7.4 and 7.5 active transports uses engergy and goes against the concentration gradient

Facilitated diffusion

despite the fact it is helped by transport proteins, is still a type of passive transport

active transport

moves substances against the concentration gradients

Hydrolysis of ATP

is the way energy is expended to preform active transport

Specific carrier proteins

what active transport is always preformed by

these specific carrier proteins are often called

pumps

Active transport is important because

it allows cells to maintain internal concentrations of chemical that differ from the surroundings

Sodium potassium pump

a type of transport system, and the main one for animal cells

membrane potential

is the voltage (difference in electrical potential) across a membrane

potential

the potential energy available to do work

voltage

is created by differences in the distribution of positive and negative ions across a membrane

Membrane potential of the plasma membrane

-50 to -200 milivolts

electrochemical gradient

electrical force and chemical force, combine to drive the diffusion of ions

electrical force

the effect of the membrane potential on the ions movement, opposites charges attract

chemical force

the diffusion of an ion down its concentration gradient

The inside of a cells membrane

has a negative voltage relative to the outside of the membrane, favoring cations in and anions out

electrogenic pump

transport proteins that generate voltage across a membrane, contributing to its potential

Proton pump

the main elecrogenic pump of plants, fungi and bacteria and are powered by ATP hydrolysis

by contributing to membrane potential, electrogenic pumps

help store potential energy that can be used for cellular work

A solute that exists in different concentrations across a membrane

can do work as it moves across the membrane by diffusion down its concentration gradient

Contransport

occurs when active transport of one solute (against its concentration gradient) indirectly drives the transports of other solutes ( against their own concentration gradient)

Plants use the gradient of hydrogen ions generated by proton pumps

to drive active transport of nutrients into the cells

what is happening in this image

• H+ gradient is crated and maintained by ATP proton pump

• It concentrates H+ outside the cell and stores potential energy for active transports

  • the sucrose H+ contransporter carrier protein use the diffusion of H+ down its electrochemical gradient into the cell to uptake sucrose against its concentration gradient

What type of transport is this

passive

What type of transport is this

active

Large molecules have to cross the membrane in

large packages in vesicles

Bulk transport

requires energy

endocytosis

forming new vesicles in the plasma membrane to uptake macromolecules an bacteria

three types of endocytosis

• phagocytosis

• pinocytosis

  • receptor mediated

Phagocytosis

the cell engulfs a foreing particle by packaging it into a food vacuole

• macrophages

Pinocytosis

molecules are taken up when extracellular fluid is “gulped” into tiny vesicles, not selective

the receptor mediated endocytosis

binding specific ligand to receptors on the extracelluar surface of a cell membrane triggers vesicle formation in the membrane

• extremely selective

Ligand

any molecule that bind specifically to a receptor site of another molecule

How does ATP attach to the Carrier protein in active transport

one phosphate group is bound to the carrier protein, this changes the proteins shape and affinity (in sodium potassium pump, changes from sodium to Potassium, and when the phosphate is lost it cycles back to sodium).

What does the sodium potassium pump do to cell charge

more positive sodium outside less positive potassium inside, the cell is surrounded by a more positive solution (the cell is more negative compared to the outside)

The pull of sodium into the cell

is strong

It is more acidic inside or outside the cell

outside: high in H+ and low in pH

What do animal cells use to cotransport

Sodium (there is excess around the cell)

What molecules can passively diffuse (most common)

CO2 and O2

What type of Transport is C

Passive transport, it flows at a steady rate

What type of transport is B

Passive transport protein- starts around 0 and needs a bump to get going

What type of transport is A

Active transport- it starts as a negative and needs help to get going

Hypocholesterolemia

High level of cholesterol, blocks LDL from entering the cells