MODULE1 WS1

• Tree of life

  A special phylogenetic tree that represents a hypothesis about the evolutionary history of all life
• Phylogenetic tree

  A tree that represents the evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characteristics
• The diagram presents the tree of life. It shows three major branches or domains: Archaea, Bacteria and Eukarya

  
• Nucleus

  • Contains chromosomes, controls protein expression
• Mitochondrion

  • Site of cellular respiration
• Rough endoplasmic reticulum

  • Secretory protein synthesis
• Lysosome

  • Fuse with incoming food vacuoles or unwanted/damaged organelles and break down/digest them
• Main macromolecule

  • Carbohydrates
  • Nucleic acids
  • Proteins
  • Lipids
• Monomers

  Monosaccharides (carbohydrates), nucleotides (nucleic acids), amino acids (proteins), heterogeneous structure most often based on linear hydrocarbon chains or ring systems (lipids)
• Functions of biological molecules

  Carbohydrates: cell-cell recognition, energy, structure

  Nucleic acids: Hereditary/genetic information, information transfer within a cell

  Proteins: Structural, regulatory, contractile, transport, storage, protective, catalytic, toxic

  Lipids: Structural, regulatory, energy
• Lipids

  Hydrophobic, examples: triacylglycerols ("fats"), steroids, phospholipids, fat soluble vitamins
• Molecules

  • Monosaccharide (glucose)

  Triacylglycerol

  Steroid (cholesterol)

  Amino acid

  Nucleotide

  Nucleic acid (RNA)
• Plasma membrane

  • Phospholipid bilayer has a hydrophobic side and hydrophilic components. It also has an integral membrane proteins and cholesterol.

  
• Membrane protein functions

  • Signal transduction, linking cytoskeleton and extracellular matrix, enzymatic activity, cell-cell recognition, cell recognition, intercellular joining
• Facilitated diffusion

  • Movement of specific substances down their concentration gradient, involves channels or carrier proteins, passive (no energy input)
• Selective permeability of plasma membrane


  Phospholipid bilayer only readily permeable to lipid soluble materials, specific integral membrane proteins involved in facilitated diffusion of water-soluble molecules and active transport of a range of molecules

  
• Co-transport


  Transporter moves both the molecule and H+ ions across the plasma membrane in the same direction, separate pump requires energy (ATP)

  
• Components of endomembrane system:

  • Smooth ER
  • Rough ER
  • Transport vesicle
  • Golgi apparatus
  • Plasma membrane
• Functions of Smooth ER:

  • synthesise lipids, metabolise carbohydrates, detoxify drugs/alcohol, store calcium
• Golgi apparatus polarity


  Has a cis face (where transport vesicles arrive) and a trans face (where vesicles leave)
• Examples of Lipids

  Phospholipids, Triacylglycerol, steroids (cholestero)
• Diffusion allows transport of hydrophobic materials across membrane
• Facilitated Diffusion allows hydrophilic molecules across membrane via channels or carrier proteins
• Plasma membrane Function:

  • selective barrier regulating passage of material
• Function of Golgi apparatus:

  • glycosylates proteins
  • sorts proteins
  • directs vesicles
• Transport vesicle function:

  • carries products of ER and Golgi to various locations
• Rough ER:

  • ribosomes produce secretory and membrane-bound proteins
• The endosymbiont theory is supported by the presence of mitochondrial DNA.
• Cristae increase the surface area of the mitochondrial inner membrane.
• number of mitochondria can vary depending on demand. Varies in cells.
• Lysosome is a membrane bound digestive organelles filed with hydrolytic enzyme which helps in the degradation/ break down of molecules. eg food from phagocytic vacuole.
• Endocytosis involves 3 processes:

  • Phagocytosis- Cell "eating" : vacuole forms around food and is transported to the lysosome for break down.
  • Pinocytosis: Cell "drinking": Vesicle form with aid of coat protein, non-selective.
  • Receptor Mediated: special type of Pinocytosis, specific.
• Movement of proteins:

  rER -> vesicles ->cis face of golgi -> trans face of golgi -> vesicles -> plasma membrane.
• Proteoglycans allows ECM to resist compression while the collagen resist tension- strength. Overall both play a part in the ECM strength.
• The number of organelles within a cell does not remain constant.
• The plasmodesmata does NOT have a continuous lignin coating however, is associated with the endoplasmic reticulum.
• Lignin confers strengths and rigidity and exlcudes water
• Vacuoles take up water through Osmosis.
• Receptor-mediated endocytosis

  • a special type of pinocytosis
  • allows bulk transport of SPECIFIC substance which may be present at only a LOW concentration in the ECM.
• Bound ribosomes attached to the rER are involved in protein synthesis, in particular protein for the endo-membrane system.