Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

1. Molecular Biology > Important Information > Flashcards

Important Information Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What are phosphodiester bonds?

2

A

Covalent bonds that link adjacent nucleotides together in both DNA and RNA

Formed between the OH group on the 3’ C of one nucleotide and phosphate on the 5’ C of the next nucleotide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are hydrogen bonds between nucleotides?

A

They join nitrogen bases of nucleotides together in complementary base pairs in the centre of DNA

This holds the 2 antiparallel strands together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a replication “bubble” in DNA replication?

2

A

Where the two separate strands open up from the origin of replication

A replication fork is found at either end of the bubble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

DNA replication is semi-conservative, what does this mean?

A

Each of the 2 daughter molecule will have one of the old parent strands and 1 newly made strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a replication fork?

3

A

A Y-shaped region found at each end of a replication bubble

This is where the new strands of DNA are elongating

They move away from the origin of replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the Origin of Replication?

A

The position in DNA where the helix is first opened

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the leading strand?

2

A

The new strand that can be synthesised continuously

The new strand in the 5’ to 3’ direction strand (complementary to the 3’ to 5’ parent strand)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are okazaki fragments

A

Short sequences of DNA nucleotides which are synthesized discontinuously and later linked together by DNA ligase to create the lagging strand during DNA replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is an exonuclease?

A

An enzyme which removes successive nucleotides from the end of a polynucleotide molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens if DNA pol finds out the previous nt is incorrect?
(3)

A

DNA pol removes the incorrect nt by cutting the phosphodiester bond

This releases the nt

DNA pol tries again to add the correct nt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What four proteins cooperate to form the replication machine?

A

Helicase

Topoisomerase

Sliding clamp

Single strand binding proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does helicase work?

A

Uses energy of ATP hydrolysis to speed along DNA and separate the strands of parental DNA ahead of polymerase

It breaks the hydrogen bonds between base pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does ligase work?

A

Joins 5’ phosphate end of one DNA fragment to 3’ OH end of the next (ATP required for ligase activity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does topoisomerase work?

A

Prevents DNA helix upstream from becoming supercoiled by relaxing it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the sliding clamp work?

2

A

Keeps DNA polymerase firmly attached to DNA template

On the lagging strand it releases polymerase from the DNA each time an Okazaki fragment is completed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the four key players in DNA replication?

A

Ligase

Helicase

Primase

DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does nuclease do?

A

Removes any incorrect nucleotides - by cleavage of phosphodiester bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Classify DNA damage.

A

Single strand

Double strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What causes single strand damage?

3

A

Endogenous replication errors

Oxidative chemicals

Non-ionising radiation e.g. UV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the two classifications of agents that can damage DNA?

A

Exogenous

Endogenous agents

21
Q

Give three examples of exogenous agents

A

Toxins

Chemicals

UV radiation

22
Q

What causes double strand damage?

2

A

Antitumor agents e.g. Cisplatin

Ionising radiation e.g. Gamma rays

23
Q

Define DNA damage

A

Any alteration to DNA that distorts its geometry

24
Q

What are the five types of single strand damage?

A

Base Mismatch

Depurination

Deamination

Thymine dimers

Bulky adducts

25
Q

What does DNA pol I primarily do?

2

A

Exonuclease activity (nuclease activity at end of chain)

Nick translation

26
Q

What does DNA pol II primarily do?

A

DNA repair

27
Q

What does DNA pol III primarily do?

A

DNA synthesis

28
Q

What is a mutation?

A

Randomly produced permanent change in a sequence of DNA

29
Q

What are the three repair processes for SSD?

A

Mismatch repair (MMR) for repairing

Base excision repair (BER)

Nucleotide excision repair (NER)

30
Q

What is meant by 5’ and 3’?

2

A

The 5’ and 3’ indicate the carbon numbers in the DNA’s sugar backbone.

The 5’ carbon has a phosphate group attached to it and the 3’ carbon a hydroxyl (-OH) group

31
Q

How do you draw deoxyribose?

7

A

Draw a pentagon - O at the top with four carbons

Label each carbon in a clockwise direction 1’ to 4’

1' = OH on top and H on bottom
2' = H on top and H on bottom
3' = H on top and OH on bottom
4' = 5' on top and H on bottom
5' = (HOCH2)
32
Q

What is the structural difference between deoxyribose and ribose?

A

2’ and 3’ of ribose have a H on top and an OH on bottom

33
Q

To which C of ribose is the nitrogenous base attached?

A

1’

34
Q

To which C of ribose is the phosphate attached?

A

5’

35
Q

Define transcription

A

A portion of DNA nucleotide sequence (gene) is copied into a RNA nucleotide sequence

36
Q

Define translation

2

A

The synthesis of polypeptide under direction of RNA

Formation of amino acid chains - proteins

37
Q

What are transcription factors?

A

A collection of proteins that mediate the binding of RNA pol II to promoter in eukaryotes

38
Q

What is RNA polymerase called when it is comprised of all five of it’s subunits?

A

Haloenzyme

39
Q

What are the three main steps in transcription in prokaryotes?

A

Binding and initiation

Elongation

Termination

40
Q

How does initiation of transcription work in eukaryotes?

4

A

A collection of proteins called transcription factors are needed

They mediate the binding of RNA pol II to promoter

A promoter DNA sequence (TATA box) is crucial for forming the transcription initiation complex

Complex then moves Pol II to start site of gene and begins to polymerise

41
Q

What is the spliceosome?

2

A

Small nuclear RNAs (snRNA)

Combined with proteins (snRNP)

42
Q

What does mRNA need to be bound to in order to be transported?
(3)

A

Poly-A-binding protein

Cap-binding complex

Nuclear transport receptor

43
Q

What is an operon?

A

A set of adjacent genes in a bacterial genome, transcribed from a single promoter into a single mRNA

44
Q

Write a note on the trytophan operon

4

A

5 genes which encode for enzyme which manufacture trytophan

These genes are arranged in a cluster on the genome (form an operon)

Genes transcribed from one promoter as 1 long mRNA molecule from which 5 proteins are translated

This operon isn’t needed if bacteria can get trytophan from their environment so it’s shut off

45
Q

Define a repressor protein.

A

A protein that switches genes off or represses them

46
Q

Define an activator protein

A

A protein that switches genes on or activates them

47
Q

Write a note on the lac operon

4

A

Operon that encodes proteins required to import and digest lactose

Consists of 3 genes: lacZ, lacY and lacA

All genes under control of 1 promoter

Allolactose - lactose digestion intermediate - binds to repressor to inactivate it

48
Q

What is the genetic code?

A

The rules by which nucleotide sequence of a gene is translated into an amino acid sequence of a protein

49
Q

What do ribosomes do in translation?

A

They add each amino acid brought to it by tRNA to the growing end of a polypeptide chain

1. Molecular Biology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions