Understanding Cell Structure and Function

Aug 22, 2024

Review flashcards

Structure and Function of the Cell

Introduction

  • Overview of lecture on cell structure and function.
  • Mention of a previous video on study methods.

Nucleus

  • Nuclear Envelope: Double-layer membrane with outer and inner layers.
    • Outer Layer: Contains ribosomes, aiding in the translation of mRNA from the nucleus to the Rough ER.
    • Inner Layer: Contains lamins, important for structural integrity and cell division; mutations cause progeria.
    • Nuclear Pores: Facilitate transport between the nucleus and cytoplasm.
  • Nucleolus: Site of rRNA synthesis and ribosome assembly.
  • Chromatin: Consists of DNA and histone proteins; exists as euchromatin (loose) and heterochromatin (tight).
  • Functions:
    • DNA replication and transcription.
    • Types of RNA: tRNA, mRNA, rRNA.

Endoplasmic Reticulum (ER)

  • Rough ER:
    • Contains ribosomes for protein synthesis.
    • Functions: Protein synthesis, folding, and N-type glycosylation.
    • Packages proteins into vesicles for transport to the Golgi apparatus.
  • Smooth ER:
    • Lacks ribosomes.
    • Functions: Lipid synthesis (fatty acids, phospholipids, cholesterol), detoxification (CYP450 enzymes), glucose-6-phosphate metabolism, calcium storage.

Golgi Apparatus

  • Receives vesicles from ER.
  • Cis and Trans Golgi: Entry and exit faces for vesicles.
  • Functions: Modifies proteins (glycosylation and phosphorylation), packages proteins for lysosomes, membranes, or secretion.

Cell Membrane

  • Phospholipid Bilayer: Polar heads (hydrophilic) and non-polar tails (hydrophobic).
  • Cholesterol: Controls membrane fluidity.
  • Proteins: Integral and peripheral; functions in transport, signaling, and structure.
  • Functions: Selective permeability and various transport processes.

Lysosomes

  • Contain hydrolytic enzymes (proteases, nucleases, lipases, glucosidases).
  • Functions:
    • Breakdown of macromolecules.
    • Autophagy of organelles.
    • Autolysis of damaged cells.

Peroxisomes

  • Contain catalase and oxidase enzymes.
  • Functions:
    • Breakdown of hydrogen peroxide into water and oxygen.
    • Fatty acid oxidation and lipid synthesis.
    • Alcohol metabolism.

Mitochondria

  • Known as the powerhouse of the cell.
  • Structure: Outer and inner membranes, cristae, and matrix.
  • Functions:
    • ATP synthesis via oxidative phosphorylation (Electron Transport Chain).
    • Metabolic pathways: Krebs cycle, heme synthesis, urea cycle, gluconeogenesis, ketogenesis.
    • Contains mitochondrial DNA (maternal origin).

Ribosomes

  • Structure: Large (60S) and small (40S) subunits.
  • Locations: Membrane-bound (Rough ER) and free (cytosol).
  • Function: Protein synthesis (translation).

Cytoskeleton

  • Components:
    • Microfilaments (Actin): Involved in muscle contraction, cytokinesis, cell shape changes, phagocytosis.
    • Intermediate Filaments: Provide tensile strength, anchor cells to each other and to ECM, stabilize organelles.
    • Microtubules: Intracellular transport, cell division (chromatid separation), cell extensions (cilia and flagella).

Conclusion

  • Comprehensive overview of cell structures and their functions.
  • Encouragement to develop similar study processes.
  • Gratitude and closing remarks.