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

Overview

This study guide covers foundational topics in General Biology, including the scientific method, biochemistry, cell structure and function, and cell division. It is organized to help students prepare for exams and understand key concepts, vocabulary, and processes relevant to introductory college biology.

Scientific Method and Biochemistry

Scientific Method

The scientific method is a systematic approach used to investigate natural phenomena and acquire new knowledge.

• Observation: Gathering information about the natural world.

• Hypothesis: A testable explanation for an observation.

• Experiment: A controlled procedure to test the hypothesis.

• Data Collection: Gathering and recording results.

• Analysis: Interpreting data to draw conclusions.

• Conclusion: Determining whether the hypothesis is supported or refuted.

• Variables: Independent variable (manipulated), dependent variable (measured), and control variables (kept constant).

Example: Testing the effect of sunlight on plant growth by varying light exposure and measuring plant height.

Biochemistry

Biochemistry focuses on the chemical processes and substances that occur within living organisms.

• Atoms and Molecules: Atoms are the basic units of matter; molecules are combinations of atoms.

• Macromolecules: Large molecules essential for life, including carbohydrates, proteins, lipids, and nucleic acids.

• Water: Essential for life due to its polarity, cohesion, adhesion, and ability to dissolve many substances.

• Enzymes: Biological catalysts that speed up chemical reactions without being consumed.

Macromolecule	Monomer	Function
Carbohydrates	Monosaccharides	Energy storage, structure
Proteins	Amino acids	Enzymes, structure, transport
Lipids	Fatty acids, glycerol	Energy storage, membranes
Nucleic Acids	Nucleotides	Genetic information

Example: Enzymes like amylase help break down starch into sugars during digestion.

Cells and Cell Membranes

Cell Theory and Types of Cells

Cells are the basic units of life. All living things are composed of cells, which arise from pre-existing 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).

Three Parts of Cell Theory:

1. All living things are made of cells.

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

3. All cells come from pre-existing cells.

Cell Structure and Function

• Nucleus: Contains genetic material (DNA).

• Mitochondria: Site of cellular respiration and energy production.

• Chloroplasts: Site of photosynthesis in plant cells.

• Endoplasmic Reticulum (ER): Synthesizes proteins and lipids.

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

• Lysosomes: Contain digestive enzymes to break down waste.

• Cell Membrane: Regulates what enters and leaves the cell; composed of a phospholipid bilayer.

Homeostasis and Transport

• Homeostasis: Maintenance of a stable internal environment.

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

• Active Transport: Movement of substances against a concentration gradient using energy (ATP).

• Feedback Mechanisms: Systems that maintain homeostasis (e.g., negative feedback loops).

Example: The sodium-potassium pump actively transports Na+ and K+ ions across the cell membrane.

Cell Division: Mitosis, Meiosis, and Cancer

Mitosis

Mitosis is the process by which somatic (body) cells divide to produce two genetically identical daughter cells.

• Phases of Mitosis: Prophase, Metaphase, Anaphase, Telophase

• Cytokinesis: Division of the cytoplasm

• Purpose: Growth, repair, and asexual reproduction

Equation:

$ext{Parent cell (2n)} ightarrow ext{2 Daughter cells (2n)}$

Meiosis

Meiosis is the process by which gametes (sperm and egg cells) are produced, resulting in four genetically unique daughter cells with half the chromosome number of the parent cell.

• Phases: Meiosis I and Meiosis II

• Genetic Variation: Crossing over and independent assortment

• Purpose: Sexual reproduction

Equation:

$ext{Parent cell (2n)} ightarrow ext{4 Gametes (n)}$

Cancer

Cancer is caused by uncontrolled cell division due to mutations in genes that regulate the cell cycle.

• Cell Cycle Regulation: Controlled by checkpoints and regulatory proteins.

• Mutations: Changes in DNA that can lead to cancer if they affect genes controlling cell division.

Example: Tumor suppressor genes and oncogenes play roles in cancer development.

Vocabulary

Key terms to know include: hypothesis, variable, control, theory, homeostasis, organelle, mitochondria, nucleus, prokaryote, eukaryote, diffusion, osmosis, mitosis, meiosis, cancer, chromosome, gene, allele, genotype, phenotype, dominant, recessive, homozygous, heterozygous, Punnett square, and more.

Additional info:

• Students should be able to compare and contrast prokaryotic and eukaryotic cells, and understand the hierarchical organization of life (cells, tissues, organs, organ systems, organisms).

• Practice with diagrams, models, and vocabulary is recommended for mastery.