2.4 Membranes Flashcards

1
Q

What is the current model of the membrane structure called?

A

fluid mosaic model

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2
Q

What is the bilayer of the membrane structure?

A

the phospholipid bilayer

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3
Q

What is the 3-carbon compound called in the phospholipid bilayer?

A

glycerol

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4
Q

What are two of the carbons in the 3-carbon compound attached to?

A

non-polar fatty acids

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5
Q

What is one of the carbons in the 3-carbon compound attached to?

A

highly polar organic alcohol group with a phosphate

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6
Q

What are the hydrophilic ends?

A

alcohol-phosphate

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7
Q

What are the hydrophobic ends?

A

fatty acids

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8
Q

Which ways do the hydrophilic ends face?

A

outward

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9
Q

Which way does the hydrophobic ends face?

A

inward

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10
Q

Why does the membrane remain fluid and flexible?

A

Because the fatty acid ends are not attracted to one another

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11
Q

What helps maintain the overall structure of the membrane?

A

Hydrogen bonds with water

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12
Q

What are glycoproteins?

A

composed of carbohydrate chains attached to peripheral proteins; recognize like cells and are involved in immune response

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13
Q

What are integral proteins?

A

completely penetrate lipid bilayer; control entry and removal of specific molecules

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14
Q

What does the cholesterol do?

A

helps regulate membrane fluidity and stability

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15
Q

composed of carbohydrate chains attached to peripheral proteins; recognize like cells and are involved in immune responsibility

A

glycoprotein

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16
Q

completely penetrate lipid bilayer; control entry and removal of specific molecules

A

integral proteins

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17
Q

helps regulate membrane fluidity and stability

A

cholesterol

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18
Q

What are the six membrane protein functions?

A

Hormone binding sites Enzymatic Action Cell Adhesion Cell-to-Cell Communication Channels for Passive Transport Pumps for Active Transport

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19
Q

What are the 3 types of passive transport?

A

diffusion, facilitated diffusion, and osmosis

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20
Q

What is diffusion?

A

Particles moving from a region of high concentration to a region of low concentration

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21
Q

What are 3 characteristics of facilitated diffusion?

A

Involves a carrier protein (non-channel protein) that helps carry substances across membrane Does NOT require energy Rate is dependent on number of carrier proteins available

22
Q

What is osmosis?

A

Movement of water across a partially permeable membrane to balance solute concentration

23
Q

What proteins does osmosis use?

A

aquaporins

24
Q

What are the 3 characteristics of a hypertonic solution(concentration, movement, and shape)?

A

Concentration of solutes is more outside the cell than inside Water flows out of cell The cell shrivels and becomes “flacid”.

25
Q

What are the 3 characteristics of a hypotonic solution(concentration, movement, and shape)?

A

Concentration of solutes is less outside the cell than in. Water flows in The cell swells with water, becomes “turgid”, and dies.

26
Q

What are the 3 characteristics of a isotonic solution(concentration, movement, and shape)?

A

Concentration is the same inside and out No net movement The cell stays the same

27
Q

What is water potential?

A

the tendency of water to leave one place in favor of another place

28
Q

How will water move?

A

Water will always move from and area of higher (less negative) water potential to an area of lower water potential (more negative).

29
Q

Compare big/polar and small/non-polar in which can cross the membrane passively?

A

It is difficult (not impossible) for large or polar molecules to cross membranes passively. It is relatively easy for smaller and non-polar molecules to cross membranes passively

30
Q

What are 2 characteristics of active transport(movement and requirement)?

A

Movement of substances against a concentration gradient Requires energy (ATP)

31
Q

What is step 1 of the sodium-potassium pump?

A

Specific protein binds to three intracellular sodium ions

32
Q

What is step 2 of the sodium-potassium pump?

A

Binding of sodium ions causes phosphorylation by ATP

33
Q

What is step 3 of the sodium-potassium pump?

A

Phosphorylation changes shape of protein, pushing sodium ions out of cell

34
Q

What is step 4 of the sodium-potassium pump?

A

Two extracellular potassium ions bind to a different part of protein, which causes release of phosphate group

35
Q

What is step 5 of the sodium-potassium pump?

A

Loss of phosphate group restores original shape causing release of potassium ions into cell

36
Q

What does endocytosis do?

A

Allows macromolecules to enter the cell

37
Q

When does endocytosis occur?

A

Occurs when portion of plasma membrane is “pinched” off to enclose a substance, forming a vesicle

38
Q

Where does the vesicle go in endocytosis?

A

This vesicle enters the cytoplasm and the substance makes its way where it is needed

39
Q

Why do the ends of the plasma membrane reattach after endocytosis?

A

Ends of the plasma membrane reattach because of the hydrophobic and hydrophilic properties of the phospholipids and the presence of water

40
Q

What is step 1 of exocytosis?

A

Protein produced by ribosomes of rough ER enters the lumen of the ER

41
Q

What is step 2 of exocytosis?

A

Protein exits ER and enters the cis side of the Golgi apparatus (vesicle is involved)

42
Q

What is step 3 of exocytosis?

A

As protein moves through the Golgi apparatus, it is modified and exits on the trans side inside a vesicle

43
Q

What is step 4 of exocytosis?

A

Vesicle with modified protein moves to membrane and fuses with it; contents are secreted out of cell

44
Q

What are the 4 parts of the membrane?

A

proteins, carbohydrates, lipids, and cholesterol

45
Q

What is number 1?

A

peripheral protein

46
Q

What is number 2?

A

phospholipid

47
Q

What is number 3?

A

tail

48
Q

What is number 4?

A

head

49
Q

What is number 5?

A

peripheral protein

50
Q

What is number 6?

A

channel protein (integral protein)

51
Q

What is number 7?

A

cholesterol

52
Q

What is number 8?

A

glycoprotein