lecture 6

Question 1

what is the structure of the cell membrane

Answer 1

fluid mosaic model, its a fluid mosaic of lipids with proteins embedded, and membrane is asymmetrical

Question 2

what evidences supports fluid mosaic model

Answer 2

membranes are not rigid, consist of fluid lipid bilayer in which proteins embedded and float freely, and human and mouse cell experiment

Question 3

why is the membrane asymmetric

Answer 3

proteins on one half are structurally and functionally distinct from other half

Question 4

what is the lipid composition of cell membrane

Answer 4

phospholipid is most dominant, head group has glycerol linked to types of alcohol or amino acid phosphate group, tail has two long chains of hydrocarbon fatty acid

Question 5

what is a fatty acid

Answer 5

a carboxylic acid with long chain of hydrocarbon, and an even number from 4- 28

Question 6

what makes phospholipids amphipathic molecules

Answer 6

hydrophilic (“water-loving”) or polar end and a hydrophobic (“water-fearing”) or nonpolar end

Question 7

how do you maintain a proper fluidity

Answer 7

depends on lipid density, composition and temp.

Question 8

how do you adjust fatty acid composition

Answer 8

change with temperature

Question 9

what influences membrane fluidity

Answer 9

cholesterol is essential structural components of animal cell membrane, it acts as membrane buffer

Question 10

what are the two distinct categories of membrane proteins

Answer 10

-integral membrane proteins
-peripheral membrane proteins

Question 11

glycolipids

Answer 11

-cell-cell interactions
-immune response
-blood types

Question 12

what are cell-cell interactions

Answer 12

the direct interactions between cell surfaces that play a crucial role in the development and function of multicellular organisms.

Question 13

what is immune responses

Answer 13

function in interaction between leukocytes and endothelial cells in inflammation

Question 14

what is blood type

Answer 14

four main blood type determined by oligosaccharide attached to specific glycolipid on surface of red blood cell

Question 15

what is the key function of membrane protein

Answer 15

transport, signal transduction, enzymatic activity, and attachment/ Recognition

Question 16

how do we know protein are inserted into membrane?

Answer 16

integral membrane protein are embedded in phospholipid bilayer
-are transmembrane proteins composed of nonpolar amino acids usually coiled into alpha helices held by covalent bonds

Question 17

peripheral membrane proteins

Answer 17

most located on cytoplasmic side of membrane, made up of polar and nonpolar amino acids, and held together by noncovalent bonds like hydrogen and ionic bonds

Question 18

membranes are semipermeable

Answer 18

permeable to non-polar or hydrophobic molecules, impermeable to large and polar molecules

Question 19

what does permeability depend on

Answer 19

solubility, charge, and solute size

Question 20

how do molecules move through membranes

Answer 20

diffusion and osmosis

Question 21

what is diffusion

Answer 21

movement of molecules from high concentration to lower concentration

Question 22

what is osmosis

Answer 22

diffusion of solvents through semipermeable membrane

Question 23

what are the two types of membrane transport

Answer 23

-active and passive transport

Question 24

what is passive transport

Answer 24

-doesn’t require energy
-high concentration to low concentration

Question 25

what is active transport

Answer 25

-low-concentration to high concentration -requires direct/indirect input of ATP

Question 26

what two types of diffusion does passive transport break down into

Answer 26

-simple and facilitated diffusion

Question 27

what is simple transport

Answer 27

-substances pass through phospholipids -rate of diffusion depends on concentration difference

Question 28

what is facilitated diffusion

Answer 28

spontaneous, and ions cross biological membrane

Question 29

what are properties of facilitated diffusion

Answer 29

-follow concentration gradients -high diffusion rate -limited binding capacity -high substrate specificity

Question 30

what are three main examples of facilitated diffusion

Answer 30

channel proteins=aquaporin ion channel protein= K+ voltage-gated channel carrier protein= glocuse transporter

