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FOO > NUTRIENT TRANSPORT ACROSS CELLULAR MEMBRANE > Flashcards

NUTRIENT TRANSPORT ACROSS CELLULAR MEMBRANE Flashcards

1
Q

TYPICAL THICKNESS OF CELL MEMBRANE

A

4-10nm

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2
Q

WHAT DETERMINES HUMAN BLOODTYPE?

A

MARKER PROTEINS ON ERYTHROCYTES

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3
Q

THE FLUID MOSAIC MODEL OF THE PLASMA MEMBRANE DESCRIBES THE MEMBRANE AS:

A

FLUID COMBINATION OF PHOSPHOLIPIDS, CHOLESTEROL AND PROTEINS. CARBOH. ATTACHED TO LIPIDS (GLYCOLIPIDS) AND PROTEINS (GLYCOPROTEINS) EXTEND FROM THE OUTWARD FACING SURFACE OF THE MEMBRANE.

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4
Q

WHAT IS THE MOST RAPIDLY METABOLIZING ORGANELLE OF THE CELL?

A

MITOCHONDRION

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5
Q

PROPORTIONS OF PLASMA MEMBRANE COMPONENTS VARY ACCORDING TO…

A

CELL TYPE

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6
Q

MEMBRANES ACTIVELY INVOLVED IN METABOLISM CONTAIN MORE OF WHICH PLASMA MEMBRANE COMPONENT?

A

PROTEIN

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7
Q

MITOCHONDRION MEMBRANE COMPOSITION VS SCHWANN CELL MEMBRANE COMPOSITION

A

M: 76% PROTEIN, 24% LIPID
S: 76% LIPID, 18% PROTEIN

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8
Q

STRUCTURE OF PHOSPHOLIPID MOLECULES:

A

HYDROPHILIC HEAD (PHOSPHATE CONTAINING GROUP ATTACHED TO A GLYCEROL MOLECULE); ATTRACTS WATER BECAUSE PHOSPHATE IS NEGATIVELY CHARGED MAKING THE HEAD POLAR
AND
TWO HYDROPHOBIC TAILS (EACH CONTAINING EITHER A SATURATED OR UNSATURATED FATTY ACID); UNCHARGED AND NON POLAR

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9
Q

WHAT ARE AMPHIPATHIC MOLECULES?

A

MOLECULES THAT CONTAIN BOTH A HYDROPHILIC AND HYDROPHOBIC REGION

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10
Q

WHAT ROLE DO PHOSPHOLIPIDS PLAY IN THE FOOD INDUSTRY AND WHY?

A

THEY ACT AS EMULSIFIERS BECAUSE OF THEIR AMPHIPATHIC NATURE

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11
Q

WHAT IS THE MOST STABLE THERMODYNAMIC STRUCTURE?

A

THE PHOSPHOLIPID BILAYER

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12
Q

IN THE PHOSPHOLIPID BILAYER, WHICH PART IS FACING OUTWARD?

A

THE HYDROPHILIC HEADS

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13
Q

IS THE LIPID BILAYER SYMETRICAL OR ASYMETRICAL?

A

ASYMETRICAL (DIFFERENT PHOSPHATE CONTAINING GROUPS, DIFFERENT PROTEINS AND CARBS, OVERALL DIFFERENT LOOK OF THE INNER AND OUTER MONOLAYER)

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14
Q

WHICH CHARACTERISTIC OF THE LIPID BILAYER IS ESSENTIAL FOR ITS STRUCTURE AND FUNCTIONS?

A

FLUIDITY (IT BEHAVES AS A 2 DIMENSIONAL FLUID) AND DYNAMICS

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15
Q

TYPES OF MOVEMENTS POSSIBLE IN THE LIPID BILAYER + EXPLANATIONS:

A

ROTATION ON THE PHOSPHOLIPID AXIS AND VIBRATION (‘FLEXION’); VERY DYNAMIC, 10 -9sec
LATERAL MOVEMENT; 10 -6sec
FLIP FLOP MOVEMENT; RARE, OCCURRING CCA EVERY 28HRS (10 5sec), PHOSPHOLIPIDS SWITCH MONOLAYERS, CATALYSED BY ENZYMES, SOME REQUIRE ATP

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16
Q

WHERE ARE CARBOHYDRATES LOCATED IN THE PLASMA MEMBRANE AND WHERE ARE PROTEINS LOCATED?

