Lecture 6 - Membrane permeability and transport

Question 1

What is a protein-free lipid bilayer organelle?

Answer 1

liposome

Question 2

how are other molecules attracted to water molecules?

Answer 2

attracted to polar or charged molecules

Question 3

how are ions dissolved in water

Answer 3

they attract the charged parts of water that forms a shell around it

stripping this shell is energetically unfavored

Question 4

what small nonpolar molecules can cross the lipid bilayer?

Answer 4

O2, CO2, N2, steroids hormones

almost all get through

some of these are dissolved gases, the hormones are hydrophobic enough

Question 5

what small uncharged polar molecules can cross the lipid bilayer?

Answer 5

H2O, ethanol, and glycerol

most don’t get passed but about 35% do

water cant but sometimes leaks through

Question 6

what large uncharged polar molecules can cross the lipid bilayer?

Answer 6

amino acids, glucose, and nucleosides

most don’t get by but about 15% do due to their size

Question 7

what ions can cross the lipid bilayer?

Answer 7

none

Question 8

If you want to deliver DNA into cells which of the following will you use as a carrier?
1. Water
2. Lipid

Answer 8

Lipid, DNA had hydrophilic regions and it would not maintain. However, liposomes can be used for transport

lipsomes are extracted from a membrane to form circular transport

Question 9

The ____ the molecule and ____ strong its assocaiation with water, the more rapidly it diffuses across the bilayer

Answer 9

smaller and less

Question 10

integral proteins use what to act as a pass?

Answer 10

transmembranes can use single pass or multipass

Question 11

describe passive diffusion transport

Answer 11

random movement of particles by either gas (O2, CO2) or by Osmosis

passive means it does not require energy to do so

Question 12

describe passive faciliitated diffusion

Answer 12

needs proteins or channels to move glucose, Na+ or K+

passive means no energy is required to do so

Question 13

desribe primary active transport

Answer 13

Na+/K+ pump ATPase

Question 14

Desribe secondary active transport

Answer 14

symport and antiport

Question 15

what is the principle force driving movement in diffusion?
A. Temperature
B. Particle size
C. Concentration gradient
D. Membrane surface area

Answer 15

c. concentration gradient

Question 16

define diffusion

Answer 16

solute molecules move fro high to low concentration

Question 17

define osmosis

Answer 17

solvent molecules move from low to high solute concentration

Question 18

in hypertonic solution, what happents to a cell

Answer 18

the cell shrinks or shrivels

Question 19

i

in hypotonic solution, what happens to the cell

Answer 19

The cell expands and sometimes lyse

Question 20

water molecules diffuse ____ aquuaporin channels

alpha helices create aquaporins

Answer 20

rapidly

like epithelial cell in kidneys, lungs, and eye lens

Question 21

Describe ion channels

Answer 21

forms pore, can transport very fast, very selective of what ions pass through, and most are gated

selectivity = width of pore and charges of amino acid side chains

Question 22

what does it mean when a channel is “gated”

Answer 22

It can open and close for selectivity filter

Question 23

what is a voltage-gated channel?

Answer 23

based on membrane potentil, responds to changes in potential for cell signaling

Question 24

what is mechanically-gated channels?

Answer 24

responds to mechanical forces on the cell like sense of touch or sense of hearing

Question 25

what is ligand-gated channels?

Answer 25

based on binding a chemical like cell signaling | can be extracellular lignad or intracellular ligand

Question 26

what is patch clamping?

Answer 26

a method to study ions

Question 27

what influences the passive transport

Answer 27

1. concentration gradient 2. membrane potential influence

Question 28

concentration gradient = ?

Answer 28

potential energy

Question 29

describe transporter protein

Answer 29

concentration dependent, switch confomrational states to bind ligand on one side and release it on the other side, slow process. bidirectional | more selective than channels

Question 30

what are three ways of active transport (pump)?

Answer 30

1. gradient-driven pump 2. ATP-driven pump 3. light driven pump

Question 31

what are the types of gradient-driven pump

Answer 31

1. uniport 2. antiport 3. symport

Question 32

describe uniport

Answer 32

transports 1 thing, can do passive transport down a concentration gradient

Question 33

Which of the following properties of lipid bilayer prevents ions from easily passing the membrane? The hydrophobic exterior of the lipid bilayer The hydrophilic interior of the lipid bilayer The hydrophobic interior of the lipid bilayer The hydrophilic exterior of the lipid bilayer

Answer 33

The hydrophobic interior of the lipid bilayer

Question 34

Which of the following statements is true? Cl- is the most abundant negatively charged ion inside the cell. Na+ is the most abundant positively charged ion outside the cell, while K+ is the most abundant inside the cell. K+ is the most abundant positively charged ion outside the cell, while Na+ is the most abundant inside the cell. K+ and Na+ are balanced on each side of the cell.

Answer 34

Na+ is the most abundant positively charged ion outside the cell, while K+ is the most abundant inside the cell.

Question 35

what plays an essential role in cell signaling?

Answer 35

movement of ions across cell membranes

Question 36

what is the most plentiful ion outside cell?

Answer 36

Na+ which is balanced by extracellular Cl-

Question 37

what is membrane potential?

Answer 37

imbalance of electrical charge across the membrane

Question 38

how do substances flow in the membrane?

Answer 38

From downhill, of high concentration to low concentration

Question 39

what is passive transport?

Answer 39

moving down membrane gradient without energy, can be channel or transport

Question 40

Where does NA+ pump get its energy from?

Answer 40

from ATP hydrolysis

Question 41

what is the electrochemical gradient?

Answer 41

when the gradient and the membrane potential influence the cell across the membrane

Question 42

what does the phosphate have to do with transports?

Answer 42

used in Na+ ATPase, where is takes the phosphate group from ATP hydrolysis and gets transferred to the pump

Question 43

what two ions are kept at low concentrations inside the cell?

Answer 43

Na and Ca

Question 44

Ca2+ can do what to cell activities?

Answer 44

it can alter them, thats why it needs to be kept at low concentrations

Question 44

define Ca2+ pumps

Answer 44

in plasma membrane and ER to remove Ca2+ from cytosol ...... uses ATP hydrolysis

Question 45

what are H+ pumps?

Answer 45

used by bacteria, and fungi to create electrochemical gradient on the plasma membrane, also found in lysosome.... ATP hydrolysis

Question 46

which pumps use Na+ gradient instead of ATP hydrolysis?

Answer 46

Na+/glucose and Na+/H+

Question 47

what is the Nernst equation?

Answer 47

a equation that relates to the concentration of the two sides of the permeable membrane potential to see if there would be movement

Question 48

what is oxidative phosphorylation?

Answer 48

makes ATP in the mitochondria from oxidation to generate H+ gradient across the membrane