Mitosis

Question 1

Somatic cell

Answer 1

Any cell in multicellular organism other than those involved in gamete formation

Question 2

Germ cell

Answer 2

Develops into egg or sperm

Question 3

Gamete

Answer 3

Sperm or an egg cell
Carry half the amount of DNA and half the number of chromosomes

Question 4

Chromatin

Answer 4

In nucleus
A complex of DNA and proteins that forms chromosomes within eukaryotic cells
DNA molecule coil around histone proteins, form nucleosomes
Nucleosomes are connected by linker DNA to give beads on a string form of chromatin
Structure is further coiled to form solenoid, forming chromatin
Can see regions of euchromatin (lighter regions) and heterochromatin (darker regions)

Question 5

DNA Replication involved proteins

Answer 5

DNA helicase
Primate
DNA polymerase 3
DNA polymerase
Single-stranded DNA binding proteins
DNA ligase

Question 6

DNA replication process

Answer 6

1) DNA helicase unwind & unzip double stranded DNA any breaking H2 bonds between CBP in double stranded DNA. Unzipping forms replication bubble. Every end of each bubble is replication fork. Each DNA strand is a template strand for synthesis of new complementary daughter strand
2) single stranded binding proteins bind to unzipped parental strands & prevent them from reannealing, until new deoxyribonucleotides CBP with parental strand via H2 bonds
3) topoisomerase relieve strain ahead of replication fork by breaking, swivelling and rejoining each DNA strand
4) primase catalyses addition of short sequence of RNA primer that is complementary to DNA parental strand to start off new DNA strand by providing free 3’ OH group for DNA polymerase 3 to add new deoxyribonucleotides
5) DNA polymerase 3 catalyses elongation of new strand by adding deoxyribonucleotides to free 3’ OH group, by recognising bases of parental strand and selecting complementary free deoxyribonucleotides to add to growing end of new strand by CBP via H2 bonds with each other.
Synthesises growing daughter stand in 5’ - 3’ direction by catalysing formation of phosphodiester bonds between adjacent deoxyribonucleotides of daughter strand.
Elongates and proofreads added deoxyribonucleotides to ensure correct ones are added. If wrong, it will excise and replace with correct deoxyribonucleotides.
6) DNA polymerase 1 proofreads synthesised region on daughter strand by checking for correct base pairings. Incorrectly paired ones are replaced.
Replaces RNA primers with deoxyribonucleotides by excising
7) DNA ligase ligase the gaps between Okazaki fragments by catalsying formation of phosphodiester bonds

Question 7

Loci definition?

Answer 7

Fixed position on a particular chromosome for each gene to occupy