Cell Membrane

Question 1

Plasma Membrane model in 1935 by J.R. Danielli and H. Davson, proteins also part included

Answer 1

Sandwich Model

Question 2

Plasma Membrane model in 1950 by J.D. Robertson

Answer 2

Unit Membrane Model

Question 3

Plasma Membrane model in 1972 by S.J. Singer and G.L. Nicolson

Answer 3

Fluid Mosaic Model

Question 4

made of Phospholipids

Answer 4

Plasma Membrane

Question 5

Red Blood Cells analyzed
Enough for Phospholipid bilayer
Polar heads face out and Nonpolar tails face in
Does not explain why some
nonlipids are permeable

Answer 5

Gorter and Grendel

Question 6

2 layers of globular proteins with phospholipid inside to make a layer and then join 2 layers together to make a channel for molecules to pass

Answer 6

Sandwich Model

Question 7

Outer layer of protein with phospholipid bilayer inside, believed all cells same composition, does not explain how some molecules pass through or the use of proteins with nonpolar parts, used transmission electron microscopy

Answer 7

Unit Membrane Model

Question 8

Phospholipid bilayer with proteins partially or fully imbedded, electron micrographs of freeze-fractured membrane

Answer 8

Fluid Mosaic Model

Question 9

Structure of the Plasma Membrane

Answer 9

Phospholipid bilayer

Hydrophilic head
Hydrophobic tails

Transmembrane / Intrinsic / Integral
Peripheral / Extrinsic

Question 10

the plasma membrane is the consistency of olive oil at body temperature, due to unsaturated phospholipids.

Answer 10

Fluid

Question 11

cells differ in the amount of _________

Answer 11

unsaturated to saturated fatty acid tails

Question 12

at body temperature it lessens fluidity by restraining the movement of phospholipids, at colder temperatures it adds fluidity by not allowing phospholipids to pack close together

Answer 12

Cholesterol affects fluidity

Question 13

membrane proteins form a collage that differs on either side of the membrane and from cell to cell (greater than 50 types of proteins), proteins span the membrane with hydrophilic portions facing out and hydrophobic portions facing in. Provides the functions of the membrane

Answer 13

Mosaic

Question 14

Proteins of the Plasma Membrane Provide 6 Membrane Functions

Answer 14

1) Transport Proteins
2) Receptor Proteins
3) Enzymatic Proteins
4) Cell Recognition Proteins
5) Attachment Proteins
6) Intercellular Junction Proteins

Question 15

How do materials move into and out of the cell?

Answer 15

Materials must move in and out of the cell through the plasma membrane.

Some materials move between the phospholipids.

Some materials move through the proteins.

Question 16

three types of passive transport?

Answer 16

Diffusion
Facilitated Diffusion
Osmosis

Question 17

Molecules can move directly through the phospholipids of the plasma membrane

Answer 17

Diffusion

Question 18

Materials that pass through the plasma membrane by diffusion

Answer 18

Gases (oxygen, carbon dioxide)

Water molecules (rate slow due to polarity)

Lipids (steroid hormones)

Lipid soluble molecules (hydrocarbons, alcohols, some vitamins)

Small noncharged molecules (NH3)

Question 19

the net movement of molecules from a high concentration to a low concentration until equally distributed.

Answer 19

Diffusion

Question 20

Diffusion rate factors

Answer 20

temperature, pressure, state of matter, size of concentration gradient, and surface area of membrane.

Question 21

substances diffuse through membranes without work by the cell or atp usage

Answer 21

passive transport

Question 22

Molecules can move through the plasma membrane with the aid of transport proteins

Answer 22

Facilitated Diffusion

Question 23

is the net movement of molecules from a high concentration to a low concentration with the aid of channel or carrier proteins.

Answer 23

Facilitated Diffusion

Question 24

How do molecules move through the plasma membrane by facilitated diffusion?

Answer 24

Channel and Carrier proteins

Question 25

Water Molecules can move directly through the phospholipids of the plasma membrane

Answer 25

Osmosis

Question 26

is the diffusion of water through a semipermeable membrane. Water molecules bound to solutes cannot pass due to size, only unbound molecules. Free water molecules collide, bump into the membrane, and pass through.

Answer 26

Osmosis

Question 27

water travels from an area of higher concentration to an area of lower water concentration

Answer 27

Osmosis

Question 28

Movement _____ when osmotic pressure equals hydrostatic pressure

Answer 28

stops

Question 29

refers to the total solute concentration of the solution outside the cell.

Answer 29

Tonicity

Question 30

What are the three types of tonicity

Answer 30

Isotonic Hypotonic Hypertonic

Question 31

prevents bursting of plasma membrane

Answer 31

cell wall

Question 32

is normally bathed in a very hypotonic solution. It takes in water until the cell is full.

Answer 32

plant cell

Question 33

A plant cell placed in a ____________ solution loses water. Ultimately outward flow stops when the cytosol concentration matches that of the solution.

Answer 33

hypertonic

Question 34

use osmosis in hypotonic soil to maintain rigidity

Answer 34

Plants

Question 35

the pressure of water molecules against the cell wall. The cell swelling stops when the expanding membrane hits the cell wall.

