General Biology Unit 1 Review: Foundations, Biochemistry, Cell Biology, and Genetics

Unit I: What is Science?

Scientific Method and Experimental Design

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

• Controlled Experiment: An experiment in which only one variable is changed at a time, allowing for a clear interpretation of the effect of that variable.

• Inference vs. Observation: An observation is information gathered directly by the senses, while an inference is a logical interpretation based on observations.

• Experimental Design: Includes identifying independent and dependent variables, control and experimental groups, and the use of data tables and graphs for analysis.

Example: Testing the effect of sunlight on plant growth by keeping all other variables constant except the amount of sunlight.

Unit II: Biochemistry

Chemical Basis of Life

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

• Organic Molecules: Compounds containing carbon, such as carbohydrates, lipids, proteins, and nucleic acids.

• Monomer vs. Polymer: Monomers are small building blocks (e.g., glucose), while polymers are large molecules made of repeating monomers (e.g., starch).

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

• Examples:

  • Carbohydrate: Glucose (monosaccharide), starch (polysaccharide)

  • Lipid: Triglyceride

  • Protein: Enzyme

  • Nucleic Acid: DNA

Example: Recognizing that cellulose is a polysaccharide found in plant cell walls.

Unit III: Cell Biology

Cell Structure and Function

Cells are the basic units of life, with structures and organelles specialized for various functions.

• Prokaryotic vs. Eukaryotic Cells: Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

• Plant vs. Animal Cells: Plant cells have cell walls, chloroplasts, and large central vacuoles; animal cells do not.

• Organelles and Functions: Nucleus (genetic control), mitochondria (energy production), ribosomes (protein synthesis), endoplasmic reticulum (transport), Golgi apparatus (modification and packaging), lysosomes (digestion), cytoskeleton (structure and movement).

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

Example: Comparing the function of mitochondria (energy production) to that of chloroplasts (photosynthesis in plants).

Unit IV: Mitosis and Cell Division

Cell Cycle and Mitosis

Mitosis is the process by which a cell divides to produce two genetically identical daughter cells, essential for growth and repair.

• Phases of the Cell Cycle: Interphase (G1, S, G2), Mitosis (prophase, metaphase, anaphase, telophase), and Cytokinesis.

• Purpose: Growth, repair, and asexual reproduction in multicellular organisms.

Example: Identifying the stage of mitosis by the arrangement of chromosomes under a microscope.

Unit V: Meiosis and Genetics

Genetic Inheritance and Variation

Meiosis is the process that produces gametes (sperm and egg cells) with half the number of chromosomes, introducing genetic diversity.

• Phases of Meiosis: Meiosis I (separates homologous chromosomes), Meiosis II (separates sister chromatids).

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

• Punnett Squares: Tools used to predict the probability of offspring inheriting particular traits.

• Dominant vs. Recessive: Dominant alleles mask the effect of recessive alleles in heterozygotes.

• Genotype vs. Phenotype: Genotype is the genetic makeup; phenotype is the observable trait.

Example: Using a Punnett square to predict the outcome of a cross between two heterozygous pea plants (Tt x Tt) for tallness.

Sample Table: Comparison of Mitosis and Meiosis

Feature	Mitosis	Meiosis
Number of Divisions	1	2
Number of Daughter Cells	2	4
Genetic Identity	Identical to parent	Genetically unique
Chromosome Number	Diploid (2n)	Haploid (n)

Key Equations and Concepts

• Probability of Inheritance:

$P = \frac{\text{Number of desired outcomes}}{\text{Total number of possible outcomes}}$

• Cell Theory: All living things are composed of cells; cells are the basic units of structure and function; all cells come from pre-existing cells.

Additional info: These notes expand on the provided review outline with academic context, definitions, and examples to support exam preparation.