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MLS 4151 - Molecular Diagnostics > Wk. 3 | Transcription and Translation > Flashcards

Wk. 3 | Transcription and Translation Flashcards

1
Q

What is transcription?

A

The transfer of information from DNA to RNA

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2
Q

Simplified version of the central dogma

A

DNA -> transcription -> RNA -> translation -> protein

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3
Q

What is the role mRNA

A

carries genetic info to the entire cell

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4
Q

Process of Transcription

A
  1. DNA strands are pulled apart
  2. A single strand of RNA molecule is made using the antisense DNA strand as a template.
    - This strand is complementary to the DNA except T replaced with U
  3. RNA is synthesized 5’ to 3’
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5
Q

Which direction is RNA synthesized in transcription

A

5’ to 3’

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6
Q

The product of transcription is

A

mRNA

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7
Q

Transcription occurs when

A

only when specific gene needed

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8
Q

The enzyme that makes RNA in transcription

A

RNA polymerase

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9
Q

RNA Polymerase Function

A

binds to DNA at the start of a gene and opens the double helix

makes RNA from the antisense strand of DNA

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10
Q

The _____ strand is the DNA strand transcribed to make mRNA

A

antisense

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11
Q

The coding or sense strand is

A

the complementary strand of DNA

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11
Q

What recognizes the promoter?

A

the sigma subunit of RNA polymerase

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12
Q

The ___________ strand matches the mRNA strand that was just synthesized

A

coding/sense strand

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13
Q

The sigma subunit of RNA polymerase recognizes what two sequences

A

-10 and -35 regions on the opposite DNA strand

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14
Q

-10 sequence codes for what

A

TATA box in eukaryotes
- TATAAT

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15
Q

-35 region sequence

A

TTGACA

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16
Q

Upstream region of DNA

A

stretch of DNA in front of a gene

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17
Q

Where does RNA polymerase bind?

A

the promotor region

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18
Q

Consensus Sequence
- can be ____________
- __________________ depends on how closely it matches consensus sequence

A

one or two bases off and sigma subunit will still recognize

Strength of a promotor

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19
Q

What is located upstream and downstream?

A

Upstream: promotor
Downstream: gene

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20
Q

Once the sigma subunit has been found…

A

a promotor + RNA polymerase binds

sigma subunit drops off, remaining portion is the core enzyme

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21
Q

2 ways transcription is terminated in prokaryotes

A

Rho-independent
Rho-dependent

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22
Q

Rho Independent
- A ______________________ tells ____________ where to stop
- Termination sequence consists of _______ separated by ~ _ bases followed by numerous ___
- The two _______ are on opposite strands of DNA

A
  • terminator sequence, RNA polymerase
  • 2 inverted repeats, 6, As
  • inverted repeats
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23
Q

Rho-independent | Inverted repeats on the same strand of RNA pair up to form a

A

hairpin loop followed by a run of U’s

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24
Q

Rho Dependent
- A protein factor Rho does this

A

destabilizes the interaction between template and mRNA, releasing the mRNA

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25
Q

Termination in Eukaryotes
- New transcript is ____________
- Followed by _____________ of the __ end

A
  • cleaved
  • polyadenylation, 3’
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26
Q

Genes that are on all the time

A
  • constitutively expressed
  • housekeeping genes
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27
Q

These types of genes have -10 and -35 regions IDENTICAL to consensus and are ALWAYS

A
  • housekeeping genes that are on all the time
  • recognized by sigma
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28
Q

Genes that are only needed under certain conditions have ________ are not recognized without _______

A

poor recognition sequences
accessory proteins

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29
Q

Gene activator proteins are a type of gene that is

A

only needed under certain conditions

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30
Q

Gene activator proteins

A

helps the RNA polymerase bind to the DNA
aka transcription factors

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31
Q

What do repressor proteins do? (3 things)

A
  • turn off genes
  • bind DNA and block action of RNA polymerase
  • bind to the operator sequence
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32
Q

Does RNA polymerase or activator protein bind to DNA first?

