Summary of Cell Biology | Cell Structure & Function

Main Ideas and Concepts

• Nucleus
  • The Nucleus is the central organelle of the cell, often referred to as the "brain" of the cell.
  • Components
    • Nuclear Envelope: Composed of an outer and inner membrane; the outer membrane has Ribosomes and facilitates mRNA transport.
    • Nuclear Pores: Allow transport of ions, proteins, and nucleotides between the Nucleus and cytoplasm.
    • Nucleolus: Site of rRNA synthesis and ribosome assembly.
    • Chromatin: Made of DNA and histone proteins; exists in two forms:
      • Euchromatin: Loosely packed, active in gene expression.
      • Heterochromatin: Tightly packed, inactive.
  • Functions: DNA replication, transcription (making mRNA), and processing various types of RNA.
• Endoplasmic Reticulum (ER)
  • Rough ER: Contains Ribosomes and is the site of protein synthesis. Functions include protein synthesis, folding, and glycosylation.
  • Smooth ER: Lacks Ribosomes and is involved in lipid synthesis, detoxification, and calcium storage.
• Golgi Apparatus: Functions as a packaging organelle that modifies, sorts, and ships proteins and lipids received from the ER. Involved in glycosylation and phosphorylation of proteins.
• Cell Membrane: Composed of a phospholipid bilayer with embedded proteins and cholesterol. Functions as a selectively permeable barrier, facilitating various transport processes.
• Lysosomes: Contain hydrolytic enzymes for breaking down macromolecules (proteins, nucleic acids, lipids, carbohydrates). Involved in autophagy (recycling damaged organelles) and autolysis (breaking down damaged cells).
• Peroxisomes: Contain enzymes like catalase and oxidase for breaking down fatty acids and detoxifying harmful substances.
• Mitochondria: Known as the powerhouse of the cell, primarily responsible for ATP synthesis through oxidative phosphorylation. Involved in various metabolic pathways, including the Krebs cycle and fatty acid metabolism.
• Ribosomes: Sites of protein synthesis, composed of rRNA and proteins. Can be free in the cytosol or bound to the rough ER.
• Cytoskeleton: Composed of microfilaments (actin), intermediate filaments, and microtubules. Provides structural support, facilitates intracellular transport, and is involved in cell division and movement.

Methodologies and Functions

• Nucleus
  • DNA Replication: Producing more DNA.
  • Transcription: Converting DNA to RNA.
• Rough ER
  • Protein Synthesis: Using mRNA to create proteins.
  • Protein Folding: Ensuring proteins are correctly shaped for function.
  • Glycosylation: Adding sugar residues to proteins for activation.
• Smooth ER
  • Lipid Synthesis: Producing fatty acids, phospholipids, and cholesterol.
  • Detoxification: Using enzymes like CYP450 to break down toxins.
  • Calcium Storage: Regulating calcium levels in muscle cells.
• Golgi Apparatus
  • Modification: Further processing proteins received from the ER.
  • Packaging: Encapsulating modified proteins into vesicles for transport.
• Cell Membrane
  • Transport Processes: Facilitating diffusion, facilitated diffusion, and vesicular transport.
• Lysosomes
  • Macromolecule Breakdown: Utilizing hydrolytic enzymes for digestion.
  • Autophagy: Recycling cellular components.
  • Autolysis: Breaking down damaged cells.
• Peroxisomes
  • Free Radical Detoxification: Converting hydrogen peroxide to water and oxygen.
  • Fatty Acid Metabolism: Breaking down fatty acids into acetyl-CoA.
• Mitochondria
  • ATP Synthesis: Generating energy through oxidative phosphorylation.
  • Metabolic Reactions: Involved in Krebs cycle, urea cycle, and gluconeogenesis.
• Cytoskeleton
  • Intracellular Transport

Notable Quotes

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