5. Microbial Metabolism: Catabolism and Anabolism Overview

Metabolism

Biochemical reactions within an organism's cells.

-ultimate function is to reproduce the organism

what are the purposes of studying metabolism?

occurs in all living cells, used in microbiology to identify organisms, possible basis for treatment

Catabolism

Breakdown of large molecules into smaller ones. -releases energy (exergonic), stored as ATP

Anabolism

Synthesis of large molecules from small ones. -requires energy (endergonic)

Exergonic

Reactions that release energy, often stored as ATP.

Endergonic

Reactions that require energy input, supplied by ATP.

ATP

Adenosine triphosphate, energy currency of cells. (stored in phosphate bonds)

Oxidative Phosphorylation

ATP generation via electron transport chain.

redox

shuffling of electrons

redox reaction

A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction.

coenzyme

something that an enzyme needs in order to do its job, assists in enzyme-catalyzed reactions by carrying chemical groups, electrons, or atoms from one molecule to another.

phosphorylation

The metabolic process of introducing a phosphate group into an organic molecule.

substrate-level phosphorylation

transfers a phosphate group from a phosphorylated substrate (a molecule that already has a phosphate group attached) to ADP during glycolysis and Krebs.

substrate

the specific molecule that an enzyme acts on during a chemical reaction.

Photophosphorylation

Conversion of sunlight energy into ATP.

Oxidation

Loss of electrons or hydrogens in reactions.

Reduction

Gain of electrons or hydrogens in reactions.

OIL RIG//LEO says GER

Acronym for Oxidation Is Loss, Reduction Is Gain.

NAD+

Nicotinamide adenine dinucleotide, accepts electrons. (oxidized)

-two sets of: a nitrogenous base, phosphate, sugar

NADH

Reduced form of NAD+, carries electrons.

FAD

Flavine adenine dinucleotide, another electron carrier. (oxidized)

FADH2

Reduced form of FAD, carries electrons.

Cofactors

Non-protein molecules aiding enzyme function.

Active Site

Region on enzyme where substrates bind. (similar to the substrate shape)

Enzymes

Biological catalysts that speed up reactions.

Secondary Structure

Local folding patterns in proteins, like alpha-helices.

Tertiary Structure

Overall 3D shape of a single polypeptide.

Quaternary Structure

Complex of multiple polypeptides in proteins.

endoenzymes

(also called intracellular enzymes) are enzymes that function inside the cell where they are produced.

exoenzymes

enzymes secreted by a cell into the external environment to perform their function outside the cell

Glycolysis

First step in glucose metabolism, producing pyruvate.

Krebs Cycle

Series of reactions generating ATP and electron carriers.

Respiratory Chain

Final stage of cellular respiration, producing ATP.

Fermentation

an anaerobic metabolic process (does not require oxygen) in which microorganisms break down organic compounds (like glucose) to produce energy (ATP), along with byproducts like acids, alcohols, or gases.

what's the main purpose of fermentation?

To reoxidize the electron carriers to serve as coenzymes in glycolysis

Active enzymes

Enzymes that are currently catalyzing reactions.

Inactive enzymes

Enzymes that are not currently catalyzing reactions.

Substrate

Molecule upon which an enzyme acts.

Constitutive enzymes

Enzymes produced continuously at constant levels.

Regulated enzymes

act like traffic signals in metabolism — ensuring that pathways run only when needed, and not too fast or too slow.

down regulated enzymes

an enzyme whose activity or production is decreased in response to certain signals or conditions.(saving energy)

Activation energy

Energy required to initiate a chemical reaction.

Exergonic reactions

Reactions that release energy, typically catabolic. (hydrolysis)

Endergonic reactions

Reactions that consume energy, typically anabolic. (dehydration)

Competitive inhibition

Inhibition where substrate and inhibitor compete for active site.

inhibit

to block

Non-competitive inhibition

Inhibition where inhibitor binds elsewhere (not at site), altering enzyme function. (reducing or stopping)

Feedback inhibition

Process where end product inhibits an earlier step.

Optimum temperature

Temperature at which enzyme activity is highest.

Denatured enzymes

Enzymes that lose structure and functionality due to conditions.

Optimum pH

pH level at which enzyme activity peaks.

Substrate concentration

Amount of substrate available for enzyme reactions.

Aerobic respiration

Respiration using oxygen as the final electron acceptor.

Anaerobic respiration

Respiration using an inorganic molecule other than oxygen.

