Cell Biology: Mitochondria Overview

Alcohol

• The liver contains the highest concentration of mitochondria, essential for energy production.

Mitochondria

• Rod or oval-shaped organelles, similar in size to bacteria.
• Enclosed by a double membrane with the inner membrane forming infoldings called cristae.
• Cristae project into the gel-like matrix, creating the intermembrane space.
• Known as energy organelles, extracting energy from nutrients to produce ATP.
• Contain enzymes required for the Citric Acid Cycle (TCA) and Electron Transport Chain.

Centrioles

• Composed of a pair of cylindrical structures oriented at right angles.
• Organize microtubules during cell division to form the mitotic spindle.
• Play a role in the formation of cilia and flagella.

Vaults

• Hollow, octagonal structures acting as transport vehicles for materials between the nucleus and cytoplasm.

Cytoskeleton

Microtubules

• Long, hollow tubes made of tubulin that maintain cell shape and facilitate complex movements.
• Serve as highways for the transport of vesicles and are vital for positioning organelles.

Microfilaments

• Smallest cytoskeletal elements made up of intertwined actin chains.
• Facilitate muscle contraction and amoeboid movement, and provide structure to microvilli.

Intermediate Filaments

• Thread-like, irregular filaments that resist mechanical stress.
• Contribute strength in multiple proteins, such as keratin found in hair.

Cytosol

• Often referred to as cell gel; it houses enzymes for metabolic reactions.

Intermediary Metabolism Enzymes

• Facilitate reactions for degradation, synthesis, and transformation of small organic molecules.

Transport, Secretory, and Endocytic Vesicles

• Membrane-bound products formed within or engulfed by the cell for transport or storage.

Inclusions

• Structures like glycogen granules and fat droplets that store excess nutrients.

Cellular Metabolism

Intermediary Metabolism

• Encompasses a range of chemical reactions in the cell involving small organic molecules, including sugars, amino acids, and fatty acids.
• Subcategories include anabolic (synthesis) and catabolic (degradation) processes.

ATP Production

• ATP (Adenosine TriPhosphate) is the primary energy currency in the body, derived from carbon bonds in food.
• Energetic processes utilize a H+ gradient to drive ATP synthesis by ATP synthase.

Plasma Membrane

• Composed of a phospholipid bilayer with proteins and some carbohydrates, serving as a barrier and communication interface.
• Separates intracellular and extracellular compartments and selectively permits molecular movement.

Structure and Composition

• Phospholipids are the most abundant lipids, each with a hydrophilic head and hydrophobic tails.
• Over a billion phospholipids are contained within a typical human plasma membrane.

Assisted Membrane Transport

• Mechanisms for large or poorly lipid-soluble molecules to cross the plasma membrane include carrier-mediated transport and vesicular transport.

Carrier Mediated Transport

• Involves proteins that change shape to move substances across the membrane.
• Two forms: passive (facilitated diffusion) and active transport, requiring energy expenditure.

Endocytosis

• Types:
  • Pinocytosis (cell drinking) for non-selective fluid uptake.
  • Receptor-Mediated Endocytosis for selective intake of specific molecules.
  • Phagocytosis (cell eating) specific to specialized cells for large multimolecular particles.

Exocytosis

• The reverse of endocytosis, used for the secretion of polar molecules and for membrane composition changes.

This quiz covers the essential functions and structures of mitochondria, the energy organelles of the cell. You will learn about their shape, membrane structure, and their role in energy extraction from nutrients. Perfect for students studying cell biology or biochemistry.