from genes to proteins

Question 1

what is formed when ssRNA folds into secondary structure?

Answer 1

a mini helix is formed, 11 bp per turn

Question 2

how many rRNAs do eukaryotes have?

Answer 2

4, two large, two small

Question 3

how many rRNAs do bacteria have?

Answer 3

3- two large, one small

Question 4

how long is tRNA?

Answer 4

76 nucleotides long

Question 5

what is meant by the term ‘proteinogenic’?

Answer 5

each tRNA is dedicated to one of the 20 amino acids

Question 6

what is the reaction for RNA synthesis?

Answer 6

(RNA)n + NTP -> (RNA)n+1 + PPi

Question 7

name 3 characteristics of RNA polymerase

Answer 7

• requires ds template even though only one strand is transcribed
• synthesis is in 5’-3’ direction
• highly processive

Question 8

name the features of RNA polymerase that are different from DNA polymerase

Answer 8

no primers or nuclease activity
not semi conservative- DNA remains unchanged
only one strand copies

Question 9

why is only one strand copied in RNA synthesis?

Answer 9

the strands in DNA run anti-parallel

RNA polymerase is directional, must synthesise 5’-3’ direction

Question 10

how does RNA polymerase know where to bind?

Answer 10

it uses a promoter region; specific binding site

Question 11

describe how RNA is synthesised from a dsDNA molecule

Answer 11

• RNAP opens promoter
• transcribes 3’-5’ strand (template)
• leaves DNA behind it unchanged
• promoter is not transcribed