Cell Biology Basics

Cell Biology

Basic Concepts

• Cell Theory:

  • All living organisms are composed of cells.
  • The cell is the basic unit of life.
  • All cells arise from pre-existing cells.

• Types of Cells:

  • Prokaryotic Cells:

    • Lack a nucleus.
    • DNA is circular and located in the nucleoid region.
    • Examples: Bacteria and Archaea.

  • Eukaryotic Cells:

    • Contain a nucleus.
    • DNA is linear and organized into chromosomes.
    • Examples: Animal cells, plant cells, fungi, and protists.

Cell Structure and Organelles

• Nucleus:

  • Contains the cell’s genetic material (DNA).
  • Surrounded by a double membrane called the nuclear envelope.

• Mitochondria:

  • Known as the powerhouse of the cell.
  • Sites of cellular respiration and energy (ATP) production.

• Endoplasmic Reticulum (ER):

  • Rough ER: Studded with ribosomes; involved in protein synthesis.
  • Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.

• Ribosomes:

  • Sites of protein synthesis; can be free in the cytoplasm or attached to the rough ER.

• Golgi Apparatus:

  • Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.

• Lysosomes:

  • Contain digestive enzymes; responsible for breaking down waste materials and cellular debris.

• Peroxisomes:

  • Contain enzymes for oxidation reactions; involved in breaking down fatty acids and detoxifying harmful substances.

• Cytoskeleton:

  • Composed of microfilaments, intermediate filaments, and microtubules.
  • Provides structural support, facilitates movement, and helps transport materials within the cell.

• Plasma Membrane:

  • Composed of a phospholipid bilayer with embedded proteins.
  • Regulates the movement of substances in and out of the cell.

Cell Division

• Mitosis:

  • A process of cell division that results in two identical daughter cells.
  • Phases: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.

• Meiosis:

  • A specialized type of cell division that reduces chromosome number by half, creating four non-identical daughter cells.
  • Essential for sexual reproduction.

Cellular Metabolism

• Metabolism:

  • The sum of all biochemical reactions in a cell, including catabolic (breakdown) and anabolic (synthesis) processes.

• Cellular Respiration:

  • Process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.
  • Stages: Glycolysis, Krebs Cycle, and Electron Transport Chain.

Signaling and Communication

• Cell Signaling:

  • Mechanisms that govern the communication between cells.
  • Types: Autocrine, Paracrine, Endocrine, and Direct Signaling.

• Receptors:

  • Molecules on cell surfaces that bind to signaling molecules (ligands), triggering a cellular response.

Apoptosis

• Programmed Cell Death:
  • A controlled process that eliminates old, unnecessary, or damaged cells.
  • Important for development and maintaining tissue homeostasis.

Cell Theory

• All living things are made of cells.
• Cells are the basic unit of life.
• All cells come from pre-existing cells.

Prokaryotes

• Lack a nucleus
• DNA in the nucleoid region, circular in shape
• Examples: Bacteria and Archaea

Eukaryotes

• Contain a nucleus
• DNA is linear and organized into chromosomes
• Examples: Animal cells, plant cells, fungi, and protists

Nucleus

• Contains DNA
• Surrounded by a double membrane, called the nuclear envelope.

Mitochondria

• Site of cellular respiration.
• Responsible for energy production (ATP).

Endoplasmic Reticulum (ER)

• Rough: Studded with ribosomes, protein synthesis.
• Smooth: Lacks ribosomes, lipid synthesis and detoxification.

Ribosomes

• Sites of protein synthesis.
• Can be free in the cytoplasm or attached to the rough ER.

Golgi Apparatus

• Modifies, sorts, and packages proteins and lipids.
• Prepares proteins and lipids for secretion or use within the cell.

Lysosomes

• Contain digestive enzymes.
• Break down waste materials and cellular debris.

Peroxisomes

• Contain enzymes for oxidation reactions
• Break down fatty acids and detoxify products.

Cytoskeleton

• Network of fibers: microfilaments, intermediate filaments, and microtubules.
• Provides structural support, facilitates movement, and helps transport materials.

Plasma Membrane

• Made of a phospholipid bilayer with embedded proteins.
• Regulates the movement of substances in and out of the cell.

Mitosis

• Process of cell division that creates two identical daughter cells.
• Stages: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis

Meiosis

• Specialized type of cell division that reduces chromosome number by half.
• Creates four non-identical daughter cells.
• Used during sexual reproduction.

Metabolism

• The sum of all chemical reactions in a cell.
• Includes: catabolic (breakdown) and anabolic (synthesis) processes.

Cellular Respiration

• Process where cells convert glucose and oxygen into energy (ATP).
• Produces: carbon dioxide, and water.
• Stages: Glycolysis, Krebs Cycle, and Electron Transport Chain.

Cell Signaling

• The communication between cells.
• Types: Autocrine, Paracrine, Endocrine, and Direct Signaling.

Receptors

• Molecules on the cell surface that bind to signaling molecules (ligands).
• Trigger a cellular response.

Apoptosis

• Programmed cell death
• Controlled process to eliminate old, unnecessary, or damaged cells.
• Important for tissue homeostasis and development.