Cell Physiology

Question 1

Plasma Membrane functions

Answer 1

Helps maintain composition of intra- and extra cellular fluids
- forms a framework for protein components of cell
- detects chemical messengers at cell surface
- links adjacent cells together

Question 2

what regulates what goes in and out of cells

Answer 2

Plasma membrane regulates traffic in and out of cells

Question 3

what links cells together

Answer 3

plasma membrane

Question 4

What does a tight membrane junction do?

Answer 4

They are very strong junctions that make an impermeable barrier

Question 5

Desmosomes

Answer 5

connect certain cells together, they are considered adherence junctions and anchor things together

Question 6

Gap junctions

Answer 6

for communication btw cells

Question 7

Permeability of Hydrophobic molecules

Answer 7

Hydrophobic molecules such as O2, CO2, N2 can easily cross the membrane, lipids can also easily cross the membrane

Question 8

permeability of small uncharged polar molecules

Answer 8

can cross the membrane, not necessarily nonpolar but if molecule is small enough it can cross

Question 9

permeability of large uncharged polar molecules

Answer 9

can not cross the membrane alone

Question 10

permeability of ions and charged polar molecules

Answer 10

do not pass through the membrane need special transport to cross the membrane

Question 11

What are electrochemical gradient?

Answer 11

gradients can be chemical, electrical, or both ie electrochemical. These gradients are a form of energy storage

Question 12

what are the 4 ways molecules can move across the cell membrane?

Answer 12

1. simple passive diffusion
2. Facilitated Diffusion
3. Active Transport
4. Bulk Transport

Question 13

which types of cell movement require energy?

Answer 13

Active transport and bulk transport

Question 14

what can affect the rate of diffusion

Answer 14

temperature, movement, and surface area

Question 15

flux

Answer 15

flux is a measure of diffusion rate

Question 16

what is net flux

Answer 16

the different btw the two one way fluxes. the net flux will be in the direction of the greater flux, it measures the net gain of molecules by one side and the net loss from the other

Question 17

Passive diffusion

Answer 17

movement of molecules due to the intrinsic kinetic energy of molecules, not ATP is used, it is just a movement of molecules from a higher concentration to a lower concentration

Question 18

In passive diffusion what does the direction and magnitude of the net flux depend on?

Answer 18

Permeability, concentration gradient, temperature, surface area, size of molecule, distance

Question 19

how does water pass through the plasma membrane?

Answer 19

by both simple and facilitated diffusion

Question 20

what is osmosis? and how is it done?

Answer 20

passive transport of water, net diffusion of water from a region of high water concentration to region of low water concentration. it is facilitated by aquaporins

Question 21

what determines the direction of water movement in osmosis?

Answer 21

direction of water movement is determined only by a difference in total solute concentration and not by types of solutes

Question 22

what is osmolarity

Answer 22

total concentration of solutes in a solution, it depends on the total number of molecules not the individual type

Question 23

Isosmotic

Answer 23

solution is in equilibrium

Question 24

hyperosmotic

Answer 24

over saturated, cell shrinks

Question 25

Hyposmotic

Answer 25

low concentration, cell swells

Question 25

Mediated transport systems

Answer 25

Molecules that are too large and/or polar to diffuse are transported across plasma membrane by mediated transport mechanisms

Question 26

What are examples of mediated transport systems?

Answer 26

Facilitated diffusion, active transport, bulk transport

Question 27

Facilitated diffusion

Answer 27

facilitated diffusion is a type of passive transport that allows substances to cross the cell membrane with the assistance of special membrane proteins. ATP is not required, instead facilitated diffusion relies on the concentration gradient of substances being transported

Question 27

examples of transport protien

Answer 27

channel proteins and carrier proteins

Question 27

Hyperpolarization

Answer 27

K+ moves out of the cell the magnitude of the membrane potential increases

Question 27

specificity of channels

Answer 27

specificity depends on charge and pore size

Question 28

facilitated diffusion by channel proteins

Answer 28

channels provide corridors for polar or charged molecules to pass through the plasma membrane

Question 29

selectivity of ion channels

Answer 29

can be selective or non selective

Question 30

constitutive channels

Answer 30

channel proteins that are always open, you have to block them or take them out if you don't want things to go through

Question 31

Gated channels

Answer 31

open in response to a trigger these can be ligand gated channels, voltage gated channels or mechanically gated channels

Question 32

Ligand Gated channels

Answer 32

when there is ligand is present the channels are open

Question 33

voltage gated channels

Answer 33

a change in charge is what opens the gate, these gates are regulated by the electrical state of the cell

Question 34

Mechanically gated channels

Answer 34

these channels are regulated by a physical change, an example of this would be a change in pressure would open the gate

Question 35

facilitated diffusion by permease/ carrier proteins

Answer 35

permease/carrier binds the substrate, undergoes a confirmation change and releases substrate to the other side. ATP is not needed, transport down the concentration gradient by carrier proteins

Question 36

Glucose Transporter Proteins (GLUT)

Answer 36

an example of facilitated diffusion via carrier proteins

Question 37

How do GLUT carrier proteins work

Answer 37

they allow glucose to get through the cell membrane by binding to the GLUT protiens

Question 38

Active transport

Answer 38

Transported molecules must bind to the transporters, metabolic energy is require.

Question 39

Primary Active Transport

Answer 39

requires ATP directly

Question 40

Secondary Active transport

Answer 40

requires metabolic energy indirectly, requires gradient made by atp

Question 41

in active transport molecules are moved ____ the gradient

Answer 41

up via ATP

Question 42

what type of transport is calcium pump?

Answer 42

primary active transport

Question 43

how does the calcium pump work?

Answer 43

atp directly moves calcium out. Hydrolysis of ATP directly required for the function of carrier, the molecule or ions binds to one side of the carrier protein which simulates phosphorylation of carrier protein which then undergoes a conformational change and then the transported molecules are released on the opposite side of the cell.

Question 44

Na+/K+ is an example of what type of transport

Answer 44

Primary active transport- an exchanger

Question 45

how does Na+/K+ pump work?

Answer 45

actively exports 2 Na+ out and important