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PIG - enzymes

PIG - enzymes. What are enzymes? [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. What is activation energy? [2]. Energy ‘barrier’

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PIG - enzymes

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

  27. Name some differences between DNA and RNA

  28. 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. 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

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