Cell Physiology Flashcards

Lecture 2,3,4

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1
Q

Plasma Membrane functions

A

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

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2
Q

what regulates what goes in and out of cells

A

Plasma membrane regulates traffic in and out of cells

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3
Q

what links cells together

A

plasma membrane

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4
Q

What does a tight membrane junction do?

A

They are very strong junctions that make an impermeable barrier

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5
Q

Desmosomes

A

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

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6
Q

Gap junctions

A

for communication btw cells

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7
Q

Permeability of Hydrophobic molecules

A

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

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8
Q

permeability of small uncharged polar molecules

A

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

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9
Q

permeability of large uncharged polar molecules

A

can not cross the membrane alone

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10
Q

permeability of ions and charged polar molecules

A

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

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11
Q

What are electrochemical gradient?

A

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

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12
Q

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

A
  1. simple passive diffusion
  2. Facilitated Diffusion
  3. Active Transport
  4. Bulk Transport
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13
Q

which types of cell movement require energy?

A

Active transport and bulk transport

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14
Q

what can affect the rate of diffusion

A

temperature, movement, and surface area

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15
Q

flux

A

flux is a measure of diffusion rate

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16
Q

what is net flux

A

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

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17
Q

Passive diffusion

A

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

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18
Q

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

A

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

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19
Q

how does water pass through the plasma membrane?

A

by both simple and facilitated diffusion

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20
Q

what is osmosis? and how is it done?

A

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

21
Q

what determines the direction of water movement in osmosis?

A

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

22
Q

what is osmolarity

A

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

23
Q

Isosmotic

A

solution is in equilibrium

24
Q

hyperosmotic

A

over saturated, cell shrinks

25
Q

Hyposmotic

A

low concentration, cell swells

25
Q

Mediated transport systems

A

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

26
Q

What are examples of mediated transport systems?

A

Facilitated diffusion, active transport, bulk transport

27
Q

Facilitated diffusion

A

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

27
Q

examples of transport protien

A

channel proteins and carrier proteins

27
Q

Hyperpolarization

A

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

27
Q

specificity of channels

A

specificity depends on charge and pore size

28
Q

facilitated diffusion by channel proteins

A

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

29
Q

selectivity of ion channels

A

can be selective or non selective

30
Q

constitutive channels

A

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

31
Q

Gated channels

A

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

32
Q

Ligand Gated channels

A

when there is ligand is present the channels are open

33
Q

voltage gated channels

A

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

34
Q

Mechanically gated channels

A

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

35
Q

facilitated diffusion by permease/ carrier proteins

A

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

36
Q

Glucose Transporter Proteins (GLUT)

A

an example of facilitated diffusion via carrier proteins

37
Q

How do GLUT carrier proteins work

A

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

38
Q

Active transport

A

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

39
Q

Primary Active Transport

A

requires ATP directly

40
Q

Secondary Active transport

A

requires metabolic energy indirectly, requires gradient made by atp

41
Q

in active transport molecules are moved ____ the gradient

A

up via ATP

42
Q

what type of transport is calcium pump?

A

primary active transport

43
Q

how does the calcium pump work?

A

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.

44
Q

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

A

Primary active transport- an exchanger

45
Q

how does Na+/K+ pump work?

A

actively exports 2 Na+ out and important