Cellular Transport and Membrane

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Cellular Transport and Membrane

Functions of Cellular Transport

Can exit, travel through vasculature system, and enter or signal a different cell

stored, modified, to make macromolecules needed to break down and to produce energy

when the metabolism uses molecules in order to transport to the correct location

Channel Proteins

Aquaporins = facilitated transport of water Ion-gated Channels = voltage gated

Bulk Transport, Exocytosis, Endocytosis

Endocytosis

Receptor Mediated Endocytosis = important for cholesterol uptake

Pinocytosis= fluid intake (unicellular, intestinal cells)

Phagocytosis = unicellular, immune cells

Exocytosis

Used by neurons (neurotransmitters release)

Used by secretory cells (insulin release by pancreatic cells)

BOTH EXO and ENDOcytosis use the plasma membrane

Active Transport

Involve carrier proteins and work AGAINST concentration gradient

Secondary = uses indirect source of energy, CO2 transport (symporter or antiporter)

Primary= uses direct source of energy ion pumps important for cell membrane potential

Cotransport (indirectly require ATP)

Require help of a membrane protein to pass

Facilitated Transport

Aided by proteins

Osmosis

FOR WATER ONLY

NO ENERGY NEEDED

Follow concentration gradient (high to low)

Passive Transport

Simple diffusion

Allowed to move freely and will achieve equilibrium

NO ENERGY needed

Follow concentration gradient (from high to low)

Types of Cellular Transport

Passive Transport, Active Transport, Bulk Transport

Can exit, travel through vasculature system, and enter or signal a different cell

Stored, modified to make macromolecules needed to break down and produce energy

Embedded Proteins

Dynamic, aqueous environment, attach site for ECM

Transport, signalization, recognition

What Can Pass?

Varies on size and polarity

A lot of (large) molecules need SPECIFIC TRANSPORTORS to pass membrane (proteins, amino acids, polysaccharides, DNA)

Small polar molecules (H2O, ethanol C2H5OH) CAN SLOWLY PASS

Gasses (O2,CO2,NO2) CAN PASS

Small hydrophobic molecules CAN PASS

Membrane Fluidity

Gradient across the membrane

Composition of endomembrane can change upon the need of the cell

Phospholipids; rotate, move latterly, flip-flop

Membrane Proteins

20-25 hydrophobic amino acids arranged in a alpha helix

Peripheral Proteins

Loosely attached!

found outside and inside surfaces of the membrane (attached to integral protein or phospholipid)

Integral Proteins

proteins inside are hydrophobic proteins exposed to cytoplasm or EXF are hydrophilic

Lipids (40%), Proteins (50%), Carbohydrates (10%)

Consist of 20-25 monosaccharide units

Carbohydrates are alone or attached to proteins (glycoproteins) to lipids (glycolipids)

Important for Immune system

Functions of Membrane

Barrier for most molecules Allows cell to communicate with outside and other cells

Major difference between procaryotes and eukaryotes cells

Cell Envelop= barrier between cell and noncell (role of Phospholipids) which allow communication with extracellular media (role of proteins)

NOT JUST A BAG (controls what goes in and out)