Exam 3 Micro Lecture

Microbial Nutrition — Microbial growth

Increase in the number of microbial cells, not the size of individual cells.

Microbial Nutrition — Media

Materials containing nutrients used to grow microorganisms.

Microbial Nutrition — Broth

Liquid growth medium.

Microbial Nutrition — Agar

Substance used to solidify culture media.

Microbial Nutrition — Environmental growth requirements

Physical conditions such as temperature, pH, and osmotic pressure.

Microbial Nutrition — Chemical growth requirements

Nutrients and chemical elements needed for cell structures and metabolism.

Microbial Nutrition — Psychrophile

Microorganism that grows best at cold temperatures, typically 15°C or lower.

Microbial Nutrition — Psychrotroph

Microorganism that can grow at refrigerator temperatures; important in food spoilage.

Microbial Nutrition — Mesophile

Microorganism that grows best at moderate temperatures; includes many human pathogens.

Microbial Nutrition — Thermophile

Microorganism that grows best at high temperatures.

Microbial Nutrition — Hyperthermophile

Microorganism with optimal growth at extremely high temperatures, often 80°C or more.

Microbial Nutrition — Minimum growth temperature

Lowest temperature at which a microorganism can grow.

Microbial Nutrition — Optimum growth temperature

Temperature at which a microorganism grows fastest.

Microbial Nutrition — Maximum growth temperature

Highest temperature at which a microorganism can grow.

Microbial Nutrition — Acidophile

Microorganism that prefers acidic environments.

Microbial Nutrition — Neutrophile

Microorganism that prefers near-neutral pH.

Microbial Nutrition — Alkaliphile

Microorganism that prefers alkaline environments.

Microbial Nutrition — Osmotic pressure

Effect of solute differences on water movement across cell membranes.

Microbial Nutrition — Hypertonic solution

Higher solute concentration outside the cell; water leaves the cell.

Microbial Nutrition — Hypotonic solution

Lower solute concentration outside the cell; water enters the cell.

Microbial Nutrition — Isotonic solution

Equal effective solute concentration; no net water movement.

Microbial Nutrition — Plasmolysis

Cell membrane pulls away from cell wall as the cell loses water.

Microbial Nutrition — Halophile

Organism that requires high salt levels for growth.

Microbial Nutrition — Carbon requirement

Carbon is needed to build organic molecules including carbohydrates, proteins, lipids, and nucleic acids.

Microbial Nutrition — Nitrogen requirement

Nitrogen is needed for proteins and nucleic acids.

Microbial Nutrition — Sulfur requirement

Sulfur is needed for certain amino acids and proteins.

Microbial Nutrition — Phosphorus requirement

Phosphorus is needed for ATP, DNA, RNA, and phospholipids.

Microbial Nutrition — Trace elements

Elements needed in tiny quantities, often as enzyme helpers, such as iron, zinc, and copper.

Microbial Nutrition — Obligate aerobe

Must have oxygen to grow.

Microbial Nutrition — Obligate anaerobe

Cannot tolerate oxygen under ordinary growth conditions.

Microbial Nutrition — Facultative anaerobe

Can grow with or without oxygen, usually better with it.

Microbial Nutrition — Aerotolerant anaerobe

Does not use oxygen for energy but can tolerate its presence.

Microbial Nutrition — Microaerophile

Requires oxygen at lower-than-atmospheric concentrations.

Microbial Nutrition — Phototroph

Uses light as an energy source.

Microbial Nutrition — Chemotroph

Uses chemicals as an energy source.

Microbial Nutrition — Autotroph

Uses carbon dioxide as its primary carbon source.

Microbial Nutrition — Heterotroph

Uses organic compounds as its carbon source.

Microbial Nutrition — Photoautotroph

Obtains energy from light and carbon from CO₂.

Microbial Nutrition — Chemoheterotroph

Obtains energy from chemicals and carbon from organic compounds.

Metabolism — Metabolism

Sum of all chemical reactions inside a cell.

Metabolism — Catabolism

Breakdown of complex molecules into simpler ones, releasing usable energy.

Metabolism — Anabolism

Builds complex molecules from simpler ones, requiring energy.

Metabolism — Metabolic pathway

Series of enzyme-catalyzed reactions; product of one reaction becomes substrate for the next.

Metabolism — Enzyme

Biological catalyst, generally a protein, that lowers activation energy.

Metabolism — Substrate

Molecule on which an enzyme acts.

Metabolism — Active site

Part of an enzyme where its substrate binds.

Metabolism — Enzyme specificity

Enzymes generally catalyze particular reactions with specific substrates.

Metabolism — Constitutive enzyme

Enzyme produced relatively continuously.

Metabolism — Regulated enzyme

Enzyme whose production or activity changes according to cell needs.

Metabolism — Denaturation

Loss of an enzyme's functional shape, often because of excessive heat or extreme pH.

Metabolism — Competitive inhibition

An inhibitor competes with substrate at the enzyme active site.

