20th Lecture: 5/12/14

Topics: Microbial Metabolism ( part 1)

Notes:
1) Catabolic ractions
- breakdown of sugars into carbon dioxide and water
-release energy ( exergonic )
- Degradative
-hydrolytic reaction

2) Anabolic reaction
- gain energy from catabolic reaction
- use energy in the form of ATP ( endergonic)
- biosynthesis
- dehydration reaction
- the formation of proteins from amino acids

3) A metabolic pathway is a sequence of enzymatically catalysed chemical reactions in a cell.
4) Enzymes act as biological catalysts that speed up the reaction by reduce the activation energy.
5) Enzymes are very specific and tertiary structure determines the activity. There are few classes of enzyme with their function:

• oxidoreductase - oxidation and reduction reaction
• transferase - transfer of functional group
• hydrolase - hydrolysis
• lyase - removal of groups of atoms without hydrolysis
• isomerase - rearrangement of atoms within molecules
• ligase - joining of two molecules

6) Apoenzyme is the protein portion in an enzyme. Cofactor is the nonprotein component in an enzyme. Holoenzyme is an active enzyme which consists of apoenzyme and cofactor.
7) The active site of an enzyme has two basic components : catalytic site and binding site.
8) Catalytic site is where the reaction actually occurs and the binding site is the area that holds substrate in proper place.
9) The factors that influence enzymatic activity are temperature, pH, concentration and inhibitors.
10) Enzyme will denature at 50 degree celcius and the optimum pH for enzyme is pH 4 to 6. The rate of reaction increase as the concentration of substrate increase.
11) Feedback inhibition is a metabolic pathway where the end product act as inhibitor and inhibits the reaction.
12) Conpetitive inhibition is where the inhibitor and substrate compete for the active site. Noncompetitive inhibition is where the inhibitor bind to the allosteric site and altered the active site.
13) There are 2 aspects of energy production: concept of oxidation-reduction and mechanisms of ATP generation.
14) Redox reactions is the utilization of chemical energy in living organisms. Oxidation is the removal of one or more electrons from a substrate. Reduction is the gain of one or more electrons.
15) Cell used oxidation-reduction in catabolism to extract energy from nutrient molecules.
16) ATP (Adenosine Triphosphate) is prime energy carrier. ADP (Phosphoanhydrides) have free energies for hydralysis,
17) Energy released during certain metabolic reactions can be trapped to form ATP from ADP and phosphate group.
18) The removal of third phosphate group will release unstable energy.
19) Phosphorylation is the addition of phosphate group to a chemical compound. The are three organisms of phosphorylation to generate ATP from ADP:

• Substrate level Phosphorylation

- A high energy phosphate group from an intermediate in catabolism is added to ADP to form ATP.

• Oxidative Phosphorylation

- occurs in plasma membrane of prokaryotes and the inner mitochondrial membrane of eukaryotes
- Energy released as electrons are passed through a series of electrons carrier and finally to oxygen. Therefore, oxygen is the last oxygen carrier.

• Photophosphorylation

- occurs in chlorophylls
- energy from light is trapped by chlorophyll and electrons are passed through a series of electrons acceptors and the electron transfer releases energy for the synthesis of ATP. Electron transport chain is involved.

Activities: Find out 30 terms and definition which are related to this topic. Each group have to prepare 6 quizzes which are related to this topic.

My own explorace:
1) Precursors are compound that participates in the chemical reaction that produces another compound.
2) The term 'organo' refers to compound that consists or organic compound while the term 'litho' refers to compound that consists of inorganic compound.
3) The optimum temperature and optimum pH for the cow rumen enzyme is 39 degree celcius and pH 6.5.

Reflection:
I felt like " Oh, No!" when studied this topic because I knew I have to memorise again all those cycles which I have learnt in Form 6. It reminds me about my hard time to memorise all those cycles in Form 6. Haha..But luckily I have learnt all those cycle in Form 6, I think I can easily understand the steps of these cycles because we have been exposed to these cycles in Form 6.