Cell bio

• Nucleus


  • Brain of the cell
  • Center of cell
• Nucleus - Nuclear Envelope


  • Outer Membrane features numerous ribosomes attached to the surface, importance of ribosomes in outer layer: DNA is converted to mRNA in nucleus, mRNA move out of nucleus via nuclear pore, mRNA attach to ribosomes, move to rough endoplasmic reticulum (ER)
  • Inner Membrane contains Lamins which are protein structures that bind to DNA and histones, controlling cell division, interact with chromatin, mutation can cause progerias
  • Nuclear Pores transport ions, proteins, and nucleotides in and out of nucleus (cytoplasm to nucleus, nucleus to cytoplasm), contains special transporters
• Nucleus - Nucleolus


  • Site of rRNA synthesis, Ribosome synthesis: Ribosome= rRNA + small proteins
• Nucleus - Chromatin


  • DNA + Histone proteins, make up the genetic material, Euchromatin is loose chromatin located in the center of the nucleus, Heterochromatin is tied chromatin located closer to the inner membrane of the nuclear envelope
• Endoplasmic Reticulum (E.R.) - Rough E.R.


  • Filamentous network, contains ribosomes, site of protein synthesis, proteins synthesized in Rough E.R., protein folding, glycosylation (N-type), packaging proteins
• Endoplasmic Reticulum (E.R.) - Smooth E.R.


  • No ribosomes, contain different enzymes, particularly those involved in lipid synthesis
• Proteins synthesized in Rough E.R.

  Lysosomes, Membrane of organelles and cell, Proteins that are excreted
• Vesicles containing the protein

  Transported to the Golgi Apparatus
• Summary Protein Synthesis in Rough E.R.

  mRNA from the nucleus is bound to ribosome and transported to Rough E.R., translated to protein, protein is pushed into the filamentous network of rough E.R., protein folding, add sugar residue on folded protein, activate protein, package protein in vesicles to be transported to Golgi Apparatus
• Types of Lipids Synthesized in Smooth E.R.

  Fatty acids, Phospholipids, Cholesterol: Can become steroid hormones like Progesteron
• Smooth E.R.


  • No ribosomes
  • Contain different enzymes, particularly those involved in lipid synthesis
• Smooth E.R. Function


  1. Lipid synthesis

  2. CYP 450 Enzymes

  3. Glucose-6-Phosphate Metabolism

  4. Stores Ca2+
• Types of Lipids Synthesized

  • Fatty acids
  • Phospholipids
  • Cholesterol
• Cholesterol


  Can become steroid hormones: Progesterone, Testosterone, Estrogen
• Smooth E.R. Function


  Precursor molecules are taken up, Enzymes use precursors to produce lipid molecules, Lipid molecules are released through vesicles, Vesicles can be sent to Golgi or cell membrane to release cholesterol, fatty acids, or phospholipids
• CYP 450 Enzymes


  Important in detoxification, Site: Liver, Breaks down toxins, drugs, alcohol via Biotransformation/Xenobiotic Metabolism
• Glucose-6-Phosphate Metabolism


  Glycogen stored in cell, Glucose-6-Phosphate is an intermediate, Glucose-6-Phosphatase enzyme in Smooth E.R. converts Glucose-6-Phosphate to glucose
• Smooth E.R. Function


  Stores Ca2+ in sarcoplasmic reticulum, Releases calcium into cytoplasm when needed during transport processes or muscle contraction
• Golgi Apparatus


  • Vesicles packed with proteins and lipids from Rough E.R. and Smooth E.R. are sent to Golgi, Acts as a packaging organelle
• Golgi Apparatus Function


  Receives vesicles from Rough and Smooth E.R., Modifies proteins through glycosylation and phosphorylation, Packages molecules into lysosomal proteins, membrane proteins, or for excretion
• Cell Membrane


  • Components: Phospholipid Bilayer, Cholesterol
• Cell Membrane Structure


  Phospholipid Head: polar, hydrophilic, negative charges, Inner surface points inwards, Outer surface points outwards, Fatty Acid Tail: saturated with Hydrogen, nonpolar, hydrophobic, point towards each other, Cholesterol controls fluidity of membrane
• Fatty Acid Tail


  • Saturated with Hydrogen
  • Nonpolar
  • Hydrophobic: don’t like to interact with water
  • No negative or slight changes in charge
  • Point towards each other
• Cholesterol


  • Came from Smooth E.R.
  • Packaged and sent to Golgi and then the cell membrane
  • Controls fluidity of membrane
  • ↑cholesterol → ↓space between phospholipids → ↓fluidity
  • ↓cholesterol → ↑space between phospholipid → ↑fluidity
• Proteins


  • Various functions
  • Transporters
  • Enzymes
  • Linker proteins between cells
• Cell transport processes


  • Moving materials into and out of cell, crossing cell membrane
  • Simple Diffusion
  • Facilitated Diffusion
  • Vesicular Transport
• Lysosomes


  • Spherical organelles
  • Contain hydrolytic enzymes
• Types of Hydrolytic Enzymes

  • Proteases
  • Nucleases
  • Lipases
  • Glucosidases
• Importance of Hydrolytic Enzymes

  • Break down macromolecules
  • Autophagy of Organelles
  • Autolysis of Damaged Cells
• Peroxisomes


  • Spherical organelle
  • Contain different enzymes
• Enzymes in Peroxisomes


  • Catalase
  • Oxidase
  • Metabolic Enzymes
• Function of Peroxisomes


  • Protect from Oxidative Damage by Free Radicals
  • Fatty Acid Oxidation
  • Make Lipids and Cholesterol
  • Ethanol Metabolism
• MITOCHONDRIA is the powerhouse of the cell and the site of ATP synthesis
• Plasmalogen


  • myelin in the white matter of brain
  • issues in peroxisomes can lead to
• Cholesterol


  • Steroid hormones
  • Bile acids
• Ethanol Metabolism


  Break down ethanol
• Mitochondria


  • Powerhouse of cell
  • Site of ATP synthesis
• Outer Membrane of Mitochondria

  • Smooth membrane
  • High permeability: many transport proteins
• Inner Membrane of Mitochondria

  • Folded
  • Cristae - inwardly projecting folds of the inner membrane of mitochondria
• Matrix of Mitochondria


  • Site of metabolic reactions
  • Location of mitochondrial DNA (MTDNA)