Question 31

how does water move through the membrane

Answer 31

by osmosis which is a passive passage

Question 32

what is tonicity

Answer 32

it is an example of membrane passage by osmosis

Question 33

tonicity (flow of water in and out of cell) has three groups, what are they

Answer 33

hypotonic, isotonic, and hypertonic

Question 34

what is a hypertonic solution

Answer 34

osmotic flow out of the cell

Question 35

what is hypotonic solution

Answer 35

osmotic flow into cell

Question 36

what is isotonic solution

Answer 36

no osmotic flow

Question 37

what are channel proteins: aquaporin (ex. of facilitated diffusion)

Answer 37

integral membrane protein that forms pore in membrane

Question 38

what are ion channel protein: ion voltage-gate channel (ex. facilitated diffusion)

Answer 38

switches between open and closed and intermediate states, this involves changing 3-D shape

Question 39

what are carrier proteins

Answer 39

bind to specific single solute and transport across lipid bilayer

Question 39

what are carrier proteins

Answer 39

bind to specific single solute and transport across lipid bilayer

Question 40

active transport has two types

Answer 40

-primary active tranport -secondary active transport

Question 41

what is primary active transport

Answer 41

-moves positively charge ions -Na+/K+ pump -h+ pumps -ca2+ pumps

Question 42

what do Na+-K+ pumps do

Answer 42

regulate cellular volume -help maintain right concentration of ions (cell swell automatically activates pump)

Question 43

what is membrane potential

Answer 43

difference in ion concentration creates difference of charge between exterior and interior part of membrane

Question 44

what are a secondary source of energy

Answer 44

electrical gradient

Question 45

what are a secondary source of energy

Answer 45

electrical gradient

Question 46

what are electrical gradients

Answer 46

provide energy to transport glucose, amino acid, and other nutrients, known as secondary active transport

Question 47

what are the two forms of secondary active transport

Answer 47

sodium-calcium exchanger, and sodium-hydrogen antiporter

Question 48

what are sodium-hydrogen antiporter

Answer 48

transport Na+ into cell and H+ out

Question 49

what is sodium-calcium exchanger

Answer 49

uses energy stored in electrochemical gradient of Na+ by allowing it to flow down gradient across plasma membrane exchange for calcium out of cell

Question 50

what are the three main functions of Na+-K+ pump

Answer 50

- maintain isotonicity cell volume by pumping out calcium -create a difference in charge between exterior and interior -create electrochemical gradient to provide energy to move molecules against concentration gradient

Question 51

what transports larger substance

Answer 51

exocytosis

Question 52

what is exocytosis

Answer 52

energy-dependent process which large molecule bulks transported out of cell

Question 53

what are 3 main function of endocytosis

Answer 53

-pinocytosis -receptor mediated endocytosis -phagocytosis

Question 54

what is pinocytosis (endocytosis)

Answer 54

extracellular fluid and molecules within it

Question 55

what are receptor-mediated endocytosis

Answer 55

small vesicles coated with cytosolic protein

Question 56

what are phagocytosis

Answer 56

bind and internalize large particles

Question 57

how is tissue stability acheived

Answer 57

cell junctions and extracellular matrix

Question 58

what are tight junctions (impermeable and tissue stability)

Answer 58

rows of transmembrane proteins that bind to corresponding membrane protein of adjacent cell

Question 59

what are tight junctions (impermeable and tissue stability)

Answer 59

rows of transmembrane proteins that bind to corresponding membrane protein of adjacent cell

Question 60

what is a gap junction

Answer 60

intercellular channels directly communicate cytoplasm of two cells, allowing passage (ions+small molecules)

Question 61

what is anchoring junction

Answer 61

link of cytoskeleton with extracellular matr

Question 61

what is anchoring junction

Answer 61

link of cytoskeleton with extracellular matr

Question 62

what stages do membrane receptors link extracellular signals with cellular responses

Answer 62

-reception - transduction -response

Question 63

what is kinases

Answer 63

adds chemical called phosphates to other molecules