Intro To Molecular Biology 4 Flashcards

1
Q

Where does mRNA exit through from nucleus into membrane?

A

Nuclear pore

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2
Q

Structure of nuclear pore:

A

Have proteins (disordered plug) to prevent other substances accidentally getting through

Cytosolic and nuclear fibril

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3
Q

What does a cap-binding protein do?

A

Leads mRNA through pore

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4
Q

What does an exon-junction-complex do?

A

Ensure full length protein is translated

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5
Q

Tyopes of mutations:

A

Deletion

Insertion

Substitution

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6
Q

What is deletion?

A

Base pair deleted

Leads to frameshift and nonsense (changes amino acid to stop)c

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7
Q

What’s insertion?

A

Base pair inserted

Leads to frameshift and nonsense (changes amino acid to stop)

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8
Q

What’s substitution?

A

Base pair substituted/replaced with different base pair

Leads to missence mutation (amino acid changed)

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9
Q

What is a silent mutation?

A

Doesn’t change amino acid

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10
Q

What defines the starting point at which to read codons on mRNA?

A

Initiation codon

AUG = methionine

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11
Q

What’s the 5’ non-coding region?

A

Guide for machinery to start translation at AUG

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12
Q

What defines the ending point at which codons are read on mRNA?

A

Stop codon

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13
Q

What is the adapter between the codon and specific amino acid?

A

Transfer RNA

TRNA

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14
Q

How does tRNA bind to mRNA?

A

Anti-codon loop on tRNA base-pairs with codon on mRNA

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15
Q

How does the right amino acid get added to the right tRNA?

A

Aminoacyl-tRNA synthetases

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16
Q

Describe structure of tRNA:

A

Clover-leaf

Attached amino acid on 3’ end

Anticodon in anticodon loop

17
Q

How does Aminoacyl-tRNA synthetase work?

A

Activates amino acid and ATP

Amino-acyl is added to tRNA

18
Q

Activation of amino acid:

A

Enzyme + amino acid + ATP —-> enzyme + PPi

19
Q

Transfer of amino-acyl group to tRNA:

A

tRNA + enzyme —-> amino-acyl-tRNA + enzyme

20
Q

What does the acceptor stem do on tRNA?

A

Site where amino acid is added

21
Q

What does editing site do on aminoacyl-tRNA synthetase?

A

Verifies tRNA charged with right amino acid

22
Q

Large subunit on ribosome:

A

23s rRNA

50 proteins

Catalytic

23
Q

Small subunit on ribosomes:

A

18s rRNA

30 proteins

Binds tRNAs

24
Q

How many binding sites do ribosomes have?

A

One for mRNA

Three for tRNA

25
Three phases of translation:
Initiation Elongation Termination
26
What happens in initiation?
5’ cap structure of mRNA recognised Ribosomes scan through 5’ non-coding region until initiation codon found
27
What’s required for initialisation?
Initiation factors
28
What happens in elongation?
Correct tRNAs bind Peptide binds made between amino acids
29
What happens in termination?
Termination codon reached Bond between protein and last tRNA is broken Whole complex disassociates
30
What is required in termination?
Release factors
31
What’s polymorphism?
Minor change in sequence Main cause of genetic variation
32
What happens after translation?
Translocation to relevant part of cell Protein folding Post-translational modification
33
Effects of mutations:
No transcription Protein incorrectly processed Inappropriately regulated Inappropriate function Unstable protein