A

CARBS: OUTER MONOLAYER
PROTEINS: EITHER INNER OR OUTER MONOLAYER OR INTEGRATED WITHIN THE BILAYER

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17
Q

WHAT IS USED TO MONITOR MOLECULAR DYNAMICS?

A

FRAP: FLUORESCENCE RECOVERY AFTER PHOTOBLEACHING

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18
Q

WHAT INFLUENCES THE FLUIDITY OF THE CELL MEMBRANE?

A

TEMPERATURE, PHOSPHOLIPID COMPOSITION (ESP NATURE OF FATTY ACID CHAINS) AND THE PRESENCE OF STEROLS (E.G. CHOLESTREOL)

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19
Q

WHAT DOES C16:0 INDICATE ABOUT A FATTY ACID?

A

C16 INDICATED THE NUMBER OF CARBONS, A 0 THE NUMBER OF DOUBLE BONDS

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20
Q

WHY ARE SATURATED FATTY ACIDS CALLED SATURATED?

A

BECAUSE THEY ONLY HAVE SINGLE BONDS SO EVERY CARBON HAS A BOND WITH MAXIMUM NUMBER OF HYDROGEN ATOMS

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21
Q

THE MOLECURAL INTERACTION BETWEEN 2 PHOSPHOLIPIDS IS STRONGER WHEN THE FATTY ACID CHAINS ARE MADE FORM WHAT TYPE OF FATTY ACIDS?

A

SATURATED

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22
Q

WHICH TYPE OF FATTY ACIDS CONTRIBUTES MORE TO MEMBRANE FLUIDITY (MAKING THE MEMBRANE LESS PACKED)?

A

UNSATURATED

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23
Q

MOLECULAR FORMULA OF CHOLESTEROL?

A

C27H46O

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24
Q

CHOLESTEROLS INTERACTIONS WITH WATER AND HYDROPHILIC MOLECULES?

A

CHOLESTEROL IS MOSTLY NON POLAR AND IS GENERALLY REPELLED TO WATER. BUT THE PRESENCE OF THE HYDROXYL GROUP (OH) ALLOWS IT TO WEAKLY INTERACT WITH HYDROPHILIC MOLECULES

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25
Q

CHOLESTEROL IS CLASSED AS A:

A

STEROID

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26
Q

HOW DOES INSERTION OF CHOLESTEROL BETWEEN THE PHOSPHOLIPIDS OF THE PLASMA MEMBRANE CHANGE ITS FLUIDITY?

A

BECAUSE OF ITS RIGID STRUCTURE CHOLESTEROL GENERATES SPACE, REDUCES INTERACTIONS BETWEEN THE FATTY ACID CHAINS AND INCREASES FLUIDITY.

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27
Q

WHEN IS CHOLESTEROL PARTICULARLY IMPORTANT FOR MAINTAINING MEMBRANE FLUIDITY?

A

WHEN TEMPERATURE CHANGES (IT CAN BOTH MODERATE THE INCREASE IN FLUIDITY WHEN IT’S WARMER, AND INCREASE IT)

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28
Q

WHAT IS THE RELATIONSHIP BETWEEN MEMBRANE FLUIDITY AND PERMEABILITY?

A

INCREASED FLUIDITY IS GENERALLY ASSOCIATED WITH INCREASED PERMEABILITY

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29
Q

WHAT DOES THE TERM ‘GLYCOCALYX’ REFER TO?

A

CARBOHYDRATES OF THE PLASMA MEMBRANE AS A WHOLE

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30
Q

MOST CARBOHYDRATES IN THE MEMBRANE ARE LINKED TO:

A

PROTEINS

31
Q

ROLE OF CARBOHYDRATE LAYER IN THE MEMBRANE + ONE EXAMPLE FOR FUNCTION:

A

THE CARB LAYER ABSORBS WATER AND LUBRICATES THE OUTER LAYER OF THE MEMBRANE, THUS HELPING E.G. ERYTHROCYTES CHANGE THEIR SHAPE WHEN GOING INTO SMALL BLOOD VESSELS
+ STRUCTURAL ROLE
+ CELL RECOGNITION AND ADHESION
+ HAVE ATTACHING SITES FOR PATHOGENS

32
Q

APPROXIMATE PROTEIN:LIPID RATIO IN MEMBRANES (IN TERMS OF NUMBER OF MOLECULES):

A

60:40

33
Q

HOW MANY OF OUR GENES CODE FOR MEMBRANE PROTEINS?

