General Biology Study Guide: Scientific Method, Biochemistry, Cells, and Cell Division

Overview of Units and Learning Targets

This study guide covers foundational topics in General Biology, including the scientific method, biochemistry, cell structure and function, and cell division. Each unit is organized by key concepts, learning objectives, and essential vocabulary to support exam preparation and mastery of biological principles.

Scientific Method and Biochemistry

Scientific Method

• Definition: The scientific method is a systematic approach to understanding the natural world through observation, hypothesis formation, experimentation, and analysis.

• Key Steps:

  • Observation

  • Formulation of a hypothesis

  • Designing and conducting experiments (including variables and controls)

  • Data collection and analysis

  • Drawing conclusions

  • Communication of results

• Experimental Design: Includes independent and dependent variables, control groups, and replication.

• Example: Testing the effect of sunlight on plant growth by comparing plants grown in sunlight versus darkness.

Biochemistry

• Definition: Biochemistry is the study of the chemical processes within and related to living organisms.

• Major Biomolecules:

  • Carbohydrates

  • Proteins

  • Lipids

  • Nucleic acids

• Properties of Water: Polarity, cohesion, adhesion, high specific heat, and its role as a universal solvent.

• Enzymes: Biological catalysts that speed up chemical reactions by lowering activation energy.

• Example: Amylase breaking down starch into glucose during digestion.

Cells and Cell Membranes

Cell Theory and Types of Cells

• Three Parts of Cell Theory:

  1. All living things are composed of cells.

  2. Cells are the basic unit of structure and function in living things.

  3. All cells come from pre-existing cells.

• Prokaryotic vs. Eukaryotic Cells:

  • 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).

Cell Structure and Function

• Major Organelles:

  • Nucleus: Contains genetic material (DNA).

  • Mitochondria: Site of cellular respiration and energy production.

  • Chloroplasts: Site of photosynthesis in plant cells.

  • Endoplasmic Reticulum (ER): Protein and lipid synthesis.

  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.

  • Lysosomes: Contain digestive enzymes.

  • Vacuoles: Storage of substances.

  • Cell Membrane: Regulates movement of substances in and out of the cell.

• Levels of Organization: Cell → Tissue → Organ → Organ System → Organism

Cell Membrane and Homeostasis

• Structure: Phospholipid bilayer with embedded proteins.

• Functions: Selective permeability, communication, and transport.

• Transport Mechanisms:

  • Passive Transport: Diffusion, osmosis, facilitated diffusion (no energy required).

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

• Homeostasis: Maintenance of a stable internal environment.

• Feedback Mechanisms: Negative and positive feedback loops regulate physiological processes.

• Example: Regulation of blood glucose levels by insulin and glucagon.

Cell Division (Mitosis, Meiosis, and Cancer)

Mitosis

• Purpose: Growth, repair, and asexual reproduction.

• Main Stages: Prophase, Metaphase, Anaphase, Telophase, followed by Cytokinesis.

• Result: Two genetically identical diploid daughter cells.

• Regulation: Cell cycle checkpoints control progression; disruptions can lead to cancer.

Meiosis

• Purpose: Production of gametes (sperm and egg) for sexual reproduction.

• Main Stages: Meiosis I and Meiosis II, each with Prophase, Metaphase, Anaphase, and Telophase.

• Result: Four genetically unique haploid cells.

• Genetic Variation: Crossing over and independent assortment increase diversity.

Cancer

• Definition: Uncontrolled cell division due to mutations in genes regulating the cell cycle.

• Causes: Genetic mutations, environmental factors, and lifestyle choices.

• Example: Tumor suppressor gene mutations leading to loss of cell cycle control.

Key Vocabulary

• Scientific Method: Hypothesis, variable, control, theory, experiment

• Biochemistry: Atom, molecule, enzyme, carbohydrate, lipid, protein, nucleic acid, pH, buffer

• Cells: Prokaryote, eukaryote, organelle, mitochondria, chloroplast, nucleus, cytoplasm, membrane

• Cell Division: Mitosis, meiosis, chromosome, chromatid, spindle, cytokinesis, cancer, tumor

Sample Table: Comparison of Mitosis and Meiosis

Feature	Mitosis	Meiosis
Number of Divisions	1	2
Number of Daughter Cells	2	4
Genetic Identity	Identical	Unique
Chromosome Number	Diploid (2n)	Haploid (n)
Function	Growth, repair, asexual reproduction	Sexual reproduction (gametes)

Sample Equations

• Photosynthesis: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$

• Cellular Respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$

Additional Info

• Practice assignments and dynamic study modules are recommended for further review.

• Vocabulary lists and video resources are available for each unit.