Lecture 2 cell structure

• Cell


  A living structural and functional unit that is enclosed by a membrane
• Cell


  • Plasma membrane
  • Cytoplasm - cytosol + organelles
• Robert Hooke

  1665
• Robert Brocon


  ↓
• Theodor Schwa


  ↓
• Nucleus


  Coordinates cellular activities
• Cytology


  The study of cells
• Cellular diversity


  • Nearly 100 trillion cells
  • Vary in size
  • Vary in shape
  • Perform different functions
• DNA transfer in Prokaryotes

  1. Conjugation

  2. Transformation

  3. Transduction
• Plant cells


  • Cellulose cell wall
  • Chloroplasts - stroma, thylakoids (grana)
  • Vacuole
• Animal cells


  • Cytoplasm has cytosol
  • Cytoskeleton - microfilaments, intermediate filaments, microtubules
• Cytoskeleton


  Network of protein fibers that maintain shape, hold organelles, and allow movement
• Cell junctions


  • Desmosome
  • Tight junction
  • Gap junction
• Lysosomes


  • Contain digestive enzymes
  • Acidic pH
  • Protein pump
• Peroxisomes

  • Break down fatty and amino acids
  • Contain oxidases
  • Break down poisons
• Proteasomes


  Destroy proteins
• Endoplasmic Reticulum


  • Membranous sacs and tubules
  • Lumen/cisternal
  • Modify proteins
  • Membrane continuous with nuclear envelope
• Rough ER


  • Ribosomes attached
  • Synthesize new proteins
• Smooth ER


  • No ribosomes
  • Lipid synthesis, carbohydrate synthesis, steroid synthesis
  • Detoxification
  • Storage of calcium
• Golgi Apparatus


  • Lipids and proteins are stored, packaged, and tagged
  • Cis and trans faces
• Nucleus


  • Stores DNA
  • Nuclear membrane has nuclear pores
• Ribosomes


  • 2 subunits
  • rRNA and proteins
  • Site of protein synthesis
• Mitochondria


  • ATP production
  • Cristae, inner matrix
• Plasmodesmata

  Channels in plant cell walls that connect cells
• Tight junctions


  Watertight seals in animal epithelial cells
• Desmosomes

  Short protein welds that join adjacent animal cells
• Gap junctions


  6 proteins in a doughnut structure that connect animal cells and form channels