CAPE Biology Unit One Manual - Cell and Molecular Biology

This module covers four main topics:

The human body is made up of various elements that form molecules including:
- Macronutrients:
- Carbohydrates (e.g., starch, glucose): Needed for ATP release.
- Proteins: Essential for cell growth and repair; hormones production.
- Fats: Function as an energy store.
Water makes up over 70% of a cell’s mass.
Molecular structure of water:
- Comprised of two hydrogen atoms covalently bonded to one oxygen atom.
- Oxygen is negatively charged (δ-) while hydrogen is positively charged (δ+).
- Results in a dipole creating hydrogen bonds critical for biological processes.

Temperature Regulation: High specific heat capacity, evaporative cooling.
Universal Solvent: Small charges attract molecules or ions, forming bonds.
Mass Flow: Cohesive properties lead to mass flow in plant systems.
Hydrogen Bonds: Important for the stability of biological molecules.
Neutral pH: Buffers and allows the absorption of H⁺ or OH⁻ ions.
Reactivity: Participates in hydrolysis reactions, crucial for digestion and photosynthesis.

Definition: Organic molecules made up of carbon, hydrogen, and oxygen.
Types:
- Monosaccharides (one unit): e.g., glucose (C₆H₁₂O₆).
- Disaccharides (two units): e.g., sucrose formed from glucose and fructose via glycosidic bond.
- Polysaccharides (many units): e.g., starch, glycogen, cellulose.
- Glycosidic bonds formed via condensation reactions, strong linkage.
Differences in Sugar Types:
- Reducing vs non-reducing sugars based on glycosidic bond reactivity.

Starch: Energy reserve in plants, stored in plastids; composed of amylose and amylopectin.
Glycogen: Energy source in animals, stored in liver and muscle cells.
Cellulose: Structural component of cell walls; forms strong hydrogen bond bundles.

Summary Table of Polysaccharides

Feature	Amylose	Glycogen	Cellulose
Sugar unit	α-glucose	α-glucose	β-glucose
Overall shape	Linear/spiral	Branched	Linear
Solubility in water	Insoluble	Insoluble	Insoluble
Glycosidic bond type	α 1-4	α 1-4 & α 1-6	β 1-4
H-bonds	Within	Within	Within/between
Location	Starch grains	Liver cells	Cell walls

Hydrolysis Reaction: Breaks covalent bonds; requires water.
Condensation Reaction: Forms bonds; may release water (dehydration).
Hydrogen Bonds: Formed between water molecules; important in biochemical interactions.

Lipids: Higher hydrogen ratio; insoluble in water; includes fats and oils.
Triglycerides: Composed of three fatty acids bound to glycerol; hydrophobic.
- Saturated (more H⁺) and unsaturated (double bonds, bend structure).
- Stored in adipose tissue for energy; linked to obesity if accumulated.
- Trans fats: Created through hydrogenation, associated with health risks.

Structure: Glycerol, two fatty acids replaced by a phosphate group creating a bilayer in membranes.
Function: Critical for plasma membranes, maintaining cellular integrity.

Proteins: Made of amino acids, used for growth and repair.
Structure: Central carbon with amino group, carboxyl group, hydrogen, and R group.
Peptide Bonds: Strong bonds linking amino acids, formed through condensation reactions.

Enzymes, used to catalyze metabolic reactions, are globular proteins.
They function by lowering activation energy and form enzyme-substrate complexes.
Factors affecting enzyme activity:
- Temperature: Each enzyme has an optimum temperature range.
- pH: Enzyme structure can be denatured by extreme pH.
- Concentration: Both substrate and enzyme concentrations can influence reaction speed.
Inhibitors: Competitive (block active site) and non-competitive (affect enzyme shape).

Describes plasma membrane structure as a mosaic of different proteins embedded in a fluid phospholipid bilayer.