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Biochemical and Physiological Basis of Nutrition I: Macronutrients > 9/7/22 > Flashcards

9/7/22 Flashcards

1
Q

to survive and grow cells must…

A

1) exchange molecules with environment
2) import nutrients (sugars and aa’s)
3) eliminate metabolic waste products
4) regulate concentration of inorganic ions in cytosol and organelles

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2
Q

molecules that diffuse across lipid bilayer of plasma membrane

A

CO2 and O2

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3
Q

membrane transport proteins

A

span lipid bilayer
provide private passageways across the membrane for select substances

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4
Q

what type of molecules can be transported across the cell membrane?

A

inorganic ions and small, water-soluble molecules

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5
Q

transporters

A

shift small organic molecules or inorganic ions from one side of the membrane to the other by changing shape

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6
Q

channels

A

form tiny hydrophilic pores across the membrane through which such substances can pass by diffusion

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7
Q

ion channels

A

permit passage of inorganic ions
ions are electrically charged, their movement causes electrical force (voltage) across the membrane

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8
Q

human body function

A

transform nutrients from foods using metabolic processes into biological structures and chemical energy

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9
Q

what type of lipids spontaneously form membrane structures?

A

amphipathic lipids!
when fatty acid touches water, micelle is formed

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10
Q

micelle structure

A

carboxyl group faces water, hydrophobic groups face inside and hide from water

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11
Q

phospholipid

A

ultimate amphipathic lipid

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12
Q

amphipathic

A

has both hydrophobic (tails) and hydrophilic (heads) properties

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13
Q

phospholipid bilayer

A

tails inside, heads outside

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14
Q

cell membrane image

A
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15
Q

cell membrane structure is

A
  • highly dynamic
  • FLUID
  • phosphatidyl choline bilayer
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16
Q

cell membrane is composed of

A

carbon/palmitic

nitrogen

oleic

oxygen

water oxygens

phosphorous

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17
Q

cell membrane structure: heterogeneous or homogeneous?

A

Highly heterogeneous!

contains lipid fluid and lipid raft domains

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18
Q

requirements for unicellular organism to survive and replicate

A
  1. import metabolic substrates
  2. export metabolic waste
  3. maintain cell volume
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19
Q

each membrane type in a cell possesses a…

A

unique lipid composition

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20
Q

where in plasma membrane is cholesterol most present?

A

lipid rafts!

more rigid structures

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21
Q

phosphatidylcholine

A

most common lipid in organelles

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22
Q

where is cholesterol produced and where is it stored

A

produced in ER, but there is low concentration of cholesterol in ER bc it sends it mostly to plasma membrane

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23
Q

sphingolipids

A

tag our cells for identification

EX: blood type

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24
Q

aquaporins

A

transport water across lipid bilayer

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25
Q

carriers aka

A

transporters

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26
Q

transporters

A
  • bind substrates with high stereospecificity
  • transport rates are well below the limits of free diffusion
  • saturable
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27
Q

channels

A
  • stereospecificity < transporters
  • transport >>> transporters
  • non saturable
28
Q

uniporters

A

membrane transport protein that transports single species of substrate across cell membrane

29
Q

symporters

A

proteins that simultaneously transport 2 molecules across a membrane in the same direction

30
Q

antiporters

A

cotransporter and integral membrane protein that uses secondary active transport of 2 of more DIFFERENT molecules or ions across phospholipid membrane

31
Q

transporters are everywhere in the cell

A

cell membrane, lysosome, mitochondria

32
Q

types of transporters

A

facilitated

single solute

coupled

counter transport

33
Q

GLUT

A

glucose transporter (uniporter or single solute)

34
Q

SGLT

A

sodium-linked glucose transporter (symporters, or coupled)

35
Q

Slc26

A

chloride/bicarbonate exchanged (antiporter, or counter)

36
Q

can facilitated transporters generate a conc gradient?

A

NO!

37
Q

secondary active transport

A

occurs when endergonic (uphill) transport of one solute is coupled to the exergonic (downhill) flow of a different solute

38
Q

primary active transporters aka

A

pumps

39
Q

pumps

A

present in all cells in body

directly couples energy of ATP hydrolysis to transmembrane ion movement

create ion gradients

40
Q

what are gradients?

A

a form of chemical energy

energy is stored in transmembrane ion gradients

41
Q

what is required to create gradients?

A

energy

42
Q

if there is a leak of ions across a membrane,

A

the cell needs to spend energy to restore the gradients

43
Q

how is energy in ion gradients captured?

A

transport proteins!

EX: electron transport chain, proton gradient, and ATP production in mitochondria

44
Q

osmosis

A

water molecules diffuse directly across lipid bilayer

SLOW PROCESS!

45
Q

aquaporins

A

specialized channel proteins in plasma membrane of some cells that greatly facilitate the flow of water

curvy paper towel roll shaped

46
Q

ion channels purpose

A

speed passage of ions across membranes by providing an aqueous path across the membrane

47
Q

ion channels (rhyme)

A

diffuse at high RATES

have a GATE regulated by a biological signal

48
Q

when ion channel gate is open

A

ions move through channel, in direction dictated by ion’s charge and the electrochemical gradient

49
Q

epithelia function

A

separates interior of body from external world

50
Q

epithelia structure

A

multicellular layers of cells joined together, side to side

layers contain diff cells:

  1. stratified (as in epidermis, outer skin layer)
  2. simple epithelium (only one cell thick, lining of gut)
51
Q

epithelial tissue is

A

purely cellular and avascular

52
Q

what does epithelial tissue cover?

A

all free surfaces: cutaneous, mucous and serous, glands

EX: gut lining, liver, pancreas, gall bladder, lungs, kidneys

53
Q

functions of epithelia

A
  1. protective barrier
  2. secretion of specialized products (hormones, milk, tears)
  3. excrete waste
  4. absorption of nutrient
  5. exchange O2 and CO2
  6. detect signals (light, sound, chemicals)
54
Q

epithelial lining is…

A

polarized!

displays two faces: apical surface and basal surface

55
Q

epithelial lining apical surface

A

free and exposed to the air or watery fluid

56
Q

epithelial lining basal surface

A

attached to a sheet of connective tissue called the basal lamina

57
Q

polarity of epithelial cells depends on…

A

junctions that the cells form with one another and with the basal lamina

58
Q

tight junctions are formed by…

A

interactions btwn strands of transmembrane proteins (occludin and claudins) on adjacent cells

59
Q

tight junctions functions

A
  1. restrict paracellular pathway in the epithelia
  2. act as a barrier to solute diffusion
  3. modulation of tight junctions may alter nutrients and drug bioavailability
60
Q

tight and leaky epithelia BOTH

A

impermeable to large hydrophilic molecules, including proteins

61
Q

leaky epithelia is more permeable to…

A

small molecules and ions

maybe relation to inflammatory diseases of intestine

62
Q

vectorial transport

A

transport of an ion or molecule across an epithelium in only one direction (EX: nutrient absorption in the gut)

requires transport proteins to be nonrandomly distributed between apical and basolateral plasma membrane

63
Q

transcellular transport

A

substances travel through cell, passing through both apical and basolateral membrane

64
Q

paracellular transport

A

substances transfer across an epithelium by passing through the intercellular space between cells

65
Q
A

Biochemical and Physiological Basis of Nutrition I: Macronutrients (12 decks)

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