Fundamentals of Organic Molecules, Cell Structure, and Physiology

Organic Molecules and Macromolecules

Definition and Composition

Organic molecules are essential compounds in living organisms, characterized by the presence of both carbon and hydrogen atoms. They form the basis of life and are involved in various biological processes.

• Key Elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), sometimes Phosphorus (P) and Sulfur (S). (CHON, sometimes CHONPS)

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, but standard academic context)

Protein Structure

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

• Primary Structure: The unique sequence of amino acids in a polypeptide chain, held together by peptide bonds.

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

• Tertiary Structure: The overall three-dimensional shape of a single polypeptide, formed by interactions among R-groups, including covalent and noncovalent bonds.

• Quaternary Structure: The assembly of multiple polypeptide subunits into a functional protein complex (e.g., hemoglobin).

Denaturation: Loss of protein shape due to heat, pH changes, 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 attractions between polar molecules, important in water and biological macromolecules

Cell Structure and Function

Organelles and Their Functions

• Mitochondria: Site of energy (ATP) production

• Ribosomes: Site of protein synthesis

• Smooth Endoplasmic Reticulum (ER): Lipid synthesis

• Nucleus: Nucleic acid (DNA, RNA) synthesis

Macromolecule Synthesis Sites

• Proteins: Ribosomes

• Lipids: Smooth ER

• Nucleic acids: Nucleus

Protein Synthesis Steps

1. Transcription: DNA is transcribed to mRNA in the nucleus

2. Translation: mRNA is translated into protein at the ribosome

Primary Tissue Types

• Epithelial

• Connective

• Muscle

• Nervous

Cell Transport Mechanisms

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

Transport of Water, Ions, and Molecules

• Water: Osmosis

• Ions: Ion channels and pumps

• Small molecules: Simple diffusion

• Large molecules: Endocytosis and exocytosis

Cell Membrane Structure

• Phospholipid Bilayer: Main structural component

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

Cell Junctions

• Tight Junctions: Seal cells together

• Desmosomes: Provide mechanical strength by anchoring cells

• Gap Junctions: Allow direct passage of molecules and ions between cells

Enzymes

Properties and Functions

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

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

• Function: Control rates of chemical reactions, communication, and metabolism

Metabolism and Energy Production

Aerobic vs. Anaerobic Respiration

• Aerobic Respiration: Uses oxygen, produces approximately 36 ATP per glucose molecule

• Anaerobic Respiration: No oxygen, produces approximately 2 ATP and lactic acid

Glycolysis and Citric Acid Cycle

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

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

Key Equations:

• $\text{Glucose} + 6\ O_2 \rightarrow 6\ CO_2 + 6\ H_2O + 36\ ATP$ (Aerobic respiration)

• $\text{Glucose} \rightarrow 2\ Lactate + 2\ ATP$ (Anaerobic respiration)

Physiology of Diabetes

Types of Diabetes

• Type 1 Diabetes: Autoimmune destruction of insulin-producing beta cells; requires insulin injections

• Type 2 Diabetes: Body cells become resistant to insulin; often associated with obesity and lifestyle factors

Hormonal Regulation of Blood Glucose

• Insulin: Lowers blood sugar by promoting glucose uptake into cells

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

Beta Cell Function

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

Other Key Concepts

Isotopes

• Atoms of the same element with different numbers of neutrons (e.g., Carbon-12 vs. Carbon-14)

Fatty Acids: Saturated vs. Unsaturated

Type	Structure	Example	Health Impact
Saturated	No double bonds, solid at room temperature	Butter	Less healthy in excess
Unsaturated	One or more double bonds, liquid at room temperature	Olive oil	Healthier
Trans fat	Artificial, hydrogenated oils	Margarine	Unhealthy

Cell Growth and Death

Term	Definition
Hypertrophy	Cells get bigger
Hyperplasia	More cells form
Necrosis	Cells die from damage
Apoptosis	Programmed cell death

Na+/K+ Pump

• Moves 3 Na+ out, 2 K+ in, using ATP

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

Summary Table: Cell Transport Mechanisms

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

Additional info: Nucleic acid monomers, details of protein synthesis, and some tissue types were inferred from standard academic context.