DNA Replication

Question 1

Deoxyribose Structure (outline)

Answer 1

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

Question 2

Ribose Structure (outline)

Answer 2

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

Question 3

Purine Bases

Answer 3

2 Rings. Adenine and Guanine

Question 4

Pyrimidine Bases

Answer 4

1 base. Thymine/Uracil and Cytosine

Question 5

Names of the 3 phosphates

Answer 5

Alpha, beta and gamma

Question 6

Nucleotide structure

Answer 6

Sugar, Base and 3 Phosphates

Question 7

5’ end of DNA strand

Answer 7

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

Question 8

3’ end of DNA

Answer 8

Not linked to other sugar

Question 9

DNA structure

Answer 9

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

Question 10

Strongest covalent bond in DNAnstructure

Answer 10

3’ to 5’ phosphodiester. DNA backbone

Question 11

Strongest non-covalent in DNA structure

Answer 11

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

Question 12

Karyotype Def.

Answer 12

Constitution and number of chromosome

Question 13

Number of Chromosomes In Average Human

Answer 13

46. 22 pairs of autosomes and 1 pair sex chromosomes

Question 14

How Chromatin is organised

Answer 14

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

Question 15

How DNA can loosen around histones

Answer 15

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

Question 16

Acetylation Promoter Enzyme

Answer 16

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

Question 17

Acetylation REverse Enzyme

Answer 17

Histone Deacetylase. Removes acetyl from histone

Question 18

Histone Deacetylase Inhibitor Outline

Answer 18

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

Question 19

Chromosome Structures

Answer 19

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

Question 20

Heterochromatin Outline

Answer 20

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

Question 21

Euchromatin Def.

Answer 21

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

Question 22

% of protein coding DNA (genes/extrons)

Answer 22

1.5%. Highly conserved

Question 23

Highly Conserved DNA Outline

Answer 23

DNA kept the same across generations and species

Question 24

% of mitochondrial DNA

Answer 24

5%. Mitochondrial DNA loops.

Question 25

Parts of Genes

Answer 25

Promoter Elements (proximal + core), 5’ untranslated region, exons, introns, 3’ untranslated region

Question 26

Promoter Elements Function

Answer 26

Recruits proteins eg RNA polymerase 2

Question 27

5’ and 3’ UTR Functions

Answer 27

mRNA stability

Question 28

Exons Function

Answer 28

Amino Acid Coding

Question 29

Introns Function

Answer 29

Unknown. Speculated splicing

Question 30

Cell Cycle

Answer 30

G0, G1, S, G2, Mitosis and cytokinesis

Question 31

Why Chromosomes are Structurally complex

Answer 31

When DNA’s replicated nucleosomes are disassembled and daughter strands are reassembled. Random distribution of old + new histones

Question 32

DNA Replication Requirements

Answer 32

Single strand template, deoxyribonucleotides triphosphates and Mg^2+

Question 33

Replisome Def.

Answer 33

Nucleoprotein Complex coordinates replication enzymes and protein, primer and free 3’ hydroxtl end

Question 34

Primer Def.

Answer 34

RNA molecule helps begin DNA processes

Question 35

Origins of Replication Def

Answer 35

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

Question 36

DNA Helicase Def.

Answer 36

Donut shaped. Wraps around and pulls helix apart

Question 37

Single Strand Binding Proteins Def.

Answer 37

Attract DNA strands when separate to keep them apart

Question 38

Topoisomerase Def.

Answer 38

Pulls apart DNA to prevent tightening and breaking of DNA helix and helix unwinds

Question 39

DNA Polymerase Function

Answer 39

Reads DNA strand template (3’ to 5’), makes complementary DNA strand (5’ to 3’) by aligning nucleotides along templates, catalyses phosphodiester bond formation

Question 40

Profilerating Cell Nuclear Anigen Function

Answer 40

Holds polymerase in place around DNA

Question 41

How errors are prevented in DNA Replication

Answer 41

Substrate Specificiy: DNA polymerase only catalysing when compleentary base + proof reading via exonuclease (removes 3’ end nucleoyides)

Question 43

How strands are simultaneously replicated despite RNA moving in 1 direction

Answer 43

Leading strand is synthesised continuosly by RNA and lagging strand is synthesised discoutinuely by different primases

Question 44

POlymerase Alpha Function

Answer 44

Instantly replicates DNA vis extending primer 5’ to 3’. No proof reading

Question 45

Polymerase Gamma Function

Answer 45

Leading strand synthesis via replicating DNA by extending 5’ to 3’. Has proof reading

Question 46

Polymerase Delta Function

Answer 46

Lagging strand synthesis via extending 5’ to 3’. Has proof reading

Question 47

Rnase H1 Function

Answer 47

Removes most alpha polymerase except 1 5’ ribonucleotide. Removes flaws

Question 48

Flap endonuclease 1

Answer 48

removes final 5’ ribonucleotide