1. PIG - enzymes

2. What are enzymes? [3]

3. 3 of the following: Biological catalysts Globular proteins
Increase the rate of (chemical) reaction
Complimentary substrate shape to its active site
Have an active site

4. What is activation energy? [2]

5. Energy ‘barrier’
Molecules must overcome this barrier in order to take part in the reaction

6. Name the 2 enzyme theories & explain them. [4]

7. Active site and substrate are complimentary shapes
Lock & Key theory [1]
Active site and substrate are complimentary shapes
Induced fit theory [1]
Arrival of the substrate causes a change in the shape of the active site

8. Which inhibitor fits the enzyme’s active site? [1]

9. Competitive inhibitor

10. Explain how a non-competitive inhibitor affects the rate of an enzyme related reaction. [3]

11. Reduces rate of reaction
Fits into site on enzyme away from the active site
Attaches to tertiary structure of enzyme
Changes shape of the active site
Substrate can no longer bind with active site
Permanent

12. Why does increasing substrate concentration eventually have no effect on the rate of reaction? [2]

13. All active sites are occupied at all times
V max
All active sites are occupied at all times

14. What are coenzymes? [2]

15. Organic, non-protein molecule
(Often) carry chemical groups between enzymes
So enzyme controlled reactions can link together in sequence

16. What is a prosthetic group? [1]

17. A coenzyme that is a permanent part of an enzyme molecule.

18. What is it called when an enzyme and substrate fit together? [1]

19. Enzyme-substrate complex

20. How does lowering the pH of a solution affect an enzyme’s tertiary structure? [3]

21. Increased concentration of H+ ions means lower pH
Hydrogen ions are positive so are attracted to negatively charged molecules
Hydrogen bonds hold tertiary structure in place
Hydrogen ions react with hydrogen bonds which alters the tertiary structure

22. What is an enzyme inhibitor? [1]

23. A substance or molecule which slows down the rate of an enzyme controlled reaction.

24. Nucleic Acid PIG

25. Describe the structure of DNA

26. Contains bases adenine, guanine, cytosine and thymine
Polynucleotide
Contains bases adenine, guanine, cytosine and thymine
Double stranded

27. Name some differences between DNA and RNA

28. Has uracil instead of thymine Single stranded
RNA contains:
Ribose sugar
Has uracil instead of thymine
Single stranded
Exist in 3 forms: Mrna, tRNA and rRNA

29. Explain how DNA replicates

30. Double helix untwisted Hydrogen bonds broken DNA unzips
During interphase
Double helix untwisted
Hydrogen bonds broken
DNA unzips
Free DNA nucleotides hydrogen bonded onto exposed bases
Covalent bonds between phosphates and sugars forming backbone

31. Explain the term anti-parallel

32. The strands lie opposite each other, parallel, but run in opposite directions (the 3’ end goes with the 5’ end)

33. What is complementary base pairing

34. Complementary base pairs pair up C-G A-T or U in RNA
Hydrogen bonds link base pairs

35. What is a gene

36. A sequence of DNA nucleotides that codes for a polypeptide

37. Outline the role of DNA in protein synthesis

38. DNA provides the template strand for mRNA and determines the sequence of amino acids and therefore the structure of proteins

39. What is mRNA for?

40. Messenger RNA
Complementary to the DNA Strand
Contains Uracil instead of Thymine
Passes through the nuclear pore and attaches to a ribosome

41. What happens at the ribosome and what is the role of tRNA

42. tRNA brings amino acids to the ribosome in the right order according to the base sequence on the mRNA
Amino acids then joined together by peptide bonds to give a protein