Another microbio 2

What is metabolism?

The sum of all chemical reactions in a cell that keep an organism alive.

What is catabolism?

The breakdown of larger molecules into smaller molecules, releasing energy.

What is anabolism?

The building of larger molecules from smaller molecules, requiring energy.

What is ATP?

The main energy-carrying molecule in cells. It stores and transfers energy for cellular activities.

How is ATP involved in metabolism?

Catabolism produces ATP, while anabolism uses ATP to build molecules.

What is an enzyme?

A protein that speeds up chemical reactions by lowering activation energy without being used up.

What is a ribozyme?

An RNA molecule that acts as an enzyme and speeds up chemical reactions.

What factors affect enzyme activity?

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

How does temperature affect enzymes?

Low temperatures slow enzyme activity

How does pH affect enzymes?

Each enzyme works best at a certain pH. Extreme pH can change its shape and stop it from working.

What is oxidation?

The loss of electrons from a molecule.

What is reduction?

The gain of electrons by a molecule.

How do oxidation and reduction work together?

When one molecule loses electrons, another molecule gains them. These reactions transfer energy.

What does OIL RIG mean?

Oxidation Is Loss of electrons

How is energy produced through oxidation and reduction?

Food molecules are oxidized, releasing electrons that are carried by electron carriers to help produce ATP.

What is a metabolic pathway?

A series of chemical reactions where each step is controlled by a specific enzyme.

What happens when a step in a metabolic pathway is inhibited?

The pathway may slow down or stop, causing the substance before the blocked step to build up and later products to decrease.

What is cellular respiration?

The process of breaking down glucose to produce ATP, usually using an electron transport chain.

What are the three main stages of aerobic cellular respiration?

Glycolysis, the Krebs cycle, and the electron transport chain.

What happens during glycolysis?

Glucose is split into two pyruvate molecules, producing 2 ATP and 2 NADH.

Where does glycolysis occur?

In the cytoplasm.

What happens during the Krebs cycle?

Acetyl-CoA is broken down, releasing carbon dioxide and producing NADH, FADH2, and ATP.

What happens during the electron transport chain?

Electrons move through proteins, creating a proton gradient that powers ATP synthase to make ATP.

What is the final electron acceptor in aerobic respiration?

Oxygen, which combines with electrons and hydrogen to form water.

What is anaerobic respiration?

Respiration that uses an electron transport chain but uses a final electron acceptor other than oxygen, such as nitrate or sulfate.

What is fermentation?

A process that breaks down glucose without an electron transport chain and regenerates NAD+ so glycolysis can continue.

How are cellular respiration and fermentation similar?

Both begin with glycolysis, break down glucose, and produce ATP.

How are cellular respiration and fermentation different?

Respiration uses an electron transport chain and produces more ATP

How much ATP does glycolysis produce?

2 net ATP per glucose.

What are the two common types of fermentation?

Lactic acid fermentation produces lactic acid

What is lactic acid fermentation?

Pyruvate is converted into lactic acid and NAD+ is regenerated.

What is alcoholic fermentation?

Pyruvate is converted into ethanol and carbon dioxide, regenerating NAD+.

How can microorganisms differ in energy production?

Some use aerobic respiration, anaerobic respiration, or fermentation depending on their enzymes and available electron acceptors.

How are lipids broken down for energy?

Triglycerides are split into glycerol and fatty acids. Fatty acids undergo beta-oxidation to form acetyl-CoA.

How are proteins broken down for energy?

Proteins are broken into amino acids. Their amino groups are removed, and the remaining carbon skeletons enter metabolic pathways.

What is deamination?

The removal of an amino group from an amino acid.

What are biochemical tests used for?

To identify bacteria by testing their enzymes, metabolic activities, and ability to use certain nutrients.

What does a positive catalase test indicate?

The bacteria produce catalase, which breaks hydrogen peroxide into water and oxygen bubbles.

What does a positive oxidase test indicate?

The bacteria have cytochrome c oxidase, shown by a color change.

What does a positive lactose fermentation test indicate?

The bacteria can ferment lactose, often producing acid that changes the indicator color.

What does a positive indole test indicate?

The bacteria can break down tryptophan and produce indole.

What does a positive coagulase test indicate?

The bacteria produce coagulase, an enzyme that causes plasma to clot.

What is an autotroph?

An organism that gets carbon from carbon dioxide to build its own organic molecules.

What is a heterotroph?

An organism that gets carbon by consuming organic molecules made by other organisms.

What is a photoautotroph?

An organism that uses light for energy and carbon dioxide for carbon.

What is a chemoautotroph?

An organism that gets energy from inorganic chemicals and carbon from carbon dioxide.

What is a photoheterotroph?

An organism that uses light for energy but gets carbon from organic molecules.

What is a chemoheterotroph?

An organism that gets both energy and carbon from organic molecules.

How are catabolism and biosynthesis connected?

Catabolism breaks molecules down and provides energy and smaller building blocks that cells use for biosynthesis.

What is biosynthesis?

The process of building complex molecules, such as proteins and DNA, from smaller molecules.

What is an amphibolic pathway?

