Untitled Quiz

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic cells are simple, unicellular organisms lacking a nucleus and membrane-bound organelles, primarily containing DNA in the nucleoid region.
• Eukaryotic cells possess a nucleus enclosed by a membrane and have various other organelles that are also membrane-bound.
• Both prokaryotes and eukaryotes can possess genetic information despite the lack of a defined nucleus in prokaryotes.
• Bacteria, often viewed negatively, play essential roles in ecosystems and human health.

Specialized Cells in Animals

• Specialized cells undergo differentiation to perform specific functions within multicellular organisms.
• Key types of specialized animal cells include epithelial, connective, muscle, and nerve cells.

Specialized Cells in Plants

• Plant cells also differentiate to carry out specialized functions, adapting to unique roles within plant tissues.

Epithelial Tissue

• Epithelial tissue serves as linings for organs and cavities, characterized by closely packed cells with tight junctions.
• Distinct arrangements of epithelial cells include:
  • Cuboidal: For secretion.
  • Simple Columnar: Brick-shaped for secretion and absorption.
  • Simple Squamous: Plate-like for material exchange via diffusion.
  • Stratified Squamous: Multilayered for protection, regenerates quickly.
  • Pseudo-Stratified Columnar: Appears layered, lines the respiratory tract, may contain cilia for mucus sweeping.

Connective Tissue

• Connective tissues include various types that provide support and structure, such as:
  • Blood: Composed of plasma, erythrocytes, leukocytes, and platelets.
  • Connective Tissue Proper (CTP): Includes loose connective tissue (found in skin) and fibrous connective tissue (tendons, ligaments).
  • Adipose Tissue: A type of loose connective tissue that stores fat and functions in insulation and energy storage.
  • Cartilage: Contains collagenous fibers in chondroitin sulfate, cushioning bones and aiding structural stability.
  • Bone: A hard mineralized tissue, formed by osteoblasts, combines collagen matrix with minerals and houses blood vessels and nerves.

Muscle Tissue

• Muscle tissues are made of long cells (muscle fibers) that allow for movement and contractibility, facilitating bodily functions.

Cell Modifications for Function

• Cells can adapt through structural changes such as:
  • Cilia: Can be motile for movement or non-motile (sensory).
  • Flagella: Whip-like structures for propulsion.
  • Microvilli: Small projections enhancing surface area for increased absorption.
  • Pseudopodia: Temporary extensions for movement and engulfing substances (phagocytosis).