Microbiology: Chapter 6 - Microbial Metabolism: Fueling Cell Growth

Metabolism

Sum total of all the enzymatic chemical reactions in a cell

Anabolism (Biosynthesis)

set of chemical reactions that requires the energy (ATP) to assemble compounds

Catabolism

the set of chemical reactions that degrade (breakdown) compounds, releasing their energy

Energy

the capacity to do work; can exist as either potential (stored) or kinetic (motion)

Exergonic Reactions

a chemical reaction that releases energy because the starting compounds have more free energy than the products

Endergonic Reactions

a chemical reaction that requires a net input of energy because the products have more free energy than the starting compounds

Metabolic Pathways

series of sequential reactions that converts starting compound to an end product; allows cells to better regulate reactions

Enzyme

a molecule, usually a protein, with complex 3-D shape that functions as an organic catalyst, speeding up reaction rates; lowers the activation energy

Substrate

Substance on which an enzyme acts to form products; surface on which an organism will grow; each enzyme only works with one of these due to its shape

- High Temperature

- Changes in pH

- Inhibition

What factors effect enzyme function?

High temperature

Changes in pH

What factors can denature an enzyme?

Cofactor

non-protein portion of an enzyme required for some enzymes to function; (ex: coenzymes)

Coenzyme

Non-protein organic compound that assists some enzymes, acting as a loosely bound carrier of small molecules or electrons

Competitive Inhibition

inhibitor binds to active sight of enzyme, blocking access of the substrate to that site; does not denature enzyme

Noncompetitive Inhibition

inhibitor binds to site on the enzyme other than the active site (allosteric site), changing the shape of the enzyme; does not denature enzyme; (ex- feedback inhibition: E. coli and production of isoleucine)

ATP

Energy in an organic compound is converted to _____.

Electrons

Energy production involves the transfer of ________.

Oxidation-reduction Reactions

Chemical reactions in which one or more electrons is (are) transferred from one molecule, atom, or ion to another; one substance in the reaction becomes reduced and the other becomes oxidized

Oxidized

refers to loss of electrons

Reduced

refers to the gain of electrons

Glucose

What is a common energy source for cells?

Aerobic

uses oxygen; involved in cellular respiration

- Glycolysis

- Transition Step (preparatory reaction)

- Krebs Cycle

- Electron Transport Chain

What are the 4 stages of cellular respiration?

Anaerobic

without oxygen; involved in fermentation

NAD+/NADH

Abbreviations for the oxidized/reduced forms of nicotinamide adenine dinucleotide, an electron carrier

NADP+/NADPH

Abbreviations for the oxidized/reduced forms of nicotinamide adenine dinucleotide phosphate, an electron carrier

FAD/FADH2

Abbreviations for the oxidized/reduced forms of flavin adenine dinucleotide, an electron carrier

Glycolysis

Metabolic pathway that oxidizes glucose to pyruvate, generating ATP and reducing power;

- produces 2 pyruvate

- occurs regardless of oxygen

- glucose is split into two

- produces 2 ATP

Transition Step

also referred to as preparatory reaction; produces...

- 2 pyruvate

- 2 acetyl coenzyme A

- 2 NADH

Krebs Cycle

In this stage...

- acetyl coenzyme A enters to become citrate

- 6 NADH and 2 FADH2 are produced

- 4CO2 is produced

- 2 ATP produced

Electron Transport Chain

a series of membrane-embedded electron carriers; NADH and FADH2 transfer their electrons; produces 32-34 ATP

mitochondria; plasma membrane

The electron transport chain occurs in the _____ of eukaryotes and the _______ of bacteria.

Chemiosmosis

A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme;

- 32-34 ATP produced

- oxidative phosphorylation

- oxygen is the final electron acceptor (6H2O)

Fermentation

- Occurs without oxygen

- Glycolysis occurs as normal

- NADH dumps it's electrons back on pyruvate or a derivative (this recycles the NAD; produces various end-products)

- Net gain of 2 ATP