chapter 3 part 2

Water diffuses through the pores called ______ of the cell membrane.

Aquaporins

osmosis

They move across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.

Give 7 functions of the plasma membrane

1) protective barrier 2) selectively permeable 3) allow cell recognition 4) provide anchoring sites for filaments for cytoskeleton. 5) provide a binding site for enzymes 6) interlocking surfaces bind together (junction) 7) contain the cytoplasm (fluid in cell)

ligand

a molecule a receptor binds to

receptor-mediated endocytosis

are some necessary proteins that have receptors on their surface to recognize and take in hormones, cholesterol, etc.

plasmolysis

cells shrink and shrivel- hypertonic

cytolysis

cells swell and burst- hypotonic

Hydrophobic

don't like water of phospholipid made of two fatty acid chains that are non polar.

active trasport

drives molecules across a membrane from a region of lower concentration to a region of higher concentration. Requires energy or ATP. Active Transport is against concentration gradient.

distinguish among endocytosis, phagocytosis, pinocytosis, receptor-mediated endocytosis and exocytosis.

endocytosis- is the process of taking liquids or fairly large molecules into a cell by engulfing them in a membrane. Phagocytosis- is cell eating which means solids are being engulfed. receptor-mediated endocytosis- is that some integral proteins have receptors on their surface to recognize & take in hormones, cholesterol, etc. Exocytosis- is the release of substances out of a cell by the fusion of a vesicle with the membrane.

Describe the structure of the cell membrane.

flexible and allows a unicellular organism to move and has a lipid bilayer.

Cell membrane (plasma membrane)

forms boundary between a cell and the outside environment and controls the passage of materials into and out of a cell.

how does cholestrol get into a cell?

integral proteins receptors recognize and take in cholesterol.

what are cell junctions?

interlocking surfaces bind cells together

Phospholipids

is a molecule that contains 2 fatty acid chains that are non-polar. Head is polar and contains a charged phosphate group.

Diffusion

is a passive process which means no energy is used to make the molecules move. they have a natural KINETIC energy. is the movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration.

Receptor

is a protein that detects a signal molecule and performs an action in response. It recognizes and binds to only certain molecules, ensuring that the right cell gets the right signal at the right time.

Phagocytosis

is a type of endocytosis in which the cell membrane engulfs large particles. "cell eating"

exocytosis

is opposite of endocytosis, is the release of substances out of a cell by the fusion of a vesicle with the membrane. Require ATP.

concentraction gradient

is the difference in the concentration of a substance from one location to another.

Describe passive transport

is the movement of molecules across a cell membrane without energy input from the cell. High to low concentration. EX:simple and facilitated diffusion

Describe active transport

is the movement of molecules across the cell membrane requiring energy or ATP. Moves materials from low to high concentration. Against concentration gradient.

Endocytosis

is the process of taking liquids or fairly large molecules into a cell by engulfing them in a membrane. Requires ATP.

Explain what happens to cells in an isotonic, hypotonic, and hypertonic solution.

isotonic- is at equilibrium no net movement hypotonic- water movement into cell hypertonic- water movement if out of cell

selectively permeability

it allows some, but not all, materials to cross the membrane. Also known as semipermeable and selectively permeable.

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane Fluid= flexible Mosaic= variety of molecules studding the membrane

Pinocytosis

most common endocytosis. cell forms a pouch. Materials dissolve in water to be brought into the cell. "cell drinking"

distinguishing between osmosis, diffusion,and facilitated transports.

osmosis- diffusion from an area of higher concentration to an area of lower water concentration. diffusion- is the movement of molecules in a fluid or gas from a region at higher concentration to a region of lower concentration. facilitated transport- high to low concentration is the diffusion of molecules across a membrane through transport proteins.

Hydrophilic

polar heads of Phospholipids "Attracted to water"

explain why transport protein is needed in the cell membrane

protein move material across the cell membrane. Channel proteins- are embedded in the cell membrane and have a pore for materials to cross Carrier Proteins- can change shape to move material from one side of the membrane to the other.

isotonic

solution has a solute concentration equal to the solute concentration inside a cell. A solution is isotonic to a cell if it has the same concentration of solutes as the cell. Equal amounts of water enters and exits the cell, so its size stays constant.

Hypertonic

solution has a solute concentration higher than the solute concentration inside a cell. Solution has more solutes than a cell. Overall, more water exits the cell in hypertonic solution causing the cell to shrivel or even die.

passive transport

the movement of substances across a cell membrane without the use of energy by the cell. It may be described as the diffusion of molecules across a membrane. Ex: simple and facilitated diffusion high to low concentration

faciltated diffusion

the transport of substances across a cell membrane along a concentration gradient though transport proteins

Aquaporins

water channel proteins pores used during osmosis

hypotonic

Having a lower concentration of solute than another solution. More water enters a cell in hypotonic solution, causing the cell to expand or even burst.

summarize how chemical signals are transmitted across the cell membrane.

Receptor detects a signal molecules and performs an action in response then it binds with ligands to change shape in order to receive chemical signals. Molecules that interact with receptors in order to change the receptor shape in order to send chemical signals.

_________ endocytosis incolves protein _________ recongnizing hormoes to help move them into the cell.

Receptor-meditaited receptors