#8 Flashcards
Passive transport
Small molecules that doesn’t requires energy ;it may involve transport proteins.
Active Transport
of small molecules requires energy and transport a protein.
Most important staple ingredient of cellular membranes are……
Lipids and proteins though carbohydrates are also important.
Most abundant lipids are
Phopholipids
Are membranes are static sheets of molecules locked rigidly?
A membrane is held together mainly by hydrophobic interactions,which are much weaker than covalent bonds.
Adjacent moment of switching position of phospholipids is about
10^7 times per second
Unsaturated phospholipids[since cannot pack closely as saturated hydrocarbons due to kinks] membrane remains fluids
in lower temperature or else solidifies
Saturated hydrocarbon make the membrane
viscous
Cholesterol present in the the animal’s plasma membrane uses
makes less fluid by restraining phospholipids movement also it hinders the close packaging of phospholipids. it lowers the temperature required for the membrane to solidify.
Fluidity buffer
Cholesterol
Why should membrane maintains its fluidity
To work properly, the fluidity of a membrane affects both its permeability and the ability of membrane proteins to move to where their function is needed. if its too fluid it cannot support protein functions either.
Function of membrane proteins
Transport
Enzymatic activity
Signal Transduction
Cell-cell recognition
Inter-cellular joining
Attachment to the cytoskeleton and extracellular matrix
How does cell recognize other cells?
by binding to molecules,often containing carbohydrates on the extracellular surface of the plasma membrane.The diversity of the molecules and their location on the cell’s surface enable membrane carbohydrates to function as markers that distinguish one cell from another.
Transport Proteins
Channel proteins
Carrier proteins
Channel proteins
functions by having a hydrophilic channel that certain molecules or ion use as tunnel through the membrane. eg.aquaporins
Channel proteins —ion channel [gated channel - chemical and electrical]
Carrier Proteins
hold on to their passengers and change shape in a way that shuttles them across the membrane.
eg.glucose transporter
Tonicity
ability of surrounding solution to cause a cell to gain or lose water.
Plant cells are healthiest in which environment
Hypo tonic solution
Hypo- turgid water intake
Isotonic-Flaccid water enter and exit
Hyper-Plasmolyzed
Animal cell are fare best in
Iso tonic solution
hypo-lysed
iso-Normal
hyper-shriveled
Active Transport
To pump solutes across the membrane against its gradient requires work ,the cell must expend the energy .
The transport proteins move solutes against its conc gradient are all carrier proteins rather than channel proteins.because they merely allow solutes to diffuse down their conc gradients rather than picking them and transporting against the gradient.
Active transport
enables a cell to maintain internal concentrations of small solutes that differ from concentration its environment .
Diffusion vs Facilitated diffusion
Diffusion is hydrophobic molecules at slow rate very small uncharged polar molecules can diffuse through the lipid bilayer.
Membrane potential
-50 TO - 200 mV minis because inside of the cell is negative
membrane potential favors
passive transport of cations into the cell and anions out of the cell. Refer pg no 208
