MICRO - WEEK 03 - UNIT 2.3 & 3.1

What is metabolism? 2 types?

All chemical reactions within a cell.

Catabolism & Anabolism

What is Catabolism?

breaks down molecules and releases energy

What is anabolism?

building up molecules, requires energy

What is ATP?

ATP (adenosine triphosphate) is the cell's energy currency.

ATP → ADP + Pi + Energy

How does ATP connect catabolism and anabolism?

Catabolism releases energy that is captured in ATP. Anabolism uses ATP to drive energy-requiring reactions.

How can microorganisms obtain energy from carbohydrates?

1. Cellular Respiration

2. Fermentation

What is cellular respiration? 2 types? Yields?

A series of reactions that extracts energy from an organic molecule in the form of ATP

It can be:

Aerobic → uses O₂, yields ~36-38 ATP

Anaerobic → does not use O₂, only yields 2 ATP

Equation for Eukaryotic aerobic respiration

Glucose + 6O₂ + ~36ADP + ~36Pi

↓

6CO₂ + 6H₂O + ~36ATP

Four stages of aerobic respiration

1. Glycolysis

2. Pyruvate Oxidation (PAO)

3. Krebs Cycle

4. Electron Transport Chain (ETC)

Why is glycolysis important? (4)

1. Universal pathway

2. Found in almost all organisms

3. Does not require oxygen

4. First step of glucose catabolism

What happens during glycolysis?

- Input

- Output

- Location (prokaryotes & eukaryotes)

Input: 1 Glucose Molecule

Output: 2 Pyruvic Acid (3C), 2 ATP, 2 NADH

Locations:

Prokaryotes - Cytoplasm

Eukaryotes - Cytoplasm

What happens during Pyruvic Acid Oxidation?

- Input

- Output

- Location (prokaryotes & eukaryotes)

Input: 2 Pyruvic Acid (3C)

Output: 2 Acetyl-CoA, 2 NADH, 2 CO₂

Locations:

Prokaryotes - Cytoplasm

Eukaryotes - mitochondrial matrix

What happens during the Kreb's Cycle?

- Input

- Output

- Location (prokaryotes & eukaryotes)

Input: 2 Acetyl-CoA

Output: 4 CO₂, 6 NADH, 2 FADH₂, 2 ATP

Locations:

Prokaryotes - Cytoplasm

Eukaryotes - mitochondrial matrix

Steps of the Krebs Cycle?

1. Acetyl-CoA (2C), brought in by Coenzyme A, joins with Oxaloacetic acid (4C) to make Citric acid (6C)

2. Citric acid is then converted into another molecule, which is then oxidized by NAD+, and

loses a carbon (as CO2)

3. The resulting 5C compound is again oxidized by NAD+, and loses another carbon, and generates 1 ATP from substrate-level phosphorylation.

4. The resulting 4C molecule goes through several changes and converted back into Oxaloacetic acid (4C), and creates 1 NADH and 1 FADH₂

This occurs twice (1 for each Pyruvic Acid)

Why are NADH and FADH₂ important?

They carry high-energy electrons to the ETC.

NAD⁺ + electrons + H⁺ → NADH

FAD + electrons + H⁺ → FADH₂

What happens during ETC?

- Input

- Output

- Location (prokaryotes & eukaryotes)

Input: 10 NADH & 2 FADH2

Output: ~36ATP

Locations:

Prokaryotes - Plasma Membrane (Periplasmic Space)

Eukaryotes - Inner mitochondrial matrix

Steps of the Electron Transport Chain

1. NADH/FADH₂ donate electrons.

2. Electrons move through proteins.

3. Proton gradient forms.

4. ions moving through ATP synthase generate ATP.

What is chemiosmosis? Describe process?

The movement of ions across a selectively permeable membrane, down their electrochemical gradient.

The ETC pumps H⁺ across a membrane.

H⁺ then flows back through ATP synthase channel, which produces ATP.

What is the final electron acceptor in aerobic respiration?

Oxygen (O₂)

Accepts electrons and forms water.

What is substrate-level phosphorylation?

ATP is produced by directly transferring a phosphate group from a metabolic intermediate to ADP.

ADP + Pi → ATP

What is oxidative phosphorylation?

ATP production driven by the electron transport chain and proton gradient.

What is the difference between anaerobic respiration, Aerobic respiration, and Fermentation?

Stages?

Final Acceptor?

ATP yield?

Aerobic Respiration

ETC present

Oxygen final electron acceptor

~ 38 ATP

Anaerobic respiration

ETC sometimes (not all Krebs & ETC function without O)

Inorganic final electron acceptor

~ 5-30 ATP

Fermentation

ETC absent

Organic final electron acceptor

2 ATP from glycolysis

Do prokaryotes or Eukaryotes produce more ATP?

Eukaryotes ~38 ATP

Prokryotes ~36ATP

Do all prokaryotes use the standard glycolytic pathway?

No

1. Entner-Doudoroff pathway (REPLACES glycolysis)

2. Pentose phosphate pathway (used WITH glycolysis)

What is the Entner-Doudoroff pathway? Yeilds?