Metabolism — Noncompetitive inhibition

An inhibitor binds somewhere other than the active site and reduces enzyme function.

Metabolism — Feedback inhibition

An end product slows an earlier enzyme in its metabolic pathway.

Metabolism — Factors affecting enzyme activity

Temperature, pH, substrate concentration, enzyme concentration, and inhibitors.

Metabolism — Oxidation

Loss of electrons (OIL).

Metabolism — Reduction

Gain of electrons (RIG).

Metabolism — Redox reaction

Paired oxidation and reduction involving electron transfer.

Metabolism — NAD⁺

Electron carrier that accepts electrons to become NADH.

Metabolism — FAD

Electron carrier that accepts electrons to become FADH₂.

Metabolism — Glycolysis

Breaks one glucose into two pyruvate; occurs in cytoplasm and nets 2 ATP plus 2 NADH.

Metabolism — Glycolysis location

Cytoplasm in both prokaryotic and eukaryotic cells.

Metabolism — Net ATP from glycolysis

2 ATP per glucose.

Metabolism — Pyruvate oxidation / intermediate step

Converts 2 pyruvate to 2 acetyl-CoA, releasing 2 CO₂ and producing 2 NADH per glucose.

Metabolism — Krebs cycle

Oxidizes acetyl-CoA and produces CO₂, NADH, FADH₂, and a small amount of ATP/GTP.

Metabolism — Krebs cycle products per glucose

Typically 4 CO₂, 6 NADH, 2 FADH₂, and 2 ATP (or GTP).

Metabolism — Electron transport chain (ETC)

Membrane-bound electron carriers transfer electrons and help generate a proton gradient.

Metabolism — Final electron acceptor in aerobic respiration

Oxygen; water forms when oxygen accepts electrons and hydrogen.

Metabolism — Chemiosmosis

H⁺ flow down a proton gradient through ATP synthase powers ATP production.

Metabolism — ATP synthase

Membrane enzyme that makes ATP using energy from the proton gradient.

Metabolism — ETC location in eukaryotes

Inner mitochondrial membrane.

Metabolism — ETC location in prokaryotes

Plasma membrane.

Metabolism — Krebs cycle location in eukaryotes

Mitochondrial matrix.

Metabolism — Krebs cycle location in prokaryotes

Cytoplasm.

Metabolism — Fermentation

Regenerates NAD⁺ so glycolysis can continue without using a respiratory ETC.

Metabolism — ATP from fermentation

Net 2 ATP per glucose from glycolysis.

Metabolism — Lactic acid fermentation

Regenerates NAD⁺ while producing lactate.

Metabolism — Alcohol fermentation

Regenerates NAD⁺ while producing ethanol and CO₂.

Metabolism — Fermentation vs anaerobic respiration

Fermentation does not use an ETC; anaerobic respiration uses an ETC with a nonoxygen final electron acceptor.

Microbial Control — Microbial control

Killing, removing, or limiting microorganisms.

Microbial Control — Sterilization

Destroys or removes all microbial life, including bacterial endospores.

Microbial Control — Disinfection

Eliminates many pathogenic organisms on inanimate objects but may not destroy endospores.

Microbial Control — Antisepsis

Reduction of microorganisms on living tissue.

Microbial Control — Sanitization

Reduction of microbial numbers to accepted public-health levels.

Microbial Control — Degerming

Physical removal of microbes, such as through handwashing.

Microbial Control — Bactericidal

Kills bacteria.

Microbial Control — Bacteriostatic

Inhibits bacterial growth without necessarily killing the cells.

Microbial Control — Asepsis

Procedures that prevent contamination.

Microbial Control — Highly resistant microbial structures

Bacterial endospores are much more resistant than most vegetative bacteria.

Microbial Control — Microbial death rate

Often logarithmic: a consistent fraction of survivors dies during each interval.

Microbial Control — Factors affecting disinfection

Microbial number/type, temperature, exposure time, agent strength, organic matter, and biofilms.

Microbial Control — Autoclave

Uses pressurized steam for sterilization and can destroy endospores.

Microbial Control — Common autoclave conditions

Often taught as 121°C at about 15 psi gauge pressure for at least 15 minutes; correct time depends on load.

Microbial Control — Boiling

Kills many vegetative microbes but is not reliable sterilization.

Microbial Control — Pasteurization

Controlled heating that reduces pathogens and spoilage microbes; not sterilization.

Microbial Control — Dry heat

Kills by oxidative damage and other heat effects, often requiring higher temperature/longer time than moist heat.

Microbial Control — Incineration

Destroys microorganisms by burning contaminated materials.

Microbial Control — Refrigeration

Slows microbial metabolism and growth; does not sterilize.

Microbial Control — Freezing

Slows or stops microbial growth but does not consistently kill all microbes.

Microbial Control — Desiccation

Removal of water that inhibits growth of many microbes.

Microbial Control — Lyophilization

Freeze-drying used to preserve some microbes and other materials.