Cell Structure and Function

• These are notes on cell structure and function

Cell Types: Prokaryotic (PRO) vs. Eukaryotic (EUK)

• PRO: No nucleus.
• PRO: Unicellular organisms like bacteria.
• EUK: Genetic material in a nucleus.
• EUK: Contains organelles.
• EUK: Can be unicellular or multicellular.

Basic Cell Components

• Maintained metabolic reactions in the cytoplasm are key for cell survival.
• Capsule: Outer layer
• Nucleiod: Area in prokaryotes where DNA is located
• Pili: Hairlike, protein structures on the surface of some bacteria
• Plasmid: A small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA
• Cell wall: Rigid structure
• Flagella: A slender threadlike structure, especially a microscopic appendage that enables many protozoa, bacteria, spermatozoa, etc., to swim
• Cytoplasm: The material or protoplasm within a living cell, excluding the nucleus.
• Cell (plasma) membrane: The semipermeable membrane surrounding the cytoplasm of a cell.
• Ribosomes: Site of protein synthesis

Organelles: Animal, Plant, and Both

• Golgi body: Modifies, sorts, and packages proteins and lipids.
• Nucleus: Control center of the cell.
• Nucleolus: Found inside the nucleus and produces ribosomes.
• Mitochondria: Powerhouse of the cell, generates energy (ATP) through respiration.
• Rough ER: Endoplasmic reticulum with ribosomes attached; involved in protein synthesis and transport.
• Smooth ER: Endoplasmic reticulum without ribosomes; involved in lipid synthesis, detoxification, and steroid hormone production.
• Vesicles: Small sacs that transport and store materials within the cell.
• Lysosomes: Contain enzymes for intracellular digestion and waste removal (more common in animal cells).
• Centriole: A minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.
• Cell wall: Provides structure and support to plant cells.
• Chloroplasts: Site of photosynthesis in plants, converting sunlight into sugars.
• Vacuole: Stores water, nutrients, and waste in plant cells; smaller in animal cells.
• Plasma membrane: Outer boundary of the cell, controls what enters and exits.

Microscopy and Cell Size

• Field of View (FOV): The diameter of the area visible when looking through the microscope.
• Magnification calculation: Image size (with ruler) / Actual size (according to scale bar).
• Catalase: An enzyme.
• Catalase breaks down hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2), protecting the cell from toxic H2O2.
• The more H2O2, the more O2 bubbles are formed.
• The rate of bubble formation indicates catalase activity.
• "Lock and key" model: Enzymes are specific to their substrates.

Organelle Functions

• Mitochondria: Respiration produces cell energy (ATP); bean-shaped with folds.
• Chloroplast: Chlorophyll converts sunlight energy into sugars; green pancake-like structures (plants).
• Nucleus: Holds genetic information (DNA) as chromosomes (DNA + protein).
• Rough ER: Protein factory; produces and transports proteins (has ribosomes).
• Smooth ER: Makes lipids (fats), detoxifies harmful substances (no ribosomes).
• Golgi Body: Packages and ships proteins and other molecules in vesicles (cell's post office).
• Lysosomes: Contain enzymes for digestion; clear up cellular debris.
• Vacuole: Stores water and nutrients, collects waste (plants).

Ribosomes and Cytoplasm

• Ribosomes: Make proteins by linking amino acids together (protein synthesis).
• Cytoplasm: Jelly-like fluid that holds organelles in place and allows movement of materials (cell's swimming pool).

Centrosomes/Centrioles

• Centrosomes/Centrioles: Help cells divide by organizing fibers that pull chromosomes apart (cell division organizer).

Vesicles

• Vesicles: Store and transport proteins, waste, and nutrition inside the cell (cell's delivery truck).

Membrane Types

• Plasma membrane: Separates the interior of the cell from the outside environment, controls what enters and exits.
• Nuclear membrane: Protects the nucleus and controls what enters/exists.
• Endoplasmic Reticulum (ER) membrane: Forms a network for transporting proteins and lipids.

Homeostasis

• Homeostasis: Maintaining a stable internal environment.