BIO MEMBRANES Flashcards
what affect dos temp have on the phospholipid bilayer?(4)
causes phospholipid to have more kinetic energy, this increases the number of gaps in membrane. The bilayer becomes more fluid and melts- proteins are denatured
state 3 functions of membranes within cells
-compartmentalization of organelles
-provides surface for attachment of enzymes
-controls what enters and leaves organelles (selectively permeable)
what is meant by cell signalling
-communication between cells-molecules released by one cell causes changes to another cell
explain how cell surface membranes contribute to the processes of cell signalling
-proteins/glycoproteins/ glycolipids act as/ have receptors
-release of a signal molecule via exocytosis
-the shape of the receptor and signal are complimentary
-attachment of a signal molecule causes change on cell surface
-cell surface allows for entry of some signal molecules
outline how vesicles are moved from one organelle to another
-the cytoskeleton provides a pathway for movement
-vesicle moves along microtubules, microtubules are extended and ATP is required
how are extracellular enzymes are secreted from cells
via exocytosis, this requires ATP and it causes a vesicle to fuse with the plasma membrane and thus the enzyme can be released
list three components of a cell surface membrane
-phospholipids
-proteins
-cholesterol
state two examples of active transport in plant cells
- mineral ions from soil to root hair cell
- potassium ions into guard cell to open stomata
what mechanism is release of enzymes into the gut
bulk transport
what mechanism is a plant taking up water
osmosis
what mechanism is calcium ions entering a nerve cell down a conc. gradient
facilitated diffusion
what mechanism is oxygen entering a red blood cell
diffusion
explain why plant cells do not burst when left in pure water
the cell wall limits the amount of water taken up when the cell is turgid, the cell wall provides strength
whats the fluid mosaic model
proteins embedded with a sea of phospholipids
