Cell Transport CELLS Unit 4 PPT#3

What do cells do with the energy they make in cellular Respiration?

A lot of ATP are needed to maintain homeostasis (happiness) within the cell!! Cells need to get rid of things AND they need to bring in things…..some is easy and no energy needed…some are harder and the cell needs to “spend” energy!

2 concepts that make Cell Transport possible Structure of cell membranes Selectively Permeable Cell Membrane ALL cells have a cell membrane made of phospholipids and proteins 2. A Concentration Gradient

Function of the Cell Membrane: Cell membrane separates the components of a cell from its environment—surrounds the cell “Gatekeeper” of the cell—regulates the flow of materials into and out of cell—selectively permeable Cell membrane helps cells maintain homeostasis—stable internal balance

Selectively Permeability: A property of biological membranes that allows some substances to cross the membrane more easily than others. Concentration gradient: The difference in the amount of solution on each side of a cell membrane

Cell membranes are made of Phospholipid bi-layer Hydro: Water Philia: Love Phobia: Fear or hate HEAD: LOVES WATER hydrophilic TAIL: HATES WATER hydrophobic Heads out, tails in… the membrane forms a bi-layer (2)

Types of Cellular Transport Passive Transport NO ENERGY Diffusion Facilitated Diffusion Osmosis https://www.youtube.com/watch?v=ufCiGz75DAk Active Transport NEEDS ATP!! Carrier Proteins pumpp in materials agaiinst gradient Endocytosis Exocytosis

Passive transport Diffusion: substances move from an area of high conc. to an area of low conc. across a membrane in which the cell expends no energy. (sliding down a slide) Oxygen, CO2, small molecules and ions

Facilitated Diffusion: the process of transporting molecules by channel proteins during diffusion, requires no energy output (someone else carrying you down the slide) EX: Glucose Sodium and Potassium

Osmosis is the diffusion of water through a selectively permeable membrane like the cell membrane Water diffuses across a membrane from an area of high concentration to an area of low concentration.

Osmosis is facilitated by channel proteins in the phospholipid bi-layer called Aquaporins.

Active transport Needs: Energy! Transport of molecules against a concentration gradient (from low conc. to high conc.) using carrier proteins in the cell membrane and energy from ATP. (walking up the slide) EX: Polysaccharides, large and small molecules

How Does that Look in a Cell? A: Passive Diffusion B: Facilitated Diffusion (needs channel protein) C: Active Transport (needs ATP & carrier protein)

2 moreTypes of Active Transport Endocytosis The bringing of materials into cell (eating) Exocytosis: The release of materials to the outside of the cell (pooping)

Cell Size and Diffusion Cells must remain small to maximize diffusion The larger a cells volume becomes, the less efficient it becomes. Prokaryotes - Limited by efficient metabolism Animal Cells (Eukaryotic) - Limited by surface area to volume ratio Surface area of cells must be proportionally larger than it’s size (volume)

SOLUTIONS Solvent: a liquid that dissolves the solute, usually water or alcohol Solute: Anything dissolved in a solvent Together they make a Solution Salt Water + =

This is why you get thirsty after eating something salty. A simple rule: Salt Sucks! When salt is inside or outside the cell, it draws water in its direction. This is why you get thirsty after eating something salty. Same thing applies for all other solutes

Solutions and Cells All solutions want to be equal on both sides of the membrane for homeostasis. Substances dissolved in solution have special vocabulary to describe them Hypertonic Hypotonic Isotonic

Hypertonic The conc. of solute outside the cell is higher than the conc. inside The solution outside is hypertonic Water diffuses out of the cell until equilibrium is established. The cell will shrink and lose mass

Hypotonic The conc. of solute outside the cell is lower than the conc. inside The solution outside is hypotonic Water diffuses into the cell until equilibrium is established. The cell will get bigger and gain mass

Isotonic The conc. of solute outside and inside the cell are equal The solution outside is isotonic Water diffuses into and out at equal rates No net change in size or mass

Higher water conc inside cell Water moves out Cell Shrinks Isotonic Hypotonic Hypertonic H2O CHO Higher water conc inside cell Water moves out Cell Shrinks Higher water conc outside the cell Water moves in Cell Swells Water moves in and out Cell Size remains same In this situation, glucose is toooo BIG to get through the membrane.