It can replace the conventional glycolytic pathway in some gram-negative bacteria.

1 ATP

1 NADH

1 NADPH

2 pyruvate

Example of bacteria that uses Entner-Doudoroff Pathway?

Pseudomonas spp.

Compare NADH and NADPH?

NADH & NADPH differ in structure by a phosphate group on ribose

NADH involved in CATABOLIC reactions (energy production)

NADPH involved in ANABOLIC reactions (biosynthesis)

What is the Pentose-Phosphate Pathway? Yields?

A pathway that processes glucose-derived molecules to generate:

NO ATP

2 NADPH

intermediates molecules (pentoses for nucleotide and amino acid synthesis)

examples of prokaryotes that use Pentose-Phosephate Pathway (3)

Escherichia coli (E. coli)

Bacillus subtilis (B. subtilis)

Enterococcus faecalis (E. faecalis)

Does anaerobic respiration mean fermentation?

No.

Anaerobic respiration:

uses ETC

uses inorganic final electron acceptor

Fermentation:

does not use an ETC

uses an organic final electron acceptor

Anaerobic ETC in Prokaryotes

does not use oxygen for the final electron acceptor but other inorganic molecules

What can serve as the final electron acceptor during anaerobic respiration? Product?

Nitrate - Nitrous oxide (N₂O) or Nitrogen gas (N₂)

Sulfate - Hydrogen sulfide (H₂S)

Carbonate - Mathane (CH₄)

What is fermentation?

An anaerobic metabolic process that partially oxidizes organic molecules and generates ATP through glycolysis.

How does fermentation create energy?

Elections in NADH are added to organic molecules to make NAD+

Total yield of Fermentation?

2 ATP from glycolysis

No oxygen required

No Krebs cycle

No ETC

2 Fermentation Pathways

1. Lactic Acid

2. Ethanol

Fermentation Pathway: Lactic Acid

1 Glucose → 2 Pyruvic Acid

- Byproducts: 2 NADH & 2 ATP

2 Pyruvic Acid + 2 NADH→ 2 Lactic Acid

- Byproducts: 2 NAD+

Fermentation Pathway: Ethanol

1 Glucose → 2 Pyruvic Acid

- Byproducts: 2 NADH & 2 ATP

2 Pyruvic Acid - 2 CO₂ → 2 Acetaldehyde

2 Acetaldehyde + 2 NADH → 2 Ethanol

Name the final electron acceptors in fermentation (2)

Pyruvate

Acetaldehyde

Lipid metabolism Pathways

Triglycerides → Extracellular lipase → Fatty Acids

Fatty acids → beta oxidation → Acetyl-CoA

Then enters: Krebs Cycle & ETC

Lipids yield more ATP than carbohydrates.

What is Beta Oxidation?

Process that breaks fatty acids into

Acetyl-CoA units

Each Acetyl-CoA enters Krebs cycle.

Protein metabolism

Proteins → Extracellular Proteases & peptidases → Amino Acids

Amino Acids → Deaminase → Carbon chains

What does deaminase do?

Removes amine group (-NH₂) from amino acids.

Produces:

Carbon skeleton

Ammonia (NH₃)

Why is ammonia important?

Can be used to identify bacteria in lab testing

What does metabolic diversity mean?

Microorganisms differ greatly in how they obtain:

- energy

- electrons

- carbon

This allows microorganisms to occupy many different environments.

Name 4 differences in cellular respiration in prokaryotes & eukaryotes

1. Location of stages (2-4)

2. Final electron acceptor in ETC (not always O₂)

3. ATP yield

4. Glycolytic pathway

Four classifications of nutritional categories

1. Chemoautotroph

2. Chemoheterotroph

3. Photoautotroph

4. Photoheterotroph

What is an autotroph?

obtain carbon primarily from CO₂ (inorganic).

What is a heterotroph?

obtain carbon from organic molecules (glucose)

Phototrophs

get energy from light

Chemotrophs

obtain energy from chemicals

Chemoautotroph - Explain? Energy? Carbon? Ex? (2)

Energy - Chemicals

Carbon source - CO₂

Uses chemical reactions to release energy. It uses CO₂ as its carbon source to build organic molecules.

ex. Nitrifying bacteria, Sulfur bacteria

Chemoheterotroph - Explain? Energy? Carbon? Ex? (2)

Energy - Organic Chemicals

Carbon source - Organic molecules

Gets energy by breaking down organic or inorganic chemicals. It gets its carbon by taking in organic molecules

ex. human, animals

Photoautotroph - Explain? Energy? Carbon? Ex? (2)

Energy - Light

Carbon - CO₂

Uses light energy to make energy molecules through photosynthesis. Uses CO₂ and converts it into organic molecules

Ex. Algae, Plants

Photoheterotroph - Explain? Energy? Carbon? Ex? (1)

Energy - Light

Carbon - Organic Molecules

Uses light as its energy source. Takes in organic molecules from the environment to obtain carbon for growth.

