Unit 2 Study Guide: Tissues, Metabolism, Cell Division, and Genetics

Tissues and Organ Systems

Types of Epithelial Tissue

Epithelial tissues line the surfaces and cavities of organs. They are classified by cell shape and arrangement.

• Squamous Epithelium: Flat, scale-like cells; found in areas of diffusion/filtration (e.g., alveoli, capillaries).

• Cuboidal Epithelium: Cube-shaped cells; specialized for secretion and absorption (e.g., kidney tubules).

• Columnar Epithelium: Tall, column-like cells; often have microvilli for absorption (e.g., lining of intestines).

Types of Muscle Tissue

• Skeletal Muscle: Voluntary, striated, multinucleated; responsible for body movement.

• Smooth Muscle: Involuntary, non-striated; found in walls of organs (e.g., intestines, blood vessels).

• Cardiac Muscle: Involuntary, striated, branched; found only in the heart, with intercalated discs for synchronized contraction.

Producers vs. Consumers

• Producers (Autotrophs): Organisms that synthesize their own food from inorganic substances (e.g., plants via photosynthesis).

• Consumers (Heterotrophs): Organisms that obtain energy by consuming other organisms.

Autotrophs vs. Heterotrophs

• Autotrophs: Use light or chemical energy to produce organic molecules.

• Heterotrophs: Depend on other organisms for organic molecules.

Nutrition Concepts

• Under-nourishment: Insufficient caloric intake.

• Malnourishment: Deficiency in essential nutrients, regardless of calorie intake.

• Simple Carbohydrates: Monosaccharides and disaccharides (e.g., glucose, sucrose); quick energy sources.

• Complex Carbohydrates: Polysaccharides (e.g., starch, glycogen); provide sustained energy.

• LDL (Low-Density Lipoprotein): "Bad" cholesterol; can deposit cholesterol in arteries.

• HDL (High-Density Lipoprotein): "Good" cholesterol; removes cholesterol from bloodstream.

Dietary Choices

• Vitamin Supplements: Can prevent deficiencies but may be unnecessary with a balanced diet; excess can be harmful.

• Organic Foods: Grown without synthetic pesticides/fertilizers; may reduce exposure to chemicals but not always more nutritious.

• Non-GMO Foods: Not genetically modified; consumer preference often based on perceived safety or environmental impact.

Organ Systems Overview

• Digestive System: Breaks down food, absorbs nutrients.

• Circulatory System: Transports nutrients, gases, wastes.

• Respiratory System: Gas exchange (O2/CO2).

• Nervous System: Coordinates responses to stimuli.

• Muscular System: Movement and posture.

• Skeletal System: Support and protection.

• Immune System: Defense against pathogens.

• Excretory System: Removes waste products.

• Endocrine System: Hormonal regulation.

• Reproductive System: Produces gametes, enables reproduction.

Enzymes, Metabolism, and Energy

Key Terms

• Entropy: Measure of disorder in a system; increases in spontaneous processes.

• Activation Energy: Minimum energy required to start a chemical reaction.

• Enzyme Active Site: Region on enzyme where substrate binds and reaction occurs.

• Substrate: Reactant molecule acted upon by an enzyme.

• Inhibitor: Substance that decreases enzyme activity.

• Chemiosmosis: Movement of ions across a membrane, generating ATP (e.g., in mitochondria).

Enzyme Activity Influences

• pH: Each enzyme has an optimal pH; deviations can denature the enzyme.

• Temperature: Higher temperatures increase activity up to a point; extreme heat denatures enzymes.

• Heavy Metals: Can bind to enzymes and inhibit function.

Enzyme Kinetics

• Competitive Inhibition: Inhibitor binds to active site, blocking substrate.

• Non-Competitive Inhibition: Inhibitor binds elsewhere, changing enzyme shape.

• Cofactors: Non-protein helpers (e.g., metal ions).

