Cell Structure Basics and Eukaryotic Cells

Cell Structure Basics

• Cells are the fundamental units of life, exhibiting a diverse range of structures and functions.
• All cells share common features: a plasma membrane, cytoplasm, and DNA.
• Eukaryotic cells, which include animal and plant cells, have membrane-bound organelles that compartmentalize cellular processes.
• Prokaryotic cells, such as bacteria, lack membrane-bound organelles.

Eukaryotic Cell Structure

• Plasma Membrane: A selectively permeable barrier that regulates the passage of substances into and out of the cell.
• Cytoplasm: The jelly-like substance filling the cell, containing various organelles.
• Nucleus: The control center of the cell, containing DNA organized into chromosomes. It's surrounded by a double membrane (nuclear envelope).
• Endoplasmic Reticulum (ER): A network of interconnected membranes involved in protein synthesis and lipid metabolism.
• Rough ER: Studded with ribosomes, involved in protein synthesis and modification.
• Smooth ER: Lacks ribosomes, involved in lipid synthesis, detoxification, and calcium storage.
• Ribosomes: Tiny structures responsible for protein synthesis. Found 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.
• Mitochondria: The powerhouse of the cell, responsible for cellular respiration and ATP production. Double membrane enclosed organelle.
• Lysosomes: Membrane-bound sacs containing digestive enzymes involved in breaking down cellular waste and foreign materials.
• Vacuoles: Fluid-filled sacs that store water, nutrients, or waste products. Plant cells often have a large central vacuole.
• Cytoskeleton: A network of protein fibers that maintains cell shape, facilitates movement, and anchors organelles.
• Centrioles: Involved in cell division in animal cells.

Prokaryotic Cell Structure

• Simpler structure than eukaryotic cells.
• No membrane-bound organelles.
• Cell Wall: Provides structural support and protection.
• Plasma membrane: Controls the passage of substances into and out of the cell.
• Nucleoid: Region where the genetic material (DNA) is located.
• Ribosomes: Smaller than eukaryotic ribosomes.

Specialized Cells

• Specialized cells have specific structures and functions.
• Their morphology is optimized for their function. For example, nerve cells have axons for signal transmission.
• Examples:
  • Nerve cells (neurons): Transmit electrical signals throughout the body. Long axons allow for long-distance communication.
  • Muscle cells: Contract to produce movement. Contain abundant contractile proteins, allowing for force generation.
  • Red blood cells (erythrocytes): Carry oxygen throughout the body. Biconcave shape maximizes surface area for oxygen uptake. Lack a nucleus to accommodate more hemoglobin.
  • Epithelial cells: Form protective layers covering surfaces.
  • Bone cells (osteocytes): Contribute to bone structure and support.
  • Plant cells: Vary widely. Guard cells are specialized for regulating stomatal pore opening to regulate gas exchange.

Differences Between Plant and Animal Cells

• Plant cells have a cell wall, chloroplasts (for photosynthesis), and a large central vacuole, absent in animal cells.

Function and Structure Relationships

• The structure of a cell directly correlates with its function.
• The specialized structures of various cells allow for efficient and specialized processes within the organism.

Explore the essential features of cell structure with a focus on eukaryotic cells. This quiz covers the plasma membrane, cytoplasm, nucleus, and organelles such as the endoplasmic reticulum. Understand how these components contribute to the overall function of cells in life processes.