DNA replication, mitosis, meiosis and protein synthesis Flashcards
Describe the process of DNA replication
- 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
Describe the structure of a nucleotide and the formation of a dinucleotide
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
why is DNA replication only in a 5’ to 3’ direction
Can make a constant strand of DNA
how does meiosis produce genetically varied gametes
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
what is chromatin
unravelled chromosomes
what happens in prophase mitosis
chromosomes condense
spindle fibres towards the chromosomes
Describe the process of viral replication
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
