Core Concepts in Anatomy & Physiology: Organic Molecules, Cell Structure, and Physiology

Organic Molecules and Macromolecules

Definition and Composition

Organic molecules are fundamental to living organisms, primarily composed of carbon and hydrogen, often with oxygen, nitrogen, phosphorus, and sulfur (CHON or CHONPS).

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

• Elements involved: Carbon, Hydrogen, Oxygen, Nitrogen, sometimes Phosphorus and Sulfur.

Monomers of Biological Macromolecules

• Proteins: Amino acids

• Fats (Lipids): Glycerol and fatty acids

• Carbohydrates: Monosaccharides (simple sugars, e.g., glucose)

• Nucleic acids: Nucleotides (Additional info: not explicitly listed in the notes)

Protein Structure

Proteins have four levels of structure, each contributing to their function:

• Primary: Sequence of amino acids in a polypeptide chain; determines the protein's unique characteristics.

• Secondary: Local folding into structures like alpha-helices and beta-sheets, stabilized by hydrogen bonds between nearby amino acids.

• Tertiary: Three-dimensional folding due to interactions among R-groups (side chains), including covalent and noncovalent bonds.

• Quaternary: Association of multiple polypeptide subunits; e.g., hemoglobin is made from four globular protein subunits.

Protein Denaturation

• Definition: 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 cell death)

Cell Transport and Membrane Structure

Modes of Cell Transport

• Passive transport: No energy required; includes diffusion, osmosis, and facilitated diffusion

• Active transport: Requires energy (ATP); includes pumps, endocytosis, and 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, considered unhealthy

Cell Membrane Structure

• Phospholipid bilayer: Main structural component

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

Na+/K+ Pump Function

• Moves 3 Na+ out, 2 K+ in, using ATP

• Keeps cell electrically balanced and ready for nerve/muscle function

Enzymes and Their Properties

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

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

• Function: Controls what enters/exits, communication

Cell Organelles and Their Functions

• Mitochondria: Energy (ATP) production

• Ribosomes: Protein synthesis

• Synthesis sites:

  • Proteins – ribosomes

  • Lipids – smooth endoplasmic reticulum (ER)

  • Nucleic acids – nucleus

Genetics and Protein Synthesis

• DNA → mRNA: Transcription (in nucleus)

• mRNA → Protein: Translation (at ribosome)

Tissue Types

• Epithelial

• Connective

• Muscle

• Nervous

Cell Junctions

• Tight junctions: Seal cells together

• Desmosomes: Anchor cells for strength

• Gap junctions: Allow molecules/ions to pass directly

Metabolism and Energy Production

Aerobic vs. Anaerobic Respiration

• Aerobic: Uses oxygen, produces ~36 ATP per glucose

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

Glycolysis and Citric Acid Cycle

• Glycolysis: Occurs in cytoplasm; input is glucose, output is pyruvate, ATP, and NADH

• Citric Acid Cycle (Krebs): Occurs in mitochondria; input is pyruvate, output is CO2, NADH, FADH2, and ATP

Key Equations:

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

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

Diabetes 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

• 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 (e.g., Carbon-12 vs. Carbon-14)

Summary Table: Cell Junctions

Junction Type	Main Function	Structure
Tight Junction	Seal cells together	Membrane proteins
Desmosome	Anchor cells for strength	Protein plaques and filaments
Gap Junction	Allow molecules/ions to pass directly	Connexon protein channels

Additional info: Some explanations and examples were expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.