Ex. Purple-Green Bacteria

Characteristics of Fungi (5)

Eukaryotic

Unicellular & Multicellular

Chemoheterotrophic

Chitin - cell wall, Ergosterol - cell membrane

Reproduce sexually and asexually

Why is ergosterol clinically important? ex. (2)

Many antifungal drugs target ergosterol (Because human cells contain cholesterol instead)

ex. Amphotericin B, Azoles

2 basic forms of Fungi?

1. Yeasts - exist as single cells (round to oval)

2. Molds - exists as hyphae

What are hyphae

long threadlike filaments of cells (give fuzzy appearance)

A tangled mass of hyphae are called?

mycelium

Most pathogenic fungi are...

dimorphic - can be yeast or mold interchangeably

What is the difference between a fungal infection and fungal intoxication?

Mycosis → fungus causes infection

Mycotoxicosis/intoxication → fungal toxin causes disease.

Example of yeast?

Saccharomyces cerevisiae

Saccharomyces cerevisiae

How do yeasts reproduce?

Asexually through Budding (form a bud & pinch off)

How do molds reproduce? (2)

Spore Formation: (asexual) a piece of a hypha breaks off and can begin new growth

Fragmentation: aerial hyphae cells form spores (sexual or asexual) , which are released and allow dispersal of fungi over long distances

What is Mycoses? name 5 types

a fungal infection

Systemic Mycoses

Subcutaneous Mycoses

Cutaneous Mycoses

Superficial Mycoses

Oppertunistic Mycoses

Systemic Mycoses + ex.

Deep within the body

Cryptococcosis

Subcutaneous Mycoses

Beneath the skin

Cutaneous Mycoses: caused by? Transmitted by? ex? (3)

Caused by: dermatophytes

Affects the hair, epidermis and nails (digest keratin)

Transmitted via skin contact w/ humans/animals

ex. Tinea pedis (athlete's foot), Tinae barbae, Tinea corporis (ringworm)

Superficial Mycoses

On the hair and skin (without keratin digestion)

Opportunistic Mycoses + ex.

Caused by normal microbiota or environmental fungi

ex. Candida albicans - thrush

What is Candida?

A genus of yeast that can be part of the normal human microbiota but can cause opportunistic infections.

What is candidiasis? ex.

Thrush

Disease caused by overgrowth/invasion of Candida species.

Why is Candida considered an opportunistic pathogen?

Candida can normally live on or in humans without causing disease, but changes in host defenses or local conditions can allow it to overgrow

What causes cryptococcosis? (2)

Cryptococcus neoformans

Cryptococcus gattii

What diseases are caused by cryptococcosis?

Iung infection or meninfitis

Where can Cryptococcus be found?

It can occur environmentally, including in soil and environments associated with bird droppings.

What is an important virulence factor of Cryptococcus?

Its gelatinous, polysaccharide capsule.

Which allows it to help evasion of phagocytosis

Who is cryptococcosis treated?

Antifungal drugs

What is a fungal intoxication?

Disease caused by toxins produced by fungi, rather than infection by the fungus itself.

Name 2 toxins are produced by fungi

1. Ergot Toxin

2. Aflatoxin

What fungus produces ergot toxins?

Claviceps purpurea

What disease is caused by Ergot toxin? 2 clinical manifestations

Ergotism

1. Seizures & Hallucinations

2. Gangrene

What fungus produces aflatoxin?

Aspergillus flavus

Where can aflatoxin contamination occur?

Grows on diverse sources of food, like peanuts & corn

Why is aflatoxin dangerous?

Some aflatoxins are strongly carcinogenic, particularly associated with increased risk of liver cancer (by mutating host DNA)

Name 4 characteristics of Algae

Unicellular & Multicellular

Phototrophs (have chloroplasts)

Cellulose cell walls

Sexual & Asexual Reproduction

Do algae usually cause human infections?

Algae DO NOT cause infection, but they do PRODUCE TOXINS

They cause INTOXICATION

What is the difference between an algal infection and algal intoxication?

The important algal diseases in this unit are primarily intoxications.

The person is harmed by algal toxins rather than by algae growing inside human tissues.

What is red tide and what is its significance?

A harmful algal bloom - A rapid increase in algae or other microalgae can produce harmful environmental or health effects.

Some produce toxins that can accumulate in seafood consumed by humans.

Name 2 Algae Toxins

1. Diatoms

2. Dinoflagellates

Describe the structure of Diatoms & Dinoflagellates

Both are Unicellular organisms

What toxin is associated with diatoms?

Domoix Acid (a neurotoxin)

What disease is caused by diatoms? Symptoms? (2)

Amnesiac Shellfish Poisoning (ASP)

Diarrhea & Memory Loss

Diatoms cell wall contains?

Silica

What toxin is associated with Dinoflaggellates?

Sacitoxins (neurotoxin)

What disease is caused by dinoflagellates? Symptoms? (3)

Paralytic Shellfish Poisoning (PSP)

Numbness in lips, dizziness, difficulty breathing

Describe Dinoflagellates flagella

has two flagella, leading to a whirling movement

4 Characteristics of Protozoa

Unicellular

No cell wall

Mainly Asexual (some Sexual) Reproduction

Have complex life cycles

Do protozoa generally have cell walls?

Generally no, but may have covering called pellicle.