General Biology: Foundations, Chemistry, and Water

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Chapter 1: Foundations of Biology

Correlation of Structure and Function

In biology, the structure of an organism or its components is closely related to their function. Understanding this relationship helps explain how biological systems work.

Structure: The physical arrangement or organization of biological molecules, cells, or organs.
Function: The role or activity performed by a biological structure.
Example: The shape of red blood cells allows them to efficiently transport oxygen.

The Cell: An Organism’s Basic Unit of Structure and Function

Cells are the fundamental units of life, performing all necessary functions for survival and reproduction.

Prokaryotic cells: Lack a nucleus and membrane-bound organelles (e.g., bacteria).
Eukaryotic cells: Have a nucleus and membrane-bound organelles (e.g., plants, animals).
Example: Escherichia coli is a prokaryote; human cells are eukaryotic.

Feedback Regulation: Negative vs Positive

Feedback mechanisms help maintain homeostasis in biological systems.

Negative feedback: Reduces the output or activity to maintain equilibrium (e.g., body temperature regulation).
Positive feedback: Enhances or amplifies changes (e.g., blood clotting).

Data: Qualitative vs Quantitative

Biological research relies on data collection and analysis.

Qualitative data: Descriptive, non-numerical information (e.g., color, shape).
Quantitative data: Numerical measurements (e.g., length, mass).

Scientific Reasoning and Experimentation

Inductive reasoning: Drawing general conclusions from specific observations.
Deductive reasoning: Making predictions based on general principles.
Hypothesis: A testable statement explaining observations.
Experiment: A controlled procedure to test a hypothesis.
Variables and Controls:
- Independent variable: The factor changed by the experimenter.
- Dependent variable: The factor measured in response.
- Control: Standard for comparison.
Theory: A well-substantiated explanation of natural phenomena.
Model Organism: Drosophila: Drosophila melanogaster (fruit fly) is widely used in genetic research.

Chapter 2: Chemistry of Life

Matter, Elements, and Compounds

All living things are composed of matter, which consists of elements and compounds.

Matter: Anything that has mass and occupies space.
Element: A substance that cannot be broken down by chemical means.
Compound: A substance formed by two or more elements in fixed ratios.

Atoms and Subatomic Particles

Atoms are the smallest units of elements, composed of subatomic particles.

Protons: Positively charged particles in the nucleus.
Neutrons: Neutral particles in the nucleus.
Electrons: Negatively charged particles orbiting the nucleus.

Structure of the Atom

Atoms consist of a central nucleus (protons and neutrons) surrounded by electrons in orbitals.

Atomic Number and Mass Number

Atomic number: Number of protons in the nucleus.
Mass number: Total number of protons and neutrons.
Formula:

Isotopes and Radioactive Isotopes

Isotopes: Atoms of the same element with different numbers of neutrons.
Radioactive isotopes: Unstable isotopes that decay, emitting radiation (used in dating fossils, medical imaging).

Energy Levels of Electrons

Electrons occupy energy levels or shells around the nucleus.

Potential energy: Energy due to position in electron shells.
Electron shells: Specific energy levels where electrons reside.

Electron Distribution and Orbitals

Valence electrons: Electrons in the outermost shell, important for chemical bonding.
Electron orbital: Region of space where an electron is likely to be found (s, p orbitals).
Example: s orbital holds 2 electrons; p orbital holds 6 electrons.

Chemical Bonds

Covalent bonds: Sharing of electron pairs between atoms.
Ionic bonds: Transfer of electrons from one atom to another, forming charged ions.
Hydrogen bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., water, ammonia).
Van der Waals interactions: Weak, transient interactions due to fluctuating charges.

Molecular Shape and Function

s orbital: Spherical, holds 2 electrons.
p orbital: Dumbbell-shaped, holds 6 electrons.
Electron configuration: Determines chemical properties and reactivity.

Chemical Reactions and Equilibrium

Reactants: Substances that start a chemical reaction.
Products: Substances formed by the reaction.
Chemical equilibrium: State where forward and reverse reactions occur at equal rates.

Chapter 3: Water and Its Properties

Polar Covalent Bonds and Hydrogen Bonding

Water molecules have polar covalent bonds, leading to hydrogen bonding between molecules.

Polarity: Unequal sharing of electrons creates partial charges.
Hydrogen bonds: Attraction between the hydrogen of one water molecule and the oxygen of another.

Emergent Properties of Water

Water exhibits unique properties essential for life.

Cohesion: Water molecules stick together via hydrogen bonds.
Adhesion: Water molecules stick to other surfaces.
Surface tension: Resistance of water surface to external force.
Moderation of temperature: Water resists changes in temperature due to high specific heat.
Expansion upon freezing: Ice is less dense than liquid water.
Versatility as a solvent: Water dissolves many substances due to polarity.
Acids, bases, salts: Water can dissociate into ions, affecting pH.
pH scale: Measures hydrogen ion concentration;
Buffers: Substances that minimize changes in pH.

Chapter 4: Organic Chemistry and Biological Molecules

Organic Chemistry and the Origin of Life

Organic chemistry studies carbon-based compounds, which are fundamental to life.

Electron configuration: Carbon forms four covalent bonds, allowing for diverse molecules.

Diversity of Carbon Compounds

Chain length: Hydrocarbons and fats vary in length.
Branching: Carbon chains can be branched or unbranched.
Double bonds: Can be cis (same side) or trans (opposite sides); affects molecule shape.
Isomers: Molecules with the same formula but different structures (structural, cis/trans, enantiomers).

Functional Groups

Functional groups: Specific groups of atoms that confer particular properties (e.g., hydroxyl, carboxyl, amino).

ATP

ATP (Adenosine Triphosphate): The primary energy carrier in cells.
Formula: