DNA Replication Flashcards

1
Q

Deoxyribose Structure (outline)

A

5 carbon sugar (1’ to 5’) On C 2’ there’s a H molecule

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2
Q

Ribose Structure (outline)

A

5 Carbon sugar. On C 2’ there’s a hydroxyl (OH) group

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3
Q

Purine Bases

A

2 Rings. Adenine and Guanine

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4
Q

Pyrimidine Bases

A

1 base. Thymine/Uracil and Cytosine

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5
Q

Names of the 3 phosphates

A

Alpha, beta and gamma

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6
Q

Nucleotide structure

A

Sugar, Base and 3 Phosphates

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7
Q

5’ end of DNA strand

A

c 5’ isn’t linked to neighboring structure at posphate molecule

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8
Q

3’ end of DNA

A

Not linked to other sugar

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9
Q

DNA structure

A

Double strand one in an antiparallel orientation (opposite directions). Opposite strands have complementary basepairs. A and T (2H) and C and G (3H)

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10
Q

Strongest covalent bond in DNAnstructure

A

3’ to 5’ phosphodiester. DNA backbone

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11
Q

Strongest non-covalent in DNA structure

A

Van der Waals. Between base pairs. Bonding is weaker between A and T (less H bonds) then G and C

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12
Q

Karyotype Def.

A

Constitution and number of chromosome

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13
Q

Number of Chromosomes In Average Human

A
  1. 22 pairs of autosomes and 1 pair sex chromosomes
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14
Q

How Chromatin is organised

A

146 base pairs are wrapped about nucleosome (8 combined histones proteins). Very compact

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15
Q

How DNA can loosen around histones

A

Acetylation - positive charge on histone (on lysine tails) is neutralised. Negatively charged DNA is less attached. Makes transcription easier

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16
Q

Acetylation Promoter Enzyme

A

Histone acetyl-transferase. Add acetyl group to histone to neutralise

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17
Q

Acetylation REverse Enzyme

A

Histone Deacetylase. Removes acetyl from histone

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18
Q

Histone Deacetylase Inhibitor Outline

A

Vorionostat. Keep acetyl group on histones leaving DNA loosely bound. Allows silenced genes to function. Causes cancer cell death in cutaneous T-cell lymphoma

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19
Q

Chromosome Structures

A

Centromeres (kinetocore and spindles attach here, repetitive DNA sequences), dark/light bands (foldings) and telomers (cap at chromosome ending, maintain structural integrity)

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20
Q

Heterochromatin Outline

A

Dark staining. Highly condensed chromatin folding, gene poor. No transcription

21
Q

Euchromatin Def.

A

Light staning. Chromatin is more extended the folding, gene rich. Active transcription

22
Q

% of protein coding DNA (genes/extrons)

A

1.5%. Highly conserved

23
Q

Highly Conserved DNA Outline

A

DNA kept the same across generations and species

24
Q

% of mitochondrial DNA

A

5%. Mitochondrial DNA loops.

25
Parts of Genes
Promoter Elements (proximal + core), 5' untranslated region, exons, introns, 3' untranslated region
26
Promoter Elements Function
Recruits proteins eg RNA polymerase 2
27
5' and 3' UTR Functions
mRNA stability
28
Exons Function
Amino Acid Coding
29
Introns Function
Unknown. Speculated splicing
30
Cell Cycle
G0, G1, S, G2, Mitosis and cytokinesis
31
Why Chromosomes are Structurally complex
When DNA's replicated nucleosomes are disassembled and daughter strands are reassembled. Random distribution of old + new histones
32
DNA Replication Requirements
Single strand template, deoxyribonucleotides triphosphates and Mg^2+
33
Replisome Def.
Nucleoprotein Complex coordinates replication enzymes and protein, primer and free 3' hydroxtl end
34
Primer Def.
RNA molecule helps begin DNA processes
35
Origins of Replication Def
Short AT rich regions on DNA where initiation begins. Multiple sites in eukaryotes. 2 replicating molecules move outwards from site in different directions. Replicons grow outwards and fuse forming 2 different strands
36
DNA Helicase Def.
Donut shaped. Wraps around and pulls helix apart
37
Single Strand Binding Proteins Def.
Attract DNA strands when separate to keep them apart
38
Topoisomerase Def.
Pulls apart DNA to prevent tightening and breaking of DNA helix and helix unwinds
39
DNA Polymerase Function
Reads DNA strand template (3' to 5'), makes complementary DNA strand (5' to 3') by aligning nucleotides along templates, catalyses phosphodiester bond formation
40
Profilerating Cell Nuclear Anigen Function
Holds polymerase in place around DNA
41
How errors are prevented in DNA Replication
Substrate Specificiy: DNA polymerase only catalysing when compleentary base + proof reading via exonuclease (removes 3' end nucleoyides)
42
43
How strands are simultaneously replicated despite RNA moving in 1 direction
Leading strand is synthesised continuosly by RNA and lagging strand is synthesised discoutinuely by different primases
44
POlymerase Alpha Function
Instantly replicates DNA vis extending primer 5' to 3'. No proof reading
45
Polymerase Gamma Function
Leading strand synthesis via replicating DNA by extending 5' to 3'. Has proof reading
46
Polymerase Delta Function
Lagging strand synthesis via extending 5' to 3'. Has proof reading
47
Rnase H1 Function
Removes most alpha polymerase except 1 5' ribonucleotide. Removes flaws
48
Flap endonuclease 1
removes final 5' ribonucleotide