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biology med 103 > topic 6 > Flashcards

topic 6 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

two properties of the plasma membrane

A
  • fluidity and mosaicism
  • selective permeability
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2
Q

selective permeability

A

to allow some substances to cross more easily than others

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3
Q

cellular membranes are fluid mosaics of

A

lipids and proteins

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4
Q

amphipathic

A

the plasma membrane consists of hydrophilic “heads” and hydrophobic “tails”

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5
Q

phospholipids form two structures in an aqueous environment

A

micelles and liposomes

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6
Q

micelles

A

single layer spherical structure

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7
Q

liposomes

A

bilayer spherical structures

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8
Q

3 types of membrane lipids

A
  • phospholipids
  • glycolipids
  • sterols (cholesterol)
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9
Q

2 types of phospholipids

A
  1. phosphoglycerides
  2. phosphosphingolipids
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10
Q

composition of a phosphoglyceride

A

glycerol + 2 fatty acids + phosphate + organic molecule

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11
Q

composition of a phosphosphingolipid

A

sphingosine + 1 fatty acid + phosphate + organic molecule

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12
Q

their basis is glycerol

A

phosphoglycerides

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13
Q

examples of phosphoglycerides

A
  • phosphatidyl-choline
  • phosphatidyl-ethanolamine
  • phosphatidyl-serine
  • phosphatidyl-inositol
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14
Q

their basis is sphingosine

A

phosphosphingolipids

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15
Q

example of phosphosphingolipid

A

sphingomyelin
(only in animal cell membrane)

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16
Q

glycolipids

A

sugar + lipids (glycosylated lipids)

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17
Q

glyosphingolipids

A

sphingosine + 1 fatty acid + sugar residue(s)

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18
Q

examples of glycosphingolipids

A
  1. cerebrosides
  2. gangliosides
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19
Q

monosaccharide glycosphingolipid

A

cerebrosides

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20
Q

oligosaccharide glycosphingolipid

A

ganglioside

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21
Q

sialic acid (NANA)

A

N-acetyl neuraminic acid

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22
Q

types of sterols

A
  1. cholesterol (animal cell membrane)
  2. phytosterols (plant cell membrane)
  3. ergosterols (fungal and protozoal cell membranes)
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23
Q

membrane protein categories

A
  • integral
  • peripheral
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24
Q

types of integral proteins

A
  • transmembrane proteins: completely span out the membrane
  • lipid-bound protein: attached to a membrane lipid
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25
Q

2 types of secondary structure
(transmembrane proteins)

A
  • α-helical structure: e.g. growth factor receptors (EGFR), insulin, membrane immunoglobulins
  • β-pleated sheet structure (β-barrel): e.g. bacterial porin
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26
Q

the hydrophobic region of transmembrane proteins contains

A

non-polar amino acids

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27
Q

EGFR

A
  • epidermal growth factor receptor
  • overexpressed in cancers (ex:breast)
  • single-pass transmembrane protein with α-helical structure
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28
Q

integral lipid-bound proteins

A

attached to the plasma membrane through a covalent bond with a lipid molecule

29
Q

2 types of attachment (in lipid-bound proteins)

A
  1. directly attached: to the lipids at the internal side of the plasma membrane
  2. indirectly attached: to the phosphatidyl-inositol at the external site of the plasma membrane through an oligosaccharide chain
30
Q

peripheral proteins

A

loosely bound to the surface of the membrane

31
Q

example of an internal membrane protein (peripheral protein)

A

erythrocyte spectrin

32
Q

six major functions of membrane proteins

A
  • transport
  • enzymatic activity
  • signal transduction
  • cell-cell recognition
  • intercellular joining
  • attachment to the cytoskeleton and ECM
33
Q

membrane carbohydrates

A
  • located on the external side of the cell membrane
  • interact with the surface molecules of other cells facilitating cell-cell recognition
34
Q

3 types of membrane-associated carbohydrates

A
  • glycoproteins: carbohydrates covalently bonded to proteins
  • glycolipids: carbohydrates covalently bonded to proteins
  • proteoglycans: proteins covalently linked to carbohydrates
35
Q

membrane-associated carbohydrate found in both membrane and ECM

A

glycoproteins

36
Q

membrane-associated carbohydrate found in ECM only

A

proteoglycans

37
Q

membrane-associated carbohydrate found in membrane only

A

glycolipids

38
Q

glycocalyx

A

carbohydrate cover on the external side of the cell membrane protecting the cell surface from mechanical/chemical damage