A

1/3

34
Q

2 MAIN GROUPS OF PROTEINS:

A

INTEGRAL AND ASSOCIATED

35
Q

WHICH PROTEINS ARE PERMANENT COMPONENTS OF THE MEMBRANE?

A

INTEGRAL PROTEINS

36
Q

WHAT KIND OF PERMEABILITY DOES THE CELL MEMBRANE HAVE?

A

SELECTIVE

37
Q

WHICH SUBSTANCES CAN MOVE UNAIDED (SIMPLE DIFFUSION!!!!) THROUGH THE LIPID BILAYER OF THE CELL MEMBRANE?

A

RELATIVELY SMALL AND NON POLAR SUBSTANCES LIKE OTHER LIPIDS, LIPID SOLUBLE VITAMINS, O2, CO2 AND ALCOHOL

38
Q

HOW DO WATER-SOLUBLE MATERIALS LIKE GLUCOSE, AMINO ACIDS AND ELECTRICALLY CHARGED IONS CROSS THE BILAYER?

A

BY INTRINSIC PROTEINS THAT FORM A VARIETY OF TRANSPORT SYSTEMS ACCORDING TO THE SUBSTANCE TYPE

39
Q

HOW DO WATER-SOLUBLE MATERIALS LIKE GLUCOSE, AMINO ACIDS AND ELECTRICALLY CHARGED IONS CROSS THE BILAYER?

A

BY INTRINSIC PROTEINS THAT FORM A VARIETY OF TRANSPORT SYSTEMS ACCORDING TO THE SUBSTANCE TYPE

40
Q

WHAT ARE THE 2 MAIN TYPES OF CELL TRANSPORT?

A

PASSIVE AND ACTIVE

41
Q

WHAT ARE THE EXAMPLES OF PASSIVE CELLULAR TRANSPORT?

A

SIMPLE DIFFUSION, OSMOSIS, FACILITATED DIFFUSION

42
Q

WHAT ARE THE 2 MAIN TYPES OF ACTIVE TRANSPORT + THEIR SUBTYPES?

A

PUMP (PRIMARY AND SECONDARY) AND VESICLE (EXOCYTOSIS AND ENDOCYTOSIS)

43
Q

WHAT ARE THE TYPES OF ENDOCYTOSIS?

A

PINOCYTOSIS, PHAGOCYTOSIS AND RECEPTOR MEDIATED ENDOCYTOSIS

44
Q

WHAT IS THE NAME FOR THE UNEQUAL DISTRIBUTION OF MOLECULES?

A

CONCENTRATION GRADIENT

45
Q

WHAT IS DIFFUSION?

A

SPREAD OF PARTICLES THROUGH RANDOM MOTION FROM AN AREA OF HIGH CONCENTRATION TO AN AREA OF LOW CONCENTRATION (DOWN THEIR CONCENTRATION GRADIENT)

46
Q

CAN NON LIVING SYSTEMS EXPERIENCE DIFFUSION?

A

YES

47
Q

02 IS TYPICALLY MORE CONCENTRATED INSIDE OR OUTSIDE THE CELL?

A

OUTSIDE

48
Q

WHAT IS FILTRATION AND WHERE DOES IT OCCUR?

A

A PROCESS WHICH IS A VARIATION OF DIFFUSION. MATERIAL MOVES ACCORDING TO ITS CONCENTRATION GRADIENT THROUGH A MEMBRANE; SOMETIMES THE RATE OF DIFFUSION IS ENHANCED BY PRESSURE
–> IT OCCURS IN THE KIDNEYS (BP FORCES LARGE AMOUNTS OF WATER AND ACCOMPANYING SOLUTES OUT OF THE BLOOD AND INTO THE RENAL TUBES; THE RATE OF DIFFUSION ALMOST TOTALLY DEPENDENT ON BP); IF THE BP IS TOO HIGH IT CAN ALSO ‘SQUEEZE’ PROTEIN THROUGH, LEADING TO PROTEIN IN URINE

49
Q

OSMOSIS?

A

SPECIFIC TYPE OF DIFFUSION; PASSAGE OF WATER FROM A REGION OF HIGHER CONCENTRATION TO A REGION OF LOWER CONC.

50
Q

CLASSIC EXAMPLE TO DEMONSTRATE OSMOSIS AND OSMOTIC PRESSURE?

A

IMMERSING CELLS (E.G. ERYTHROCYTES) INTO SUGAR SOLUTIONS OF VARIOUS CONCENTRATIONS.

