Microbiology Ch 5

Metabolism - sum of all chemical reactions in an organism

Anabolic - requires energy - building - endergonic - dehydration synthesis

Catabolic - releases energy - breaking down - exergonic - hydrolysis

Enzymes are biological catalysts - they speed up reactions without increasing the temp or concentration of reactants (lover activation energy)

• normal chemical reactions : reactants → products
• you can increase rate of reaction by increasing temp or concentration of reactants (sometime impractical or impossible)

Apoprotein - protein part

cofactor - non-protein part

coenzyme - if cofactor is organic)

holoenzyme -whole enzyme

• apoprotein + cofactor (or coenzyme) = holoenzyme
• substrate - being acted upon - changed - fits in active site

active site - where substrate binds

allosteric site - where noncompeditive inhibitor binds

The enzyme/ substrate complex orients the substrate to increase the probability of the reaction occuring ( allows most effective collisions to occur)

substrate + enzyme → enzyme-substrate complex → products released + enzyme unchanged

number of products being produced per second

• NAD⁺ nicotinamide adenine dinucleotide
• NADP⁺ nicotinamide adenine dinucleotide phosphate
• CoA - coenzyme A

enzyme looses its tertiary structure due to unfavorable temp or pH (hydrogen and other non-covalent bonds are broken)

1. Temperature - best at 35-40 ^OC - too high = denaturation

2. pH - large changes cause denaturation

3. concentration of substrate - ↑ substrate = ↑ rate of reaction UNTIL saturation - after saturation is reached more substrate w WILL NOT affect rate of reaction

• 4. inhibitors
• a. compeditive - fill active site
• b. non-compeditive - fill allosteric stive
• c. feedback inhibition - high concentation of products feeds back to enzyne and fills allosteric site to stop reaction

Oxidize = remove e^- = remove H and add O

reduced = gain e^- = add H to it

redox reaction - oxidation-reduction reactions are always couples - when one substance is oxydized another is reduced so called a redox reaction

the purpose of redox reactions is to extract energy from nutrients (glucose) and couple it to ATP production.

Phosphorylation - adding a P (phosphate) to a chemical compound

ADP + P + Energy → ATP

• 1. Substrate level phosphorylation - direct transfer of P
• 2. Oxidative phosphorylation - use of electron carriers *the transport of e^{- from one carrier to another releases energy→ATP made (electron transport chain)}

• 3. photosynthetic phosphorylation - in photosynthetic cells - uses electron carriers
• light + ADP + P → ATP

Most organisms use carbs as primary energy source but all (carbs, lipids, proteins, nucleic acids) can be used to produce ATP.

• Aerobic path
• 1. glycolysis
• 2. krebs cycle
• 3. oxidative phosphorylation (electron transport chain)

• Anerobic path
• 1. Glycolysis
• 2. fermentation → ethanol or lactic acid

the oxidation of glucose to pyruvic acid, is usually the first stage in carbohydrate catabolism

glycolysis means splitting of sugar

also called the Embden-Meyerhof pathway

glucose + ATP → 2 pyruvic acid (3 carbon sugar) + 2 net ATP

• purpose is to make NADH
• also called the citric acid cycle
• pyruvic acid must be decorboxylation → CO₂ - removal of CO₂ → acetyl CoA

acetyl CoA → redox reactions to produce NADH

uses electron carriers - series of redox reactions

as e^- pass through chain, energy is released and coupled to ATP production called chemiosmosis

• 3 electron carriers:
• 1. flavoproteins
• 2. cytochromes
• 3. ubiquinones - coenzyme Q

Protein has C,H,O,N so can make carbohydrates, lipids, and protein + P = nucleic acid

C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O

nets 36 ATP (eukaryotes) and 38 (prokaryotes)

light + 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

• purpose if to make glucose + oxygen
• -it "fixes" the CO₂

• light reaction = photo → ATP + NADPH + O₂
• dark reaction = synthesis → glucose

energy that is created in the light reaction is used to make glucose in the dark reaction