Campbell Biology 12th edition: Chapter 7

plasma membrane

- in every cell

- separate cell from surroundings

- selectively permeable

- all cell membranes vary in chemical composition

- adapt membrane through enviornment

transport proteins

responsible for controlling passage across cellular membranes

Amphipathic molecules

has both hydrophobic and hydrophilic reigons

phosphate group

hydrophilic

fatty acids

hydrophobic

Fluid mosaic model

individual units that make up a membrane; has some movement

cholesterol

used to keep fatty acids in line

peripheral proteins

on surface of membrane, don't go through membrane (external or internal)

integral proteins

go through membrane; will go into hydrophobic region (lipids) must be chemically different

- hydrophobic reigon has stretches of nonpolar amino acids in a alpha helix

transmembrane proteins

type of integral protein that goes through the entire membrane

functions of cell-surface membrane proteins

-transport

-location of Enzyme activity

-signal transduction

-cell-cell recognition

-intercellular joining

-attach to cytoskeleton and ECM

cell-cell recognition

cells contain glycoproteins or sugars for other cells to identify it on plasma membrane

signal transduction

The process by which a cell responds to substances outside the cell through signaling molecules found on the surface of and inside the cell

glycolipids

membrane carbohydrates covalently bonded to lipids

What passes through membranes easily

Hydrophobic lipids/ nonpolar molecules

What needs a protein to pass through membranes

Hydrophilic molecules including ions and polar molecules

types of transport proteins

carrier proteins and channel proteins

Carrier proteins

the substance will bind to carrier protein, then change shape as modified form

channel proteins

they have an opening straight through to the cell

aquaporins

channel proteins that will transport water

passive transport

does not require ATP/ energy to transport substance across membrane

(from high concentration to low concentration)

active transport

requires ATP/ energy to transport substance across membrane

(from low concentration to high concentration)

types of passive transport

- Diffusion (simple)

- Facilitated Diffusion

- Equilibrium

- Osmosis

Concentration Gradient

occurs when the concentration of particles is higher in one area than another

Diffusion (simple)

- Goes right across the membrane

- passive transport

- moves along concentration gradient

Take a sugar cube and put into coffee

Facilitated Diffusion

requires use of transport proteins; needs help

- passive transport

Osmosis

looking at concentration and movement of water

Tonicity

the concentration of the solutes

Types of Osmosis

- refers to concentration of solute outside the cell than inside cell

Isotonic solution

Hypertonic solution

Hypotonic solution

Isotonic solution

Iso=equal

equal amount/ concentration of solute inside the cell and outside the cell; equal movement of water inside and outside of cell (animal cell's normal state)

Hypertonic solution

hyper=more

more amount of solutes outside the cell than inside the cell; water leaves the cell

Hypotonic solution

hypo= less

less concentration of solute outside cell than inside cell; water moves into the cell; causes the cell to blow up

(burst in animal cells, blood cells will be lysed, normal for plant cells)

why are cell membranes different

- asymmetrical distribution of proteins, lipids, and associated carbohydrates in the plasma membrane is determined when the membrane is built by the ER and Golgi Apparatus

- Based on how they get produced and released will determine how they are arranged in cell membrane

carbohydrates on extracellular side

vary among species individuals and even cell types in and individual

active transport characteristics

- goes against concentration gradient

- all proteins involved in active transport are carrier proteins

- allows cell to maintain concentration gradients that differ from surroundings

types of active transport

Bulk transport

cotransport

basic active transport

basic active transport

transport that needs ATP to happen

sodium-potassium pump

Sodium-Postassium Pump

a transport protein that is energized by transfer of a phosphate group from the hydrolysis of ATP

(all animal cells have high potassium inside and low sodium outside)

- takes sodium out of cell through carrier protein

- with ATP

- releases it out of cell

- gains potassium and releases inside cell

membrane potential

is the voltage across a membrane

- Created by differences in the distribution of positive and negative ions across the membrane

- cytoplasm side of the membrane is negative in charge compared to the extracellular side

electromechanical gradient

Two combined forces that drive the diffusion of ions across a membrane

chemical force

an ion's concentration gradient

electrical force

the effect of the membrane potential on the ion's movement

electrogenic pump

a transport protein that generated voltage across a membrane

- store energy

- used for cellular work

electrogenic pump of animal cells

sodium potassium pump

electrogenic pump of plants (fungi/bacteria)

proton pump

proton pump

- involved in metabolism

- actively transports hydrogen ions H+/protons out of cell

-Hydrogen protons get concentrated on one side

- they want to come back through

- When they come back through they generate a generous amount of energy

-wind turbine

cotransport

co= together

- Active transport diffusion of a solute indirectly drives transport of other substances

- both down concentration gradient

bulk transport

- active transport

exocytosis

endocytosis

exocytosis

substances leave the cell

ex. proteins being exported from the cell

endocytosis

substances are brought into the cell

types of endocytosis

phagocytosis

pinocytosis

receptor mediated endocytosis

phagocytosis

phag= eat

bringing in larger molecules

pinocytosis

pino= drink

bringing in smaller molecules

receptor mediated endocytosis

substrate binds to a receptor in order to come in to the cell