Chapter 6 -  Metabolism

 

I. Metabolism - Sum total of all biochemical reactions  (Anabolic + Catabolic)
Two fundamental tasks -

 A.  Anabolic reactions -

1. Photosynthesis & Chemosynthesis-

2. First Law of Thermodynamics -

B. Catabolic Reactions -

            1. respiration - energy releasing metabolic pathway

                        a. Aerobic respiration

                        b. Anaerobic - Fermentation

                    2. Relationship between catabolism and anabolism

 

C. Role of Enzymes in metabolism

1. Description

a. protein with tertiary structure

b. Not used up

c. Catalytic - lowers energy of activation

d. Substrate specificity

e. Active site - 3D

f.  ase - ending

g. inhibition and rate of the reaction

        i. substrate concentration

        ii. allosteric -

        iii. competitive inhibition-

 

 

h. cofactors & coenzymes

        i. cofactors -

        ii. coenzymes -

 

2. Enzymes and ATP

a. ATP stores energy and makes it available

b. ATPase splits P

 II. Sample Metabolism - Catabolism of Glucose

A. Overall equation

 

Glucose + Oxygen catabolyzed to Carbon Dioxide and water with useable energy


B. Process

 

1. Glycolysis - splitting of glucose into 2-3 carbon compounds = pyruvic acid

a. occurs in cytoplasm is anaerobic

b. yields very little energy 2ATP

2. Krebs Cycle - TCA Tricarboxylic Cycle - pyruvic acid to CO2+H

a. occurs in mitochondria

b. requires many enzymes in cyclic pathway

c. requires coenzymes (NAD, FAD)

              3.  - Oxidative Phosphorylation - ETS         electron transport system

a. occurs in mitochondrial membranes or prokaryotic cell membranes (cytochromes)

b. chemiosmosis - oxygen receives H ion (carried by NAD and FAD from TCA and glycolysis) 2H + O = water

c. many ATP are produced

 

C. Other sources for energy

1. Polysaccharides

2. Fats

3. Proteins

4. Comparison of energy produced

 

III. Anaerobic respiration

A. not requiring oxygen

1. Nitrate test -see atlas

2. Sulfate - hydrogen sulfide

3. CO2 - methane

      

IV. Fermentation-

A. Large organic molecule accepts hydrogen

            B. Stops before TCA, not as efficient, end products are still "food" for other organisms

V. Anabolism

       A. Synthesis of  Carbohydrates - Photosynthesis

       B. Carbon fixation - recycling

       C. Protein Synthesis - Directed by DNA occurs in ribosomes

 

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Bakersfield College | Kern Community College District | Janet Fulks
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Date last updated 02/23/2005
ŠJanet Fulks