Micro - Modules 5-8

What is metabolism?

The sum of all biochemical reactions occurring inside of a cell.

Germicides

Chemicals that denature proteins, mutate DNA, and distrupt membranes

overall reaction of aerobic respiration

Glucose + oxygen → CO2 + water +ATP

Lysis

bursting of cell membrane in hypotonic solution

plasmalysis

skrinkage of cytoplasam away from cell in hypertonic solution

What is catabolism and what happens during catabolic reactions?

Catabolic reactions are decomposition reactions where chemical bonds are broken and energy is released (exergonic process).

What is anabolism and what happens during anabolic reactions?

Anabolism consists of synthetic reactions that build bonds, requiring energy (endergonic process).

How do exergonic and endergonic reactions differ?

Exergonic processes lose energy and are spontaneous, while endergonic processes require energy.

How do exergonic and endergonic reactions relate to catabolism and anabolism?

Catabolic reactions are exergonic (release energy) and anabolic reactions are endergonic (require energy).

What is meant by energy coupling?

Energy released from an exergonic process is used to fuel an endergonic process.

Why is energy coupling necessary in cells?

To get rid of Carbon Dioxide and Ammonia as waste.

What is ATP and how does ATP store energy?

ATP is Adenosine Triphosphate, storing energy in the bonds between its phosphate groups.

What three components are used to build a single molecule of ATP?

Adenosine (nitrogenous base-Adenine), 3 phosphate groups, and 5 Carbon Sugar (Ribose).

Why is ATP useful during energy coupling?

It allows for efficient energy coupling, releases energy without wasting it, and is easily recyclable.

What is activation energy?

The energy required to initiate a reaction; higher activation energy means a slower reaction.

What are enzymes?

Proteins with unique 3D shapes that catalyze specific biochemical reactions by lowering activation energy.

How do enzymes catalyze biochemical reactions?

By lowering activation energy requirements.

What is a substrate?

The reactant that binds to the active site of an enzyme. (Lock and key model)

induced fit model

active site conforms around substrate after binding

Reactant

Aka substrate -> what binds to the active site

non-competive inhibition (allostaric inhibitor)

binds to allostaric site and changes shape of active site; revirsible

How do substrates relate to products?

The product is the result of the breakdown of the substrate.

What is the active site of an enzyme?

The region where the reaction takes place.

Which environmental factors affect enzyme activity and what are their effects?

Temperature, pH, and salt concentration can denature proteins and affect enzyme functionality.

phosphorylation

phosphate added to allostaric site to activate the enzyme

What is meant by feedback inhibition?

Negative feedback inhibition occurs when the product of a process inhibits that process.

What is an allosteric site?

A site that allows enzyme activity to be regulated by negative feedback inhibition.

How does the allosteric site differ from an enzyme's active site?

The product binds to the allosteric site and chnages the shape of the active site, inhibiting substrates from binding to that enzyme.

What role does the allosteric site play in feedback inhibition?

It allows the product to stop the enzymatic process.

How does enzyme phosphorylation affect enzyme function?

Phosphate binding causes the enzyme to fold into an active site, which can be reversible.

What is meant by competitive inhibition?

An inhibitor that binds to an active site and blocks substrate from binding, inhibiting enzyme activity.
-Ex: tamiflu - antiviral

How does competitive inhibition relate to antibiotic therapy for infections?

Penicillin and ibuprofen act as competitive inhibitors of enzymes involved in cell wall synthesis and inflammatory responses.

Which antibiotics act as competitive inhibitors?

Penicillin and sulfa drugs.

How do sulfa drugs function and why are they safe therapies for animals?

Sulfanilamide binds as a competitive inhibitor to inhibit PABA substrate from binding, and it doesn't affect human enzymes.

What is aerobic metabolism?

The breakdown of glucose in the presence of oxygen, releasing energy to make ATP.

What is the overall chemical equation for aerobic cellular respiration?

Glucose + 6O2 → 6CO2 + 6H2O + Energy → 38 ATP.

How many ATP are produced by bacteria during aerobic cellular respiration?

38 ATP.

What occurs during glycolysis? How many ATP are produced?

Glucose is broken down into 2 pyruvic acid molecules, producing 2 ATP.

What happens to hydrogen during glycolysis?

2 hydrogen atoms are split into 2 electrons bound to NADH and 2 protons.

What are electron carriers? Provide two examples.

Electron carriers bind to free hydrogen electrons; examples include NAD+ and NADH.

What occurs during the transition reaction (aka pyruvate oxidation)?

1 carbon is removed from each pyruvic acid, releasing 2 CO2 and forming 2 Acetyl-CoA.

Oxidation

Loss of electrons (LEO)

Reduction

Gain of electrons (GER)

What occurs during the Krebs cycle? How many ATP are produced?

All carbons in Acetyl-CoA are released as CO2, gaining 2 ATP and electrons on FADH2 and NADH.

What is the electron transport chain and where is it located in bacteria?

A group of proteins in the bacterial cell membrane that produces ATP.

What role does oxygen serve in the electron transport chain?

Oxygen acts as the final electron acceptor in the chain.

How does the electron transport chain produce ATP? How many ATP?

It creates a hydrogen ion gradient to produce 34 ATP.

What is ATP synthase? How does it work?

A protein machine that synthesizes ATP by spinning as hydrogen ions pass through.

What roles do active transport and facilitated diffusion play in the electron transport chain?

Active transport creates a gradient, while facilitated diffusion causes ATP synthase to spin.

