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Bio 20A > Cell Membrane > Flashcards

Cell Membrane Flashcards

Know all components of the plasma membrane

1
Q

What is the purpose of the plasma membrane?

A

To surround and separates the cell from the environment.

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2
Q

What are the key features of plasma membrane?

A
  • Composed of mostly lipids and proteins
  • Controls movement in + out of the cell
  • Provides structural support
  • Interacts with the environment
  • Separates fluids into separate compartments (Extracellular fluid + intracellular fluid)
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3
Q

ECF

A

Extracellular Fluid:
Composed of water and dissolved chemicals outside of the cell
Blood, lymph & interstitial fluid

high in Na+, Ca++, Cl- (salt, calcium, chlorine)

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4
Q

ICF

A

Intracellular Fluid= fluid inside cells –> Cytosol
- high in K+ (potassium), amino acids + nucleic acids

usually negative in charge to ECT

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5
Q

What is the Endomembrane system?

A

ECF + ICF
Membranes within the cell to separate it into different parts.

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6
Q

Components of Plasma Membrane

Phospholipid Bilayer

brief summary

A
  • 2 layers of phospholipids
  • 40% of the biological membrane
    Most important structural part

Is amphilic

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7
Q

Components of Plasma Membrane

Amphilic

definition, components, placement

A

=hydrophillic + hydrophobic
1 hydrophillic head w/ phosphorus
- inside layer sticks in to tough water inside the cell
- outside layer sticks out to touch water ouside the cell
2 hydrophobic tails
- attracts hydrophonoc
- faces towards the other layers hydrophobic tails
- between the 2 bilayers

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8
Q

Components of Plasma Membrane

Cholesterol facts

A

=Steroid
* 10% of the plasma membrane
* % varries between cells
* +makes the membrane more rigid, - makes it less permeable to water

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9
Q

Components of Plasma Membrane

Pollysaccarides

Types of them.

What is it?

A

Pollysaccarides stick out of cells acting as a signal to other cells for indentification.
1. Glycolipids
2. Glycoproteins
3. Glycolax

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10
Q

Components of Plasma Membrane

Glycolipids

A
  • pollysaccharide
  • lipids bound to carbs
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11
Q

Components of Plasma Membrane

Glycoproteins

A
  • pollysaccaride
  • proteins bound to carbs
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12
Q

Components of Plasma Membrane

Glycolax

A

A layer of pollysaccharides on the outside of the cell

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13
Q

Components of Plasma Membrane

Proteins

Name the proteins in the plasma membrane

A
  1. peripherial membrane proteins
  2. integral membrane proteins
  3. transmembrane proteins
  4. receptor proteins
  5. structural proteins

Proteins in the plasma membrane make up 50%

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14
Q

Peripherial Membrane Proteins

A

Not in the phospholipid bilayer - Attached to the edge

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15
Q

Integral Membrane Proteins

A

Partially penetrate or span across

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16
Q

Transmembrane Proteins

A

Touches the ECF + ICF by going through the membrane

extracellular fluid + intracellular fluid

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17
Q

Receptor Proteins

A

Direct elements outside the cell

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18
Q

Transport Proteins

A

Move things between the ECT + ICF

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19
Q

Structural Proteins

A

Connects to the cytoskeleton inside the cell + extracellular matrix inside the cell

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20
Q

Diffusion

What is it? What does it do?

A

Diffusion moves solutes from high to low concentrations
* doesn’t need energy - actually releases
* happens naturally + spontaneously
* leads to equillibrium
* solutes move with gradient

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21
Q

Solute

A

chemical disolved in water

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22
Q

Concentration

A

amount of solute disolved in a given amount of water

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23
Q

Dilute

A

Lower concentration

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24
Q

Concentration Gradient

definition + attributes

A

The concentration between inside and outside of the cell
* happens across the plasma membrane
* has energy
* bigger difference in solutes leads to more energy

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25
Q

Homeostasis

definition + attributes

A

Homeosasis maintains the difference in concentration between the inside + outside of the cell
* NOT equilibrium = death for living cells
* Requires energy

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26
Q

What affects the rate of diffusion in the plasma membrane?

and how do they affect the membrane?

A
  • +concentration gradient = +rate
  • +membrane thickness = -rate
  • +surface area = +rate
  • +temp = +rate
  • +molecules = -rate
  • +permeability = +rate
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27
Q

Osmosis

A

How water moves across membranes following salt.
* diffusion of water
* only way the body can move water across membranes
* the body uses energy to move salt from one side of membrane

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28
Q
A
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29
Q

Semipermiable membrane

A

Membrane that allows some chemicals to pass.
- solutes that can pass will diffuse

30
Q

Tonicity

A

The total concentration of solutes that can’t diffuse.

30
Q

Hypotonic

A

Occurs when there are fewer solutes outside than inside the cell.
water moves in –> cell swells (could explode)

hypo = water loving

31
Q

Hypertonic

A

Occurs where there’s more solutes outside than inside the cell.
Water leaves the cell –> cell shrinks

hyper = out

31
Q

Isotonic

A

Occurs when the same solutes are in and outside the cell
- no water movement

Iso = still

32
Q

Passive Transport

A

Occurs when solutes move / diffuse from high to low concentration.
* requires no energy

33
Q

Active Transport

A

Occurs when solutes move from low to high concentrations.
Requires E

34
Q

Simple Diffusion

What is it? What does it diffuse? What doesn’t diffuse?

A

Occurs when solutes move through the phospholipid bilayer.
Hydrophobic molecules that can pass:
* lipids + steroids
* gas - oxygen + carbon monoxide
* small polar molecules: water + ethanol (moves slowly)
Molecules that can’t pass:
* ions
* sugars
* amino acids
* proteins

35
Q

Facilitated Diffusion

A

Occurs when solutes move though a transport protein passively.

