Eukaryotes vs Prokaryotes Overview

Eukaryotes and Prokaryotes

• Eukaryotes are characterized by the presence of a nucleus, a membrane-bound organelle, which separates genetic material from the cytoplasm.
• Prokaryotes lack a nucleus and membrane-bound organelles.

Organelles

• Organelles are small structures within cells that perform specific functions.
• Unlike organs, which are larger systems composed of many cells (e.g., liver, pancreas), organelles are microscopic subunits with specialized tasks.

Protoplasm

• Protoplasm is defined as the living content of the cell, including both the cytoplasm and nucleoplasm.
• It is surrounded by the plasma membrane, which regulates what enters and leaves the cell.

Membrane Structure

• The plasma membrane consists of a phospholipid bilayer, with hydrophilic (water-attracting) heads facing the aqueous environment and hydrophobic (water-repelling) tails facing inward.
• Cellular membranes are structured with an outer membrane, inner membrane, and intermembrane space, as seen in mitochondria and the nuclear membrane.

Genetic Material

• The nucleus contains genetic material organized into chromosomes, which is crucial for cell function and reproduction.

Cytosol and Diffusion

• Cytosol, the fluid component of the cytoplasm, facilitates the diffusion of molecules throughout the cell.

Key Organelles and Their Functions

• Mitochondria: Known as powerhouses of the cell, providing energy.
• Lysosomes: Function as the cell's cleanup crew, breaking down waste materials and cellular debris.
• Endosomes: Act as delivery mechanisms, packaging and transporting cellular products.
• Endoplasmic Reticulum (ER): Exists as rough ER (involved in protein synthesis) and smooth ER (responsible for lipid synthesis).
• Golgi Apparatus: Sorts and modifies cellular products for distribution.
• Peroxisomes: Enzyme-rich organelles that help detoxify harmful substances, akin to personal trainers for the cell.

Cytoskeleton

• The cytoskeleton provides structural support to the cell, analogous to a skeleton in multicellular organisms.

Function and Adaptation

• Cellular structures are often adapted to their specific functions; for instance:
  • Sperm cells require energy and thus have numerous mitochondria.
  • Islets of Langerhans in the pancreas, responsible for hormone secretion, contain abundant Golgi apparatus and ER.
  • Mature red blood cells lack organelles and a nucleus to maximize space for oxygen transport, while immature red blood cells contain a nucleus.

Summary of Organelles

• Mitochondria: Energy production.
• Lysosomes: Waste destruction.
• Endosomes: Packaging and delivery.
• Rough ER: Protein translation.
• Smooth ER: Fat synthesis.
• Golgi Apparatus: Modifying and sorting products.
• Peroxisomes: Detoxification and metabolic processing.