39
Q

examples of hydrophobic molecules

A

CO2, O2, hydrocarbons

40
Q

examples of hydrophilic molecules

A

sugars, ions

41
Q

2 types of transport proteins

A
  • channel proteins
  • carrier proteins
42
Q

aquaporins

A
  • special channel proteins
  • transports water
43
Q

channel vs carrier proteins

A

channel - transport proteins using a hydrophilic channel

carrier - transport proteins that bind to molecules and change shape to shuttle them across

44
Q

example of a carrier protein

A

glucose transporters (GLUT)

45
Q

active transport

A

transport of a substance across a membrane that requires energy investment

46
Q

passive transport

A

transport of a substance across a membrane with no energy investment

47
Q

2 types of passive transport

A
  1. diffusion - movement of solute molecules across the plasma membrane down their concentration gradient
  2. osmosis - movement of solvent (water) molecules across the plasma membrane against the solute concentration
48
Q

facilitated diffusion

A

passive transport by transport proteins

(movement of molecules is always down their concentration gradient)

49
Q

some diseases are caused by malfunctions in specific transport proteins

A
  • cystic fibrosis
  • cystinuria
50
Q

cystic fibrosis

A
  • mutation in chloride ion channel protein
  • viscous secretions in respiratory tract causes pulmonary infections
51
Q

cystinuria

A

(kidney disease)
- mutations in a renal membrane carrier protein

  • prevention of cysteine reabsorption into the blood
  • cysteine concentrates in urine then forms kidney stones (crystals)
52
Q

tonicity

A

the ability of a solution to cause a cell to gain or lose water

53
Q

an animal cell will _____ in a hypotonic solution and _____ in a hypertonic solution

A

lyse, shrivel

54
Q

plant cells in a hypotonic environment become _____, become _____ in an isotonic environment, and become _____ in a hypertonic environment

A

turgid, flaccid, plasmolyzed

55
Q

plant cells are happier in a _____ environment, while animal cells are happier in a _____ environment

A

hypotonic, isotonic

56
Q

molecules move against their concentration gradient through

A

active transport

57
Q

membrane protein used for active transport

A

ion pumps

58
Q

example of an ion pump

A

sodium/potassium (Na+/K+) pump

59
Q

steps of Na+/K+ pump

A
  1. cytoplasmic Na+ binds to the sodium-potassium pump
  2. Na+ binding stimulates phosphorylation by ATP
  3. phosphorylation causes the protein to change its conformation, expelling Na+ to the outside
  4. extracellular K+ binds to protein, triggering release of the phosphate group
  5. loss of phosphate group, restores protein’s original conformation
  6. K+ is released, Na+ sites are receptive again, cycle repeats
60
Q

electrogenic pumps

A

transport proteins that generate voltage across a membrane (create membrane potential)

ex: H+ pump

61
Q

cotransport

A

passive transport of H+ to the inside of the cell by diffusion coupled in active transport of sucrose

62
Q

bulk transport of large macromolecules across the plasma membrane using transport vesicles occurs by

A

exocytosis and endocytosis

63
Q

3 types of endocytosis

A
  • pinocytosis
  • phagocytosis
  • receptor-mediated endocytosis
64
Q

phagocytosis

A

“cellular eating”
the intake of solid/insoluble material by the cell or ingestion of whole cells

65
Q

pinocytosis

A

“cellular drinking”
the intake of liquid or soluble material by the cell

66
Q

receptor-mediated endocytosis

A

the intake of specific molecules selected by a receptor

ex: binding of ligands to receptors triggers vesicle formation

67
Q

ligand

A

a molecule that binds specifically to a receptor molecule

68
Q

example of receptor-mediated endocytosis

A

cholesterol uptake by hepatocytes

  1. cholesterol circulates to blood bound to liposomes
  2. the cell takes in the lipoproteins-cholesterol vesices
  3. cholesterol is released in the liver cell

biology med 103 (13 decks)

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