Glycosidic bond

Bond formed between two monosaccharides during dehydration.

Peptide bond

Bond formed between amino acids during protein synthesis.

Phosphoenolpyruvate

Final glycolysis intermediate before pyruvate.

Pyruvate

End product of glycolysis, enters Krebs cycle.

Net Yield of ATP

2 ATP produced from one glucose in glycolysis.

carbohydrate catabolism

the breakdown of carbohydrate molecules, especially (oxidize) glucose, to extract energy.

aerobic reaction

C6​H12​O6​+6O2​→6CO2​+6H2​O+ 38ATP

anaerobic reaction

6CO2​+6H2​O+ 38ATP----C6​H12​O6​+6O2​

cellular respiration

the process by which cells break down glucose (or other food molecules) to release energy in the form of ATP the cell's energy currency.

what are the 3 stages of cellular respiration?

1. synthesis of acetyl-CoA

2. krebs cycle

3. final series of redox reactions (electron transport chain)

Synthesis of Acetyl-CoA

Preparation step for Krebs cycle from pyruvate. (2acetyl-CoA go in, 2CO2 and 2 pyruvate come out)

Krebs Cycle in cellular respiration

second stage of cellular respiration, in which pyruvic acid is broken down into CO2 in a series of energy-extracting reactions

Electron Transport Chain

Final stage of cellular respiration, produces ATP via oxidative phosphorylation

oxidative phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.

holoenzyme

enzyme with its cofactor

kinase

transfers some phosphates and results in ATP and pyruvate

Total ATP from Glucose

Net 2 ATP from glycolysis, 4 ATP from Krebs.

Metabolic Products of Glucose

6 CO2 produced from one glucose during respiration.

intermediate

in-between molecule in a pathway

Electron Transport Chain (ETC)

a chain of steps where electrons are passed from one molecule to another, and each step releases energy, which is used to make ATP.

Proton Gradient

a difference in proton concentration across a membrane, and it's used by cells to make ATP. (oxidative)

-Potential energy created by protons across a membrane.

:Proton gradient → ATP synthase → ATP production (oxidative phosphorylation).

ATP Synthase

Enzyme that synthesizes ATP using proton gradient.

what is the final electron acceptor in the Electron Transport Chain (ETC).

molecular oxygen (forms water-reduction) "aerobic respiration"

where does aerobic respiration occur in prokaryotic and eukaryotic cells?

Occurs in the bacterial plasma membrane (in prokaryotes) and the mitochondria (in eukaryotes).

Theoretical ATP Yield

Maximum ATP produced during cellular respiration: 38 ATP.

Terminal Electron Acceptors

the final molecule that receives electrons at the end of the electron transport chain (ETC) during respiration.

carrier molecules

a protein that functions in transport of molecules across a membrane

what are the 4 categories of carrier molecules?

Flavoproteins

Ubiquinones

Metal-containing proteins

Cytochromes

Chemiosmosis

using a proton gradient to power ATP production through ATP synthase. (oxidative phosphorylation)

Flavoproteins

Carrier molecules in ETC containing flavin groups.

Ubiquinones

Mobile electron carriers in the electron transport chain.

Metal-containing Proteins

Proteins that facilitate electron transfer in ETC.

Cytochromes

Heme-containing proteins involved in electron transport.

Proton Pumping

Movement of protons out of the cell during ETC.

what's the order of best efficient to least in ATP production in cellular respiration?

aerobic, anaerobic, fermentation

O2 as Electron Acceptor

Best acceptor, yielding largest proton gradient.

Amphibolism

when a metabolic pathway can work in both directions, it can be used for breaking down molecules (catabolism) and for building up molecules (anabolism).

Inorganic Molecules as Acceptors

Less efficient than O2; examples include nitrate.

Gluconeogenesis

the process of making glucose from non-carbohydrate sources; literally means "new glucose formation."

Weak Proton Gradient

Generated during anaerobic respiration, yielding less ATP.

Strong Proton Gradient

Generated during aerobic respiration, yielding maximum ATP.

Metabolic Water Formation

Final product of electron transport involving O2.

ATP Production Mechanism

Protons entering ATP synthase drive ATP formation.

ATP Yield

Total of 36-38 ATP produced per glucose molecule.

Organic Electron Acceptor

Molecule like pyruvate accepting electrons in fermentation.

Facultative Anaerobes

Organisms that can switch between aerobic and anaerobic metabolism.