Chap. 3: Cellular Level of Organization

cell membrane

flexible barrier that surrounds the cell, keeping its contents inside while controlling what goes in and out

phospholipids

type of lipid that is a major component of cellular membranes, characterized by a polar head group linked to a glycerol or sphingosine backbone and 2 hydrophobic fatty acyl chain

what are the two parts of phospholipids

a head that is hydrophilic and two tails that are hydrophobic

how does the phospholipids arrange themselves

their tails face away from water and their heads face outwards. one layer facing inside the cell, the other facing outside

amphipathic

molecule that part of can react with water and other cannot (phospholipids)

what are the other important parts of the membrane?

cholesterol and proteins

cholesterol

mixed with the phospholipids helping the membrane stay flexible

proteins

embedded in the membrane and perform different jobs like helping materials move in and out of cells

extracellular fluid (ECF)

fluid environment outside the enclosure of the cell membrane

intracellular fluid (ICF)

fluid interior of the cell

what are the two types of proteins used to help the membrane

integral and peripheral

where is the integral protein located

inside the membrane

integral protein

embedded in the membrane

channel protein

example of an integral protein that selectively allows particular materials, such as certain ions, to pass into or out of the cell

receptor proteins

another group of integral proteins, that can selectively bind a specific molecule outside the cell and this binding induces a chemical reaction within the cell

ligand

molecule that binds to receptor proteins

glycoprotein

another group of integral proteins, has carbohydrates molecules attached to them which can extend to the extracellular matrix

extracellular matrix

A large network of proteins and other molecules that surround, support, and give structure to cells and tissues in the body.

what do the glycoprotein do

help recognize each other and can also assist in communication

glycocalyx

formed from glycoproteins, coating of sugar molecules that surrounds the cell membrane

what are the roles of the glycocalyx?

sticky, allow cells to bind onto one another, contain receptors for hormones, enzymes to break down nutrients

where is the peripheral proteins located?

on the surface of the membrane

peripheral proteins

found on inner or outer surface of lipid bilayer but can also be attached to internal or external surface of an integral protein and usually perform specific tasks

what are the two types of transport

passive and active

passive transport

the movement of substances across the membrane without the need of energy

when does passive transport happen

happens when molecules move naturally from a high concentration to a low concentration

concentration gradient

the difference in concentration of a substance across a space

what is an example of concentration gradient

molecules or ions will diffuse from where they are more concentrated to where they are less, until they are equally distributed

diffusion

movement of particles from an area of higher concentration to an area of lower concentration

what are the types of diffusion

simple, facilitated, and osmosis

simple diffusion

small nonpolar molecules can pass through the lipid bilayer

what is an example of molecules that can pass through the lipid bilayer in simple diffusion?

oxygen and carbon dioxide

facilitated diffusion

takes place with the help of proteins