36
Q

Transport Proteins

Definition + types

A

Transmembrane proteins that chemicals can pass through - pumps
1. Channel Proteins
2. Carrier Proteins

37
Q

Channel Proteins

A

Transmembrane proteins (pumps) that only do facilitated diffusion.

38
Q

Pumps

A

A general form of carrier proteins that do facilitated diffusion.

39
Q

Carrier Proteins

Definition

A

Responsible for transporting protins though ficilitated diffusion and active transport.
Need to change in shape when moving something

40
Q

Carrier Proteins: Process

A

bind chain on one side –> push through membrane –> release on the other side
1. Form (active transport) a hole in the plasma membrane for certain chemicals to diffuse
2. Facilitated diffusion occurs in the pumps

41
Q

Glucose Transporter
(GLUT)

A

Type of carrier protein that does facilitated diffusion of glucose in and out of the cell.

42
Q

Uniport

A

Involves 1 protein channel

43
Q

Cotrasport

A

Process of moving 2 chemicals across the membrane.

44
Q

Symport

A

Process of moving 2 chemicals in the same direction.

45
Q

Antiporter

A

Process of moving chemicals in the opposite direction.

46
Q

Aquaporin

A

Protein channel that allows water to pass.

47
Q

Ion Channels

A

Channels for ions to pass, specific to the type of ion.

48
Q

Channel Proteins

Types + responsibilities

A
  • Leak channels - always open + leaking chemicals
  • gated channels - only respond to stimulus (Chemical, mechanical force, voltage change)
49
Q

Primary Active Transport

Definition + users

A

When carriers to use ATP as energy and can only be done by pumps.
1. Proton pump - ATP moves from H+ from low to high
2. Sodium Potassium (Na+K+) Pump - ATP moves 3 Na+ out of the cell, 2 K+ in.
* extracellular fluid moves Na+, intracellular fluid moves K+

50
Q

Secondary Active Transport

Definition + Process

A

When energy is aquired to allow Na+ to diffuse into the cell
1. Primary active transport created Na+ gradient (Energy is present)
2. Let Na+ diffuse into the cell and uses energy to move another chemical from low to high concentration (Energy is released)

51
Q

Sodium Glucose Transporter
(SGLT)

What does it do?

A
  1. Na+K+ pumps create a gradient with high Na+ outside the cell
  2. SGLT lets Na+ back into the cell, energy is used to pull glucose in too
52
Q

Membrane Potential

Definition + attributes

A

The difference in charge between two sides of the membrane.
1. membrane potential is maintained by opening and closing ion channels
* ions flow in or out of the cell changing the charge on either side
* different channels = different effects on membrane

53
Q

Channels that affect the plasma membrane & how

A
  • Open Na+ or Ca++ = Move Na+&Ca++ into the cell = more positive
  • Open K+ = Move K+ into the cell = more negative
  • Open Cl- = Move Cl- into the cell = more negative
54
Q

Electrochemical Gradient

Definition

A

The difference in chemical concentrations and electrical charge across the membrane.

55
Q

Effectors of Electochemical Gradient

A
  • ions = charge
  • ^ cations (+) outside the cell = ouside ECF creates a positive charge relative to the outside – inside the cell will have a negative charge relative to outside
56
Q

Voltage

Definition

A

Units used to measure potential

57
Q

Membrane Potential

A

= inside charge - outside charge
* usually negative
* at rest

58
Q

Vesicular Transport

A

Occurs when substances move in + out of the cell with vesicles.

59
Q

Exocytosis

What is it? What is the process?

A

A type of vesicular transport.
Occurs when a vesicle goes up to the plasma membrane, merges with the membrane, and releases substances outside the cell.

60
Q

Endocytosis

What is it? What is the process?

A

A type of vesicular transport.
Occurs when part of the membrane pinches off and forms a vesicule, this process pulls substances from outside the cell into it.

61
Q

What are the other types of endocytosis occur in cells?

List them

A
  1. Pinocytosis
  2. Receptor-Mediated Endocytosis
  3. Phagocytosis
62
Q

Pinocytosis

A

A non-specific process that pulls small substances outside of the cell (like taking a sip).

63
Q

Receptor-Mediated Endocytosis

A

Endocytosis of certain specific chemicals - something specific bonds to a receptor.

64
Q

Phagocytosis

A

Phago = eat
Occurs when a lysome merges with a vesicle and releases what’s inside.
Ex: large molecules, baterial cells, dead tissue

65
Q

ECM

Definition and functions

A

Extracellular Matrix is a mesh of macromolecules and ions outside the cell that gives structure to the tissue.
* holds the cell in place
* gives tissues their characteristics (stretch, shape, etc.)
* has lots of connective tissue
* is secreated by the cell
* attaches to membrain proteins to hold it in place

66
Q

Cell Junctions

A

A combination of membrane proteins + other proteins that connect cells to others on the ECM. These connections between cells hold them together, they can be long lasting or transmit/ transient.

67
Q

CAMs

A

Cell Adhesion Molecules are transmember proteins that attach to molecules outside of the cell on the ECM. BUT large protein complexes inside the cell attach to CAMs on the cytoskeleton.

68
Q

Gap Junction

A

Small membrane channels that are attached to cells for small substances to pass between cells, ions + chemical signals.

69
Q

Tight Junctions

A

Protein complexes that hold cells closely together so substances can’t pass between cells.

70
Q

Desmosomes

A

Structures where 2 cells are attached inside by intermediate fillaments to create a sheet of cells inside and outside.
Substances can still pass between cells.

Bio 20A (21 decks)

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