chapter 3 cells Flashcards
(55 cards)
cells
are the basic structural and functional unit of living organisms
vary in size, shape and function
what are the 3 main parts of the cells?
plasma (cell) membrane
cytoplasm
nucleus
plasma membrane
forms the boundaries of the cell –> operates the intracellular from extracellular fluid
structure is described by “fluid mosaic model”. it consist of a bilayer of fluid lipids (98%) within which are a verity of protein (2%)
lipid component of membrane is 75% phopholipids, 20% chlosterla and 5% glycolipids
phospholipids molecules are arranged in 2 layer
function as selectively permeable barrier that regulates the flow of materials into and out of the cells
phospholipids
molecules that have polar heads (hydrophilic) and non polar tails (hydrophobic)
phospholipids molecules are organized with their heads facing both sides of the membrane and their tails pointing towards each other
fluid mosaic model
refers to its made up of different things
glycolipids
phospholipid with a sugar group attached to it
selectively permeable
only some things can pass through it
what are the two types of membrane proteins?
intergral transmembrane proteins and peripheral membrane proteins
intergral transmembrane proteins
extend through the phospholipid bilayer. in contact with the outside and the inside of the membrane
peripheral membrane proteins
are associated loosely with only one side of the membrane. don’t go all the way through they are in contact with EITHER the outside OR the inside
what are the membrane protein functions?
transporter = as channels or carriers
receptor for chemical messenger (bind to something and can active or reactive the cell in some way)
enzyme that catalyze recation
marker in cell recognition
anchors to cells cytoskeleton
membrane permeability
a membrane is permeable to substance that can pass through impermeable to substance that can’t
cell membranes are selectively permeable
- allow some things to pass more easily than others
usually permeable to bipolar, uncharged and small molecules
usually impermeable to ions, charged or polar molecules exception: water
membrane transport
getting things across the membrane
they are a variety of mechanics for transport of substance across membranes.
in passive processes, substances move down their concentration gradients (from high to low) with no energy required from the cell
active process
energy is required to move substances against their concentration gradients from low to high or for substances otherwise unable to pass
pass transport- diffusion
net movement of molecules from an area of high to an area of low until equilibrium is reached
how is rate affected?
temperature
particle size- (smaller particles move faster, larger particles move slower)
[] gradient- the bigger the difference between the two areas the faster the reaction
surface area- smaller are going to decrease (more traffic). larger are is going to increase because you go faster.
distance - shorter distance the rate will be faster
what are the two types of diffusion?
simple
faciliated
simple diffusion
non polar and lipid soluble substances diffuse directly through the lipid bilayer eg. CO2, O2, fat soluble vitamins (A D E K)
facilitated diffusion
polar and charged molecules require transmembrane proteins as carriers or use ion channels to move through the lipid bilayer. eg. glucose, amino acids, ions
passive transport
energy is not required
passive transport- OSMOSIS
net movement of water from an area of high [water] to an area of low [water] though a semipermeable membrane, until equilibrium is reached.
similar to diffusion but this is strictly for water. during osmosis water can pass through the membrane, polar molecule bc the electrons are shared unequally. can go through the phospholipid gaps. the other way it can get through is through aquaporins dedicated protein channels to allow only water to pass through
osmotic pressure
the ability of a solution to attract or draw in water
the greater the # of solute particles in a solution, the greater the osmotic pressure.
more dissolved particles (solute) in a solution, the less space for water
the greater the tendency to draw in water
active transport
substances cross the membrane by moving against their concentration gradient and energy is required
primary active transport
energy from ATP hydrolysis (break ATP, breaking off the last phosphate of and release all of the energy to form ADP + a free floating phosphate) changes the shape of a transporter protein and it “pumps” a substance across the membrane
eg. Na+\K+ pumps transport Na+ out of the cell and K+ in.
40% of the ATP the cell uses is for primary active transport
