General Biology 1 - Module 1: Cells

General Biology 1 - Quarter 1, Module 1: Cells

• General Biology 1, Quarter 1, Module 1: Cells - by Raffy R. Padrigano, LPT

Lesson 1: Cell Theory

• Cell Theory: A foundational concept in biology, describing the properties of cells.
• Cell Theory Principles:
  • All living organisms are composed of cells. Cells are the basic units of life.
  • The cell is the smallest unit of life; it is the basic structural and functional unit in living organisms.
  • All cells arise from pre-existing cells via cell division (e.g., mitosis or binary fission).

Contributions to Cell Theory

• Robert Hooke (1665): First observed and named "cells" in cork tissue.
• Anton van Leeuwenhoek: Observed living cells, including bacteria, using a simple microscope.
• Matthias Schleiden and Theodor Schwann (1839): Proposed that plants and animals are made of cells.
• Rudolf Virchow (1855): Stated that all cells come from pre-existing cells (Omnis cellula e cellula).

Lesson 2: Cell Structure and Functions

• Cells are comprised of distinct parts with specific roles, ensuring efficient functioning.
• Cell Structures and Functions:
  • Plasma Membrane: A semi-permeable barrier made of a lipid bilayer; controls substance movement in and out of the cell.
  • Cytoplasm: Jelly-like substance filling the cell; includes organelles.
  • Nucleus: Houses genetic material (DNA), regulating cellular activities like growth, metabolism, and reproduction.

Organelles in Eukaryotic Cells

• Mitochondria: The cell's powerhouse; site of ATP (energy) production.
• Endoplasmic Reticulum (ER):
  • Rough ER: Studded with ribosomes; synthesizes proteins.
  • Smooth ER: Synthesizes lipids and detoxifies substances.
• Golgi Apparatus: Modifies, packages, and transports proteins and lipids.
• Lysosomes: Contain enzymes for digestion and waste removal.
• Ribosomes: Synthesize proteins.
• Chloroplasts (plant cells only): Site of photosynthesis.
• Vacuoles (plant cells primarily): Store water, nutrients, and waste (large in plants).
• Cytoskeleton: Provides structural support and facilitates movement.

Lesson 3: Prokaryotic vs. Eukaryotic Cells

• Prokaryotic Cell: A simple, unicellular organism lacking a true nucleus and membrane-bound organelles. Genetic material is in a nucleoid region; examples are bacteria and archaea.

• Eukaryotic Cell: A complex cell with a true nucleus enclosed by a nuclear membrane and membrane-bound organelles; found in multicellular and some unicellular organisms like plants, animals, fungi, and protists

• Prokaryotic vs. Eukaryotic Cells (Summary):

  Feature	Prokaryotic Cells	Eukaryotic Cells
  Size	Small (1-10 µm)	Larger (10-100 µm)
  Nucleus	Absent	Present
  DNA	Circular, in nucleoid	Linear, in nucleus
  Organelles	No membrane-bound	Membrane-bound
  Examples	Bacteria, Archaea	Plants, animals, fungi, protists
  Reproduction	Binary fission	Mitosis and meiosis

Lesson 4: Cell Types

• Cells are categorized based on organism types and functions.
• Based on Organisms:
  • Prokaryotic Cells: Found in bacteria and archaea.
  • Eukaryotic Cells: Found in plants, animals, fungi, and protists.
• Based on Function:
  • Somatic Cells: Body cells (e.g., skin, muscle).
  • Germ Cells: Reproductive cells (e.g., sperm, egg).
• Specialized Cells:
  • Red Blood Cells (RBCs): Transport oxygen.
  • Neurons: Transmit signals in the nervous system.
  • Muscle Cells: Responsible for movement.
  • Plant Cells (e.g., Guard Cells): Regulate gas exchange.

Lesson 5: Cell Modifications

• Cells adapt their structures to carry out specific functions.
  • In Animals:
    • Microvilli: Increase surface area for absorption.
    • Cilia and Flagella: Aid in movement.
    • Pseudopodia: Extensions of the cytoplasm for movement and engulfing food.
  • In Plants:
    • Cell Wall Thickening: Provides strength and protection.
    • Plasmodesmata: Channels for transport and communication.
    • Storage Vacuoles: Store nutrients, waste, or water. Keratinization, formation of Endospores