Chapter 6 and 7

What are the six essential elements needed by bacteria (CHOPN)?

Carbon, Hydrogen, Oxygen, Phosphorus, Nitrogen, and Sulfur.

: What is the difference between macronutrients and micronutrients?

• Macronutrients: Needed in large amounts (carbohydrates, lipids, proteins, nucleic acids)

• Micronutrients (trace elements): Needed in small amounts (vitamins and minerals)

What does "chemo" mean?

Energy comes from chemicals.

What does "photo" mean?

Energy comes from light.

What does "heterotroph" mean?

Gets carbon from organic compounds (other organisms).

What does "autotroph" mean?

Gets carbon from CO₂ (inorganic carbon).

What are humans?

Chemoheterotrophs

What is a saprobe?

An organism (usually fungi) that feeds on dead organic matter.

What is a parasite?

Lives on or in another organism and harms it.

What is a mutualist?

Both organisms benefit.

What is diffusion?

Movement of molecules from high concentration to low concentration.

What is osmosis?

Diffusion of water across a selectively permeable membrane.

What happens in an isotonic solution?

Equal solute concentration → No net water movement → Cell stays the same.

What happens in a hypotonic solution?

Water enters the cell → Cell swells (may burst).

What happens in a hypertonic solution?

Water leaves the cell → Cell shrinks (plasmolysis).

Name two passive transport methods.

• Diffusion

• Osmosis

Name one active transport method.

Active transport (uses ATP).

Psychrophiles grow at what temperatures?

: 0–20°C (cold lovers)

Mesophiles grow at what temperatures?

0–40°C
(Human pathogens usually grow at 37°C.)

Thermophiles grow at what temperatures?

40–60°C (heat lovers)

Obligate aerobes

Require oxygen.

Obligate anaerobes

Oxygen kills them.

Facultative anaerobes

Grow with or without oxygen but grow best with oxygen.

Salt lovers.

Halophiles

Acidophiles

Prefer low pH.

Alkalinophiles

Prefer high pH.

Neutralophiles

Prefer pH around 7.

Barophiles

Prefer high pressure.

Mutualism

Both benefit.

Parasitism

One benefits, host harmed.

Synergism

Organisms work together for greater benefit.

Antagonism

Compete for nutrients or release chemicals to kill competitors.

What is a biofilm?

A community of microbes attached to a surface inside a protective matrix.

Why are biofilms clinically important?

Hard to remove and resistant to antibiotics.

Steps of binary fission

• DNA replicates

• Cell grows

• Septum forms

• Cell divides into two identical cells

Growth Curve

Q: Lag phase

A: Cells prepare to divide.

Log phase

Rapid growth; cells most sensitive to antibiotics.

Stationary phase

Cell growth equals cell death.

Death phase

More cells die than divide.

Selective media

Allows some bacteria to grow while inhibiting others.

Differential media

Distinguishes bacteria by color or biochemical reactions.

What is metabolism?

All chemical reactions in a cell.

Catabolism

Breaks molecules apart and releases energy.

Anabolism

Builds molecules using energy.

What is an enzyme?

A protein catalyst that speeds up reactions without being used up.

What is the substrate?

The molecule an enzyme acts on.

What are products?

Molecules formed after the reaction.

Three pathway types

• Linear

• Branched

• Cyclic

Constitutive enzymes

Always present.

Regulated enzymes

Turned on or off as needed.

What affects enzyme activity?

• Temperature

• pH

• Substrate concentration

• Product concentration

• Inhibitors

Competitive inhibitor

Competes for the active site.

Noncompetitive inhibitor

Binds elsewhere and changes enzyme shape.

What is ATP?

The cell's energy currency.

ATP is made from?

ADP + Pi

What does LEO GER mean?

• Loss of Electrons = Oxidation

• Gain of Electrons = Reduction

Main electron carriers

• NAD⁺

• FAD

Reduced forms

• NADH

• FADH

Aerobic respiration

A:

• Oxygen is final electron acceptor

• ~38 ATP

Anaerobic respiration

A:

• Final electron acceptor is nitrate or sulfate

• Less ATP than aerobic

Fermentation

• No ETC

• Organic molecule is final electron acceptor

• 2 ATP

Where does glycolysis occur?

Cytoplasm.

Glycolysis starts with?

Glucose.

glycolysis produces?

• 2 Pyruvate

• Net 2 ATP

• 2 NADH

Krebs starts with?

2 Pyruvate (converted to Acetyl-CoA).

Krebs produces

• 6 CO₂

• 2 ATP

• 8 NADH

Purpose of ETC

Makes most ATP using electrons from NADH.

Final electron acceptor in aerobic respiration

Oxygen

Enzyme that makes ATP

ATP synthase.

Why is fermentation important?

Regenerates NAD⁺ so glycolysis can continue.

Three fermentation products

• Lactic acid

• Ethanol

• CO₂

How are fats used?

Broken into glycerol and fatty acids.

How are proteins used?

Broken into amino acids that enter metabolism.

What is anabolism?

A: Uses ATP to build larger molecules.

What is amphibolism?

Pathways that function in both catabolism and anabolis

Which phase are bacteria most sensitive to antibiotics?

A: Log (exponential) phase.

Which pathway makes the most ATP?

Aerobic respiration (~38 ATP).

Oxygen is the final electron acceptor in ________?

A: Aerobic respiration.

Fermentation produces how much ATP?

A: 2 ATP.

Glycolysis occurs where?

Cytoplasm

ATP synthase does what?

Produces ATP.

Which process regenerates NAD⁺?

Fermentation.

Which transport requires ATP?

Active transport.

Hypertonic solution causes what?

Water leaves the cell → cell shrinks.

Hypotonic solution causes what?

Water enters the cell → cell swells.