Fundamental Concepts in Anatomy & Physiology: Biomolecules, Cell Structure, and Metabolism

Organic Molecules and Biomolecules

Definition and Composition

Organic molecules are essential components of living organisms, characterized by the presence of both carbon and hydrogen atoms.

• Organic Molecules: Molecules containing carbon and hydrogen in living things.

• Main Elements: Carbon, hydrogen, oxygen, nitrogen, sometimes phosphorus and sulfur (CHON or CHONPS).

Monomers of Major Biomolecules

Biomolecules are polymers made from repeating monomer units.

• Proteins: Amino acids

• Fats (Lipids): Glycerol and fatty acids

• Carbohydrates: Monosaccharides (simple sugars like glucose)

• Nucleic Acids: Nucleotides

Protein Structure

Proteins have four levels of structural organization, each contributing to their function.

• Primary Structure: Sequence of amino acids in a polypeptide chain.

• Secondary Structure: Local folding into alpha helices or beta sheets due to hydrogen bonding between nearby amino acids.

• Tertiary Structure: Three-dimensional folding driven by covalent and noncovalent interactions.

• Quaternary Structure: Assembly of multiple polypeptide subunits (e.g., hemoglobin).

Denaturation: Loss of protein shape due to heat, pH, or chemicals, resulting in loss of function.

Major Chemical Bonds in Biology

• Ionic Bonds: Transfer of electrons (e.g., NaCl, sodium chloride)

• Covalent Bonds: Sharing of electrons (e.g., H2O, CO2)

• Hydrogen Bonds: Weak bonds between molecules, important in water and DNA structure

Cell Growth and Death: Hypertrophy, Hyperplasia, Necrosis, Apoptosis

• Hypertrophy: Cells get bigger

• Hyperplasia: More cells form

• Necrosis: Cell death from damage

• Apoptosis: Programmed cell death (clean, controlled)

Cell Transport and Membrane Structure

Modes of Cell Transport

Cells move substances across membranes using passive and active mechanisms.

• Passive Transport: No energy required (diffusion, osmosis, facilitated diffusion)

• Active Transport: Requires energy/ATP (pumps, endocytosis, exocytosis)

Saturated vs. Unsaturated Fats

• Saturated Fats: No double bonds, solid at room temperature (e.g., butter)

• Unsaturated Fats: Double bonds, liquid at room temperature (e.g., olive oil)

• Trans Fats: Artificial, hydrogenated oils, unhealthy

Cell Membrane Structure

• Phospholipid Bilayer: Forms the basic structure of cell membranes

• Membrane Proteins: Act as channels, pumps, and receptors

Cell Junctions

Type	Function
Tight Junctions	Seal cells together
Desmosomes	Anchor cells for strength
Gap Junctions	Allow molecules/ions to pass directly

Na+/K+ Pump

• Function: Moves 3 Na+ out, 2 K+ in, using ATP

• Purpose: Maintains electrical balance, essential for nerve and muscle function

Enzymes and Their Properties

Enzyme Properties and Examples

• Properties: Speed up reactions, reusable, specific to one reaction

• Examples: Amylase (starch → sugar), Lipase (fats → fatty acids)

• Function: Controls what enters/exits, communication

Cellular Organelles and Synthesis

Function of Major Organelles

• Mitochondria: Energy (ATP) production

• Ribosomes: Protein synthesis

Sites of Synthesis

• Proteins: Ribosomes

• Lipids: Smooth endoplasmic reticulum (ER)

• Nucleic Acids: Nucleus

Protein Synthesis Steps

1. DNA → mRNA (transcription, nucleus)

2. mRNA → protein at ribosome (translation)

Tissue Types

• Epithelial

• Connective

• Muscle

• Nervous

Metabolism: Glycolysis and Citric Acid Cycle

Aerobic vs. Anaerobic Respiration

• Aerobic: Uses oxygen, produces ~36 ATP

• Anaerobic: No oxygen, produces ~2 ATP (lactic acid formed)

Glycolysis

• Location: Cytoplasm

• Process: Input glucose, output pyruvate, small ATP

• Equation: $\text{Glucose} + 2\text{NAD}^+ + 2\text{ADP} + 2\text{P}_i \rightarrow 2\text{Pyruvate} + 2\text{NADH} + 2\text{ATP} + 2\text{H}_2\text{O}$

Citric Acid Cycle (Krebs Cycle)

• Location: Mitochondria

• Process: Input pyruvate, output CO2, NADH, FADH2, ATP

• Equation: $\text{Acetyl-CoA} + 3\text{NAD}^+ + \text{FAD} + \text{ADP} + \text{P}_i \rightarrow 2\text{CO}_2 + 3\text{NADH} + \text{FADH}_2 + \text{ATP} + \text{CoA}$

Diabetes Physiology and Hormonal Regulation

Types of Diabetes

• Type 1: Immune system destroys insulin-producing cells; requires insulin injections

• Type 2: Body cells resist insulin, often linked to obesity/lifestyle

Insulin and Glucagon Regulation

• Insulin: Lowers blood sugar by moving glucose into cells

• Glucagon: Raises blood sugar by signaling the liver to release stored glucose

Beta Cell Function

• Beta cells in the pancreas sense high blood glucose and release insulin

Isotopes

• Definition: Atoms of the same element with different numbers of neutrons

• Example: Carbon-12 vs. Carbon-14

Summary Table: Cell Transport Mechanisms

Type	Energy Required?	Examples
Passive	No	Diffusion, osmosis, facilitated diffusion
Active	Yes (ATP)	Pumps, endocytosis, exocytosis

Additional info:

• Some explanations and equations have been expanded for clarity and completeness.

• Scientific names and terms have been italicized where appropriate.