Biology Chapter: Eukaryotic Cells

Defining Eukaryotic Cells

• Eukaryotic cells have a membrane-bound nucleus and other membrane-bound organelles.
• Prokaryotic cells lack a nucleus and membrane-bound organelles.
• Eukaryotic cells are generally larger than prokaryotic cells.

Key Organelles and Their Functions

• Nucleus: Contains the cell's DNA, organized into chromosomes, controlling gene expression.
• Ribosomes: Synthesize proteins—free in the cytoplasm or bound to the endoplasmic reticulum.
• Endoplasmic Reticulum (ER): A network for protein and lipid synthesis; smooth ER makes lipids, rough ER has ribosomes for protein synthesis.
• Golgi Apparatus: Processes, sorts, and packages proteins and lipids for secretion or cell use.
• Mitochondria: "Powerhouses" of the cell, responsible for cellular respiration and ATP production.
• Lysosomes: Contain digestive enzymes to break down waste and cellular debris.
• Vacuoles: Storage organelles, storing water, nutrients, or waste products; plant cells often have a large central vacuole.
• Cytoskeleton: Network of protein fibers (microtubules, microfilaments, intermediate filaments) providing structural support, cell shape, and movement.
• Peroxisomes: Contain enzymes, breaking down fatty acids and detoxifying harmful substances.
• Chloroplasts (plant cells only): Sites of photosynthesis, converting light energy into chemical energy.

Cell Membrane Structure and Function

• The selectively permeable cell membrane, a phospholipid bilayer with embedded proteins, controls passage of molecules into and out of the cell.
• The fluid mosaic model describes the membrane's dynamic structure, with proteins embedded within the phospholipid bilayer.
• Passive transport (diffusion, osmosis) and active transport move substances across the membrane.

Cellular Processes in Eukaryotic Cells

• Metabolism: The sum of all chemical reactions in the cell, catalyzed by enzymes.
• Transcription and Translation: DNA's genetic information becomes proteins; transcription occurs in the nucleus, while translation happens in the cytoplasm.
• Cell Division: Eukaryotic cells divide via mitosis (somatic cells) or meiosis (reproductive cells). These processes maintain chromosome number stability.
• Signaling: Intercellular communication via mechanisms involving receptors and signaling pathways.
• Endocytosis and Exocytosis: Processes moving large molecules or material into and out of the cell across the membrane.

Types of Eukaryotic Cells

• Animal Cells: Lack cell walls and chloroplasts.
• Plant Cells: Contain cell walls, chloroplasts, and a large central vacuole.
• Fungi Cells: Have cell walls made of chitin and various intracellular structures.
• Protist Cells: Diverse collection of unicellular eukaryotic organisms with various functions and structures.

Comparing Eukaryotic and Prokaryotic Cells

• Eukaryotes have nuclei and membrane-bound organelles; prokaryotes do not.
• Prokaryotic cells are generally smaller, simpler, and evolve more rapidly.
• Eukaryotic cells are more complex and efficient due to compartmentalization, allowing simultaneous and efficient multiple functions.

This quiz explores the characteristics and functions of eukaryotic cells. Key organelles such as the nucleus, ribosomes, and mitochondria are covered, providing insight into their roles in cellular processes. Test your knowledge on how these organelles contribute to the overall function of eukaryotic cells.