Chapter 5: Cellular Processes

Enzymes and Biological Catalysis

Enzymes are biological catalysts that accelerate chemical reactions in living organisms by lowering activation energy. They are essential for metabolic processes and cellular function.

• Enzyme: Biological catalyst; lowers activation energy.

• Substrate: The molecule upon which an enzyme acts.

• Factors Affecting Enzyme Activity: Temperature, pH, concentration of substrate and enzyme.

• Functions: Digestion, biosynthesis, energy production.

Transport Across Membranes

Cells regulate the movement of substances across their membranes to maintain homeostasis and support cellular activities.

• Passive Diffusion: Movement of molecules from high to low concentration without energy input.

• Osmosis: Diffusion of water across a selectively permeable membrane.

• Facilitated Diffusion: Passive transport using protein channels.

• Active Transport: Movement against gradient; requires energy (ATP).

• Bulk Transport: Endocytosis (into cell), exocytosis (out of cell).

Cell Signaling

Cells communicate using signaling molecules and receptors to coordinate activities and respond to environmental changes.

• Signal Molecules: Hormones, neurotransmitters.

• Receptors: Proteins that bind signal molecules.

• Types: Autocrine, paracrine, endocrine, juxtacrine.

Chapter 6 & 7: Cellular Respiration and Photosynthesis

Cellular Respiration (3 Stages)

Cellular respiration is the process by which cells extract energy from glucose. It occurs in three main stages: glycolysis, Krebs cycle, and electron transport chain.

• Glycolysis: Glucose is split into pyruvic acid; produces 2 ATP and NADH.

• Krebs Cycle (Citric Acid Cycle): Pyruvic acid is broken down; produces CO2, NADH, FADH2, and ATP.

• Electron Transport Chain: NADH/FADH2 donate electrons; ATP is produced; O2 is the final electron acceptor.

• Overall Equation:

• Anaerobic Respiration: Occurs without oxygen; lactic acid fermentation (in animals), alcoholic fermentation (in yeast).

Photosynthesis (2 Stages)

Photosynthesis is the process by which plants convert light energy into chemical energy, producing glucose and oxygen.

• Light-dependent Reactions: Occur in thylakoid membranes; produce ATP and NADPH.

• Calvin Cycle (Light-independent Reactions): Occur in stroma; use ATP and NADPH to fix CO2 into glucose.

• Overall Equation:

Chapter 8: Cellular Reproduction

Cell Cycle and Mitosis

The cell cycle describes the sequence of events in cell growth and division. Mitosis is the process by which somatic cells divide to produce genetically identical daughter cells.

• Cell Cycle Phases: G1, S, G2, M (mitosis).

• Mitosis Stages: Prophase, metaphase, anaphase, telophase.

• Chromosome Movement: Chromosomes align and separate.

• Cytokinesis: Division of cytoplasm.

Meiosis

Meiosis is the process by which gametes (sperm and egg cells) are produced, resulting in genetic diversity through recombination and reduction division.

• Meiosis Stages: Meiosis I and II.

• Purpose: Produces gametes with half the chromosome number of parent cell.

• Genetic Variation: Crossing over, independent assortment.

Homologous Chromosomes

Homologous chromosomes are pairs of chromosomes with the same genes but possibly different alleles. They are important for genetic variation in meiosis.

• Homologous Chromosomes: Same structure, different alleles.

• Significance: Allow for recombination and genetic diversity.

Chapter 21: Unifying Concepts of Animal Structure and Function

Organ Systems and Homeostasis

Animals are organized into organ systems that work together to maintain homeostasis, the stable internal environment necessary for survival.

• Organ Systems: Groups of organs with coordinated functions (e.g., digestive, nervous, circulatory).

• Open vs. Closed Systems: Open systems exchange matter and energy with surroundings; closed systems do not.

• Thermoregulation: Maintenance of body temperature.

• Homeostasis: Regulation of internal conditions.

• Control Center, Effector, Response: Components of homeostatic regulation.

Chapter 25: Hormones

Hormonal Regulation

Hormones are chemical messengers produced by endocrine glands that regulate physiological processes throughout the body.

• Hormone: Chemical messenger; travels through blood to target organs.

• Endocrine System: Glands that secrete hormones (e.g., pituitary, thyroid, adrenal).

• Functions: Growth, metabolism, reproduction, stress response.

• Examples: Insulin (regulates blood glucose), adrenaline (fight-or-flight response).

Additional Nervous System Notes

Neurons and Nervous Tissue

The nervous system is composed of neurons and supporting cells that transmit signals for communication and control.

• Neuron Structure: Dendrites, cell body, axon.

• Function: Transmit electrical and chemical signals.

Nervous System Organization

• CNS (Central Nervous System): Brain and spinal cord; integrates information.

• PNS (Peripheral Nervous System): Cranial and spinal nerves; connects CNS to body.

• ANS (Autonomic Nervous System): Involuntary control; includes sympathetic and parasympathetic divisions.

Brain Structure and Function

• Major Structures: Cerebrum, cerebellum, brainstem, diencephalon.

• Functions: Sensory processing, motor control, regulation of vital functions.

Reflexes

• Reflex: Quick, involuntary response to stimulus.

• Reflex Arc Components: Receptor, sensory neuron, CNS integration, motor neuron, effector.