

A

complementary seq of newly synthesized RNA

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24
Q

Coding Strand

A

DNA strand w/ same seq as RNA product (w/ T instead of U)

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25
RNA polymerase catalyzes this rxn:
(RNA)n residues + ribonucleoside triphosphate (RNA)n+residues + PPi
26
Transcription Mech of Chain-Elongation Rxn Catalyzed by RNA Polymerase
driven thermodynamically by hydrolysis of pyrophosphate
27
Transcription begins near?
promoter sites
28
Transcription Ends at?
terminator sites
29
Promoters
specific DNA seq's that direct polymerase to proper initiation site.
30
Consensus Seq
average variation in seq of promoter for diff genes
31
Promoter Sites for Transcription in Prokaryotes
-35 Region -10 Pribbenow box +1 Start of RNA
32
Promoter Sites for Transcription in Eukaryotes
-75 CAAT box -25 TATA box +1 Start of RNA
33
Elongation continues until?
detects termination signal
34
Transcription Termination 1: Palindromic DNA
simplest stop signal is a transcribed product of a segment of this
35
Transcription Termination 2: Hairpin Loop
RNA complement of DNA stop signal forms this followed by several uracil residues
36
Transcription Termination 3: | Hairpin Synthesis
polymerase stalls RNA product released DNA double helix reforms
37
Transcription Termination 4: | Protein
rho | sometimes req'd
38
``` Post Transcription (Eukaryotes): mRNA Modification ```
5' nucleotide "cap" added | 3' poly(A) tail added
39
What are the adaptor molecules in protein synthesis?
tRNA
40
tRNA
react w/ specific AAs in rxn catalyzed by aminoacyl-tRNA synthetases
41
Anticodon
template recognition site in tRNA molecules consists of 3 bases recognizes a complementary codon
42
Codon
complementary 3 base seq in mRNA
43
Aminoacyl-tRNA
attached at 3' end of RNA anticodon is template-recognition site cloverleaf structure w/ many H-bonds btw bases
44
Protein Synthesis is a process of?
translation | NA seq info translated into AA seq info
45
The genetic code links?
NA info and AA info
46
Genetic Code Characteristics
1. 3 nucleotides (codon) encode AA 2. nonoverlapping 3. no punctuation 4. has directionality, read 5' mRNA to 3' 5. degenerate - some AA's encoded by >1 codon, minimizes deleterious effects of mutations
47
mRNA
translated on ribosomes | 1st codon almost always AUG - codes for methionine
48
AUG in prokaryotes
preceded by purine-rich seq Shine-Dalgarno seq.
49
AUG in eukaryotes
5' end is initiator codon
50
The location of the initiator codon establishes the?
reading frame
51
Start Codons
req'd for initiation of protein synthesis in prokaryotes and eukaryotes
52
The genetic code is nearly?
universal
53
Exons
coding regions in eukaryotic genes that are discontinuous.
54
Introns
noncoding regions initially detected by e- microscopy size range 50-10,000 nucleotides ~ human has 8, some > 100
55
RNA processing generates?
mature mRNA
56
Eukaryotic Pre-Messenger RNA
contains exons and introns 1st modified by 5' cap and 3' poly(A) tail mature mRNA generated by splicesosomes
57
Splicesosomes
large complexes that splice introns to generate mature mRNA | recognize specific seq's w/i intron that specify splice sites
58
Introns almost always begin w/?
GU
59
Introns almost always end w/?
AG
60
Once mRNA precursors are spliced mature mRNA if formed because these come together.
Exon 1 and Exon 2
61
TPA Tissue Plasminogen Activator
was generated by Exon shuffling | encodes enzyme that functions in hemostasis
62
Alternative Splicing
forms set of proteins that are variants of basic motif w/o requiring separate gene for each protein

Biochemistry 304 (14 decks)

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