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Biochemistry > Module 8: V1 - V4 > Flashcards

Module 8: V1 - V4 Flashcards

1
Q

What is the structure of DNA?

A

double-helix

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2
Q

How does DNA encode information?

A

the balance between A=T and G=C pairs

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3
Q

Which biological processes involve DNA?

A

transcription, replication, recombination, repair and regulation

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4
Q

What biological processes is RNA involved in?

A

transcription, replication, translation, regulation and viruses

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5
Q

Which types of structures does RNA often form?

A

hairpins and loops

also complex 3D structures such as tRNA

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6
Q

What are nucleotides for?

A

components for RNA and DNA
used for energy storage e.g. ATP
cofactors in metabolism e.g. NAD+ and FAD+

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7
Q

Which nucleotides are purines?

A

nucleotides with a double-ring structure

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8
Q

Which nucleotides are pyrimidines?

A

nucleotides with a single-ring structure

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9
Q

What is the 5’ and 3’ end of DNA?

A

the 5’ end terminates at 5C and the 3’ end terminates at a phosphate group

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10
Q

Why is A always paired with T and G always paired with C?

A

this is because purines must always be matched up with pyrimidines

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11
Q

How many hydrogen bonds are there between A and T?

A

two

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12
Q

How many hydrogen bonds are there between G and C?

A

three

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13
Q

When does a cell replicate its DNA?

A

during the S (DNA synthesis) phase

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14
Q

What is DNA synthesised by?

A

DNA polymerases

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15
Q

What is the role of DNA polymerase III?

A

the main polymerase in DNA replication

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16
Q

What is the role of DNA polymerase I?

A

has functions in repair and recombination too

17
Q

What allows the synthesis reaction of DNA to occur?

A

coordination of Mg2+ by aspartic acids
Mg2+ ions coordinate phosphate groups
DNA polymerases can only extend at the 3’ end
DNA polymerases need a double stranded section to start

18
Q

Activity of which enzymes occurs in DNA polymerase I?

A

3’ -> 5’ exonuclease (proofreading) and 5’ -> 3’ exonuclease

19
Q

Activity of which enzyme occurs in DNA polymerase III?

A

3’ -> 5’ exonuclease (proofreading)

20
Q

What is the DUE section of the oriC sequence rich in?

A

AT base pairs

21
Q

What is the role of DnaA protein?

A

recognises ori sequence; opens duplex at specific sites in origin

22
Q

What is the role of DnaB protein (helicase)?

A

unwinds DNA

23
Q

What is the role of primase (DnaG protein)?

A

synthesises RNA primers

24
Q

What is the role of single-stranded DNA-binding protein (SSB)?

A

binds single-stranded DNA

25
Q

What is the role of DNA gyrase (DNA topoisomerase II)?

A

relieves torsional strain generated by DNA unwinding

26
Q

What are the major differences between RNA and DNA, both in their components and their overall structure?

A

RNA is ribonucleic acid while DNA is deoxyribonucleic acid as it contains a ribose which lacks one oxygen atom
RNA is single stranded while DNA is double stranded
RNA has uracil instead of thymine

27
Q

What are nucleotides used for in the cell?

A

building blocks for the synthesis of DNA and RNA

also messengers and energy moving molecules

28
Q

What would be different about the structure of DNA if the base pairing were between a purine and a purine, and a pyrimidine and a pyrimidine?

A

since the matching of purines to pyrimidines allows for constant width of DNA to be maintained, if purines were to bind to purines or if pyrimidines were to bind to pyrimidines, the width of DNA would vary

29
Q

Explain how the mechanism of replication of DNA is immediately apparent from its structure.

A

the structure of DNA is what allows replication to occur as each parent strand is used as a template for the complimentary replicated strand

30
Q

Why is it important that part of the sequence of the origin of replication is AT-rich?

A

because AT-rich regions of the origin prevent DNA strands from separating due to tension

31
Q

How does a nucleic acid ‘recognise’ another nucleic acid? We will see this happen in many different processes, but one example would be a nucleotide entering the DNA polymerase during replication, and staying long enough for the phosphate backbone to be polymerised.

A

the key to recognition of specific nucleic acid sequences is base pairing between complementary strands of RNA or DNA

Biochemistry (30 decks)

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