Microbiology Chapter 7 Microbial Metabolism

Metabolism

pertains to all chem reactions and physical workings of the cell

Anabolism

any process that results in synthesis of cell molecules and structures

requires input of energy

stores energy (by building)

catabolism

breaks the bonds of larger molecules into smaller molecules

releases energy

catalysts

substance that alters the rate of reaction without being consumed or permanently changed by it

• enzymes

starts reaction

holoenzyme

enzyme complete with its apoenzyme and cofactors

apoenzyme

the protein part of an enzyme

rather than nonprotein or inorganic cofactors

cofactors

enzyme accessory

can be organic (Ex. coenzymes)

can be inorganic (ex. Fe²⁺, Mn²⁺, Zn²⁺ ions

coenzymes

type of cofactor

organic compoundsthat work in conjuction w an apoenzyme

gen func is to remove a chem group from one substate molecule and add it to another substate molecule

carry and transfer hydrogen atoms, electrons, carbon dioxide, and amino groups

many derived from vitamins

constitutive enzymes

present in bacterial cells in constant amounts

• regardless of presence of substrate

Ex) enzymes of the central catabolic pathways

add more substrate → no change in amount of enzyme

regulated enzymes

add more substrate -→ enzyme is induced

remove substrate → enzyme is repressed

extent of transcription or translation is influenced by changes in the environment

competitive inhibition

control process that relies on the ability of metabolic analogs to control microbial growth by successfully competing w necessary enzyme to halt the growth of bacterial cells

repression

genetic machinery responsible for synthesizing enzymes is automatically suppressed by a molecule of surplus end product

synthesis resumes when all end products are consumed

induction

enzymes appear (are induced) only when suitable substrates are present

synthesis halts when no more substrate is available

endergonic

require input of energy

exergonic

releases energy as it goes forward

oxidation

loss of electrons

reduction

gain of electrons

phosphorylate

process in which inorganic phosphate is added to a compound

active site

specific region on an enzyme where chem reaction takes place

substrate

specific molecule upon which an enzyme acts

exoenzymes

extracellular enzyme chiefly for hydrolysis of nutrient macromolecules that are otherwise impervious to the cell membrane

functions in saprobic decomposition of organic debris

can be a factor in invaiveness of pathogens

endoenzymes

functions inside cell where it is produced

aerobic respiration

respiration in which the final electron acceptor in the electron transport chain is O₂

pathways:

• glycolysis

• krebs cycle

• electron transport chain

anaerobic respiration

respiration in which the final electron acceptor in the electron transport chain is an inorganic molecule containing sulfate, nitrate, nitrite, carbonate, etc.

same 3 pathways as aerobic respiration

fermentation

incomplete oxidation of glucose

oxygen not required

organic compounds are terminal electron acceptors

glycolysis

breakdown (fermentation) of glucose

turns glucose into two copies of pyruvic acid or lactic acid

Kreb’s cycle

complete the process of primary catabolism

electron transport chain

hydrogen ions sequester outside

oxidative phosphorylation

Describe the difference between feed-back inhibition and substrate induction

Describe how environmental factors can affect enzyme activity

What is ATP? ADP? AMP? What is the significance of ATP?

What is the overall equation for Respiration?

What are the 4 metabolic pathways involved in respiration?

How many ATP is produced in each pathway?

How many NADH are produced in each pathway?

How many FADH₂ are made in each pathway?

How many ATP can be produced from each NADH that goes through the electron transport chain?

How may ATP can be produced from each FADH₂?

What is the end product of glycolysis that goes on into Kreb’s cycle or fermentation?

Name some products from Fermentation.

What molecule does fermentation start from?

Which pathways operate under which conditions? (aerobic and anaerobic)