Membrane structure ,synthesis ,transport B7F857EF-CA9A-49AD-BFE4-7AA24EB035BE

Membrane structure

Phospholipid are amphipathic

Fluid-mosaic model

Membrane is phospholipid bilayer contain also protein and carbohydrates

Hydrophobic

Hydrophilic

Region faces out

Protein bound to membrane

Mosaic

Fluid

Lipid , protein , carbohydrates

Lipids and proteins can move

Integral membrane protein

Extrinsic membrane protein

Transmembrane proteins

Lipid-anchored proteins

Non Covalenty bound

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Region faces in

fluidity of membrane 34985794-6F40-4F36-8708-241A747251CB

Flippase requires ATP

Lipid rafts

Flip-flop of lipids

Factors affecting fluidity

Rotation = move laterally

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Membrane are semi fluid

Lipids associate with each othe and form it

Group of lipids floats together as a unit

Composition

Unique set of membrane proteins

Play role in endocytosis and cell signaling

High concentration of cholesterol

Presence of double bonds

Presence of cholesterol

Length of fatty acrylic tails

Synthesis of membrane components

Transfer of lipids to other mambrane

Synthesis of transmembrane proteins

Process occurs at cytosolic leaflet of the smooth ER

Glycosylation

Fatty acid building blocks are made via enzyme in cytosol

Transported via vesicles

Lipid exchange proteins

Lipids in ER membrane can diffuse laterally to nuclear envelop

Most tensmembrane proteins are directed to the ER membrane first

Membrane protein can be transferred via vesicles to other membrane

Process attaching a carbohydrate to protein or lipid

Glycolipid

Glycoprotein

Carbohydrate to lipid

Carbohydrate to protein

N-linked Glycosylation

O-linked Glycosylation

Attachment ofcarbohydrate to nitrogen atom of asparagine

Occur in ER

Addition of sugars to O atom of serine or threonine side chain

Occurs in Golgi

Membrane transport

Cells maintain gradients

Phospholipid bilayer barrier

Tonicity

Way to move o cross membranes

Osmosis

Plasma membrane is selectivity permeable

Transport protein

Passive transport

Active transport

Facilated diffusion

Require energy - up or against gradient

Passive diffusion

Diffusion of a solute through a membrane without transport protein

Diffusion of a solute through a membrane with the aid of a transport protein

Rate of diffusion

Example ; diethylurea

Hydrophobic interior

Transmembrane gradient

Ion electrochemical gradient

Hypertonic

Hypotonic

Isotonic

Equal water and solute concentration in both side

Solute concentration is higher and water concentration lower on one side

Solute concentration is lower and water concentration higher on one side

Osmotic pressure

Osmosis in animal cells

Water diffuses

Osmosis in plant cells

Crenation

Osmotic lysis

Maintain a balance between extra cellular and intracellular solute concentration

Shrinkage

Swelling and bursting

Turgor pressure

Plymolysis

Cell wall prevent major change in cell size

Pushes plasma membrane against cell wall

Plant wilting because water leaves plant cells

Type of movement

Large molecule transport :

Channels

Transporters

Open passageway for direct diffusion of ion or olecules across the membrane

Example ; Aquaporins

Conformational change transport solute across membrane

Such as ; Sugar , amino acid , nucleotides

Transporter types

Uniporter

Symporter

Antiporter

Single molecule or ion

Two or more ion or molecule transported in same direction

Two or more ions or molecules transported in opposite direction

Active transport

Movement of the solute across a membrane against its gargient

Type of active transport

Require energy (ATP)

Primary active transport

Secondary active transport

Exocytosis

Endocytosis

Material inside the cell packaged intro vesicles

Pinocytosis

Phagocytosis

Receptor- mediated endocytosis

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