L1 : Structure and function of cell components

• LEVELS OF ORGANIZATION

  • Atoms
  • Molecule
  • Cells
  • Tissue
  • Organ
  • System
  • Organism
• Cell theory

  • All organisms are composed of one or more cells
  • The cell is the structural unit of life - Theodor Schwann and Matthias Schleiden
  • Cells can arise only by division from a preexisting cell
  • Cells contain genetic information in the form of DNA, and that information is passed from parent to daughter cell
• Prokaryotic and eukaryotic cells

  Bacterial cell<|>Plant cell<|>Animal cell
• Which one is eukaryotic cell?
• Features of eukaryotes not found in prokaryotes

  • Cytoplasm of a eukaryotic cell is filled with a great diversity of structures
  • Eukaryotic cells divide by a mitosis which duplicated chromosome condense into compact structure that are segregated by "mitotic spindle"
  • The flagella of eukaryotic cells are much more complex than the simple protein filament of bacteria and they generate movement by a different mechanisms
• Stem cells

  Self-renewal<|>Capable of differentiating into 2 or more mature cells
• Stem cell transplantation
• Outside a living cells, the virus exists as a particle called "virion"
• Virion contains a small amount of genetic material
• The genetic material of the virion is surrounded by a protein capsule or "capsid"
• Virions are unable to reproduce, metabolize, or carry on any of the activities associated with life
• Plasma membrane

  Compartmentalization<|>Providing a selectively permeable barrier<|>Transporting solutes<|>Responding to external signals<|>Intercellular interaction
• Membrane lipid

  • Phosphoglyceride
  • Sphingolipid
  • Glycolipid
• Glycosphingolipid


  GM1 gangliosidosis is an inherited lysosomal storage disorder that progressively destroys nerve cells (neurons) in the brain and spinal cord. It is caused by genetic changes in the GLB1 gene and is inherited in an autosomal recessive manner.
• Liposomes


  Lipid bilayer has ability to self-assemble<|>Liposome have also been developed as vehicles to deliver drugs or DNA molecules within the body
• Membrane carbohydrates

  Glycoprotein<|>A person has type A, B, AB, or O blood is determined by a short chain of sugar covalently attached to membrane lipid and proteins of the RBC membrane
• Membrane protein

  • Receptors
  • Channels or transporters
  • Enzyme
  • Receptors
  • Enzymes
  • Cell-adhesion proteins
• Paroxysmal nocturnal hemoglobinuria

  GPI-anchored protein<|>Self protective complement regulatory factor<|>Deficiency in GPI synthesis
• Membrane fluidity

  If the temperature of the bilayer is relatively warm (~37oC), the lipid exists in a relatively fluid state<|>If the temperature is slowly lowered, the lipid is converted to a frozen crystalline gel
• Importance of membrane fluidity

  • Cell movement
  • Cell growth
  • Cell division
  • Formation of intracellular junction
  • Secretion
  • endocytosis
• The movement of substances across cell membrane

  • Simple diffusion
  • Facilitated diffusion
• The diffusion of water through membrane

  Water moves through a semipermeable membrane from a region of lower solute concentration to a higher
• Facilitated diffusion

  The diffusing substances first binds selectively to a membrane protein called "facilitative transporter"<|>Insulin-responsive cells share a common isoform of the facilitative glucose transporter, specifically "GLUT4"
• Glucose transporter (GLUT)

  • GLUT1
  • GLUT2
  • GLUT3
  • GLUT4
  • GLUT5
• Defects in ion channels and transporters as a cause of inherited disease
• • Dehydrating the mucous layer
  • Trapped bacteria cannot moved out of the airways
  • Bacterial biofilm
  • Chronic infection
• CF: Cystic fibrosis
• Membrane potential and nerve impulses

  Neurons are specialized for the collection, conduction, and transmission of information, which is coded in the form of electrical impulse or membrane potential
• Which glucose transporter (GLUT) is the most important for glucose hemostasis after a meal?
• Endoplasmic reticulum
• Rough endoplasmic reticulum


  Site of synthesis of cytosolic and secreted proteins<|>Synthesize peptide neurotransmitter for secretion<|>Mucous secreting globlet cells of the small intestine also rich of RER
• Smooth endoplasmic reticulum


  Steroid hormone synthesis occurs in SER-rich cell such as the Leydig cells of testis<|>Cell synthesizing fatty acids and phospholipids are rich in SER<|>Drug detoxification occurs in hepatocytes are rich in SER<|>SER involve in the muscle contraction and relaxation involve the release and recapture of Ca2+
• Which organelle is the most responsible for synthesis of amylase in the pancreatic cell?
• Which organelle is mainly responsible for progesterone synthesis in an ovary?
• Golgi body / Golgi apparatus

  Golgi is the distribution center for proteins and lipids from the ER to the vesicles and plasma membrane<|>Perform post-translational modifications (e.g. adds mannose-6-phosphate to protein) before trafficking
• Which organelle is the most specific site for adding mannose-6-phosphate to proteins?
• Which of the following used for releasing produced insulin out of cell?
• Lysosome


  Contain digestive enzyme e.g. "lysozyme"<|>In charge of waste removal in animal cells and fighting diseases in host organisms
• Lysosomal storage disease


  A deficiency in one of the many lysosomal enzyme result in an accumulation of abnormal metabolic products
• Gaucher disease


  The most common lysosomal storage disorder<|>Glucocerebroside accumulate mainly in phagocytes<|>Gaucher cell is a plump macrophage that characteristically have the appearance in cytoplasm of crumpled tissue paper due to accumulation of glucocerebroside