Answer 35

Turgor Pressure

Question 36

when a plant wilts (sags) in a hypertonic environment, since the water in the cells diffuses out and turgor pressure is lost

Answer 36

Plasmolysis

Question 37

three types of Active transport

Answer 37

1) Active Transport 2) Exocytosis 3) Endocytosis

Question 38

types of Endocytosis

Answer 38

Phagocytosis Pinocytosis Receptor-Mediated endocytosis

Question 39

ATP energy is required to move the molecules through

Answer 39

Active transport

Question 40

Molecules move from areas of low concentration to areas of high concentration with the aid of ATP energy. Requires protein carriers called Pumps

Answer 40

Active Transport

Question 41

occurs when active transport of a solute indirectly drives transport of other substances

Answer 41

Cotransport

Question 42

Plants commonly use the gradient of __________ generated by ___________ to drive active transport of nutrients into the cell

Answer 42

hydrogen ions, proton pumps

Question 43

Importance of Active Transport

Answer 43

Bring in essential molecules: ions, amino acids, glucose, nucleotides Rid cell of unwanted molecules Maintain internal conditions different from the environment Regulate the volume of cells by controlling osmotic potential Control cellular pH Re-establish concentration gradients to run facilitated diffusion. (Ex. Sodium-Potassium pump and Proton pumps)

Question 44

Movement of large molecules bound in vesicles out of the cell with the aid of ATP energy (i.e. cell wall materials). Vesicle fuses with the plasma membrane to eject macromolecules.

Answer 44

Exocytosis

Question 45

example molecules that uses exocytosis

Answer 45

Proteins, polysaccharides, polynucleotides, whole cells, hormones, mucus, neurotransmitters, waste

Question 46

Movement of large molecules into the cell by engulfing them in vesicles, using ATP energy.

Answer 46

Endocytosis

Question 47

“Cellular Eating” – engulfing large molecules, whole cells, bacteria

Answer 47

Phagocytosis

Question 48

examples of cells that do phagocytosis

Answer 48

Ex. Unicellular organisms engulfing food particles.

Question 49

“Cellular Drinking” – engulfing liquids and small molecules dissolved in liquids; unspecific what enters.

Answer 49

Pinocytosis

Question 50

Types of Cell Junctions in animal cells

Answer 50

Tight Junctions Desmosomes Gap Junctions

Question 51

Types of Cell Junctions in plant cells

Answer 51

Plasmodesmata

Question 52

Channels between the cell walls of plant cells that are lined with the plasma membranes of adjacent cells and smooth ER runs through

Answer 52

Plasmodesmata

Question 53

Allows for the exchange of cytosol between adjacent cells; moving water, small solutes, sugar, and amino acids.

Answer 53

Plasmodesmata

Question 54

parts of the plant that uses Plasmodesmata

Answer 54

Xylem and Phloem in Plants

Question 55

It is a quantitative description of the free energy states of water.

Answer 55

Water Potential

Question 56

The concepts of free energy and water potential are derived from the

Answer 56

second law of thermodynamics

Question 57

is based on the ability of water to do work

Answer 57

Water Potential

Question 58

Forces that act on any molecule which affect its ability or potential to do work:

Answer 58

pressure concentration electrical gravity

Question 59

Pressure + Concentration + Electrical + Gravity =

Answer 59

Chemical Potential

Question 60

greek symbol for Water Potential

Answer 60

ΨW, is the letter ‘psi’ (pronounced ‘sigh’)

Question 61

not simplified Definition of Ψw

Answer 61

ΨW = ΨP + ΨS + ΨM + ΨE + ΨG

Question 62

meanings of ΨP ΨS ΨM ΨE ΨG

Answer 62

ΨP = pressure potential ΨS = osmotic or solute potential Ψm = membrane potential ΨE = electrical potential - ignore because water is uncharged ΨG = gravitational potential - ignore because gravity is not a large force for small trees

Question 63

Simplified Definition of Ψw

Answer 63

Ψw = ΨP + ΨS + ΨM

Question 64

- represents the pressure in addition to atmospheric pressure

Answer 64

pressure potential

Question 65

represents the effect of dissolved solutes on water potential;

Answer 65

osmotic or solute potential

Question 66

addition of solutes will always ______ the water potential

Answer 66

lower

Question 67

represents the effect of other membranes in the cell on water potential

Answer 67

membrane potential

Question 68

Water Potential of Plant Tissue has _____ components and is always ____

Answer 68

Water Potential of Plant Tissue has three components and is always negative

Question 69

Water Potential of Plant Tissue three components

Answer 69

Pressure Potential (+) Osmotic or Solute Potential (-) Membrane Potential (-)

Question 70

Pure water water potential

Answer 70

Ψw = 0

Question 71

pressure that keeps cell membrane pressed against cell wall

Answer 71

Membrane potential

Question 72

water potential soil>roots

Answer 72

true

Question 73

water potential moves from greater water potential to lesser water potential

Answer 73

true

Question 74

allow ions, small solutes, and water to pass in facilitated diffusion

Answer 74

Channel Proteins

Question 75

move glucose and amino acids in facilitated diffusion

Answer 75

Carrier Proteins

Question 76

Facilitated diffusion is rate limited, by

Answer 76

the number of proteins channels/carriers present in the membrane.

Question 77

The net pressure that drives reabsorption—the movement of fluid from the interstitial fluid back into the capillaries draws fluid back in

Answer 77

Osmotic pressure

Question 78

forces fluid out of the capillary The pressure exerted by a fluid at equilibrium at any point of time due to the force of gravity

Answer 78

hydrostatic pressure