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Flashcards in Membranes Deck (74):
1

Semi-permeable layer that separates the cell from the external environment

Plasma membrane

2

Controls the passage of material into and out of the cell (gate keeper but does not protect)

Plasma membrane

3

Name the 5 components of cellular membranes.

1. phospholipid bilayer
2. cholesterol
3. integral and peripheral proteins
4. glycoproteins
5. glycolipids

4

They form bi-layer framework

Phospholipids

5

It stabilizes phospholipid fluidity

Cholesterol

6

Bio-molecules found in membranes

-Lipid
-Protein
-Glyco-molecules (carbs)

7

What is glycolipid?

A complex of oligosaccharide bound to lipid used in tissue recognition

8

What is glycoprotein?

A complex of oligosaccharide bound to protein used in cell (“self”) recognition

9

Describes the membrane organization

Fluid mosaic model

10

Has AMPHIPATHIC properties (molecule is both polar and non-polar) which will influence what can cross the membrane

Phospholipid

11

Lipid bilayer

Plasma membrane

12

It has different effects on membrane fluidity at different temperatures

Cholesterol

13

At warm temperatures, it restrains movement of phospholipids

Cholesterol

14

At cool temperatures, it maintains fluidity by preventing tight packing

Cholesterol

15

Proteins that are embedded within the membrane

Integral Proteins

16

Proteins that are temporarily bound to surface of bilayer

Peripheral Proteins

17

Membrane protein functions (6)

1. transporters: control movement of material
2. enzymes: catalyze
3. cell surface receptors: bind signal molecules
4. cell surface identity markers: ID a cell type
5. cell-to-cell adhesion proteins: bind cells
6. attachments to the cytoskeleton: structure and guide

18

Active transport

Carrier, protein changes shape to move molecules, ATP needed (requires cellular energy)

19

Passive transport

Channel, selected ions (NA+) channels in heart, moves by diffusion (from high concentrartion to low), no energy needed

20

Special channel protein passively transports water

Aquaporin, osmosis

21

Determine shape of the cell

Spectrins

22

Anchor certain proteins to specific sites, especially on the exteriror plasma membrane in receptor-mediated endocytosis

Clathrins

23

Self recognition

Glycoproteins

24

Tissue recognition

Glycolipid

25

Bulk transport

Complex active mechanism

26

It is a response to a concentration gradient

Movement

27

Due to motion of bilayer: phospholipids slide along each other.

Fluid

28

Associated mix of molecules: globular proteins (cholesterol and glycolipids & glycoproteins).

Mosaic

29

Name transport proteins (3)

Carriers
Channels
Receptors

30

What is passive transport?

Movement of molecules through the plasma membrane

31

Is energy required for passive transport?

No

32

No energy required for this type of transportation protein.

Passive transport

33

Molecules move in response to a concentration gradient (igh to low) in this type of transport protein.

Passive transport

34

What is diffusion?

Movement of molecules from high concentration to low concentration.

35

Permeability of the plasma membrane.

-Small, nonpolar molecules readily pass directly through the plasma membrane
-Hydrophobic interior of the plasma membrane obstruct passage of charged or polar molecules

36

What is a selectively permeable membrane?

Membrane proteins choose which molecules can pass through the plasma membrane

37

What do channel proteins permit to pass through the membrane?

Only specific solutes (water, hydrophilic solutes some ions).

38

How do carrier proteins do to carry a molecule to the other side of the plasma membrane?

Change their shape, binding a specific molecule to move it across the pm (i.e. glucose)

39

Facilitated diffusion is a type of _______ transport.

Passive

40

-requires no energy (is passive)
- is specific
- saturates when all carriers are occupied

Channel or carrier protein (passive)

41

What is osmosis?

Movement of water across selectively permeable PM from an area of high to low concentration of water.

42

When osmosis, through what does water move?

Aquaporins channels

43

Hypotonic

Low solute concentration, so high water concentration

44

Hypertonic

High solute concentration, so low water concentration

45

Does water move towards hyper or hypo tonic?

Hypertonic

46

What does isotonic mean?

Solutes concentrations are equal on both sides

47

Water ejected from cell through vacuoles

Extrusion

48

Keeping cells isotonic with their environment, salts balanced

Isosmotic regulation

49

What do cells use to push the cell membrane against the cell wall and keep the cell rigid (blocking entry of too much water)

Turgor pressure

50

The contractile vacuoles in paramecium, euglena and amoeba, pump excell water out

Extrusion

51

Rate of diffusion can be affected by____

Temperature, concentration

52

What does carrier protein do?

Shape change

53

What does channel protein do?

No shape change

54

What does active transport need asbolutely?

ATP

55

Does active transport require energy?

YES

56

Require the use of carrier proteins.

Active transport

57

Can saturate

Active transport

58

Can move a single type of molecule

Uniporters

59

Can move two different molecules in the same direction

Symporters

60

Can move two different molecules in opposite directions.

Antiporters

61

ATP energy is used to do what?

Change the shape of the carrier protein

62

How does the sodium potassium pump work?

1- Sodium gets inside the protein carrier from the inside
2-ATP phosphorylates (shape changes)
3-Sodium leaves outside the cell
4-Potassium from outside gets inside the carrier
5-Phosphate group leaves the carrier (dephosphorylates, shape changes)
6-Potassium leaves the carrier to get into the cell

63

A coupled transport: energy released by a molecule moving by simple diffusion is used to supply energy to actively transport a different molecule, which is moving through the membrane against a concentration gradient.

Cotransport

64

Example of cotransport

Glucose moves across the membrane against a concentration gradient

65

Movement of bulk substances into the cell

Endocytosis

66

Movement of bulk materials out of the cell

Exocytosis

67

When does endocytosis occur?

When the plasma membrane envelops food particles and/or liquids to ring then into the cell

68

The cell takes in particulate matter

Phagocytosis

69

The cell takes in only fluid

Pinocytosis

70

Specific molecules are taken in after thet bind to a receptor

Receptor-mediated endocytosis

71

When does exocytosis occur?

It occurs when material is discharged from the cell (such as waste).

72

During exocytosis, what fuses with the cell membrane and release their contents to the exterior of the cell?

Vesicles

73

What is used in plants to export cell wall material?

Bulk transport

74

What is used in animals to secrete hormones, neurotransmitters, digestive enzymes?

Bulk transport