1. Enzymes are biological which speed up the rate of a biochemical reaction. enzymes work inside cells; enzymes function outside cells.
2. A molecule of enzyme is composed of . It has an active site which is to the molecular structure of its substrate, like a lock and key.
3. To function efficiently an enzyme requires a suitable temperature, an appropriate pH and an adequate supply of .
4. An inhibitor is a substance that or halts the rate of an enzyme-controlled reaction. A inhibitor is affected by both concentration of inhibitor and concentration of substrate; a non-competitive inhibitor is affected by concentration of only.
5. Many enzymes require the presence of a to function properly; some enzymes are activated by other .
6. Each stage in a pathway is controlled by an enzyme. If a genetic fault occurs, an enzyme may be absent causing an inborn of metabolism.
7. In addition to carbon, hydrogen and oxygen, proteins always contain .
8. A protein consists of sub-units called which are joined together by bonds to form polypeptides.
9. A molecule of protein consists of chains arranged in parallel. It has a structural function.
10. A molecule of protein consists of polypeptide chains folded into a spherical shape. Some are structural in function; others act as enzymes, hormones or .
11. A molecule of protein consists of globular protein associated with a non- protein part.
12. DNA consists of two strands twisted into a double . Each strand is composed of . Each nucleotide consists of sugar, phosphate and one of four types of base (, thymine, , and cytosine).
13. Adenine always pairs with ; guanine always pairs with .
14. RNA consists of a single strand of nucleotides. is found in place of thymine; ribose replaces .
15. The bases along a DNA strand take the form of a molecular language called the genetic . Each of bases codes for a particular amino acid.
16. Messenger RNA (mRNA) is from a strand of DNA and carries this genetic message from the nucleus out into the cytoplasm. At a mRNA meets molecules of RNA(tRNA) each carrying a specific amino acid.
17. Protein synthesis occurs in ribosomes; mRNA's triplets of bases, called are "read" and matched to tRNA's . This enables peptide to form between adjacent amino acids.
18. Rough reticulum (ER) bears ribosomes on its surface; smooth ER lacks ribosomes.
19. Freshly synthesised protein is transported via the rough ER to the apparatus where it is processed and packaged into .
20. Some protein is out of the cell by vesicles moving towards and fusing with the plasma membrane.