A

activator protein, then RNA polymerase

“help yourself before helping others put their mask on”

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33
Q

How do regulators work?

A

Fits into the binding site on regulatory protein -> signal molecule changes shape (allosteric)

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34
Q

What is global regulation

A

the coordinated control of large groups of genes

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35
Q

What is an operon

A

a group of genes that all have the same promotor and are regulated together

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36
Q

Operons are found in

A

prokaryotes

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37
Q

Antisense RNA is

A

RNA that is complementary to the mRNA and can base pairs with it

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38
Q

If you make an RNA from the non-template strand, you would produce an RNA molecule that’s

A

complementary to the mRNA

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39
Q

Function of antisense RNA

A

blocks translation by preventing mRNA binding to the ribosome by base pairing with the complementary mRNA

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40
Q

Prokaryote vs Eukaryote Transcription
Prokaryote
- Occurs in _________
- mRNA is usually __________

A
  • Cytoplasm alongside translation
  • NOT modified
41
Q

Prokaryote vs Eukaryote Transcription
Eukaryote
- Location: _____________
- DNA access controlled by
- mRNA ___________ through RNA splicing, 5’ end capping, and polyA tail

A
  • localized in nucleus, transcript is transported to cytoplasm where translation occurs
  • chromatin
  • modified
42
Q

Polyadenylation
- _________ nucleotides added to the __ end of mRNA by ______________
- Typical run is ___ nucleotides

A
  • adenine
  • 3’
  • polyadenylate polymerase
  • 200
43
Q

The polyA tail is _______ in genomic DNA

A

not coded

44
Q

5’ Capping
- Addition of ________ _________ to the 5’ end of mRNA.
- Function:

A

methyl guanosine
- protective, acts as a recognition signal

45
Q

The 5’ cap is made of a

A

5’ - 5’ pyrophosphate bridge to a methylated guanosine

46
Q

Prokaryotic genes are

A

uninterrupted open reading frames

47
Q

What happens during splicing

A

Eukaryotic coding sequences separated by introns
Introns are removed by splicing
Only exons (able to code for proteins) remain

48
Q

Exons

A

Eukaryotic sequences that code for proteins

49
Q

Introns

A

long stretches of non-coding sequence that separate exons

50
Q

Does mRNA perform any work?

A

NO, it is just a message

51
Q

There are __ amino acids total

A

20

52
Q

Aminos consist of a central hydrocarbon surrounded by:

A
  1. NH2 (amino group)
  2. COOH (carboxyl) group
  3. A variable group (side chain)
53
Q

______ bonds join amino acids

A

peptide

54
Q

4 Roles of proteins

A
  1. Structural proteins: flagella, microtubules, etc
  2. Enzymes: carries out chemical rxns
  3. Regulatory proteins
  4. Transport proteins
55
Q

Regulatory Proteins

A

A protein that controls expression of a gene or activity of another protein

56
Q

Transport Proteins

A

A protein that carries other molecules across membranes or around the body

57
Q

Amino terminus

A

amino (NH2) group at the end of the first amino in the chain

58
Q

Carboxyl terminus

A

carboxy (COOH) group at the end of the last amino in the chain

59
Q

A complete protein can have ______ polypeptide chain
a.) only one
b.) more than one

A

more than one

60
Q

Cofactors are or are not made up of amino acids

A

NOT

61
Q

Primary Structure

A

The sequence/order of monomers

62
Q

Secondary Structure

A

The folding of the original polymer chains thru H bonding

63
Q

Tertiary Structure

A
  • 3D folding
  • Result of hydrophobic inner and hydrophilic outer groups
64
Q

Quaternary Structure

A

Assembly of several individual polypeptide chains to give final structure

65
Q

Ribosomes bind to ____ and do what

A

bind to the 5’ end of mRNA and translates it

66
Q

After binding, the ribosome

A

moves along the mRNA adding a new amino each time it reads a codon

67
Q

Translation Rule

A

In general, 1 gene codes for 1 protein

68
Q

Adaptor Molecules

A

Transfer RNA, carries amino to ribosome
Codon and anti-codon pairing

69
Q

tRNA has a

A
  • an anticodon at one end
    (3 bases complementary to the mRNA)
70
Q

Wobble Rule
- Allows tRNA to ________
- Less rigid _________ for __________ pairing so
- _____ tRNA base can wobble around