51
Q

WHAT IS LYSIS?

A

BREAKDOWN OF A CELL

52
Q

WHAT STOPS HYDROPHILIC MOLECULES, CHARGED IONS AND RELATIVELY LARGE MOLECULES LIKE GLUCOSE FROM CROSSING THE MEMBRANE AND HOW DO THEY OVERCOME THAT?

A

ALTHOUGH THERE IS A CONCENTRATION GRADIENT FOR ALL THESE MOLECULES BUT THEY ARE REPELLED BY HYDROPHOBIC PARTS OF THE MEMBRANE. THEY USE FACILITATED TRANSPORT PROTEINS TO SHIELD THEM FROM THE REPULSIVE FORCE OF THE MEMBRANE.

53
Q

CHANNEL (AND PORES) PROTEINS?

A
  • INTEGRAL TRANSMEMBRANE PROTEINS CONTAINING HYDROPHILIC PASSAGES
  • CHANNELS ARE SPECIFIC FOR THE SUBSTANCE BEING TRANSPORTED (DIFFERENT DIAMETERS)
  • ALWAYS PASSIVE MOVEMENTS SINCE IONS MOVE THROUGH BY GRADIENT CONCENTRATION
  • CAN BE VOLTAGE DEPENDENT, LIGAND DEPENDENT, MECHANOSENSORY, THERMORECEPTOR CHANNELS ETC, DEPENDING ON WHICH STIMULI REGULATES THEM
54
Q

WHAT ARE AQUAPORINS, WHY ARE THEY IMPROTANT AND HOW MANY OF THEM ARE THERE IN HUMANS?

A

WATER HAS A FREE PASSAGE THROUGH THE MEMBRANE VIA OSMOSIS, BUT THAT IS NOT ALWAYS FAST ENOUGH SO SOME CELLS HAVE DEVELOPED A MORE SOPHISTICATED AND RAPID WATER TRANSPORT SYSTEM VIA CHANNEL PROTEINS (AQUAPORINS)

  • THEY ARE HIGHLY EXPRESSED IN KIDNEYS
  • 11 MAMMALIAN AQPs HAVE BEEN IDENTIFIED
55
Q

APART FROM WATER, WHICH OTHER MOLECULES CAN PASS THE CELL MEMBRANE VIA AQUAPORINS?

A

CO2, GLYCEROL, UREA, PURINES, PYRIMIDINES AND NUCLEOSIDES

56
Q

WHICH PROTEINS HAVE A HIGHER TRANSPORT SPEED, CHANNEL OR CARRIER PROTEINS?

A

CHANNEL PROTEINS (10S OF MILLIONS OF MOLECULES PER SEC VS THOUSAND TO A MILLION MOLECULES PER SEC)

57
Q

CARRIER PROTEINS AKA TRANSPORTERS?

A
  • TRANSMEMBRANE PROTEINS THAT USE ELECTROCHEM GRADIENTS TO MOVE MOLECULES ACROSS MEMBRANES
  • VERY DIVERSE AND ABUNDANT, >100 FAMILIES
  • CAN BE FOUND IN ALL CELL MEMBRANES
  • BEFORE CROSSING THE MEMBRANE, A MOLECULE IS FIRST RECOGNIZE BY A TRANSPORTER, WHICH INCLUDES A CONFORMATIONAL CHANGE OF THE TRANSPORTER, ALLOWING THE TRANSFER OF THE MOLECULE ACROSS THE MEMBRANE
58
Q

WHAT ARE THE TYPES OF TRANSPORTERS + EXPLANATIONS OF EACH TYPE?

A
  • UNIPORT TRANSPORT: ONE TYPE OF MOLECULE IS MOVED
  • CO-TRANSPORT: 2 TYPES OF MOLECULES TRANSPORTED SIMULTANEOUSLY, CAN BE ANTIPORT/ COUNTER TRANSPORT (MOLECULES MOVING IN OPPOSITE DIRECTIONS) OR SYMPORT TRANSPORT
59
Q

HOW MANY TYPES OF GLUTs ARE THERE

A

14

60
Q

IS GLUCOSE POLAR OR NON POLAR?

A

POLAR

61
Q

WHAT ARE PUMPS?

