BIOL 103 - Cell Structure and Function

Cell Theory

1. Cells are basic units of life. 2. All living organisms are composed of cells. 3. All cells come from existing cells. 4. Modern cells evolved from a common ancestor.

Bacterial vs. Eukaryotic Cells

Bacterial cells lack internal membrane-bound organelles and are smaller; eukaryotic cells contain membrane-bound organelles, including a nucleus, and are larger.

Nucleus Function

Encloses the cell's DNA and serves as the site where reactions for interpreting genetic instructions take place.

Endoplasmic Reticulum (ER)

Network of membrane-covered pipes where proteins and lipids are synthesized (Rough ER has ribosomes; Smooth ER produces lipids).

Golgi Apparatus

Stacked, flattened membrane compartments that package and transport proteins made in the rough ER.

Mitochondria Function

Extract energy from food and convert it into a useful form; site of aerobic respiration ("power plants").

Chloroplasts

Found in plants and algae; sites of photosynthesis, capturing sunlight and converting it into a usable form.

Lysosomes

Digestive and recycling centers full of enzymes that break down worn-out cell parts or molecules.

Cytoskeleton

Network of protein fibers providing cell support, cell movement, and movement of structures within cells.

Endosymbiosis Theory

Free-living bacteria cells engulfed other free-living prokaryotic cells billions of years ago, forming eukaryotic organelles like mitochondria and chloroplasts.

Cell Membrane Structure

A phospholipid bilayer with embedded proteins, featuring hydrophilic phosphate heads pointing out and hydrophobic tails facing in.

Osmosis

The diffusion of water across a semipermeable membrane from an area of lower-solute to higher-solute concentration.

Hypertonic Solution

Solution with a higher solute concentration than the cell; water moves out and the cell shrinks.

Hypotonic Solution

Solution with a lower solute concentration than the cell; water moves in and the cell swells.

Isotonic Solution

Solution with the same solute concentration as the cell; no net movement of water, cell stays the same size.

Simple Diffusion

Small, uncharged substances move from higher to lower concentration without requiring energy.

Facilitated Diffusion

Large or hydrophilic molecules use transport proteins to cross the bilayer down their concentration gradient without energy.

Active Transport

Transport proteins pump solutes from regions of lower to higher concentration, requiring energy input.

Antibiotic

A chemical that can slow or stop the growth of bacteria, often naturally produced by living organisms.

Mechanism of Penicillin

Weakens bacterial peptidoglycan cell walls, causing bacterial cells to fill up with water via osmosis and burst.

Antibiotic Resistance

Changes in bacteria caused by random mutations or gene transfer that make them unresponsive to antibiotics.