Unit 1 - Biochemistry

Unit 1 - Biochemistry

Biochemical Compounds

  • Life functions include digesting nutrients, excreting waste, synthesizing chemicals, and reproducing.

  • The basic unit of life is the cell, and new cells arise from existing cells.

Cell Structure
Components of a Cell:

  • Nucleus:

    • Control center of the cell.

    • Contains chromosomes made of DNA, which encase genes that encode proteins.

  • Cell Membrane:

    • Surrounds the cell; composed of a lipid bilayer.

    • Functions to selectively regulate transport in and out of the cell.

  • Cytoplasm:

    • Fluid medium inside cells that transports nutrients and waste.

  • Mitochondria:

    • Powerhouse of the cell; produces energy through cellular respiration.

    • Contains its own DNA and has a dual membrane structure.

  • Ribosomes:

    • Sites of protein synthesis, composed of amino acid chains (20 types).

  • Lysosomes:

    • Contain enzymes that degrade cellular waste and bacteria; play a role in cellular immunity.

  • Vacuole:

    • Stores materials and provides support, particularly in plant cells.

  • Plastids:

    • Chloroplasts: Perform photosynthesis and contain chlorophyll and their own DNA.

    • Chromoplasts: Store pigments (e.g., orange, yellow).

    • Amyloplasts: Store starch.

Extracellular Fluid

  • Composed primarily of water and salts.

  • Maintains homeostasis and aids in the transport of fluids and nutrients.

Water Properties

  • Hydrogen Bonds: Strong attraction forces when hydrogen bonds with N, O, or F.

  • Miscibility:

    • Miscible Liquid: Can dissolve in another liquid.

    • Immiscible Liquid: Does not mix (e.g., oil in water).

    • Hydrophobic: Nonpolar molecules avoid water.

Organic Compounds

  • Hydrocarbons: Composed of carbon and hydrogen; typically nonpolar.

Macromolecules
Proteins

  • These are composed of amino acids linked by peptide bonds.

  • Functions include catalyzing reactions, providing structural support, facilitating transport, enabling movement, and immune defense.

  • Amino Acids Structure: Central carbon atom, amino group, carboxyl group, hydrogen, and variable R group.

  • Types of Amino Acids:

    • 20 total: 8 essential and 12 non-essential.

  • Polypeptide: A chain of amino acids forming a functional protein; requires proper structure.

Protein Structure Levels

  • Primary Structure: The sequence of amino acids in a chain.

  • Secondary Structure: Forms α-helices and β-sheets, stabilized by hydrogen bonds.

  • Tertiary Structure: The overall 3D shape formed from R-group interactions.

  • Quaternary Structure: Composed of multiple polypeptide chains (e.g., hemoglobin).

Carbohydrates

  • Monomers: Monosaccharides linked by glycosidic bonds.

  • Forms:

    • Monosaccharides: Simple sugars (e.g., glucose, fructose).

    • Disaccharides: Two monosaccharides combined (e.g., maltose, sucrose).

    • Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

Polysaccharide Characteristics

  • Starch: Energy storage in plants; easily digestible.

  • Glycogen: Energy storage in animals; highly branched and easy to digest.

  • Cellulose: Provides structural integrity in plants; indigestible by humans.

Lipids

  • Composed of C, H, and O with many C-H bonds.

  • Functions include energy storage, forming cell membranes, signaling, insulation, and protection.

  • Types of Lipids:

    • Triglycerides: Three fatty acids linked to glycerol.

    • Phospholipids: Contains glycerol, two fatty acids, and a phosphate group.

    • Steroids: Diverse structures including hormones.

    • Waxes: Solid at room temperature; provide waterproofing.

Fatty Acid Types

  • Saturated: No double bonds, solid at room temperature.

  • Unsaturated: Contains one or more double bonds; typically liquid at room temperature.

Nucleic Acids

  • General Structure: Composed of nucleotide monomers linked by phosphodiester bonds.

  • Components of Nucleotide: Pentose sugar, phosphate group, and nitrogen base.

DNA and RNA

  • DNA: Encodes genetic material; double-stranded, contains deoxyribose.

  • RNA: Single-stranded, involved in protein synthesis; contains ribose.

  • Nitrogenous Bases: Includes purines (adenine, guanine) and pyrimidines (thymine, cytosine, uracil).

Movement of Substances

  • Cell Membrane Transport Mechanisms:

    • Passive Transport: Movement along concentration gradients without energy.

    • Active Transport: Movement against concentration gradients; requires energy.

    • Endocytosis/Exocytosis: Engulfing large particles or expelling waste.

    • Diffusion: Movement from high to low concentration.

    • Facilitated Diffusion: Requires transport proteins for larger polar molecules.

    • Osmosis: Movement of solvent through semipermeable membranes.

  • Fluid Mosaic Model: Describes the cell membrane structure with proteins embedded in a phospholipid bilayer.