BIOL10002 Lecture Notes - Reaction Rate, Glycolysis, Key Type Stamp

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2 Jul 2018
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Week 2
Lecture 4
Lipids and Membranes
Lipids
- fatty acid chain
- protective coatings (wax)
- chemical messengers (steroids)
- energy storage (fats and oils)
- structural component of phospholipid bilayer
Note: fats – solid at room temperature, oils – liquids at room temperature
Phospholipid Bilayer
All membranes composed of;
- phospholipid bilayer
- other components: proteins, glycoproteins, sterols
- different membranes have different ancillary components
Movement across membranes
Membranes are selective barriers - molecules can enter by:
- Diffusion (incl. osmosis)
- Facilitated diffusion
- Active Transport
- Pinocytosis & Phagocytosis
Phospholipids have a hydrophilic (polar) head and a hydrophobic (non-polar) tail;
- only small, uncharged, non-polar (+ some polar) molecules and all gases can pass through the phospholipid bilayer,
e.g. lipids, CO2, water
Osmosis;
- A special case of diffusion.
- It is the movement of water through a differentially permeable membrane from a region of high water
concentration to a region of low water concentration
- Osmotic Potential: greater solute concentration = more negative potential.
Water moves from higher to lower (more negative) potential = Pressure required to prevent the movement of water
into a solution if the solution is separated from that water by a selectively permeable membrane
Role of Membrane Proteins and Glycoproteins
- Some are enzymatically active
- Structure
- Determinants of individuality
- Surface receptors for stimuli
- Transport mechanisms
- Role as a selective barrier
Note: Pino = drink, Phago = eat
Lecture 5
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Document Summary

Note: fats solid at room temperature, oils liquids at room temperature. Membranes are selective barriers - molecules can enter by: Phospholipids have a hydrophilic (polar) head and a hydrophobic (non-polar) tail; Only small, uncharged, non-polar (+ some polar) molecules and all gases can pass through the phospholipid bilayer, e. g. lipids, co2, water. It is the movement of water through a differentially permeable membrane from a region of high water concentration to a region of low water concentration. Osmotic potential: greater solute concentration = more negative potential. Water moves from higher to lower (more negative) potential = pressure required to prevent the movement of water into a solution if the solution is separated from that water by a selectively permeable membrane. Can be polar but uncharged (hydrophilic), charged (hydrophilic), or non - polar (hydrophobic) Some have special properties (e. g. cysteine links two amino acids by forming disulphide bonds) s - s. Proteins are formed by condensation of amino acids.

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