Zusammenfassung der Ressource
Membranes: Bio110-2016
- Components of a membrane
- cholesterol: a saturated fat.
When conc. inc. in a
membrane, fluidity dec
- phospholipids: fatty acid lipids which
assemble via hydrophobid
interactions. Can move within the
plane of the membrane
- Saturated v. Unsaturated fatty acid tails:
Saturated fatty acid tails are very straight and
can pack together tightly. When conc. inc. of
sat. fat. acids, fluidity dec.
- Long tails have more opportunity for
hydrophobic interactions and therefore
can pack more tightly. When length of
fat. acids inc, fluidity dec
- Proteins: must have hydrophobic "interiors" made
of alpha helices to pass through membrane
- Made on the Rough Endoplasmic
Reticulum
- Movement through a membrane
- Passive transport: requires no E to move
molecules down a conc. gradient
- Diffusion: random movement of molecules
- Facilitated Diffusion: uses a protein to move molecules
- Osmosis: movement of Water through a
membrane with Aquaporins
- Hypertonic Solution
- Isotonic Solution
- Hypotonic Solution
- KIDNEY FUNCTION
- Nephrons
- Glomerulus: where small mol. from
blood are forced into glomerulus
tubules via blood pressure. Cells not
held together here
- Bowman's Capsule. Cells
held together via tight
junctions
- Proximal Convoluted
Tubules
- Salt and nutrients ACTIVELY pumped out
- As salt conc. dec, water conc. inc. inside
tube (hypertonic). Therefore water
flows out, down gradient
- No ADH receptors
- Loop of Henle
- Distal Convoluted Tubules
Water conc. regulated
- Salt and nutrients continue to be
pumped out
- Water transport is regulated. If
water is not needed, then no
aquaporin and water becomes
waste (dilute urine). If water
needed by the body, aquaporins
are present and water is
reabsorbed (conc. urine)
- Cells have ADH receptors. When
ADH present, aquaporins present
on membrane. When ADH absent,
no aquaporins
- Collecting Duct
- Water transport further
regulated
- Descending loop. At the
bottom, osmotic pressure
VERY high. Water still
leaves due to very high
U/P ratio (osmotic
pressure)
- In mammal for
further conc. of
urine
- Ascending loop: Only
salts move out of the
tube
- Carrier Proteins: eg Glucose.
- Channel Proteins: eg aquporins, always open
- AQUAPORINS
- Gated-channel proteins: responds to a stimulus/ligand
- Active transport: eg: Na/K pump. requires energy to
move molecules AGAINST a conc.
gradient. Uses ATP as energy
- Vesicles