BIOL10002 Lecture Notes - Lecture 4: Facilitated Diffusion, Amphiphile, Glycerol
Lecture 4: Proteins, carbohydrates & lipids
Lipids: fats & oils for energy storage & insulation
● waxes for protective coating
● chemical messengers (eg. sterols)
● cholesterol: chemically modified to
produce the male and female sex
hormones: estradiol & testosterone
(anabolic/androgenic steroids: make
you more male)
● structural components of membranes
Fatty acid composed of carboxyl group + hydrocarbon tail
Stearic acid and oleic acid are isomers
● oleic acid: one double bond therefore unsaturated with hydrogen
● linoleic acid: two double bonds therefore polyunsaturated so becomes
quite bent
● arachidonic acid: four double bonds so polyunsaturated
Double bonds cause a kink in hydrocarbon tail; # of double bonds can vary
Fatty acids nearly always esterified (condensation reaction) to glycerol
Unsaturated: oil, liquid at room temp, lower melting point
Saturated: fat, solid at room temp eg. butter
Triglycerides: storage compounds
Cell membrane:
● Phospholipid bilayer: creates all membranes (proteins, glycoproteins, sterols); different membranes have different ancillary components;
selective barriers; 2 fatty acids + 1 phosphate attached to glycerol which interact with other groups; amphiphilic, bilayer due hydrophobic
and hydrophilic nature; membrane allows some lipid soluble (non-polar) molecules in: O2, CO2
○ Two fatty acid molecules attached to glycerol unit by ester bonds in eukaryotes & bacteria
○ The longer & more saturated the fatty acid chain, the less fluid it becomes
○ Cholesterol regulates membrane fluidity
● Molecules can pass through selectively permeable membrane by:
○ simple diffusion: uses channel proteins: H2O, CO2, O2 can pass via simple diffusion as they are lipid soluble molecules; can be
small uncharged molecules, or small polar molecules
○ facilitated diffusion: uses carrier proteins: interacts with molecule→conformational change→can pass
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○ active transport: eg. Na/K pump uses ATP so can pump against gradient; 3 Na+ in→1 ATP phosphorylates the
pump→conformational change→ 2K+ bind and go in→phosphate ion released; sets up gradients to allow other molecules to
diffuse and then collect that energy; transport is coupled - can be symport or antiport
○ pinocytosis: cell drinking form of endocytosis; cell brings in pieces of environment by pinching them off with cellular membrane
○ phagocytosis: cell eating form of endocytosis, phagocyte engulfs surrounding material, forming vesicles (phagosomes) derived
from plasma membrane; white blood cell example of phagocyte
○ osmosis: diffusion of water from regions of high water concentration to regions of low water concentration or from low solute
concentrations to high solution concentrations; moves down concentration gradient
● Osmotic potential: higher [solute] has a more negative potential
● Hypotonic →isotonic→hypertonic
● Water in plant cells keeps leaves turgid therefore leaf in salt solution goes floppy as water flows out (plasmolysis)
● Water is polar
Membrane proteins: create gates, usually have directionality, some enzymatically active, structural role, determinants of individuality, surface
receptors for stimuli, transport mechanisms
Lecture 5: Proteins & Enzymes
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lipids: fats & oils for energy storage & insulation. Fatty acid composed of carboxyl group + hydrocarbon tail. Waxes for protective coating chemical messengers (eg. sterols) cholesterol: chemically modified to. Double bonds cause a kink in hydrocarbon tail; # of double bonds can vary you more male) Fatty acids nearly always esterified (condensation reaction) to glycerol structural components of membranes. Unsaturated: oil, liquid at room temp, lower melting point. Saturated: fat, solid at room temp eg. butter. Two fatty acid molecules attached to glycerol unit by ester bonds in eukaryotes & bacteria. The longer & more saturated the fatty acid chain, the less fluid it becomes. Pinocytosis: (cid:1446)cell drinking(cid:1447) form of endocytosis; cell brings in pieces of environment by pinching them off with cellular membrane. Phagocytosis: (cid:1446)cell eating(cid:1447) form of endocytosis, phagocyte engulfs surrounding material, forming vesicles (phagosomes) derived from plasma membrane; white blood cell example of phagocyte.