A
  • recognize different codons
  • base pairing
  • codon/anticodon
  • First
70
Q

Each tRNA carries _______

A
  • a single amino acid
71
Q

There are __ codons to be recognized

A

64

72
Q

For each tRNA there is an enzyme that

A

recognizes the tRNA and the corresponding amino acid

73
Q

What charges tRNA

A

amino-acyl tRNA synthetase

74
Q

What is a charged tRNA?

A

tRNA with its amino attached

75
Q

What is the structure of tRNA?

A

Cloverleaf
4 short base-paired stems + 3 loops

76
Q

Where is the amino acid bound on tRNA?

A

the free acceptor stem (on the opposite end of the anticodon

77
Q

The other two ends of the tRNA are needed for

A
  • binding to the ribosome
  • recognizing the adaptor enzyme
78
Q

What is a reading frame?

A

one of 3 possible ways to read the bases of mRNA in groups of 3 to give codons

79
Q

Start Codon(s)

A

AUG - methionine

80
Q

What is an open reading frame?

A

What is translated into a protein!
A stretch of RNA beginning with a start codon that can be translated into protein

81
Q

How many open reading frames per mRNA are there

A

several

82
Q

An initiator tRNA is

A

charged and chemically tagged with methionine
- Formyl-methionine (fMet)

83
Q

fMet binds to the

A

start codon

84
Q

Proteins are made from a linear chain of

A

monomers (aminos)

84
Q

________ allows proteins to carry out their function. This must be done correctly

A

Folding

85
Q

Amino acids have a central hydrocarbon atom surrounded by

A
  1. NH2 amino group
  2. COOH carboxyl group
  3. R or variable group
86
Q

Stop Codons

A
  1. UAG
  2. UGA
  3. UAA
87
Q

Each protein is made using

A

the genetic info stored on the chromosomes

88
Q

Shine-Delgarno sequence is the

A

site of initiation in prokaryotes
- includes ribo binding site, spacer, and AUG

89
Q

Kozak Sequence

A

helps the ribosome identify the start codon in eukaryotes

89
Q

Initiation
1. mRNA binds to ______________________
2. ________________ recognizes AUG start
3. __ ____________________ help arrange all components
4. _____ ribosome subunit arrives and the ______________ fall off

A
  1. small subunit of ribosome
  2. Initiator tRNA w/ fMet
  3. 3 initiation factor proteins
  4. Large; initiation factors
90
Q

Ribosome sites for tRNA in elongation

A

A-site: acceptor site
P-site: peptide site

90
Q

Elongation
1. fMet initiator tRNA starts at the ______
2. Another tRNA carrying next amino enters the _____
3. fMet is cut loose and bonded to _______
4. tRNA number 2 now carries _______________

A
  1. P-site
  2. A-site
  3. Amino number 2
  4. 2 linked amino acids
91
Q

Elongation factors do what

A

supervise shifting of tRNAs on the ribosome

92
Q

EF-T function

A

delivers tRNA to ribosome and installs it into the A-site

93
Q

EF-T is made of these two elongation factors

A

EF-Tu
EF-Ts

94
Q

Function of EF-G

A

oversees that everything moves sideways at the correct time

95
Q

Termination
1. Stop codon reaches the _____________________
2. _____________ chop completed polypeptide chain from tRNA
3. Ribosome falls off and __________________

A
  1. A site of the ribosome
  2. Release factors
  3. separates into its subunits
96
Q

Polysome

A

complex formed when multiple ribosomes are translating the same mRNA into proteins

97
Q

DNA is made in the 5’ to 3’ direction by adding nucleotides to the __ end

A

3’

MLS 4151 - Molecular Diagnostics (3 decks)

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