• Coenzymes: Organic cofactors (e.g., vitamins).

Energy in Reactions

• Exergonic Reactions: Release energy; products have less free energy than reactants.

• Endergonic Reactions: Require energy input; products have more free energy.

ATP Generation

• Phosphorylation: Addition of phosphate group to a molecule.

• Substrate-Level Phosphorylation: Direct transfer of phosphate to ADP to form ATP.

• Redox Reactions: Transfer of electrons; essential in cellular respiration.

• NADH Electron Transport Chain: NADH donates electrons, driving ATP synthesis via chemiosmosis.

Cellular Respiration

• Aerobic Respiration: Uses oxygen; produces more ATP.

• Anaerobic Respiration: Does not use oxygen; less ATP produced.

• Glycolysis: Glucose → 2 pyruvate + 2 ATP + 2 NADH.

• Citric Acid Cycle: Completes glucose breakdown; produces NADH, FADH2, ATP, CO2.

• Oxidative Phosphorylation: Electron transport and chemiosmosis; most ATP generated here.

ATP Yield Table

Stage	ATP Produced (per glucose)
Glycolysis	2
Citric Acid Cycle	2
Oxidative Phosphorylation	~28
Total	~32

Poisons Affecting Cellular Respiration

• Block electron transport chain (e.g., cyanide).

• Inhibit ATP synthase.

• Uncouple chemiosmosis from electron transport.

Cell Division and Genetics

Reproduction Types

• Asexual Reproduction: Offspring genetically identical to parent (e.g., mitosis).

• Sexual Reproduction: Offspring genetically unique; involves gametes and fertilization.

Homologous Chromosomes

• Pairs of chromosomes with the same genes but possibly different alleles; one from each parent.

Mitosis vs. Meiosis

• Mitosis: Produces two identical diploid cells; for growth and repair.

• Meiosis: Produces four non-identical haploid gametes; for sexual reproduction.

Comparison Table: Mitosis vs. Meiosis

Feature	Mitosis	Meiosis
Number of Divisions	1	2
Number of Cells Produced	2	4
Genetic Identity	Identical	Unique
Chromosome Number	Diploid	Haploid

Cytokinesis

• Animal Cells: Cleavage furrow forms, pinching cell in two.

• Plant Cells: Cell plate forms, dividing cell.

Phases of Mitosis and Meiosis

• Prophase: Chromosomes condense, spindle forms.

• Metaphase: Chromosomes align at cell equator.

• Anaphase: Sister chromatids (mitosis) or homologs (meiosis I) separate.

• Telophase: Nuclear envelope reforms, chromosomes decondense.

Genetic Variability in Meiosis

• Crossing over (prophase I).

• Independent assortment (metaphase I).

• Random fertilization.

Sex Determination

• Chromosomal basis (e.g., XX = female, XY = male in humans).

Cancer and the Cell Cycle

• Cancer results from uncontrolled cell division due to mutations in genes regulating the cell cycle.

Chromosome Alterations

• Deletion: Loss of a chromosome segment.

• Duplication: Repetition of a segment.

• Inversion: Reversal of a segment.

• Translocation: Segment moves to a non-homologous chromosome.

Factors in Cell Division

• Growth factors.

• Cell size.

• DNA integrity.

Laboratory Applications

Microscope Slide Identification

• Recognize tissue types (epithelial, muscle, etc.) by cell shape and arrangement.

Enzyme Kinetics Lab

• Study how substrate concentration, inhibitors, and environmental factors affect enzyme activity.

Key Equations

• Cellular Respiration:

$ \mathrm{C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy (ATP)}} $

• Gibbs Free Energy:

$ \Delta G = \Delta H - T\Delta S $

• Enzyme Reaction Rate (Michaelis-Menten):

$ v = \frac{V_{max}[S]}{K_m + [S]} $

Additional info: Some explanations and tables were expanded for clarity and completeness based on standard biology curricula.