Chapter 8

Metabolism

All the chemical reactions of the cell, including making proteins, DNA, RNA, and new cells.

Catabolic Reactions

Reactions that involve breaking down large molecules into smaller subunits.

Anabolic Reactions

Reactions that involve building up or synthesizing molecules.

Aerobic Reactions

Reactions that require oxygen, although they don't necessarily use it directly.

Anaerobic Reactions

Reactions that do not require oxygen, even if oxygen is present.

Redox Reactions

Reactions that involve the transfer of electrons.

Reduction

A process where a compound or atom receives electrons, becoming more negatively charged.

Oxidation

A process where a compound or atom gives away electrons, becoming less negatively charged or more positively charged.

Chemoautotrophs

Organisms that obtain energy from inorganic chemical compounds.

Chemoheterotrophs

Organisms that obtain energy from organic compounds.

Photoautotrophs

Organisms that obtain energy from light and carbon from inorganic sources.

Photoheterotrophs

Organisms that obtain energy from light and carbon from organic sources.

Enzymes

Proteins that catalyze reactions by acting on substrates to create products.

Substrates

Chemical reactants that an enzyme acts upon.

Active Site

The location on the enzyme where substrates bind.

Conformation Change

A change in shape that occurs when a substrate binds to the active site of an enzyme.

Cofactors

Helper molecules that make an enzyme functional.

Coenzymes

Organic cofactors that assist enzymes in catalyzing reactions.

Apoenzyme

An enzyme without its cofactor or coenzyme (incomplete enzyme).

Holoenzyme

An enzyme with its necessary cofactor or coenzyme (complete enzyme).

Competitive Inhibition

A process where an inhibitor binds to the active site of an enzyme, preventing substrate binding.

Non-competitive Inhibition

A process where an inhibitor binds to an allosteric site, altering the shape of the enzyme.

Allosteric Activation

A regulatory molecule binds to an allosteric site to create a functional active site.

Feedback Inhibition

A process where the end product of a metabolic pathway inhibits an earlier enzyme in the pathway.

Glycolysis

The process converting glucose into energy-rich products, primarily ATP and NADH.

Krebs Cycle

A series of reactions producing NADH, FADH2, and ATP from acetyl CoA.

Electron Transport Chain (ETS)

The final aerobic step of respiration that generates ATP using oxygen as the final electron acceptor.

Anaerobic Catabolism

A metabolic process that occurs in the absence of oxygen, using alternate electron acceptors.

Photosynthesis

The process of converting light energy into chemical energy in the form of glucose.

Bioremediation

The use of microbes to break down pollutants in the environment.

NAD+ (Nicotinamide Adenine Dinucleotide)

An electron carrier that accepts electrons during metabolic reactions.

NADP+ (Nicotinamide Adenine Dinucleotide Phosphate)

Similar to NAD+, used primarily in photosynthesis.

FAD (Flavin Adenine Dinucleotide)

An electron carrier involved in the Krebs cycle.

ATP (Adenosine Triphosphate)

The primary energy currency of cells.

GTP (Guanosine Triphosphate)

A nucleotide similar to ATP, functioning in energy transfer.

Substrate-level Phosphorylation

A method of forming ATP by transferring a phosphate group from a substrate to ADP.

Fermentation

An anaerobic process that converts sugars into acids, gases, or alcohol.

Citric Acid Cycle

Another name for the Krebs cycle, where acetyl CoA is metabolized.

Proton Gradient

A difference in proton concentration across a membrane, used for ATP synthesis.

ATP Synthase

An enzyme that produces ATP using the proton gradient created during electron transport.

Calvin Cycle

The part of photosynthesis that synthesizes glucose from carbon dioxide using ATP and NADPH.

Oxaloacetic Acid

A four-carbon compound that combines with acetyl CoA to initiate the Krebs cycle.

Pyruvic Acid

A three-carbon compound produced by glycolysis that enters the Krebs cycle.

Acetyl CoA

A two-carbon molecule that enters the Krebs cycle after the decarboxylation of pyruvic acid.

Light Reactions

The phase of photosynthesis where water is split to generate ATP and NADPH.

Dark Reactions

Reactions in photosynthesis that do not require light directly, such as the Calvin Cycle.

Chlorophyll

The green pigment in plants that absorbs light energy for photosynthesis.

Hydrogen Ion Gradient

The concentration difference of hydrogen ions that aids in ATP synthesis during respiration.

CO2 Fixation

The conversion of atmospheric carbon dioxide into organic compounds in the Calvin cycle.

Light-Harvesting Complex

A group of proteins and pigments that capture light energy in photosystems.

Reduction Phase (Calvin Cycle)

The part of the Calvin cycle where ATP and NADPH are used to convert 3-PGA into G3P.

