DNA and cell division

Question 1

What does a nucleotide consist of ? (3)

Answer 1

1 Pentose sugar
1 Nitrogenous base
1 Phosphate group

Question 2

What process and what bonds are formed between neucleotides?

Answer 2

Condensation reactions form phosphodiester bonds

Question 3

What are the complementary base pairs

Answer 3

Adenine - Thymine
Cytosine - Guanine

Question 4

How is Eukaryotic DNA similar to Prokaryotic DNA? (2) Spy fam dog

Answer 4

Identical nucleotide structure
Nucleotides are both joined via phosphodiester bonds

Question 5

How is Eukaryotic and Prokaryotic DNA different?
3 for each + E.G

Answer 5

Eukaryotes : Has Extron and introns, Long, linear and histones, chromosomes,80S ribosomes E.G mitochondria/chloroplast
Prokaryotes: Only has Extron’s, short, circular and no histones, no chromosomes, 70S ribosomes - E.G plasmids

Question 6

Before mitosis comes the cell cycle. What makes the cell cycle?

Answer 6

G1 phase / checkpoint, S phase, G2 phase / checkpoint. If bad then G0

Question 7

What happens in the G1 phase / checkpoint

Answer 7

Phase : Organelles replicate and cell grows in size
Checkpoint : Checks size, organelle and DNA damage, if fail sent to G0 to prevent further division and harm

Question 8

What happens in the S phase?

Answer 8

DNA replicates its self

Question 9

What happens in the G2 phase / checkpoint

Answer 9

phase : Further growth/protein synthesis
checkpoint : checks DNA damage, cell size and complete replication

Question 10

What is mitosis and its purpose?

Answer 10

growth and repair. Cells divide once to produce 2 genetically identical daughter cells

Question 11

Mitosis: What happens in Prophase

Answer 11

chromosomes condense to chromatic (2 sister chromatids)
nuclear envelope breaks down

Question 12

Mitosis: What happens in Metaphase

Answer 12

Chromosomes line up at equator via spindle fibres attached to their centromeres

Question 13

Mitosis: What happens in Anaphase

Answer 13

Spindle fibres shorten, chromatids r pulled to opposite poles

Question 14

Mitosis: What happens in Telophase
Tele deez nuts

Answer 14

Nuclear envelope forms around each chromatid and chromosomes decondense into chromatids

Question 15

How does DNA replication happen? (3) - Break float poly

Answer 15

1) DNA helicase breaks H-bonds in-between complementary base pairs (splits and exposes the strand and bases
2) New floating DNA nucleotides form H-Bonds to the exposed bases
3)DNA polymerase joins nucleotides via condensation forming phosphodiester bonds (continues to happen until a new nucleotide is formed)

Question 16

What is Meiosis and its purpose?

Answer 16

Produce gametes for sexual reproduction. Cells divide twice and it produces 4 genetically different haploid cells

Question 17

What happens in meiosis 1?

Answer 17

prophase I : Homologues chromosomes pair up and nuclear envelope breaks down
Metaphase I : homologous pairs line up at equator
Anaphase I : Homologues chromosomes are pulled to opposite poles via spindle fibres
Telophase I : chromosomes decondense and nuclear envelope forms around each group

Question 18

What happens is meiosis 2?

Answer 18

Diff cuz starts w hapolid
Prophase II : chromatin recondenses into 23 chromosomes
Metaphase II : Chromosomes r lined up at the equator
Anaphase II : Sister chromatids are pulled to opposite poled via spindle fibres
Telophase II : Decondenses to chromatin and nuclear envelope forms around each group

Question 19

How does meiosis contribute to genetic variation? (2)

Answer 19

1) different combos as independent assortment in metaphase I when the homologous pair randomly line up in the equator of the cell
2)Crossing over and chromosomes twisting around each other causing portions to exchange in Prophase I