Cell Biology Basics

Cell Membrane

• Encloses the cell, acting as a gatekeeper.
• Double-layered and semi-permeable.
• Controls the movement of substances into and out of the cell.

Cell Wall

• Rigid structure surrounding and protecting the cell membrane.
• Provides support.
• Composed of cellulose (carbohydrate).
• Found in plant cells.

Ribosomes

• Small structures involved in protein synthesis.
• Crucial for cell growth and reproduction.

Chloroplasts

• Organelles found in plant cells.
• Contain chlorophyll.
• Essential for photosynthesis.
• Photosynthesis equation:
  • CO2 + H2O → C6H12O6 + O2

DNA

• Thread-like structures carrying genetic information.
• Determines hereditary traits.

Cytoplasm

• The fluid-filled region inside the cell.
• Site of nutrient absorption, transport, and processing.
• Contains numerous organelles.
• Primarily composed of water.
• Location of many chemical reactions.

Cytoskeleton

• Network of protein fibers providing structural support.
• Anchors organelles within the cell.
• Allows for cell shape changes and movement.

Endoplasmic Reticulum (ER)

• Network of branching canals within the cytoplasm.
• Transports substances within the cell.
• Two types:
  • Rough ER: has ribosomes attached, involved in protein synthesis.
  • Smooth ER: lacks ribosomes, involved in lipid synthesis.

Golgi Apparatus

• Stores proteins until needed within or outside the cell.
• Processes and packages materials for removal from the cell.
• Creates mucus (e.g., in the intestines).

Lysosomes

• Sac-like structures formed by the Golgi apparatus.
• Contain enzymes to break down large molecules and cell components.
• Found in animal cells.

Mitochondria

• Oval-shaped organelles, the "powerhouses" of the cell.
• Generate cellular energy through cellular respiration.
• Found in animal cells.

Nucleolus

• Spherical structure within the nucleus.
• Involved in ribosome production.

Nucleus

• Control center of the cell.
• Directs cell activities.
• Contains chromosomes and DNA.

Vacuoles

• Membrane-bound compartments.
• Stores water, waste products, and other substances.
• Larger in plant cells.
• Maintains turgor pressure (cell firmness) in plant cells.

Passive Transport

• Movement of molecules across a membrane without energy input.
• Driven by concentration gradients.
  • Osmosis: Movement of water across a semipermeable membrane.
  • Simple Diffusion: Movement of molecules from high to low concentration.
  • Facilitated Diffusion: Movement of molecules across a membrane with the help of proteins.

Active Transport

• Movement of molecules across a membrane against a concentration gradient.
• Requires energy input.
• Endocytosis: Bringing bulk materials into the cell.

Cell Division

• Process of cell reproduction, growth, and repair.
  • Asexual Reproduction: Creates genetically identical offspring from one parent.
  • Sexual Reproduction: Creates offspring with genetic information from two parents.

Cell Cycle

• Two major phases: interphase and mitosis.
  • Interphase: Period of growth, DNA replication, and preparation for cell division, comprising 3 stages: G1, S, and G2.
  • Mitosis: Cell division process, resulting in two identical daughter cells, followed by cytokinesis. (PMAT)

Cell Specialization

• Different cells in an organism have specialized structure and functions due to differentiation of cells.
  • Stem Cells: Unspecialized cells, capable of differentiating into other cell types.
    • Embryonic stem cells: totipotent—can develop into any cell type, including the placenta.
    • Adult stem cells: multipotent—can develop into specific types of cells within a particular tissue.

Tissues and Organs

• Tissues: Groups of similar cells organized to perform specific functions.
• Organs: Groups of different tissues working together to perform specific tasks.

Summary of Organelle Function

• Intake of nutrients
• Movement of materials
• Growth
• Exchange of gases
• Waste removal
• Reproduction
• includes cell division

Solutions

• Solvent: The substance capable of dissolving another substance. (Water).
• Solute: The substance that dissolves into the solvent.
• Solution: The solvent and solute after they combine.
• ECF: Extracellular fluid surrounding cells.
• Concentration: Mass of solute dissolved in a solvent.

Diffusion, Osmosis and Solutions

• Hypertonic: Higher solute concentration, lower water concentration.
• Isotonic: Equal solute and water concentration.
• Hypotonic: Lower solute concentration, higher water concentration.
• Diffusion: Movement of molecules from high to low concentration.
• Facilitated Diffusion: Passive transport assisted by protein channels and carriers.

Respiratory System

• Lungs are composed of alveoli, thin air sacs surrounded by capillaries for gas exchange.
• Inspiration (breathing in) involves diaphragm and intercostal muscle contraction.
• Expiration (breathing out) involves relaxation of these muscles.

Digestive System

• Breaks down food for absorption and egestion (waste removal).
• Organs involved: Mouth, esophagus, stomach, small intestine, large intestine.

Circulatory System

• Blood is pumped through a network of arteries, capillaries, and veins.
• Heart has four chambers (two atria and two ventricles) for efficient blood circulation.

Cell Specialization

• Different cell types specialized cells performing specific function through differentiation.