Introduction to Molecular Biology 4 Flashcards

1
Q

How does mRNA leave the nucleus?

A

Through nuclear pores.

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2
Q

What is the nuclear pore usually blocked by?

A

Disordered proteins.

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3
Q

Is nuclear export an energy dependent process?

A

Yes indeed.

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4
Q

How is genetic information read?

A

In triplets of three or codons.

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5
Q

What does degenerate mean?

A

One amino acid can be coded for by more than one triplet.

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6
Q

What does a deletion or insertion mutation result in?

A

A frame shift resulting in a nonsense mutation.

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7
Q

What does a substitution of bases result in?

A

A point mutation resulting in a missense mutation.

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8
Q

How do silent mutations arise?

A

Degenerate nature of genetic code means that some mutations do not change the AA sequence.

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9
Q

What is polymorphism?

A

A minor change in the DNA sequence that is present in less than 1% of the population.

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10
Q

What is the starting point of the read information called?

A

The initiation codon, at the 5’ end.

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11
Q

What is the end point of the read information called?

A

The stop codon, at the 3’ end.

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12
Q

What is the adaptor between the codon and the specific AA?

A

Transfer RNA.

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13
Q

What pairs with the AA in the cytoplasm?

A

The anti codon loop of the tRNA base pairs with the codon of an mRNA.

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14
Q

What is an aminoacyl-tRNA synthetase?

A

An enzyme that attaches the appropriate AA onto its tRNA.

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15
Q

How does the right AA get added to the right tRNA?

A

20 different aminoacyl-tRNA synthetases, each one recognises only one AA and all its compatible tRNAs.

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16
Q

What is always the starting codon and AA?

A

AUG and methionine.

17
Q

Describe the structure of the tRNA-AA bond.

A

AA esterified to the 3’ OH of the terminal adenosine of the tRNA.

18
Q

What are the properties of large subunits of RNA?

A

Catalytic.

19
Q

How does the ribosome bind to mRNA and tRNA?

A

One binding site for mRNA and three for tRNA.

20
Q

What three stages does translation occur in?

A

Initiation, elongation and termination.

21
Q

What is required for initiation?

A

Initiator tRNA and initiation factors.

22
Q

What does the initiator factor bind to?

A

The cap on the 5’ end of the mRNA.

23
Q

What is the second step of initiation?

A

Peptide bond between carboxyl of tRNA at P site to amino group at A.

24
Q

What is the first step of translocation?

A

The large subunit of the ribosome translocates along the mRNA.

25
Q

What is the second step of translocation?

A

The small subunit of the ribosome translocates one triplet down the mRNA.

26
Q

What is required at termination?

A

Requires release factors.

27
Q

What occurs at termination?

A

The ribosome dissociates and falls apart.

28
Q

What happens after translation?

A

Translocation to relevant part of the cell, protein folding and post-translational modification.

29
Q

What do signals also dictate?

A

Post-translational modifications.

30
Q

What is Tau-hyperphosphorylation associated with?

A

Neurofibrillar tangles in dementia.