1. Biochemistry Important cellular chemicals.

2. Protein Proteins are made of chains of amino acids. There are 20 amino acids. 12 of these are called essential amino acids because we don’t have the ability to synthesize them inside our bodies. Protein have various functions: –Enzymes that catalyze (speed up or slow down) chemical reactions. –Structural proteins, like collegen, elastin, etc. –Hormones, chemical signals like insulin. –In rare cases as a source of energy.

3. Carbohydrates These are made of sugars Sugars are mostly used as an energy source but can also have structural function (like in cellulose or chitin) or a signaling function as in glycoproteins. Complex carbohydrates are chains of simple sugars e.g. starch, cellulose (dietary fibre). They are know are polysaccharides. Disaccharides are made of two simple sugars joined together e.g. Maltose Monosaccharides are simple sugars on their own e.g. glucose.

4. Nucleic Acids Two types: DNA or Deoxyribonucleic Acid and RNA or Ribonucleic Acid. DNA carries genetic information it sort like the cell’s hard drive. Messenger RNA transfers information from the DNA to the protein making machinery. The three types of RNA are messenger RNA or mRNA, transfer RNA or tRNA and ribosomal RNA or rRNA. DNA is made of chains of nucleotides, they are made of a sugar (deoxyribose), nitrogenous base (adenine, guanine, thymine and cytosine) and phosphate group. RNA is made of chains of nucleotides, they are made of a sugar (ribose), nitrogenous base (adenine, guanine, uracil and cytosine) and a phosphate group.

5. Lipids: Fats and Oils Functions: Make up cell membranes,, insulation, energy source, hormones. Fats are solid – made from saturated fats. Oils are liquid – made from unsaturated fats.

6. Metabolism The sum total of all an organism’s chemical processes. This includes –Anabolic pathways AND –Catabolic Pathways

7. Anabolic Pathways Are pathways where chemicals are synthesized from simpler chemicals. Memory device: Anabolic Steroids help build up muscles  Anabolic pathways help build up chemicals. Examples include: –building proteins from amino acids, –making complex carbohydrates from simple sugars –Making DNA from nucleotides

8. Catabolic Pathways Breaking down chemicals into simpler ones. Memory device: When things all fall apart or break down it is a CATASTROPHE Examples include: –The digestive system breaking proteins in amino acids, lipids into fatty acids an glycol, Starch in glucose and nucleic acids in nucleotides.

9. Enzymes Help both catalyze (speed up or slow down) anabolic and catabolic pathways. In other words they are responsible for most of our metabolism. Are made out of protein. Work best under small range of environmental conditions such as temperature and pH (acidity/alkalinity). This is called its optimum range. This is part of the reason your body temperature is kept within such a small temperature range. Each enzyme is specific to a particular chemical/s, the chemical/s it works on is/are called a SUBSTRATE. There is a groove on an enzyme that actually interacts with the substrate called an ACTIVE SITE. The active site fits the substrate like a lock and a key.

10. Question: Is this an Anabolic of catabolic reaction?

11. Enzymes continued The reason why enzymes have an optimum range is that the shape of proteins changes depending on their environment. If the shape of their active sites changes it will affect their ability to work. When a protein or enzyme changes from its working shape to a non-working shape it is said to be denatured. For example when you cook an egg it is denatured which why it goes hard and the egg white goes from clear to white.

12. Notice how enzymes work best at a fairly limited range of temperatures and pHs

13. Enzymes An important thing to note about enzymes, or any catalyst is that they are NOT used up during the reaction. Therefore the same enzyme can catalyse the same reaction over and over again. As a consequence to stop a particular reaction any enzyme will need to be deactivated. This is where feedback mechanisms come in.

14. Feedback mechanisms These mechanism apply to other biological processes not just chemical pathways. They help us maintain homeostasis. Sometimes the products or by-products of a chemical pathway will turn the pathway on or off or make it go faster or slower.. The two main types of feedback mechanism are: –Negative feedback: this is where the products or by- products turn off the pathway or slows it down. –Positive feedback: the products or by-products signals the pathways to continue or speed up. Negative feedback is far more common than positive feedback.

15. Notice how chemical pathways usually consist of several enzymes. This allows for more points of control – sort like how an airport might have several security points.

16. Enzyme inhibition and feedback In addition to its active site and enzyme may have an allosteric site. An allosteric site fits a specific inhibitor molecule. When this inhibitor binds it changes the shape of the active site and therefore deactivates the enzyme. The inhibitor is often a product or by- product of the enzymes chemical pathway.

17. Competitive and Non Competitive inhibition Inhibition via allosteric sites is called non- competitive inhibition because it doesn’t compete with the substrate for the active site. Competitive inhibition is therefore when a substance competes for a active site on and enzyme. Competitive inhibitors fit into the active site but do not react. The therefore block the reaction site.

18. Question What affect will increasing the amount of substrate have on enzyme activity in the case of: – a competitive inhibitor? –A non-competitive inhibitor?

19. Answer Competitive: Increasing the amount of substrate will increase the enzyme activity as it will overwhelm the competitive inhibitor Non-competitive: Increasing the amount of substrate will have no affect enzyme activity as the active site will still be the wrong shape fit the substrate.

20. Fun facts Poisons are often enzyme inhibitors. Cyanide, for example, inhibits an enzyme involved in cellular respiration. Heavy metals like mercury inhibit enzymes by binding to enzymes and changing their shape like a non-competitive inhibitor.

21. Activating enzymes Enzyme may produced in an inactive form. Some enzymes are activated by the substrate itself. Some are activated by allosteric activators (the functional opposite of non-competitive inhibitors) Some need co-factors or co-enzymes. The former is a inorganic thing like a metal atom, the latter an organic molecule like vitamin. In the case of the enzyme in our stomach it is activated by Hydrochloric Acid. The inactive form pepsinogen in converted to pepsin. This probably prevents it from digesting the cells that make it.

22. Naming conventions Enzyme names are often derived from the name of the substrate with the suffix – ase. Example: The disaccharide Maltose is catabolised into glucose by Maltase. Other enzymes are named for their function. Example: DNA polymerase, which helps replicate DNA.

24. Terminology Initial Substrate: The chemical that is at the start of a chemical pathway and is eventually altered to become the final product. Product: they chemical or chemicals produced at the end of a pathway. By-product: and intermediate chemical or a waste product produced by a pathway. Intermediate metabolite: A by-product that is eventually altered to become the final product.

25. Terminology continued Competitive inhibitor: competes with a substrate for the active site. Non-competitive inhibitor: binds to and allosteric site and changes the shapes of the active site preventing it binding with the substrate.