What is anaerobic metabolism and what is an example?

The breakdown of glucose without oxygen; an example is fermentation.

How many ATP are made during fermentation?

2 ATP molecules.

What are the two main types of fermentation?

Lactic acid fermentation in animals and ethanol + CO2 fermentation in fungi.

How do aerobic cellular respiration and fermentation differ?

Fermentation occurs without oxygen and produces only 2 ATP, while aerobic respiration is more efficient.

What are oxidation-reduction (redox) reactions?

Reactions involving electron transfers between molecules, essential in cellular respiration and fermentation.

What is a mixed culture?

Multiple species of bacteria in a single growth environment.

What is a pure culture and its importance?

A population of organisms descended from a single cell, important for identifying and diagnosing infections.

What is the cause of an infection that can be identified and diagnosed?

Bacteria

How was pure-culturing discovered?

Serratia marcescens growing onto Communion bread.

Who pioneered growing bacteria in pure culture?

Robert Koch

How was the use of agar in growth media discovered?

Fannie Hesse added too much 'Agar-Agar' to her soup, and it solidified. Walther Hesse (her husband) presented their findings.

What are the advantages of solid and liquid media?

You can have pure cultures in both solid and liquid media.

What are streak plates and how do they produce pure cultures?

A petri dish with agar that is streaked with an inoculating loop to isolate cells.

What is aseptic technique?

Techniques to prevent contamination, such as keeping the lid over plates and flaming loops.

What are photoautotrophs?

Bacteria that harness energy via photosynthesis to build glucose, e.g., Cyanobacteria.

What are chemoheterotrophs?

Bacteria that obtain energy molecules (glucose) directly from the environment, e.g., human pathogens.

What are psychrophiles, mesophiles, thermophiles, and hyperthermophiles?

Psychrophiles: -5 to 20°C; Mesophiles: 20 to 45°C; Thermophiles: 45 to 70°C; Hyperthermophiles: 70 to 110°C.

Which category includes most pathogenic organisms?

Mesophiles, as they can survive in human body temperature (37°C).

Thioglycolate broth

complex medium that separates microbes based on oxygen requirements

julius richard petri

invented the petri dish

What are obligate aerobes?

Organisms that rely on aerobic respiration exclusively, e.g., Pseudomonas aeruginosa.

What are facultative anaerobes?

Organisms that prefer O2 but can live without it, e.g., Escherichia coli.

What are obligate anaerobes?

Organisms that cannot have O2, e.g., Clostridium botulinum.

What are aerotolerant anaerobes?

Organisms that cannot perform aerobic respiration but can live with O2, e.g., Streptococcus pyogenes.

What are microaerophiles?

Organisms that need O2 but prefer lower amounts, e.g., Helicobacter pylori.

How can oxygen requirements be determined experimentally?

By creating an O2 gradient and observing growth patterns.

What are neutrophiles, acidophiles, and alkaliphiles?

Neutrophiles prefer pH 5-8; acidophiles prefer pH <5; alkaliphiles prefer pH >8.

What are microenvironments?

Small sub-environments with conditions that differ from the macro environment.

How does Helicobacter pylori create a microenvironment?

It produces an enzyme that breaks down urea into CO2 and ammonia, neutralizing the pH around it.

What is generation time?

The time required for a population to double, approximately 30 minutes under ideal conditions.

What is binary fission?

Bacterial division where a cell splits into two after copying its chromosomes.

What are the stages of a bacterial growth curve?

1. Lag phase: slow growth; 2. Log phase: rapid growth; 3. Stationary phase: equilibrium; 4. Death phase: population decrease.

How do bacterial growth curves relate to signs and symptoms of disease?

Antibiotics or immune response can cause bacteria to enter the death phase.

What does sterilization mean in microbiology?

The removal or destruction of all live microbes, including endospores.

What is disinfection?

Removal, destruction, or inhibition of growth of most microbes.

What are disinfectants and antiseptics?

Disinfectants are chemicals used on surfaces; antiseptics are suitable for living tissue.

What is sanitization?

Reduction of microbes to a level considered safe for public health.

What is degerming?

Mechanical removal of microbes from a limited area.

What kind of hand soap is recommended for routine at-home hand washing?

Regular liquid soap.

What makes Bacillus and Clostridium hard to control?

They produce endospores.

What are critical, semicritical, and noncritical medical items?

Critical: penetrate tissues (e.g., needles); Semi-critical: contact mucous membranes (e.g., endoscopes); Non-critical: contact unbroken skin (e.g., stethoscopes).

How does heat kill microorganisms?

By denaturing proteins.

What are two examples of dry heat sterilization?

Microincinerator and oven (170°C for 3-4 hours).

What is an example of moist heat?

Boiling at 100°C for 10 minutes.

Why is boiling not sufficient for sterilization?

It does not destroy endospores.

How does an autoclave work?

Uses pressure to raise the boiling point of water to sterilize at 121°C, 15 PSI for 15 minutes.

What is pasteurization?

Rapid heating at 72°C for 15 seconds to reduce microbes and extend shelf life.

How does membrane filtration work?

Uses a filter with pores <0.4 micrometers to remove bacteria from liquids.

How does radiation control microorganisms?

By mutating DNA, particularly with ultraviolet radiation.

When is ultraviolet radiation used in healthcare?

To sterilize environments in operating rooms.

non-ionizing radiation (UV)

high energy capable of removing electrons from atoms; can damage DNA and cells