[Unit 2.3] Transport Across Cell Membranes Flashcards
Cells
what is diffusion
the net movement of particles down a concentration gradient+
what factors affect diffusion
temp
concentration gradient
distance
surface area
moist
what is Fick’s Law
Rate of diffusion is proportional to (Surface Area x Concentration Gradient)/Thickness
what is facilitated diffusion
large or charged molecules diffuse through carrier proteins or channel proteins respectively
how do carrier proteins work
move large molecules in/out cell
molecule attaches to protein
protein changes shape
allowing molecule in
how do channel proteins work
pores allow charged molecules through.
what is osmosis
net movement of water across a ppm from high to low water potential
what is water potential
how likely water molecules are to diffuse
what is an isotonic solution
water potential is same in and out cell
what is hypotonic
water potential of cell is lower than solution (water moves in)
water potential of cell is lower than solution (water moves in)
water potential is higher than solution (water moves out)
describes what happens to a plant and animal cell in a: isotonic, hypertonic and hypotonic solution
plant:
iso - flacid
hypo - turgid (normal)
hyper - cell membrane pulls from cell walll
animal:
iso - normal
hypo - lysed
hyper - shrivelled
define active transport
move molecules against concentration gradient. requires energy
what is ATP
adenosine triphosphate. produced by respiration in mitochondria
how does ATP aid in active transport
changes shape of carrier or channel proteins using energy
how do carrier proteins move solutes from low to high concentration (active transport)
solute attaches to protein
proteins changes shape
moves across membrane
ATP used to move solute against gradient
how do co-transporters move solutes from low to high concentration (active transport)
its a type of carrier protein
binds to 2 molecules at a time
they help each other get in and out of the cell.
how can you increase the speed of active transport
more ATP
more carrier proteins
faster carrier proteins
how does glucose enter blood from lumen
-high conc of sodium “drags” glucose to co-transporter.
-both bind to the ct
-the ct changes shape to allow the molecules into the epithelial cell
-sodium leaves cell through Na-K pump (requires ATP)
-one ATP removes 3 Na, and brings 2 K
-glucose accumulates in epithelial cell
-glucose leaves cell via facilitated diffusion
why is sodium removed from the epithelial cell during the diffusion of glucose
to keep conc. low in epithelial cell. this means higher conc. gradient of sodium between lumen and cell. means more glucose will be dragged into the cell
what is the plasma membrane made of
phospholipids
proteins
carbohydrates
cholesterol
what are the functions of the cell membrane
role in cell communication and recognition
control substances moving in and out of cell
allows cells to bind with adjacent cells
what are the different parts of the cell membrane
phospholipid
intrinsic protein
extrinsic protein
glycoprotein
glycolipid
cholesterol
what is the fluid mosaic model
phospholipid bilayer is ‘fluid’ because the phospholipids are constantly moving
protein molecules are scattered around the bilayer like a mosaic
how are cells able to communicate in terms of cell membrane
cell membrane has receptor proteins which detects chemicals from other cells, which signal the cell to react in a certain way
how are cells able to be recognised in terms of cell membrane
glycolipids and glycoproteins tell white blood cells that the cell is your own
how are cells fluid in terms of cell membrane
phospholipids make the bilayer fluid
cholesterol regulates fluidity
more cholesterol = less fluid
