DNA replication, mitosis, meiosis and protein synthesis

Question 1

Describe the process of DNA replication

Answer 1

• unwinding of the double helix
• by DNA helicase which breaks hydrogen bonds between complementary bases
• template strand is exposed
• free nucleotides are attracted to their complementary base pairings
• process is catalysed by DNA polymerase
• both strands acts as templates
• forms phosphodiester bonds

Question 2

Describe the structure of a nucleotide and the formation of a dinucleotide

Answer 2

nucleotide has one pentose sugar which is joined to a phosphate molecule and a nitrongenous base. Bond between the phosphate molecule and pentose sugar is an ester bond and the bond between the base and sugar is a glycosidic bond

Question 3

why is DNA replication only in a 5’ to 3’ direction

Answer 3

Can make a constant strand of DNA

Question 4

how does meiosis produce genetically varied gametes

Answer 4

crossing over- homologous pairs exchange genetic material by swapping sections of the genes - alleles
Independent assortment - the random sequence that the chromosomes line up and get pulled apart to different cells

Question 5

what is chromatin

Answer 5

unravelled chromosomes

Question 6

what happens in prophase mitosis

Answer 6

chromosomes condense
spindle fibres towards the chromosomes

Question 7

Describe the process of viral replication

Answer 7

Attachment proteins on the virus attaches to the surface of the host cell
Viral RNA is injected into the host cell
Reverse transcriptase converts RNA to DNA
New viral proteins are replicated
Proteins are assembled and released from cell