Catégories : Tous - diffusion - osmosis - atp

par Rather Sufyan Il y a 5 années

1102

Cell Membrane

Cell membrane transport is a critical process in cellular function, involving various mechanisms to move substances across the membrane. Passive transport allows molecules to move without energy expenditure, following a concentration gradient.

Cell Membrane

Floating topic

Cell Membrane Transport

Fluid Membrane Mosaic Model

Active Transport
transports substances across the cell membrane with the use of energy; requires ATP for initialization.

Moves up the gradient

Protein Pumps

use energy of an ATP molecule to move substances up the gradient

Calcium Pump

moves calcium out off the cell membrane

responsible for maintaining the electrochemical concentration Ca2+ at a steep slope across the gradient

Sodium-Potassium Pump

for one unit expenditure of ATP molecule against the gradient:

the pump keeps two potassium ions in

the pump moves three sodium ions out

uses hydrolysis of ATP to harvest energy

moves sodium and potassium ions across the membrane

Antiport

Allows two molecules to pass through in two directions

Symport

Allows two molecules pass through in one direction

Uniport

Allows one molecule to pass in one direction

Secondary Active Transport

get ATP from the concentration gradients that Proteins pumps already created

use ATP indirectly

Vesicle (Bulk) Transport

Endocytosis

Phagocytosis

the ingestion of bacteria or other solid materials into the cell membrane

Pinocytosis

the ingestion of fluid into a cell membrane

the process of substances moving from the exterior to the interior of the cell.

Substances are gathered and stored inside a vesicle once in contact with the cell membrane and travels to parts inside the cell.

Exocytosis

the process of substances moving from the interior to the exterior of the cell.

A vesicle carrying substances fuses with the cell membrane and releases it's contents outside the cell membrane.

Passive Transport
Allows for transport across the cell membrane without the use of energy

Moves down the gradient

Osmosis

Movement of H2O across biological membranes

Hypotonic

the concentration of solute is higher within the cell than outside the cell.

Hypertonic

the concentration of solute is higher outside the cell than inside the cell.

Isotonic

the concentration of solute within the membrane is the same as outside the membrane; osmotic pressure is equal across the membrane.

Diffusion

movement of molecules from an area of high concentration to an area of low concentration

factors affecting Diffusion

Molecule size

the bigger the molecules, the longer it takes to diffuse

temperature can increase energy or reduce energy, thus, it can make it a faster or slower process

Concentration

require longer to diffuse completely

Facilitated Diffusion

molecules move across the membrane with help of membrane proteins.

A Carrier Protein

much slower transport than a channel protein

open or close depending on physical or chemical stimulus

A Channel Protein

some have gates and some remain open indefinitely

allows specific molecules to pass through the membrane

Phospholipid Bilayer: A layer encompassing the cell membrane; controls the transport of molecules and maintains structure.
Phospholipids A lipid containing a Phosphate group; amphophilic.

Glycerol

Phosphate Group

Hydrophillic Head

Micelle A lipid molecule.

helps absorb minerals, vitamins, and fats

Three Fatty Acids

Hydrophobic Tails

Carbohydrate Chains

Oligosaccaharides

Immune Response with White Blood Cells

Cell Recognition

Steroid

Cholesterol

Prevents movement in the bi-layer during warmer temperatures.

Maintains membrane fluidity

Factors Affecting Fluidity

Intramoleculaer forces of large molecules

Length of fatty acid tails

Double Bonds

Temperature

Prevents compression in the bilayer during colder temperatures.

Proteins

Trans-membrane Protein A protein that spans the entire cell membrane and is a gateway for transporting substances across the bilayer.

Introduce immunological defense; provide White Blood Cells

Regulates traffic of substances passing in/out of the cell membrane.

Contributes to Cell Membrane Structure and Fluidity.

Glycoproteins Proteins attached to sugar.

Serve many important functions:

Immune Response

White Blood cells attach to Glycoproteins to travel along the body

Protection

Glycoproteins allow skin cells (epithelial cells) to attach to each other; keep skin healthy.

Integral Membrane Protein A protein that exists inside the bilayer; integrated in the cell.

Act as Entry and Exit routes for:

Large Molecules such as DNA

Drugs

Waste Products

Nutrients

Ions

Peripheral Membrane Proteins A protein that is on the perimeter of the bilayer; it can exist within the cell or outside of it.

Aid in Molecule Transfer

Carry out Enzyme functions

Destruction Reactions

Synthesis Reactions

For Structural Support of the Bilayer.

Used for signaling