Mrs Duffy Flashcards
Name some plasma membrane functions inside and outside the cell.
Outside - separates cell contents , controls transport, cell recognition , cell signalling
Inside- separates organelles , controls transport, surface for reactions , isolates potentially damaging enzymes.
What are glycolipids and glycoproteins?
They allow cells to recognize one and other. Receptors for chems and hormones.
Describe cholesterol
Embedded in the membrane, keeps it mechanically stable and reduces fluidity at Hugh temperatures.
Describe membrane proteins.
Channel- moves charged particles.
Carrier-moves large
Describe diffusion.
No energy needed, molecules move down a concentration gradient.Can move non polars, lipid soluble substances (oxygen) and polar substances as long as there small ( C02), diffusion happens between phospholipids.
Describe facilitated diffusion.
No energy required , moves large and charged molecules with proteins , high to low concentration gradient.
Describe active transport.
Needs ATP, goes against conc gradient from low to high , can move anything but only uses carrier proteins.
Describe osmosis.
No energy needed , uses a water potential gradient from low to high , moves water.
What factors can determine the rate of diffusion?
Steepness of gradient, surface area , the distance over which diffusion occurs, temperature, the type of molecule diffusion, composition and number of proteins.
What happens when a plant cell is placed in distilled water ?
Water enters cell by osmosis down the water potential gradient , cell expands , cell wall stops it from bursting TURGID
What happens when water leaves the vacuole.
FLACCID, if lots of water leave the cytoplasm pulls away from cell wall PLASMOLYSED.
What happens when water enters / leaves an ANIMAL cell.
Enters cell = haemolysed (bursts)
Loses water - crenated
What is the process of active transport ?
1) Cartier proteins take up molecules from outside membrane ( low conc)
2) ATP binds to the protein and splits to ADP+P
3) the binding of the molecule to the protein causes the protein to change its shape so that the molecule can enter the inside of the membrane.
4) the protein no longer binds to the molecules and they are released with the aid of ATP
5) the protein reverts to its binding configuration.
Define and explain co transport.
Ion goes from epithelial cell to blood via AT, co transport of ion and molecule by FD from lumen into the epithelial cell , FD of ions and molecules from epithelial cell into blood.
Describe the non specific defense.
Immediate , physical barriers , phagocytosis.
