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