lecture 3 part 1

Question 1

plasma membrane

Answer 1

-selective barrier for molecules into and out cell and btwn organelles and cytosol
-determines cell composition
-maintains differences in ion concentration inside and outside cell
-detects chemical messengers from other cells
-links adjacent cells together by membrane junctions
-anchors cells to extracellular matrix

Question 2

bilayer

Answer 2

-is fluid and embedded with proteins and carbohydrates
-phospholipids are the most abundant lipid
-cholesterol is there too
-proteins inserted within or attached to the bilayer
-short carbohydratae chains attach to proteins or lipids on outer surface only

Question 3

phospholipids

Answer 3

-most abundant
-nonpolar fatty acid chains in center
-polar regions oriented toward surfaces of membrane

Question 4

cholesterol

Answer 4

-contributes to fluidity and stability of membrane
-molecules are tucked between phospholipids and prevent fatty acid chains from packing together and crystalizing

Question 5

2 types of membrane proteins

Answer 5

-integral and peripheral

Question 6

integral membrane proteins

Answer 6

-amphipathic
-span entire membrane= transmembrane protein

Question 7

transmembrane protein

Answer 7

-integral
-form channels through which ions/ water cross membrane
-associated with transmission of chemical signals across membrane or anchor extracellular and intracellular protein filaments to the plasma membrane

Question 8

peripheral

Answer 8

-not amphipathic
-dont associate with nonpolar regions of lipids in interior of membrane
-on membrane surface where they are bound to polar regions of integral membrane proteins

Question 9

what is responsible for the fluidity of the membrane?

Answer 9

lipid bilayer

Question 10

functions of membrane proteins

Answer 10

-form channels for passage of water and small ions
-carriers for transport of substances unable to cross membrane on their own
-docking marker acceptors bind to docking markers of secretory vesicles to secrete content via exocytosis
-membrane bound enzymes
-proteins on outer surface are receptors that bind to specific extracellular chemical messangers
-cell adhesion molecules that hold cells within tissues and organs together

Question 11

functions of membrane carbohydrates

Answer 11

-serve as self identify markers which enable cells to identify and interact with one another
-involves in tissue growth

Question 12

cell to cell adhesion

Answer 12

-membrane binds participates in adhesion
-adhesions bind groups of cells together into tissues and organs
-integrins
-3 types of ways to hold cells together

Question 13

integrins

Answer 13

-transmembrane proteins that serve as a structural link between outer membrane surface and its extracellular surroudnings and connect inner membrane surface to intracellular cytoskeleton scaffolding

Question 14

3 types of groupings for adhesion

Answer 14

-cell adhesion molecules (velcro adjacent cells)
-ecm
-specialized cell junctions (desmosomes, tight junctions and gap)

Question 15

ecm

Answer 15

-biological glue
-fibrous proteins embedded in watery gel composed of complex carbohydrates
-the watery gel is interstitial fluid= pathway for nutrients, wastes, and water soluble traffic btwn blood and tissue
-protein fibers: collagen, elastin, fibronectin

Question 16

collagen

Answer 16

-forms flexible but nonelastic fibers
-provides tensile strength
-most abundant protein in body
-scurvy caused by vit c deficiency

Question 17

elastin

Answer 17

-rubber protein fiber
-most common in tissues that must that stretch (lungs)

Question 18

fibronectin

Answer 18

-promotes cell adhesion and holds cells in position

Question 19

desmosomes

Answer 19

-strongest attachment
-adhering/ anchoring junctions
-cells DO NOT TOUCH
-2 parts: pair of plaques on cytoplasmic surface and inter cellular filaments containing cadherins (extend btwn 2 cells attaching plaques)
-in areas that stretch

Question 20

tight junctions

Answer 20

-adjacent cells bind firmly at point of direct contact