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Exam 2 Review Notes

Plant Cell Structure

• Cell Wall: Protects the cell and gives it shape.

• Nucleus: Contains the genetic material and is involved in the synthesis of ribosomal proteins.

• Nucleolus: Site of ribosome synthesis.

• Mitochondria: Known as the powerhouse of the cell; contains its own DNA and is responsible for ATP production.

• Chloroplasts: Site of photosynthesis, containing chlorophyll.

• Rough Endoplasmic Reticulum (RER): Involved in protein synthesis and processing (ribosomes attached).

• Smooth Endoplasmic Reticulum (SER): Synthesizes lipids and detoxifies certain chemicals.

• Cytoskeleton: Composed of fibers that provide structural support.

• Central Vacuole: Regulates cell concentration and stores substances; affects turgidity of the plant cell.

• Golgi Apparatus: Packages and sorts proteins into transport vesicles.

• Ribosomes: Responsible for protein synthesis; made of rRNA.

• Cytoplasm: Jelly-like substance that houses organelles.

• Peroxisome: Detoxifies poisons.

• Lysosome: Breaks down cellular waste (garbage disposal).

• Vesicles: Store and transport materials.

• Cilia: Short hair-like structures that aid in movement.

Cytoskeletal Fibers

1. Microfilaments:

   • Supports cell shape and allows movement (muscle contraction).

2. Intermediate Filaments:

   • Reinforce the cell's shape and anchor organelles.

3. Microtubules:

   • Provides tracks for organelle movement and aids in cell division.

Intercellular Junctions

• Describes three types: Gap Junctions, Tight Junctions, and Anchoring Junctions.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic Cells: Small, simple structure without a nucleus or membrane-bound organelles.

• Eukaryotic Cells: Larger, complex cells with a nucleus and organelles.

Plasma Membrane Structure

• Integral Proteins: Penetrate the hydrophobic core of the lipid bilayer.

• Peripheral Proteins: Bound to the membrane surface but do not span the membrane.

• Cholesterol: Stabilizes the membrane fluidity.

• Glycoproteins: Proteins with carbohydrate chains attached; involved in cell signaling.

• Glycolipids: Lipids with carbohydrate chains that contribute to cell recognition.

• Phospholipid Bilayer: Composed of hydrophilic heads and hydrophobic tails.

Osmotic Solutions

1. Hypertonic Solution: Higher solute concentration outside the cell, leading to water moving out.

2. Hypotonic Solution: Lower solute concentration outside the cell, leading to water moving in.

3. Isotonic Solution: Equal solute concentration with no net water movement.

Effects on the Cell

• Hypertonic: Cell shrinks.

• Hypotonic: Cell swells and may burst.

• Isotonic: Cell maintains normal shape.

Turgor Pressure and Plasmolysis

• Turgor Pressure: Pressure exerted by the central vacuole against the cell wall in plants, maintaining structure.

• Plasmolysis: Occurs when the cell loses water in a hypertonic environment, leading to contraction away from the cell wall.

Transport Mechanisms

1. Passive Transport: Movement of substances across a membrane without energy (e.g., diffusion, facilitated diffusion, osmosis).

2. Active Transport: Movement of substances against a concentration gradient, requiring energy (e.g., Na+/K+ pump).

Examples of Energy

• Potential Energy: Stored energy (e.g., glucose, water behind a dam).

• Kinetic Energy: Energy of movement (e.g., flowing water, moving car).

Enzyme Function

• Induced Fit Model: Describes how substrates bind to an enzyme's active site, forming an enzyme-substrate complex which leads to product formation.

Regulation of Enzymes

1. Competitive Inhibition

2. Non-competitive Inhibition

3. Allosteric Regulation

4. Covalent Modification

microscope

• Parts of a microscope must be labeled and understood to focus an object correctly.