Intro to Biology and Chemistry of Life

Chapters 1-3: Intro Biology, Chemistry of Life, Macromolecules & Cells

Basic Principles of Biology

• Characteristics of Life:

  • Organization: All living organisms exhibit structured organization from cells to complex organisms.

  • Metabolism: All living organisms engage in metabolic processes that involve energy transformation and matter utilization.

  • Homeostasis: Living organisms maintain stable internal conditions despite external environmental changes.

  • Growth: Organisms exhibit growth and development through cellular division and differentiation.

  • Response: Living beings respond to stimuli in their environment, demonstrating adaptability.

  • Reproduction: Capable of reproducing to ensure species continuity, either sexually or asexually.

• Levels of Biological Organization:

  • Begins at the atomic level and progresses through various hierarchical levels:

  • Atom

  • Molecule

  • Cell

  • Tissue

  • Organ

  • Organ System

  • Organism

• Anabolic vs Catabolic Reactions:

  • Anabolic Reactions: Constructive processes that build larger molecules from smaller ones, requiring energy (e.g., protein synthesis).

  • Catabolic Reactions: Degradative processes that break down larger molecules into smaller ones, releasing energy (e.g., cellular respiration).

Basic Chemistry

• Atomic Structure:

  • Consists of subatomic particles:

  • Protons: Positively charged particles located in the nucleus.

  • Neutrons: Neutral particles also found in the nucleus.

  • Electrons: Negatively charged particles that orbit the nucleus.

• Ions:

  • Cations: Positively charged ions formed by loss of electrons.

  • Anions: Negatively charged ions formed by gain of electrons.

• Chemical Bonds:

  • Ionic Bonds: Formed through the electrostatic attraction between oppositely charged ions.

  • Polar Covalent Bonds: Formed when electrons are shared unequally between atoms (e.g., H₂O).

  • Nonpolar Covalent Bonds: Formed when electrons are shared equally between identical atoms (e.g., O₂).

  • Hydrogen Bonds: Weak interactions between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Water & Solutions

• Water Polarity and Hydrogen Bonding:

  • Water is a polar molecule, with a partial negative charge near the oxygen atom and a partial positive charge near the hydrogen atoms.

• Cohesion: The tendency of water molecules to stick to each other, leading to surface tension.

• Adhesion: The tendency of water molecules to stick to other substances.

• High Specific Heat Capacity: Water can absorb significant amounts of heat without drastic temperature changes due to extensive hydrogen bonding.

• Hydration Spheres: Water molecules surround solutes, aiding in their dissolution.

• Types of Mixtures:

  • Solutions: Homogeneous mixtures where solute is dissolved in solvent.

  • Colloids: Mixtures where small particles are dispersed throughout but not fully dissolved (e.g., milk).

  • Suspensions: Heterogeneous mixtures where larger particles settle out over time (e.g., sand in water).

Macromolecules

• Monomers and Polymers:

  • Monomers: Basic building blocks of macromolecules (e.g., amino acids, nucleotides).

  • Polymers: Large molecules made up of repeating monomer units.

• Dehydration Synthesis and Hydrolysis:

  • Dehydration Synthesis: Process of joining two molecules by removing a water molecule, forming bonds between monomers.

  • Hydrolysis: Process of breaking down polymers into monomers by adding water.

• Major Macromolecules:

  • Carbohydrates: Include sugars and starches; primary source of energy.

  • Lipids: Fats and oils; involved in long-term energy storage, insulation, and cell membrane structure.

  • Proteins: Composed of amino acids; perform a vast array of functions (e.g., enzymes, structure, transport).

  • Nucleic Acids: DNA and RNA; responsible for genetic information storage and transfer.

Enzymes

• Function of Enzymes:

  • Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required for those reactions to occur.

Cell Membrane

• Phospholipid Bilayer Structure:

  • Comprised of a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails, creating a semi-permeable membrane barrier.

• Membrane Proteins: Essential components for various functions including transport, communication, and reaction catalysis.

• Selective Permeability: The ability of the cell membrane to allow certain substances to pass while excluding others, maintaining homeostasis.

Transport Mechanisms

• Passive Transport: Movement of substances across the membrane without the use of energy (e.g., diffusion, facilitated diffusion).

• Primary Active Transport: Requires energy (usually ATP) to move substances against their concentration gradient.

• Secondary Active Transport: Involves the movement of one substance down its gradient to drive the movement of another substance against its gradient.

• Tonicity Effects:

  • Isotonic: Equal concentration of solutes inside and outside the cell; no net movement of water.

  • Hypertonic: Higher concentration of solutes outside the cell; causes water to leave the cell, resulting in cell shrinkage.

  • Hypotonic: Lower concentration of solutes outside the cell; causes water to enter the cell, potentially resulting in swelling or bursting.

Key Short Response Topics

• Hydration Spheres and Molecular Polarity: Discuss the importance of hydration spheres in biological systems and how molecular polarity affects solvation.

• Protein Structure Levels and Function: Describe the four levels of protein structure (primary, secondary, tertiary, quaternary) and their functional implications.

• Steps of the Central Dogma: Overview of DNA transcription to RNA and RNA translation to protein, ensuring gene expression.

• Comparison of Membrane Transport Mechanisms: Analyze the differences between passive transport, primary active transport, and secondary active transport, with examples of each.