Cell Transport

What are the two major active membrane transport processes?

-Active transport -Vesicular transport

What are the two types of active transport?

-Primary active transport -Secondary active transport

ATP is required when...

-Solute is too large for channels -Solute is not lipid soluble -Solute is not able to move down concentration gradient

Requires carrier proteins, Bind specifically and reversibly, Some carriers transport more than one substance, Requires energy (ATP) Moves solutes against concentration gradient (low to high)

Active Transport

Transport one substance into cell while transporting a different substance out of the cell.

Antiporters

Some cells "free" not bound to any other cells , most bound together to form tissues and organs , 3 ways cells can be bound together; tight junctions, desmosomes, gap junctions.

Cell junctions

Rivet like cell junctions formed when linker proteins of neighboring cells interlock like the teeth of a zipper.

Desmosomes

Collisions between molecules in areas of high concentration cause them to be scattered in areas with less concentration.

Diffusion

Transport into cell, Formation of protein coated vesicles, involve receptors; can be very selective, some pathogens are capable of hijacking receptor for transport into cell.

Endocytosis

This transport process includes..

Endocytosis, Exocytosis, Transcytosis, and Vesicular trafficking.

Transport out of the cell,Process where material is ejected from the cell, opposite of phagocytosis, usually activated by cell-surface signals or changes in membrane voltage, substances being ejected are enclosed in secretory vesicle.

Exocytosis

Transmembrane proteins (connexons) form tunnels that allow small molecules to pass from cell to cell.

Gap junctions

Function as specific biological makers for cell-to-cell recognition, Carbohydrates sticking out of cell surface, attach to lipids or proteins, every cell has a different pattern of "sugar coating"

Glycocalyx

Transport protein channels and carries enzymes and receptors. Firmly inserted into membrane, most transmembrane(span membrane) both hydrophobic and hydrophilic regions

Integral Proteins

a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others. The main biological functions include storing energy, signaling, and acting as structural components of cell membranes.

Lipids

Movement of solvents such as water across a selectively permeable membrane.

Osmosis

Requires no energy

Passive transport

Function as enzymes motor proteins( for shape during cell division and muscle contraction, cell-to-cell connections,Loosely attached to integral proteins, include filaments on intracellular surface used for plasma membrane support.

Peripheral proteins

Type of endocytosis "cell eating" Membrane projections called pseudopods form and flow around solid particles that are being engulfed, forming a vesicle which is pulled into cell. Formed vesicle is called a phagosome, Used by macrophages and other white blood cells, move by amoeboid motion.

Phagocytosis

There are 3 different types of endocytosis they include

Phagocytosis, Pinocytosis, receptor-mediated endocytosis.

Type of endocytosis that is referred to as "cell drinking" or fluid-phase endocytosis, plasma membrane unfolds bringing extracellular fluid and dissolved solutes inside the cell, used by some cells to sample environment, main way in which nutrient absorption occurs in the small intestine.

Pinocytosis

Hydrolysis of ATP causes change in shape of transport protein, Causes solutes (ions) bound to protein to be pumped across membrane Example of pumps; calcium,hydrogen(proton),Na+ -k+

Primary active transport

Cell communication with environment, Half the mass od plasma membrane, specialized membrane functions, some float freely some tethered to intracellular structures two types; integral and peripheral.

Proteins

involves endocytosis and transcytosis of specific molecules, receptors embedded in clathrin-coated pits(protein).

Receptor - mediated endocytosis

Electrical potential energy produced by separation of oppositely charged particles across plasma membrane in all cells, difference in electrical charge between two points is called voltage, cells that have no charge are said to be polarized, voltage only occurs at membrane surface.

Resting membrane potential (RMP)

Depends on ion gradient that was created by primary active transport system, Energy stored in gradients is used indirectly to drive transport of other solutes.

Secondary active transport

most studied pump, Enzyme, Na+ -k+ ATPase, Pumps Na+ out of cell and K+ back into the cell, Located in all plasma membranes, Especially active in excitable cells ( nerves and muscles)

Sodium-Potassium Pump

They are carbohydrates, composed of carbon, hydrogen, and oxygen. There are various types derived from different sources.

Sugar

Transport two different substances in the same direction.

Symporters

Integral proteins on adjacent cells fuse to form an impermeable junction that encircles whole cell , prevent fluids and most molecules from moving in between cells. Not free floating.

Tight junctions

Transport into, across, and then out cell.

Transcytosis

Transport from one area or organelle in cell to another.

Vesicular Trafficking

Involves transport of large particles, macromolecules, and fluids across membrane in membranous sacs called vesicles, Requires cellular energy (usually ATP)

Vesicular Transport