Structure And Function Of The Cell Membrane

Front 1

Roles of membrane Proteins?

Back 1

- clip into one another forming tight junctions -create channels for communication between adjacent cells (gap junctions) -attach to cytoskeleton / extracellular matrix helping to maintain cell shape/position of the cell in the tissue.

Front 2

types of membrane proteins

Back 2

- peripheral: attached to the inner or the outer face of the membrane -Integral: embedded right in/through the membrane

Front 3

what do phospholipids vary according to?

Back 3

head groups, fatty acid tail length, degree of unsaturation

Front 4

Cholestrol improves membrane stability

Back 4

help hold a more solid membrane but also help to keep membrane from completely solidifying

Decrease membrane permeability to small water soluble molecules

Front 5

lipid rafts (in membrane):

Back 5

more solid areas of the membrane taht span a greater diameter. greater amounts of cholestrol here. contribute to membrane polarity.

Front 6

what is the interaction of peripheral proteins with the membrane?

Back 6

they are attached to one single face of membrane or to another protein through ELECTROSTATIC INTERACTIONS

Front 7

types of integral proteins:

Back 7

transmembrane proteins: contain hydrophobic stretches that allow the protein to span the entire membrane 1-12 times. non-covalently attached to the membrane

lipid anchored protein: attached directly to the membrane lipid, often covalently, other times attached to the lipid by a carbohydrate bridge. protein is to one side of the membrane only. common in lipid rafts

Front 8

what is cytoskeleton

Back 8

an intracellular network of insoluble protein, composed of microfilaments, intermediate filaments, microtubules. important for cell shape and motility of intracellular material.

Front 9

where does the extracellular matrix come from?

Back 9

its produced and secreted by cells in a given tissue. composition and density depends on the tissue type. it is composed of glycoprotein (proteoglycans) and protein fibers.

Front 10

Muscular Dystrophy:

Back 10

pathological condition

unable to produce proper form of dystrophin

anchors the cytoskeleton to the extracellular matrix

important for shock absorption

results in muscles that are easily damaged

Front 11

Malignant Cancer

Back 11

pathological condition

cancer cells able to break free from the extra-cellular matrix can migrate to other locations in the body

Front 12

what impacts diffusion?

Back 12

polarity of a solute together with solute size impact whether or not diffusion is possible.

polar molecules including sugars and ions require hydrophilic protein channels to cross the hydrophobic membrane interior.

Front 13

what alters the rate of diffusion?

Back 13

-Temperature

-Solute size: smaller molecules have faster rate of diffusion

-Distance travelled: doubling the distance travelled, increases the transit time by distance^2

-molecules able to diffuse freely will do so more quickly than molecules needing to cross a membrane.

Front 14

any polar molecules cross the membrane through diffusion?

Back 14

water is able to pass from areas of low concentration of areas of high concentration because of aquaporins. Urea which is small and polar can also move freely.

Front 15

effect of membrane composition on diffusion?

Back 15

High cholesterol and protein concentration in the membrane will slow diffusion. types of phospholipids present will also determine the rate of diffusion

Front 16

membrane permeability if proportional to:

Back 16

lipid solubility / molecular size

Front 17

fick's law of diffusion

Back 17

diffusion rate will directly increase when the concentration gradient, surface area, or membrane permeability increase.

Front 18

tonicity

Back 18

describes volume changes for a cell in a solution. tonicity always compares the solution to the cell and describes only the solution.