Helminths and Microbial Nutrition

• Helminths: Includes three major types:
  • Trematodes (flatworms)
  • Cestodes (tapeworms)
  • Nematodes (roundworms)

Environmental Factors Influencing Bacteria

• Temperature: Growth is influenced by:

  • Cardinal Temperatures:
  • Minimum: Lowest temperature for growth/metabolism
  • Maximum: Highest temperature for growth/metabolism
  • Optimum: Temperature promoting the fastest growth

• Microbial Classifications by Temperature Preference:

  1. Psychrophiles: Cold-loving (0-20°C)
  2. Mesophiles: Moderate temperature (20-45°C)
  3. Thermophiles: Heat-loving (45-80°C)

Oxygen Requirements of Bacteria

• Categories:
  • Obligate Aerobes: Require oxygen (e.g., Micrococcus)
  • Facultative Anaerobes: Prefer oxygen but can grow without it (e.g., E. coli)
  • Obligate Anaerobes: Cannot tolerate oxygen (e.g., Clostridium)
  • Aerotolerant Anaerobes: Do not use oxygen but can survive in its presence
  • Capnophiles: Prefer high CO2 concentration (e.g., Neisseria, Streptococcus pneumoniae)

Toxic Oxygen Byproducts

• Types:
  1. Singlet Oxygen: Very reactive, produced by phagocytes to kill bacteria
  2. Superoxide Free Radicals (O2-): Require dismutation by SOD to be neutralized
  3. Hydrogen Peroxide (H2O2): Toxic; neutralized by Catalase or Peroxidase

Bacterial Reproduction

• Binary Fission: Process by which bacteria reproduce

• Exponential Growth: Model expressed as:

  Nf = Ni imes 2^n

• Variables:

  • N_f: Final number of bacteria
  • N_i: Initial number of bacteria
  • n: Number of generations

Growth Phases of Bacteria

1. Lag Phase: Preparation for growth
2. Log Phase: Exponential growth
3. Stationary Phase: Growth rate equals death rate
4. Death Phase: Death rate exceeds growth rate

Enzymes Overview

• Types of Enzymes:
  1. Simple Enzymes: Composed only of protein
  2. Conjugated Enzymes (Holoenzymes): Comprised of a cofactor + apoenzyme

Cellular Respiration

• Anaerobic Cellular Respiration Steps:

  1. Glycolysis
  2. Fermentation

• Aerobic Cellular Respiration Steps:

  1. Glycolysis
  2. Krebs Cycle
  3. Electron Transport System (ETS)

Glycolysis

• Breaks down glucose into 2 pyruvates, producing 2 ATP and 2 NADH
• Formula:
  C6H{12}O_6
  ightarrow 2 ext{Pyruvate} + 2 ext{ATP} + 2 ext{NADH}

Krebs Cycle

• Takes place in mitochondria; outputs are:
  • 2 CO2, 2 ATP, 6 NADH, 2 FADH2

Electron Transport Chain (ETC)

• Process: Electrons from NADH and FADH2 are passed through proteins, generating ATP through chemiosmosis
• Final electron acceptor is oxygen which combines with protons to form water

Energy Carriers: ATP and ADP

• Structure: ATP consists of ribose sugar, adenine base, and three phosphate groups

• Energy is released when a phosphate bond is broken, producing ADP and inorganic phosphate

• Equation for ATP Reactions:
  ext{ATP}
  ightarrow ext{ADP} + ext{Pi} + ext{energy}

• ATP can also be regenerated:
  ext{Energy} + ext{ADP} + ext{Pi}
  ightarrow ext{ATP}

Phosphorylation

• Process by which phosphate groups are transferred from ATP to other molecules, energizing them for reactions

Oxidation-Reduction Reactions

• Concepts:
  • Oxidation: Loss of electrons
  • Reduction: Gain of electrons
• Example:
  • NADH: Reduced form (contains electrons)
  • NAD+: Oxidized form (when NADH donates electrons)