Ch. 7 Membrane Support & Function Flashcards
know everything there is to do with the plasma membrane - pro tip - this video goes over everything here way better than i ever could: https://www.youtube.com/watch?v=AsffT7XIXbA
what is the function of the plasma membrane?
-provide protection for a cell
-keep organelles inside and regulate the entry/exit of foreign materials
why are phospholipids amphipathic?
-they have a hydrophilic phosphate head and two hydrophobic fatty acid tails
what is the function of cholesterol in the cell?
maintains cell fluidity: if temperature goes up, fluidity goes up, so cholesterol brings it back down, and vice
what are the fluid properties of the cell membrane?
lateral movement = 10^7 times a second
vertical movement = once a month
what does the fluid mosaic model of the cell describe?
it describes the cell membrane as flexible, fluid, and composed of many different structures [proteins, carbs, phospholipids)
what is an integral protein?
a protein that is transmembrane = it goes through both sides of the cell membrane
what is a peripheral protein?
a protein that is on one side of the cell membrane = loosely bound to proteins or phospholipids (or cytoskeleton on the cytoplasmic side)
what are the six major functions of plasma membrane proteins?
- transport - Na/K pump
- enzymes - lactase
- signal transduction - neurotransmitters
- cell-cell recognition - blood types
- intercellular joining - desmosomes
- ECM/cytoskeleton attachment - integrins
what are aquaporins?
protein channels for water to enter / exit cell
what molecules are permeable to the cell membrane?
oxygen, co2, small amounts of water, small lipids
how do aquaporins affect the rate of water transport?
by providing an open channel for large amounts of water to enter/exit the cell
what membrane factors affect the selective permeability of membranes? [how do things get in/out of the membrane?]
-membrane proteins & vesicles
what is passive transport?
movement of a particle across a membrane with no energy spent
what is diffusion?
the movement of molecules from a high concentration to a low concentration
what is facilitated diffusion?
diffusion with the aid of a membrane protein [gated channel], such as an aquaporin
what is active transport?
transport of a solute against its gradient using ATP
how do concentration gradients create potential energy?
the energy released by solutes moving down a gradient can be used to power other functions in the cell
what is osmosis?
the diffusion of water across a selectively permeable membrane [moves from high solute [] to low solute []]
what happens to a cell placed in hypotonic solution?
-water moves into cell, cell bursts/lyses
-in plant cells - cell becomes turgid, which is normal and healthy
what happens to a cell placed in an isotonic solution?
water enters and exits at the same rate - no change
what happens to a cell placed in a hypertonic solution?
animal cells: water leaves cell, cell shrivels up
plant cell: becomes plasmolyzed
what is membrane potential?
the electrical potential difference between the inside and outside of a cell, established by active transport (Na/K pump)
what is co-transport?
when two different molecules or ions are moved across a cell membrane at the same time - established by concentration gradients [one moves down, one moves against]
what is the function of the sodium potassium pump? how many molecules of each does it pump in/out of the cell?
-creates electrochemical gradient by pumping 3Na+ OUT of the cell and 2K+ INTO the cell
what is the function of a proton pump?
to create H+ gradients that are used to transport many other nutrients, commonly found in plants, fungi, and bacteria
