Brainscape's Knowledge GenomeTM

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


See full index

102 - Theme 3 > T3L3 - DNA replication > Flashcards

T3L3 - DNA replication Flashcards

1
Q

M Phase [2]

A

Mitosis (nuclear division) and cytokinesis (cytoplasmic division)

Interphase 
Prophase 
Prometaphase 
Metaphase 
Anaphase 
Telophase 
Cytokinesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Cell cycle

A

M Phase
G1 Phase
S Phase
G2 Phase

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

Kinetochore

A

Spindle fibres form and pull chromatids apart

Telomeres get shorter as you age

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

Prophase

A

Replicated chromosomes consist of 2 chromatids which condense
Mitotic spindle assembles between 2 centrosomes

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

Prometaphase

A

Starts abruptly with breakdown of nuclear envelope

Chromosome attach to spindle microtubules via kinetochore and undergo active movement

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

Metaphase

A

Chromosomes align at equator of spindle - midway between spindle poles
Paired kinetochore microtubules on each chromosome attach to opposite poles

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

Anaphase

A

Sister chromatids synchronously separate and each is pulled slowly towards spindle pole attached to it
Kinetochore microtubules get shorter and spindles poles move apart

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

Telophase

A

2 sets of chromosomes arrive at poles of spindles
Nuclear envelope reassembles around each set and complete formation of 2 nuclei
Assembly of contractile ring

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

Cytokinesis

A

Cytoplasm divides in 2 by a contractile ring of actin and myosin filaments

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

S phase [8]

A

Every time cell divides must replicate 6 billion bp

Accuracy and speed required

(~100 nt/s)

Complementary base-pairing

DNA strands run in opposite directions (polar)

Nucleotides added to 3’ end

DNA synthesised in 5’ to 3’ direction

Energy provided from breakage of triphosphate bond

Phosphodiester bond formed
(-O-P-O-)

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

DNA enzymes [6]

A

DNA Helicase: Unwinds double helix

DNA Polymerase: adds nucleotides to 3’ end of leading strand

Exposed lagging strand protected by single-strand DNA binding proteins

DNA Primase: adds small RNA primer to lagging strand

DNA Polymerase: adds nucleotides to 3’ end of lagging strand

DNA Ligase: joins together small gaps

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

Characterising mutations [3]

A

Effect on heritability (somatic or germ line)

Scale of mutation (chromosome or SNP)

Effect on normal function (loss or gain of function)

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

Mutations can be prevented through [3]

A

Proof-reading capacity of DNA polymerase during DNA replication

Excision repair systems act throughout cell life repairing DNA damage

Polymerase can detect distortion in shape due to wrong base pair (rungs no longer same length)

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

Primers in DNA synthesis

A

Primase creates primer (10 nucleotide long RNA)
Primase = RNA polymerase
RNA primer needed for leading strand

DNA polymerase adds deocyribonucleotide to 3’ side

Nuclease degrades RNA primer & repair polymerase replaces it with DNA

• DNA  helicase uses energy from hydrolysis of ATP to propel itself forward -> pries double helix apart
• Opening of DNA makes It tightly wound on otherside -> DNA topoisomerase needed to relieve tensions -> produce transient nicks in DNA backbone -> temporary release tension Sliding clamps keep DNA  polymerase firmly attached to template
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

DNA damagae causes [3]

A

Undergoes thermal collusions with other molecules

Trillion purine bases lost (depurination) -> does not break phosphodiester backbone & remove purine bases

UV radiation promotes covalent linkage between adjacent pyrimidine bases -> thymine dimer

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

DNA repair [4]

A

Damaged DNA recognised & removed by mechanisms involving nucleases -> cleave covalent bonds that join damaged nucleotides to DNA strand

Repair DNA polymerase binds to 3’ hydroxoyl end of cut DNA strand -> elongates chains in 5’ to 3’ direction

After repair DNA polymerase has filled the gap, a break remains in the sugar phosphate backbone of repaired strand -> nick in helix sealed by DNA ligase (same as that which joins Okazaki fragments)

Mismatch pair: recognise mistake & remove newly made DNA

17
Q

DNA replication

A

Initiator proteins bind to specific DNA sequences
Pry DNA strand apart and break hydrogen bonds
DNA being replicated contains Y shaped junction
DNA replication in bacterial and eukaryotic chromosomes is bidirectional

18
Q

Polymerisation energy provided by

A

Hydrolysis of deoxyribonucleotside triphosphate - release pyrophosphate

19
Q

Depurination

A

does not break phosphodiester backbone & removes purine base

20
Q

Ultraviolet radiation promotes

A

covalent linkage between adjacent pyrimidine bases to form a thymine dimer

21
Q

DNA topoisomerase

A

needed to relieve tensions -> produce transient nicks in DNA backbone -> temporary release tension

22
Q

Sickle cell disease [3]

A

Single nucleotide substitution in HBB gene (beta chain of haemoglobin)

Misshapen blood cells do not survive as long (can cause anaemia) and clog up capillaries

~12,500 SCD in the UK

23
Q

Huntington’s disease [4]

A

• Neurodegenerative disease (starts to appear age 30-50)
uncontrollable muscular movements
loss of memory and depression
difficulties with speech and swallowing
• Damage of the nerve cells in areas of the brain
• ~7,000 cases in the UK
Caused by increase in number of CAG trinucleotide repeats (encoding glutamine) in the Huntingtin (HTT) gene

24
Q

Polyglutamine residues

A

stick together creating a toxic product (gain of function) which causes neuron cell death through multiple mechanisms

25
Q

Xeroderma pigmentosum

A 
• Most mutations in DNA repair lethal
	• XP: mutation in UV repair
		Unable to remove thymine dimers
		Autosomal recessive disorder
	• Acute sun sensitivity
	• Hypo- and hyper-pigmentation
	• Multiple cancers at young age
	• Mental retardation
Progressive degeneration
26
Q

Single nucleotide polymorphism (SNP)

A

• Single base change in DNA sequence
• Normal genetic variation in population
• Synonymous: no change in amino acid sequence
Non-synonymous: change to amino acid sequence

27
Q

Werner Syndrome

A

Mutations to mitosis or DNA replication genes usually lethal

Range of syndromes result from loss of minor components

Werner Syndrome (1/200,000 in USA)

Premature aging disorder

Mutation in a DNA Helicase (WRN)

Errors in DNA replication and DNA repair

Increase in risk of cataracts, atherosclerosis, osteoporosis and cancer

Model for the aging process
Life expectancy is anywhere from 45 to 50 years

102 - Theme 3 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions