2B

Question 1

What is the induced fit hypothesis

Answer 1

• Active site changes to fit the substrate
• When there is no substrate the enzyme is in its inactive form
• When substrate binds > goes to active form
• Substrate released > enzyme goes inactive again
• Shape changes

Question 2

What does DNA helicase do

Answer 2

• Unzips 2 strand of DNA
• Breaks hydrogen bonds

Question 3

What does DNA polymerase do

Answer 3

• Lines up new nucleotides along DNA template strands
• Forms hydrogen bonds

Question 4

What does DNA ligase

Answer 4

• Catalyses the formation of phosphodiester bonds between nucleotides
• Forms phosphodiester bonds

Question 5

Define mRNA

Answer 5

• One strand
• U instead of T
• Every mRNA starts w AUG (start codon)
• Formed in nucleus
• Single stranded
• Complimentary to antisense

Question 6

Define tRNA

Answer 6

• Small units of RNA that pick up specific amino acids from cytoplasm and transport them to surface of ribosome to align with mRNA

Question 7

Define transcription

Answer 7

• Nucleus
• DNA sequence used to make strand of mRNA in nucleus

Question 8

Define translation

Answer 8

• Cytoplasm
• DNA converted into protein from mRNA strand (made in nucleus)

Question 9

Describe the process of transcription

Answer 9

1. DNA helicase breaks hydrogen bonds
2. One of the DNA strands used to make template for mRNA
3. RNA polymerase lines up free RNA nucleotides attatched to antisense by complimentary base pairs
4. Adjacent nucleotides join by phosphodiester bonds > RNA ligase catalyses forms single strand of DNA
5. Once RNA polymerase reaches stop codon > mRNA detatches from template
6. Moves thru nuclear pore + attatches to ribosome in cytoplasm

Question 10

Describe the process of translation

Answer 10

1. mRNA leave thru nuclear membrane pores to cytosplasm
2. Bind itself to ribosomes for protein synthesis
3. Ribosomes act as enzymes controlling process of protein synthesis
4. tRNA binds thru hydrogen bonds to mRNA (anticodons of tRNA complimentary to mRNA)
5. Specific amino acids will attatch themselves to opposite side of tRNA which carry the anticodons complimentary to codons of mRNA
6. Peptide bonds form > forming polypeptide chains > released out of ribosomes