Chapters 1 - 3 Study Guide

1. Homeostasis

Levels of Organization of Living Organisms (from smallest to largest):

1. Atom – Basic unit of matter.

2. Molecule – Two or more atoms bonded together.

3. Organelle – Specialized structures within cells (e.g., mitochondria).

4. Cell – Basic unit of life.

5. Tissue – Groups of similar cells performing a common function (e.g., muscle tissue).

6. Organ – Composed of different types of tissues working together (e.g., heart).

7. Organ System – Group of organs that perform related functions (e.g., cardiovascular system).

8. Organism – A complete living entity capable of independent existence.

Concept of Homeostasis:

• Homeostasis refers to the body's ability to maintain a stable internal environment despite changes in external conditions. It involves regulating variables like temperature, pH, and ion concentrations within a narrow range to support life.

Control Mechanisms Involved in Homeostasis:

1. Local Control means that responses are confined to a specific area (e.g., blood vessel constriction in response to injury).

2. Negative Feedback: The response reduces the stimulus (e.g., body temperature regulation: when body temperature rises, mechanisms like sweating cool the body, bringing it back to normal).

3. Positive Feedback – The response amplifies the stimulus (e.g., childbirth: uterine contractions lead to more contractions until delivery).

Purpose of Homeostasis:

• General Purpose: To maintain conditions favorable for cell function and survival.

• Negative Feedback: Stabilizes the system, reduces the deviation from the set point.

• Positive Feedback: Amplifies a change to promote a specific outcome.

Control Mechanism Example Classifications:

• Negative Feedback Example: Regulation of blood sugar by insulin.

• Positive Feedback Example: Blood clotting cascade during injury.

2. Cell Structure

Cellular Structures & Their Functions:

1. Nucleus – Contains genetic material (DNA), controls cell activities.

2. Mitochondria – Site of ATP production through cellular respiration.

3. Ribosomes – Protein synthesis.

4. Endoplasmic Reticulum (ER):

   • Rough ER – Has ribosomes; synthesizes proteins.

   • Smooth ER – Synthesizes lipids, detoxifies drugs.

5. Golgi Apparatus – Modifies, sorts, and packages proteins for transport.

6. Lysosomes – Digestion and waste removal.

7. Peroxisomes – Detoxification, breakdown of fatty acids.

8. Cytoskeleton – Provides structure, shape, and aids in cell movement.

9. Plasma Membrane – Controls movement of substances in/out of the cell.

Processes Involved in ATP Making:

1. Glycolysis:

   • Location: Cytoplasm.

   • ATP Produced: 2 ATP.

2. Citric Acid Cycle (Krebs Cycle):

   • Location: Mitochondria (matrix).

   • ATP Produced: 2 ATP.

3. Electron Transport Chain (ETC):

   • Location: Inner mitochondrial membrane.

   • ATP Produced: ~34 ATP.

   • How ATP is Made in ETC: Electrons move through proteins in the membrane, creating a proton gradient that drives ATP synthase to generate ATP.

Impact of Diseases/Drugs on Cellular Function:

• Example: A drug that affects the mitochondria could impair ATP production, leading to symptoms like fatigue, muscle weakness, or organ dysfunction.

• Example: If lysosomes are damaged, waste could accumulate in cells, leading to disorders like Tay-Sachs disease.

Organelles and Their Functions:

• High Mitochondria Count: Cells with a lot of energy demand (e.g., muscle cells, neurons).

• High Ribosome Count: Cells that produce a lot of protein (e.g., pancreas cells producing insulin).

3. Cell Membrane

Components of the Cell Membrane:

1. Phospholipid Bilayer – Basic structural framework; hydrophilic heads, hydrophobic tails.

2. Proteins:

   • Integral proteins – Span the membrane, transport molecules.

   • Peripheral proteins – Attached to inner/outer membrane, involved in signaling and structure.

3. Cholesterol – Stabilizes membrane fluidity.

4. Carbohydrates – Form glycoproteins and glycolipids; involved in cell recognition.

Types of Membrane Transport:

1. Passive Transport (No energy required):

   • Diffusion – Movement of molecules from high to low concentration.

   • Facilitated Diffusion – Movement through a membrane protein (e.g., glucose transport).

   • Osmosis – Movement of water across a semipermeable membrane.

2. Active Transport (Energy required):

   • Primary Active Transport – Uses ATP to move molecules against their concentration gradient (e.g., Na+/K+ pump).

   • Secondary Active Transport – Uses the gradient of one molecule to move another against its gradient.

Penetrating vs. Non-Penetrating Solutes:

• Penetrating solutes (e.g., ethanol) can cross the membrane, affecting water movement.

• Non-penetrating solutes (e.g., Na+, Cl-) cannot cross and influence water movement by osmosis.

Osmolarity Calculations:

• Osmolarity = concentration of solute particles in solution.

• Example: 1M NaCl → 2 Osm/L (because NaCl dissociates into two ions).

Predicting Diffusion and Osmosis Direction:

• Diffusion: Movement from higher to lower concentration.

• Osmosis: Water moves toward the higher solute concentration.

Tonicity:

• Isotonic: Equal solute concentration inside and outside the cell.

• Hypotonic: Lower solute concentration outside, water enters the cell.

• Hypertonic: Higher solute concentration outside, water exits the cell.

Carrier-Mediated Transport:

• Characteristics: Transport proteins bind to molecules, causing a conformational change to move the molecule across the membrane.

• Types: Symport (same direction), Antiport (opposite direction).

Fick’s Law of Diffusion:

• Fick’s Law: Rate of diffusion = (Concentration gradient × Surface area × Permeability) / Distance.

• Increasing any of the variables (except distance) increases the rate of diffusion.

Fluid Compartments of the Body:

• Intracellular Fluid (ICF): Inside cells (about 2/3 of body water).

• Extracellular Fluid (ECF): Outside cells (about 1/3 of body water), including:

  • Interstitial Fluid: Surrounding cells.

  • Plasma: Found in blood vessels.