A pathway that functions in both breakdown (catabolism) and building (anabolism). The Krebs cycle is an example.

What are physical requirements for microbial growth?

Temperature, pH, moisture, and appropriate osmotic pressure.

What are chemical requirements for microbial growth?

Water, carbon, nitrogen, sulfur, phosphorus, trace elements, and sometimes oxygen and growth factors.

What are psychrophiles?

Microorganisms that grow best in cold temperatures, usually around 15°C or lower.

What are psychrotrophs?

Microorganisms that can grow in refrigerated temperatures but grow best at warmer temperatures.

What are mesophiles?

Microorganisms that grow best at moderate temperatures, usually around 20–45°C. Many human pathogens are mesophiles.

What are thermophiles?

Microorganisms that grow best at high temperatures, usually around 45–80°C.

What are hyperthermophiles?

Microorganisms that grow best at extremely high temperatures, usually above 80°C.

What are obligate aerobes?

Microorganisms that require oxygen to grow.

What are obligate anaerobes?

Microorganisms that cannot grow in oxygen because it is toxic to them.

What are facultative anaerobes?

Microorganisms that can grow with or without oxygen but usually grow better with it.

What are aerotolerant anaerobes?

Microorganisms that do not use oxygen but can survive and grow in its presence.

What are microaerophiles?

Microorganisms that require oxygen but at lower concentrations than are found in the atmosphere.

What is culture media?

A substance containing nutrients used to grow microorganisms in a laboratory.

What is chemically defined media?

Media where the exact chemical ingredients and amounts are known.

What is complex media?

Media containing ingredients such as yeast extract or peptones, whose exact chemical composition is not completely known.

What is reducing media?

Media that removes or lowers oxygen to help grow anaerobic microorganisms.

What is selective media?

Media containing substances that prevent certain microbes from growing while allowing others to grow.

What is differential media?

Media that allows different microorganisms to be distinguished by visible changes, such as color changes.

What is enrichment media?

Media that encourages the growth of a particular microorganism by providing conditions that favor it.

What is a pure culture?

A culture containing only one species or strain of microorganism.

How are pure cultures isolated?

Using techniques such as the streak plate method to separate individual cells so they form isolated colonies.

What is the streak plate method?

A technique that spreads bacteria across an agar plate in sections to separate individual cells.

How are microbial cultures preserved?

By refrigeration for short-term storage, freezing, or freeze-drying (lyophilization) for long-term storage.

What is binary fission?

A type of asexual reproduction where one bacterial cell copies its DNA and divides into two genetically similar cells.

How does binary fission cause exponential growth?

Each cell divides into two, so the population doubles with each generation.

What is the lag phase?

Cells adjust to their environment and prepare to divide, with little increase in population.

What is the log phase?

Cells divide rapidly at a constant rate, causing exponential growth.

What is the stationary phase?

The number of new cells equals the number of dying cells because nutrients decrease and waste builds up.

What is the death phase?

More cells die than are produced, so the living population decreases.

How is microbial growth measured?

By direct cell counts, viable plate counts (CFUs), turbidity, or metabolic activity.

What is a colony-forming unit (CFU)?

A measure of viable microorganisms capable of forming a visible colony.

What is turbidity?

The cloudiness of a liquid culture, which can be used to estimate microbial growth.

What is sterilization?

The complete destruction or removal of all microbial life, including endospores and viruses.

What is disinfection?

The destruction of many or most harmful microorganisms on nonliving surfaces, but not necessarily endospores.

What is sanitization?

Reducing microbial numbers to levels considered safe by public health standards.

What is bacteriostasis?

The stopping or slowing of bacterial growth without necessarily killing the bacteria.

What is degerming?

The physical removal of microbes from a limited area, such as cleaning the skin before an injection.

What is antisepsis?

The use of antimicrobial chemicals on living tissue to reduce or kill microorganisms.

What is the microbial death curve?

A graph showing the decrease in the number of living microorganisms over time during treatment.

What does decimal reduction time (D-value) mean?

The time needed to kill 90% of a microbial population, leaving 10% remaining.

How do you calculate the remaining microbial population using D-values?

Remaining population = Initial population × (0.1)^number of D-values.

If 1,000,000 bacteria are reduced by 3 D-values, how many remain?

1,000 bacteria remain because each D-value reduces the population by 90%.

What are the three major cellular targets of microbial control?

Cell walls, cell membranes, and proteins or nucleic acids.

How can cell walls be targeted?

Antibiotics such as penicillin prevent proper cell wall formation, causing susceptible bacteria to burst.

How can cell membranes be targeted?

Heat, alcohols, and detergents damage membranes, causing cell contents to leak out.

How can proteins and nucleic acids be targeted?

Heat can denature proteins

How is the effectiveness of chemical disinfectants measured?

By testing how well a chemical kills or inhibits microorganisms under specific conditions, including concentration and exposure time.

What is the phenol coefficient?

A comparison of a disinfectant's effectiveness to phenol under standardized conditions.

What factors affect disinfectant effectiveness?

Concentration, contact time, temperature, pH, organic matter, and the type and number of microorganisms.