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Biology I > Ch. 5 - Membranes > Flashcards

Ch. 5 - Membranes Flashcards

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1
Q

What are all membranes made of?

A

Lipids.

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2
Q

How many layers make up a membrane?

A

2 layers.

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3
Q

What type of lipid is located in membranes?

A

Phospholipids.

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4
Q

What are the 3 parts of a phospholipid?

A

1) Glycerol
2) Phosphate group (polar, hydrophilic)
3) Two fatty acids chains (non-polar, hydrophobic)

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5
Q

What happens when phospholipids are put into water

A

They form a lipid bilayer.

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6
Q

How is the lipid bilayer formed when phospholipids are placed in water?

A

The lipid bilayer is formed by hydrophobic exclusion; the non-polar tails align and the hydrophilic head align.

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7
Q

How is the lipid bilayer held together?

A

By Hydrogen bonding.

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8
Q

What determines the fluidity of the membrane?

A

The fatty acid chains; Chains with lots of double bonds typically are more fluid than chains without double bonds.

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9
Q

What do surface proteins do with the membrane?

A

Float on the membrane (actually in the membrane) like boats on a pond.

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10
Q

What is the Fluid Mosaic Model?

A

A depiction of how models were inserted into the plasma membrane.

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11
Q

What are the four parts of membranes?

A

1) Lipid bilayer
2) Transmembrane proteins
3) Supporting fibers
4) Exterior proteins and glycolipids

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12
Q

What are transmembrane proteins?

What are 3 functions?

A

Proteins that are inserted in the membrane.

1) Receptors
2) Channels
3) Act as Enzymes

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13
Q

What are supporting fibers?

What is the function of supporting fiber?

A

Fibers attached to transmembrane proteins.

Function: Help the cell maintain shape.

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14
Q

How are the exterior proteins and glycolipids created?

What are they made of?

What are the functions?

A

Membrane proteins are made in the ER and transported to the Golgi.

A coating made of carbohydrates and lipids.

Function:

1) “Self” recognition
2) Recognizing other cell types

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15
Q

What are the 6 kinds of transmembrane protein?

A

1) Transporters
2) Enzymes
3) Receptors
4) Surface identity markers
5) Cell adhesion points
6) Attachment to the cytoskeleton.

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16
Q

What is the function of transporter transmembrane proteins?

A

Used to move molecules in and out of the cell.

1) Channels and carriers; allow certain molecules to diffuse into the cell.
2) Pumps; These transport proteins are often used for active transport when the cell need to expend energy.

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17
Q

What are the function of enzymes in the transmembrane proteins?

A

Many chemical reactions are carried out by enzymes that are attached to the plasma membrane.

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18
Q

What is the function of receptor transmembrane proteins?

What is an example?

A

These types of proteins are very sensitive to specific chemicals, once the chemical attaches to the receptor protein, a series of chemical reaction is initiated in the cell.

Example: Hormones; When it attaches to the specific receptors of the desired cell, the reaction starts.

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19
Q

What is attached to surface identity marker proteins?

A

glycocalyx.

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20
Q

What are cell adhesion points?

A

Where cells stick to each other.

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21
Q

What is the function of attachment proteins for the cytoskeleton?

A

Anchoring points for the actin fibers of the cytoskeleton.

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22
Q

What is diffusion?

Is diffusion considered active or passive transport, and why?

A

The net movement of a substance from an area of high concentration to a lower concentration.

Passive transport; requires no energy from the cell.

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23
Q

What three proteins do facilitated diffusion utilize?

Is facilitated diffusion considered active or passive transport?

A

1) Transport proteins
2) Ion channels
3) Carrier proteins

Passive transport.

24
Q

How do transport proteins work in regards to facilitated diffusion?

A

These proteins are selective, allowing only certain types of molecules to pass through, but is activated via diffusion (Flow from areas of high concentration to low concentration).

25
Q

What is the difference between facilitated diffusion and diffusion?

A

Facilitated requires proteins to allow certain larger molecules to pass through the membrane.

