2.4 Membranes Flashcards Preview

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Flashcards in 2.4 Membranes Deck (52):
1

What is the current model of the membrane structure called?

fluid mosaic model

2

What is the bilayer of the membrane structure?

the phospholipid bilayer

3

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

glycerol

4

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

non-polar fatty acids

5

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

highly polar organic alcohol group with a phosphate

6

What are the hydrophilic ends?

alcohol-phosphate

7

What are the hydrophobic ends?

fatty acids

8

Which ways do the hydrophilic ends face?

outward

9

Which way does the hydrophobic ends face?

inward

10

Why does the membrane remain fluid and flexible?

Because the fatty acid ends are not attracted to one another

11

What helps maintain the overall structure of the membrane?

Hydrogen bonds with water

12

What are glycoproteins?

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

13

What are integral proteins?

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

14

What does the cholesterol do?

helps regulate membrane fluidity and stability

15

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

glycoprotein

16

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

integral proteins

17

helps regulate membrane fluidity and stability

cholesterol

18

What are the six membrane protein functions?

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

19

What are the 3 types of passive transport?

diffusion, facilitated diffusion, and osmosis

20

What is diffusion?

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

21

What are 3 characteristics of facilitated diffusion?

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

What is osmosis?

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

23

What proteins does osmosis use?

aquaporins

24

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

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

25

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

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

26

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

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

27

What is water potential?

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

28

How will water move?

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

29

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

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

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

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

31

What is step 1 of the sodium-potassium pump?

Specific protein binds to three intracellular sodium ions

32

What is step 2 of the sodium-potassium pump?

Binding of sodium ions causes phosphorylation by ATP

33

What is step 3 of the sodium-potassium pump?

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

34

What is step 4 of the sodium-potassium pump?

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

35

What is step 5 of the sodium-potassium pump?

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

36

What does endocytosis do?

Allows macromolecules to enter the cell

37

When does endocytosis occur?

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

38

Where does the vesicle go in endocytosis?

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

39

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

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

40

What is step 1 of exocytosis?

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

41

What is step 2 of exocytosis?

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

42

What is step 3 of exocytosis?

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

43

What is step 4 of exocytosis?

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

44

What are the 4 parts of the membrane?

proteins, carbohydrates, lipids, and cholesterol

45

What is number 1?

peripheral protein

46

What is number 2?

phospholipid

47

What is number 3?

tail

48

What is number 4?

head

49

What is number 5?

peripheral protein

50

What is number 6?

channel protein (integral protein)

51

What is number 7?

cholesterol

52

What is number 8?

glycoprotein

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