A

TRANSMEMBRANE PROTEINS THAT ALLOW IONAS AND SMALL MOLECULES TO MOVE IN OUR OUT OF THE CELLS AGAINST THEIR CONCENTRATION GRADIENT, WHICH REQUIRES AN ENERGY SOURCE, USUALLY ATP –> TYPE OF PRIMARY ACTIVE TRANSPORT

62
Q

EXAMPLE OF A PUMP (PRIMARY ACTIVE TRANSPORT)

A

Na+/K+ pump

63
Q

WHAT PERCENTAGE OF THE TOTAL CELLULAR ATP OF ANIMAL CELLS DOES THE NA+/K+ PUMP USE?

A

25%

64
Q

MECHANISM AND FUNCTION OF NA+/K+ PUMP:

A

MOVES 2 K+ INTO THE CELL AND 3 NA+ OUT OF THE CELL.
GAINS ENERGY THROUGH ATP HYDROLYSIS.
ENSURES THE INTERIOR OF THE CELL IS ALWAYS SLIGHTLY MORE NEGATIVE THAN THE EXTERIOR, WHICH CONTRIBUTES TO THE MEMBRANE POTENTIAL (ENABLES NEURONAL EXCITABILITY, CELL MUSCLE CONTRACTION, DIGESTED MOLECULE ABSORPTION..).

65
Q

SECONDARY ACTIVE TRANSPORT EXAMPLE?

A

SGLT1 AND SGLT2 (GLUCOSE TRANSPORT COUPLED WITH NA+ TRANSPORT, ENERGY GAINED THROUGH NA+K+ATPase

66
Q

WHAT IS ENDOCYTOSIS?

A

THE PROCESS OF A CELL IMPORTING MATERIAL BY ENVELOPING IT IN A PORTION OF ITS CELL MEMBRANE

67
Q

WHAT IS EXOCYTOSIS?

A

THE PROCESS OF A CELL EXPORTING MATERIAL USING VESICULAR TRANSPORT.

68
Q

WHAT IS PHAGOCYTOSIS?

A
  • TYPE OF ENDOCYTOSIS
  • USED FOR TRANSPORT OF LARGE MOLECULES
  • MANY IMMUNE CELLS ENGAGE IN PHAGOCYTOSIS OF INVADING PATHOGENS
  • WHEN THE VESICLE IS FULLY IN THE CELL, IT MERGES WITH A LYSOSOME FOR BREAKDOWN OF THE IMPORTED MATERIAL
69
Q

WHAT IS CLATHRIN?

A

A PROTEIN THAT COATS A PIECE OF MEMBRANE WHICH WILL ENVELOP A MOLECULE UNDERGOING PHAGOCYTOSIS
– ALSO USED IT RECEPTOR MEDIATED ENDOCYTOSIS

70
Q

WHAT IS PINOCYTOSIS?

A
  • TYPE OF ENDOCYTOSIS
  • FOR FLUIDS AND SOLUTES
  • THE CELL MEMBRANE INVAGINATES CREATING A POUCH AND SURROUNDS A SMALL VOLUME OF FLUID/AND SOLUTES AND THEN PINCHES OFF
71
Q

DIFFERENCES BETWEEN PHAGOCYTOSIS AND PINOCYTOSIS?

A
  • TYPE OF MOLECULES THEY TRANSFER
  • PINOCYTOSIS RESULTS IN MUCH SMALLER VESICLE
  • THE VESICLE IN PINOCYTOSIS DOESN’T MERGE WITH A LYSOSOME
72
Q

FAMILIAL HYPERCHOLESTEROLEMIA IS RELATED TO WHICH FORM OF ACTIVE TRANSPORT AND HOW?

A

LDL IS USUALLY REMOVED FROM BLOOD BY RECEPTOR-MEDIATED ENDOCYTOSIS. IN FAMILIAL HYPERC. THE LDL RECEPTORS ARE DEFECTIVE OR MISSING ENTIRELY WHICH IS WHY PEOPLE END UP HAVING LIFE THREATENING LEVELS OF PLASMA CHOLESTEROL

73
Q

5 STAGES OF EXOCYTOSIS:

A 
VESICLE TRAFFICKING
VESICLE TETHERING
VESICLE DOCKING
VESICLE PRIMING
VESICLE FUSION
74
Q

EXAMPLES OF EXOCYTOSIS:

A

SECRETION OF NEUROTRANSMITTERS INTO THE SYNAPTIC CLEFT, SECRETION OF ECM PROTEINS, SECRETION OF ENZYMES, PEPTIDE HORMONES, AND ANTIBODIES!!!!!!!!

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