Cell Membrane: Lecture 5

Question 1

Schleiden & Schwann: 3 tenets of cell theory

Answer 1

1. all living organisms are composed of cells
2. the cell is the most basic unit of life
3. all cells come from preexisting cells

Question 2

modern cell theory: 4 tenets

Answer 2

1. cell contains hereditary information that is passed on during cell division
2. all cells are basically the same in chemical composition and metabolic activities
3. all basic chemical and physiological functions are carried out inside the cells
4. cell activity depends on the activities of sub-cellular structures within the cell

Question 3

morphology

Answer 3

shape and size of cells; most human cells 10-15 um

Question 4

fluid mosaic model

Answer 4

flexible layer of lipid molecules is interspersed with large protein molecules that act as channels through which other molecules enter and leave the cell

Question 5

membrane make-up

Answer 5

90% of membrane molecules are lipids:
75% phospholipids
20% cholesterol
5% glycolipids

Question 6

integral proteins

Answer 6

span membrane

Question 7

peripheral membranes

Answer 7

only on one side of the membrane

Question 8

channel proteins

Answer 8

act as channels through which substances pass to enter or exit the cell

Question 9

carrier proteins

Answer 9

membrane proteins bind and transport substances into or out of the cell

Question 10

receptor proteins

Answer 10

membrane proteins act as receptors, binding to a ligand to trigger a change in the membrane protein or the cell

Question 11

enzymes

Answer 11

membrane proteins act as enzymes, catalyzing chemical reactions

Question 12

structural support proteins

Answer 12

membrane proteins in the ECF and/or cytosol, supporting the cell

Question 13

linking adjacent cells

Answer 13

membrane proteins link adjacent cells in a tissue together

Question 14

glycocalyx

Answer 14

covers the surface of cells
glycolipids, glycoproteins
guides embryonic cells to destinations, immune functions, adhesion functions

Question 15

passive transport

Answer 15

transport does not require energy- movement down a gradient; diffusion and osmosis

Question 16

diffusion

Answer 16

movement of particles from high concentration to low concentration

Question 17

diffusion across a membrane

Answer 17

cell membranes selectively permeable based on size, charge, and membrane protein specificity

Question 18

facilitated diffusion

Answer 18

transport of ions through a channel or carrier

Question 19

factors affecting membrane diffusion rate

Answer 19

temp, molecular mass, conc gradient, surface area, permeability

Question 20

osmosis

Answer 20

diffusion of solvent molecules across a membrane from areas of lower concentration to higher concentration of solute

Question 21

osmotic pressure

Answer 21

driving force exerted by solute molecules that causes water molecules to move until equilibrium reached

Question 22

hydrostatic pressure

Answer 22

force water exerts on walls of its container

Question 23

isotonic

Answer 23

solute concentration is equal inside and outside the cell; no net movement of water

Question 24

hypertonic solution

Answer 24

solute concentration is greater outside the cell; water leaves the cell causing it to shrivel (crenate)

Question 25

hypotonic solution

Answer 25

solute concentration is greater inside the cell; water enters the cell, which may swell and burst (lyse)

Question 26

aquaporin channel

Answer 26

proteins embedded in the membrane that allow water to diffuse easily

Question 27

sports drinks v. water- dehydration

Answer 27

sports drinks are hypotonic- replenish lost water as water moves back into cell
water- can rehydrate cells to quickly/overhydrate

Question 28

active transport

Answer 28

requires energy; up/against a concentration gradient

Question 29

primary active transport

Answer 29

membrane protein uses ATP energy directly to ‘pump’ against concentration gradient

Question 30

secondary active transport

Answer 30

membrane protein uses concentration gradient energy created by a different ATP dependent ‘pump’

Question 31

vesicular transport

Answer 31

membrane vesicles bud off membrane to transport molecules wholesale

Question 32

uniport pump

Answer 32

transport single substance through membrane in one direction (into or out of cell)

Question 33

symport pump

Answer 33

transport two or more substance through membrane in same direction (into or out of cell)

Question 34

antiport pump

Answer 34

transport two or more substances in opposite directions through membrane

Question 35

sodium potassium pump

Answer 35

antiporter-like
maintain [Na] outside and [K] inside;
crucial for nerve cell signaling, skeletal muscle contraction, heart beat, osmotic balance

Question 36

electrophysiology

Answer 36

study of charge separation that exists across plasma membrane due to ion transport; pos. outside, neg. inside

Question 37

electrical gradient

Answer 37

created by separation of charges; provides energy for work

Question 38

membrane potential

Answer 38

electrical potential across plasma membrane

Question 39

vesicular transport

Answer 39

movement of large particles or many molecules simultaneously through membranes in membrane derived vesicles

Question 40

endocytosis

Answer 40

vesicular transport into cell; phagocytosis/pinocytosis

Question 41

exocytosis

Answer 41

vesicular discharge out of cell (secretion); vesicles fuse with plasma membrane opening into ECF

Question 42

transcytosis

Answer 42

molecules brought into cell by endocytosis, transported across cell to opposite side, and secreted by exocytosis