Microorganisms: Prokaryotic vs. Eukaryotic

Microorganisms: Prokaryotic vs. Eukaryotic

• Prokaryotes are single-celled organisms without a nucleus or membrane-bound organelles. Examples include bacteria and archaea (e.g., E. coli, Salmonella).
• Eukaryotes can be single-celled or multicellular, possessing a nucleus and membrane-bound organelles. Examples include protists (single-celled), plants, animals, and fungi (multicellular) (e.g., humans, fungi, plants, amoebas, algae).

Historical Figures and Contributions

• Robert Hooke: Coined the term "cell," published Micrographia, and used the first compound microscope.
• Antonie van Leeuwenhoek: "Father of Microbiology," first observed various types of microbes, and ground his own lenses.
• John Needham: Proposed spontaneous generation, believing life arose from non-living matter.
• Lazzaro Spallanzani: Challenged spontaneous generation but couldn't definitively disprove it.
• Louis Pasteur: Disproved spontaneous generation using swan-neck flasks, developed pasteurization, and proposed the germ theory of disease.
• Edward Jenner: Developed the first vaccine, preventing smallpox.
• John Snow: "Father of Epidemiology," studied the 1854 cholera outbreak and demonstrated how public health measures could curb disease.
• Robert Koch: Developed Koch's postulates which provide a method to determine if a specific microbe causes a specific disease through systematic investigation.
• Florence Nightingale: Known as the "Founder of Medical Statistics."

Bacterial Cell Structures and Functions

• Cell Wall: Provides structure, support, protection, and maintains cell shape.
• Cell Membrane: Regulates the passage of substances into and out of the cell, with selective permeability.
• Ribosomes: Sites of protein synthesis, translating mRNA into proteins.
• Plasmids: Small pieces of DNA carrying extra genetic information beyond the chromosome.
• Flagella: Long, whip-like structures for bacterial movement through rotation.
• Capsule: A protective layer of polysaccharides or proteins shielding the bacterium from the immune system.
• Endospores: Highly resistant structures formed by bacteria in harsh conditions allowing survival.

Bacterial Growth and Nutrition Terminology

• Lag Phase: Initial phase of growth where cells adapt to a new environment, with little to no increase in cell number.
• Log Phase: Exponential growth phase where the population doubles at a constant rate.
• Stationary Phase: Growth rate slows as nutrients deplete.
• Death Phase: Population decreases due to various factors.
• Generation Time: Time for a population to double in number.
• Aerobes: Microorganisms requiring oxygen for growth.
• Anaerobes: Microorganisms that do not require oxygen.
• Facultative Anaerobes: Can grow with or without oxygen.

Bacterial Division and Growth

• Bacterial DNA replication results in two identical copies of the genetic material.
• Cell division involves completing the cell wall and separating the daughter cells.

Glucose Catabolism (Glycolysis, TCA, ETC)

• Glycolysis: Cytoplasmic process yielding 2 ATP, 2 NADH, and 2 pyruvate molecules per glucose.
• Citric Acid Cycle (TCA): Mitochondrial process generating 3 NADH, 1 FADH2, 1 ATP, and 2 CO2 per acetyl-CoA.
• Electron Transport Chain (ETC): Mitochondrial process utilizing oxygen to produce a large amount of ATP via oxidative phosphorylation.

Fermentation vs. Respiration

• Fermentation: Regenerates NAD+ to sustain glycolysis in the absence of oxygen, producing less ATP.
• Respiration: Efficiently produces ATP using the energy in glucose through a series of steps, requiring oxygen.

Aerobic vs. Anaerobic Respiration

• Aerobic Respiration: Requires oxygen, highly efficient ATP production, producing carbon dioxide and water.
• Anaerobic Respiration: Does not require oxygen, less efficient than aerobic respiration, with various end products depending on the organism.

Enzyme Function

• Enzymes facilitate reactions by lowering activation energy.
• Substrate recognition and induced fit are crucial steps in enzyme function.
• Product release allows for repeated interactions with substrates.
• Enzyme activity is regulated by various factors (substrate concentration, pH, temperature, etc.).

DNA Replication, Transcription, and Translation

• DNA Replication: Enzymes like DNA polymerase, helicase, primase, and ligase are involved in initiating, elongating, and completing replication.
• Transcription: RNA polymerase synthesizes mRNA from DNA, using promoters and enhancers.
• Translation: Ribosomes synthesize proteins using mRNA and tRNA, involving initiation, elongation, and termination steps.

Types of Mutations

• Point Mutations: Single nucleotide changes that may lead to silent, missense, or nonsense mutations.
• Frameshift Mutations: Insertions or deletions of nucleotides altering the reading frame.
• Missense Mutations: Different amino acid incorporated into the protein.
• Nonsense Mutations: Premature stop codon resulting in a non-functional protein.
• Silent Mutations: Point mutations not affecting amino acid sequences.

Gene Expression Regulation

• Gene expression is regulated at transcriptional, post-transcriptional, translational, and post-translational levels.

Horizontal Gene Transfer

• Transformation: Bacteria absorb and incorporate free DNA from their environment.
• Transduction: Bacteriophages transfer bacterial DNA between cells.
• Conjugation: Direct transfer of genetic material between bacteria.

Viral Replication

• Viruses replicate through specific steps, such as attachment, entry, replication, assembly, and release. Key principles include host specificity and error-prone replication.

Eukaryotic Reproduction

• Sexual Reproduction: Involves gamete formation (meiosis), fertilization, and genetic variation.
• Asexual Reproduction: Uses mitosis, including binary fission, budding, and fragmentation for reproduction with less variation.