Microbial Metabolism

Enzymes

biological catalysts that speed up biochemical reactions.

Biological Catalysts

they increase the rate of biochemical reactions without being permanently changed by the reaction.

Enzymes Specificity

This allow an enzymes to recognize and act on its appropriate substrate.

enzyme-substrate complex

a form when a substrate binds to the active site of an enzyme

• Apoenzyme

• Cofactor

• Coenzyme

• Holoenzyme

enzyme components

apoenzyme

the protein portion of the enzyme. It is inactive by itself when a cofactor is required.

cofactor

the nonprotein component that helps activate the enzyme. Examples include iron, zinc, magnesium, and calcium ions.

coenzyme

an organic cofactor. The PDF gives FAD, NAD⁺, and NADP⁺ as examples of organic cofactors.

holoenzyme

the complete, active enzyme, formed when the apoenzyme combines with its cofactor.

• oxidoreductase

• transferase

• hydrolase

• lyase

• isomeras

• ligase

6 classes of enzymes

oxidoreductase

a class of enzyme where it catalyzes oxidation-reduction reactions

transferase

a class of enzyme where it transfers functional group such as amino, acetyl, or phosphate groups

hydrolase

a class of enzyme where it catalyzes hydrolysis, which involves addition of water

lyase

a class of enzyme where it removes groups of atoms without hydrolysis

issomeras

a class of enzyme where it causes the rearrangement of atoms within a molecule

ligase

a class of enzyme where it joins two molecules, usually energy from ATP

microbial metabolism

the sum of all chemical reactions within a living organism. These reactions can either release energy or require energy.

• catabolism

• anabolism

two major sides of metabolism

catabolism

The breakdown of complex organic compounds into simpler ones. degredative

• hydrolytic

• exergonic

catabolic reactions

exergonic

produce more energy than they consume

anabolism

The building of complex organic molecules from simpler ones. biosynthetic

• dehydration synthesis

• endergonic

anabolic reactions

carbohydrate catabolism

the breakdown of carbohydrate molecules to produce energy.

glucose

the most common carbohydrate energy source used by cells

• cellular respiration

• fermentation

2 general processes of carbohydrate catabolism

glycolysis

the oxidation of glucose to pyruvic acid, it is usually the first stage in carbohydrate catabolism. splitting of sugar

embden-meyerhof pathway

Glycolysis is also called the ________ pathway

• pentose phosphate pathway

• entner-doudoroff pathway

additional pathways to glycolysis

pentose phosphate pathway

(or hexose monophosphate shunt) operates simultaneously with glycolysis and provides a means for the breakdown of five-carbon sugars (pentoses) as well as glucose.

Entner-Doudoroff Pathway

produces 1 NADPH, 1 NADH, and 1 ATP per glucose.

cellular respiration

is defined as an ATP generating process in which molecules are oxidized and the final electron acceptor comes from outside the cell and is (almost always) an inorganic molecule.

• aerobe the final electron acceptor is Oxygen

• anaerobe the final electron acceptor is an inorganic molecule other than Oxygen or, rarely, an organic molecule

2 types of cellular respiration

krebs cycle

also called the tricarboxylic acid (TCA) cycle or citric acid cycle, is a series of biochemical reactions in which the large amount of potential chemical energy stored in acetyl CoA is released step by step

THE ELECTRON TRANSPORT CHAIN (SYSTEM)

CONSISTS OF A SEQUENCE OF CARRIER MOLECULES THAT ARE CAPABLE OF OXIDATION AND REDUCTION.

• flavoproteins

• cytochromes

• ubiquinones/coenzyme

3 classes of carrier molecules in Electron transport chain

anaerobic respiration

is ATP generating respiration that does not use oxygen as the final electron acceptor. Instead, another electron acceptor, such as nitrate or sulfate, is used

fermentation

• Does not require the use of the Krebs cycle or an electron transport chain

• Uses an organic molecule synthesized in the cell as the final electron acceptor

• lactic acid fermentation

• alcohol fermentation

2 types of fermentation

Lipid catabolism

is the breakdown of lipids into smaller molecules that can enter metabolic pathways and contribute to energy production.

lipids

A diverse group of organic compounds including fats, oils, waxes, and steroids.

lipase

•Microorganisms produce an enzyme called _____. _____breaks down fats into their two major components, glycerol and fatty acids.

glycerol

One of the components produced when fats are broken down; it can be converted to DHAP and enter glycolysis.

fatty acids

The other major components released from fats; they undergo β-oxidation.

b oxidation

The breakdown of fatty acids into two-carbon units that form acetyl-CoA.

acetyl-coa

A central metabolic intermediate that connects fatty acid breakdown to the Krebs cycle.

krebs cycle

A central metabolic pathway in which acetyl-CoA is further oxidized as part of energy production.

protein metabolism

the process by which microorganisms break down and use proteins as sources of carbon and energy.

proteases

break proteins into smaller peptides by breaking the peptide bonds that hold amino acids together.

peptidases

break peptides into smaller peptides or individual amino acids.

deamination

the removal of the amino group from an amino acid. The removed amino group is converted into ammonium ion (NH₄⁺), which may be excreted from the cell.

decarboxylation

removes the –COOH group

desulfurization

removes the –SH group.