DNA replication and synthesis

Question 1

what is the structure of DNA?

Answer 1

• deoxyribose sugar
• nitrogenous base
• phosphate
• double stranded

Question 2

what is the structure of RNA ?

Answer 2

• ribose sugar
• nitrogenous base
• phosphate
• single stranded

Question 3

what are the 3 different types of RNA

Answer 3

• mRNA
• tRNA
• rRNA

Question 4

what is the structure of a nucleotide ?

Answer 4

• pentose sugar
• nitrogenous base
• phosphate group

Question 5

which bases are purine bases ?

Answer 5

• adenine
• guanine

Question 6

which bases are pyrimidine bases ?

Answer 6

• uracil
• cytosine
• thymine

Question 7

what are difference in DNA and RNA structure ?

Answer 7

• RNA has U vs DNA has T
• RNA single stranded vs DNA double stranded
• RNA has ribose vs DNA has deoxyribose

Question 8

what is the role of DNA Polymerase ?

Answer 8

• adds nucleoside triphosphates and forms phosphodiester bonds
• only works in 5’ to 3’

Question 9

what are the 3 stages of transcription ?

Answer 9

• initiation
• elongation
• termination

Question 10

what are transcription factors ?

Answer 10

• proteins that bind to DNA - switch gene on or off

Question 11

stages of initiation of transcription

Answer 11

• transcription factors bind to promoter region
• RNA polymerase binds to promoter region
• DNA strand unwinds + separates

Question 12

stages of elongation of transcription ?

Answer 12

• RNA polymerase moves along template strand (anti -sense) and adds RNA nucleotide
• in the 5’ to 3’ direction

Question 13

termination stages of transcription

Answer 13

• RNA polymerase encounters termination signal
• released from DNA strand and mRNA formed

Question 14

What are the 3 sites on ribosomes ?

Answer 14

• A (amino acid joins)
• P (peptide made)
• E (exit - holds tRNA before it leaves ribosome)

Question 15

initiation of translation ?

Answer 15

• small ribosomal subunit binds to mRNA
• tRNA with comp anti-codon to mRNA condon binds
• large ribosomal subunit joins

Question 16

elongation of translation ?

Answer 16

• initiation tRNA has amino acid MET goes to P site
• new tRNA with next amino acid and complementary anti-codon to mRNA codon goes to A site
• AA in P site transferred to A site
• ribosome moves along so both AA in P site (peptidyl transferase)
• empty tRNA now in E site to exit

Question 17

termination of translation ?

Answer 17

• riobosome reaches stop codon on mRNA
• A site accepts release factor instead of tRNA
• release factor hydrolyses bond between tRNA and last amino acid
• peptide chain free from ribosome
• ribosomal sub-units separate