Biology Chapter 8

Cells and Their Environment

Sodium-Potassium Pump

• Carrier protein that uses ATP as it moves potassium ions and sodium ions across the cell membrane.

Cells• The human body contains two hundred and

ten different cell types, that are found only in humans. Every cell in the body has a sodium-potassium pump

• Along with that there is the fact that there are over one hundred trillion cells in the body at any given time.

Cells• Each cell has a sodium potassium pump, this

pump operates on an automatic mechanism of active movement that move the ions of potassium into the plasma membrane of a cell and the ions of sodium out of the plasma membrane of a cell.

Lipid Bilayer• Double layer that makes up a cell membrane

Concentration Gradient• The difference in the concentration

of a substance across a region.

Facilitated Diffusion• A form of passive transport that involves membrane

proteins that aid the movement of substances.

Active Transport• The moving of a substance to an area of

higher concentration, using energy

Passive Transport• The moving of a substance to an area of lower

concentration without any energy use.

Equilibrium• The state that exists for a substance when the

substance is distributed evenly across a space.

Hypertonic Solution

Hypotonic Solution

Isotonic Solution

Cells in Solutions

Cells•The cell-surface markers identifies the cell type.

Cell Membranes• The outer surface is polar,

while the interior is nonpolar.

Cells• By controlling what enters and leaves a cell,

the cell membrane aids in maintaining homeostasis within the cell.

Cells• Small nonpolar molecules can pass

unaided through the cell membrane

Diffusion• Is the movement of a substance

down its concentration gradient

Facilitated Diffusion• When particles move out of a cell through

facilitated diffusion, the cell does not experience any change related to energy.

Osmosis• The diffusion of water through a

selectively permeable membrane

Endocytosis• Molecules that are too large to be moved

through a cell membrane can be transported into the cell by endocytosis.

Osmosis• If the concentration of a sugar solution is

lower outside outside the cell than inside the cell, water will move into the cell

Sodium-Potassium Pump• Is used to remove sodium from a cell and

bring potassium into a cell against their concentration gradients

Vesicles• Endocytosis always involves the movement of

a vesicle.

Cell Surfaces• When a molecule fits into the binding site of a

receptor protein on a cell’s surface– The receptor can open an ion channel in the cell

membrane– The receptor can act as a n enzyme, causing

chemical changes in the cytoplasm– The receptor can cause the information of a

second messenger

Receptor Protein•Membrane receptor

proteins transmit information into the cell by responding to signal molecules

Messengers• A second messenger always carries a signal

within a cell

Chapter 8 Test is tomorrow