26
Q

What do ion channels allow?

A

For hydrophilic ions to diffuse into the cell.

27
Q

What are carrier proteins?

How is the process done?

A

Similar to channel proteins except that the molecule that is going to be transported binds to the carrier proteins and is “carried” across the plasma membrane.

Done via diffusion.

28
Q

What is an aqueous solution?

A

A mixture of something in water.

29
Q

What is a solvent?

A

The liquid part (water).

30
Q

What is a solute?

A

The solid part (what is dissolved).

31
Q

What is osmosis?

A

The net movement of water across a membrane via diffusion?

32
Q

Can water diffuse across the plasma membrane?

Why?

A

No

Water is highly polar, which cannot cross the hydrophobic plasma membrane. This means water requires a special channel protein to diffuse in and out of the cell (facilitated diffusion).

33
Q

What are aquaporins?

A

Specialized channel proteins for water.

34
Q

What is osmotic concentration?

A

The concentration of all of the solute in the water.

35
Q

What does it mean if a solution is hyperosmotic (hypertonic)?

A

A solution with a higher osmotic concentration.

36
Q

What does it mean if a solution is hypo osmotic (hypotonic)?

A

A solution with a lower osmotic concentration.

37
Q

What does it mean if a solution is isosmotic (isotonic)?

A

A solution with equal osmotic concentration.

38
Q

What happens to cells in a hypertonic solution?

A

Cells lose water.

39
Q

What is osmotic pressure?

A

The pressure that must be applied to stop the osmotic movement of water across a membrane.

40
Q

What is an example of osmotic pressure?

A

A cell in a hypotonic solution; the pressure of water moving into the cell.

41
Q

What is hydrostatic pressure?

A

The pressure from the water in the cell.

42
Q

How many methods are used to solve osmotic problems?

What are they?

A

3

1) Extrusion
2) Isotonic solution
3) Turgor

43
Q

What is extrusion?

What types of cells use this?

A

The process of getting rid of excess water in vacuoles.

Used by many single cell organisms.

44
Q

How can isotonic solutions resolve osmotic problems?

A

Often, organisms that live in hypertonic environments can adjust by allowing their cells to maintain the same concentrations as the solution.

45
Q

What is turgor?

What types of cells does this happen too?

A

The cell wall prevents the membrane from splitting and the high hydrostatic pressure helps keep non-woody tissues upright (celery).

Organisms with cell walls do this. The cells are hypertonic and absorb lots of water.

46
Q

What is endocytosis?

A

A process whereby the plasma membrane envelopes something and forms a vacuole.

47
Q

What are the three kinds of endocytosis?

A

1) Phagocytosis
2) Pinocytosis
3) Receptor mediated endocytosis

48
Q

What is phagocytosis?

A

Taking in particulate matter.

49
Q

What is pinocytosis?

A

Taking in liquids via same method.

50
Q

What is receptor mediated endocytosis?

A

Once receptors are filled with a specific target molecule, the whole are forms a vacuole and the material is brought into the cell.

51
Q

What is exocytosis?

A

The opposite of endocytosis.

Molecules are ejected from the cell by the fusion of a vesicle with the plasma membrane.

52
Q

What is active transport?

A

If a cell needs to move something against the concentration gradient and requires the cell to expend energy.

53
Q

What is a sodium/potassium pump?

A

Used by a cell to actively transport sodium out and potassium into the cell; requires ATP (energy).

54
Q

Once ATP is used during active transport, what does it turn into?

A

ADP (Adenosine diphosphate)

55
Q

What is the ratio of sodium ions to potassium ions going out/into the cell?

A

3:2

3 sodium ions leave per 2 potassium ions entering.

56
Q

What is a proton pump?

How does it work?

A

A pump that moves protons across membranes.

1) Proton binds to protein
2) Protein changes shape
3) Proton is ejected

57
Q

What are proton pumps important for?

A

Important for the manufacture of ATP.

Biology I (12 decks)

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