RuBisCO

An enzyme that catalyzes the first step of carbon fixation in the Calvin cycle.

3-PGA (3-Phosphoglycerate)

A three-carbon compound formed in the first step of the Calvin cycle.

G3P (Glyceraldehyde-3-phosphate)

A three-carbon sugar produced in the Calvin cycle that can be converted into glucose.

Carbon Sink

An ecosystem or habitat that absorbs more carbon dioxide than it releases.

Dynamic Homeostasis

The state of steady conditions maintained by physiological processes.

Induced Fit Model

A model of enzyme action in which the enzyme changes shape to accommodate the substrate.

Hydrolysis

A chemical reaction involving the breaking down of a compound by water.

Phosphorylation

The addition of a phosphate group to a molecule, often related to energy transfer.

Cyclic Photophosphorylation

A process in photosynthesis where ATP is generated through an electron transport chain without NADPH production.

Chemiosmosis

The process by which ATP is generated in mitochondria and chloroplasts using the energy of a proton gradient.

Anaerobic Respiration

A type of respiration that occurs in the absence of oxygen, using alternative electron acceptors.

Metabolic Pathways

A series of chemical reactions occurring within a cell that lead to the conversion of substrates into products.

Energy Coupling

The use of energy released from one reaction to drive another reaction.

Glycogen

A storage form of glucose found primarily in the liver and muscles.

Acidosis

A condition in which the blood becomes too acidic due to excess hydrogen ions.

Fermentative Organisms

Organisms that can perform fermentation to obtain energy in the absence of oxygen.

Deamination

The removal of an amino group from an amino acid or other compound.

Biological Nitrogen Fixation

The process by which nitrogen in the atmosphere is converted into ammonia by certain bacteria.

Photosystem I

A protein and pigment complex that captures photons during photosynthesis.

Photosystem II

The first protein and pigment complex in the light reactions of photosynthesis.

Fermentation Pathways

Different metabolic routes that can be taken when glucose is broken down anaerobically.

Phosphofructokinase

An important regulatory enzyme in glycolysis that controls the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate.

NADH Oxidase

An enzyme that catalyzes the oxidation of NADH in the electron transport chain.

Decarboxylation

The removal of a carboxyl group from a molecule, releasing carbon dioxide.

Lipid Metabolism

The processes through which lipids (fats) are synthesized and degraded.

Protein Metabolism

The processes involved in the synthesis and degradation of proteins.

Fermentative Feedback Mechanism

A regulatory mechanism in anaerobic pathways to control product formation.

Respiratory Chain

A series of electron carriers involved in oxidative phosphorylation.

Substrate-level generating ATP

The process of ATP production that involves the transfer of phosphate groups to ADP.

Enzyme kinetics

The study of the rates at which enzyme-catalyzed reactions occur.

Chemical Equilibrium

A state in a reversible reaction where the rates of forward and reverse reactions equal each other.

Oligomerization

The process of combining monomers to form oligomers, particularly in protein structure.

Primary Metabolites

Compounds produced during the growth phase of microorganisms.

Secondary Metabolites

Compounds produced by organisms as part of their defense or survival strategy.

Electromotive Force

The voltage generated by an electrochemical cell or a proton gradient in biological membranes.

Microbial Fuel Cells

Devices that convert chemical energy to electrical energy through microbial metabolism.

Ammonia Assimilation

The process by which microorganisms incorporate ammonia into organic compounds.

Krebs Cycle

Also known as the Citric Acid Cycle or TCA Cycle, it begins with pyruvic acid and consists of the feeder chain and the cycle itself.

Pyruvic Acid

A three-carbon compound that enters the Krebs cycle after glycolysis.

Acetyl CoA

A two-carbon molecule formed from acetic acid and coenzyme A, crucial for the Krebs cycle.

Oxaloacetic Acid

A four-carbon compound that combines with Acetyl CoA to form citric acid.

Citric Acid

A six-carbon compound formed when Acetyl CoA combines with oxaloacetic acid.

Carbon Dioxide (CO2) Release

Occurs during the conversion of citric acid to a five-carbon compound and again to a four-carbon compound.

2 NADH and 1 ATP Formation

Generated during the conversion of citric acid and other intermediates in the Krebs cycle.

FADH2

Produced during the Krebs cycle when FAD takes electrons and hydrogens from a four-carbon compound.

Electron Transport Chain

A series of proteins in the inner mitochondrial membrane involved in transferring electrons and creating a proton gradient.

NADH and FADH2 Donation

NADH and FADH2 donate electrons to the electron transport chain to facilitate ATP synthesis.

Hydrogen Ion Gradient

Created when hydrogen ions are pumped into the periplasmic space during electron transfer, driving ATP synthesis.

Oxygen's Role in ETS

Serves as the final electron acceptor, reacting with electrons and protons to form water.