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Nutrition & Metabolism > W4 - CHO Metabolism & Diet Analysis > Flashcards

W4 - CHO Metabolism & Diet Analysis Flashcards

1
Q

What are glycated proteins?

A

Modified proteins formed by the addition of glucose mol to aa chains.

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2
Q

What are glycosaminoglycans (GAGs)?

A

Linear polysaccharides

Consist of repeating disaccharide units containing a uronic sugar + an amino sugar.

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3
Q

Examples of glycosaminoglycans (GAGs)

A

Hyaluronic acid

Keratan sulfate

Heparan sulfate

Proteoglycans

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4
Q

What is keratan sulfate important for?

A

Cornea

Joints

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5
Q

Where are monosaccharides transported to once absorbed into the blood from the small intestine?

A

Liver via hepatic portal vein

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6
Q

Where does fructose metabolism mainly occur?

A

Liver

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7
Q

What is fructose mainly used for in the liver?

A

To make liver glycogen

But some to glucose + lactate

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8
Q

Overview of fructose metabolism in liver

A

Fructose – (Fructokinase) + ATP–> Fructose-1-P + ADP

Fructose-1-P –(aldolase B)–> Dihydroxyacetone-P (DHAP) + Glyceraldehyde

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9
Q

Other than the liver, where else can fructose be metabolised?

A

Intestine

Kidney

Skeletal muscle

Fat tissues

Brain

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10
Q

Is fructose transported into cells via insulin-density pathways (insulin reg transporters GLUT1 + GLUT4)?

A

NO, instead…

Fructose taken in by GLUT5

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11
Q

What is fructose phosphorylated by in muscles + adipose tissue?

A

Hexokinase

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12
Q

Is fructose uptake insulin dependent?

A

NO

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13
Q

FRUCTOSE METABOLISM IN LIVER

After aldolase B has caused:

Fructose-1-P -> Dihydroxyacetone-P (DHAP) + Glyceraldehyde

What happens to the glyceraldehyde?

A

Glyeraldehyde – (triose kinase) –> Glyceraldehyde-3-P

OR…

Glyceraldehyde + NADH —> NAD+ + Glycerol

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14
Q

FRUCTOSE METABOLISM IN LIVER

After aldolase B has caused:

Fructose-1-P -> Dihydroxyacetone-P (DHAP) + Glyceraldehyde

And then glyceraldehyde follows this route:

Glyceraldehyde + NADH —> NAD+ + Glycerol

What are the options for glycerol?

A

To undergo lipid metabolism

OR

Glycerol – (glycerol kinase) – > Glycerol 3-phosphate – ( Glycerol-3-P dehydrogenase) –> Dihydroxyacetone -P (DHAP)

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15
Q

FRUCTOSE METABOLISM IN LIVER

After aldolase B has caused:

Fructose-1-P -> Dihydroxyacetone-P (DHAP) + Glyceraldehyde

What happens to the Dihydroxyacetone-P (DHAP)?

A

Can undergo a reversible reaction by aldolase A, B to fructose-1,6-biphosphate (in glucose metabolism pathway)

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16
Q

What type of hormone is insulin?

A

Anabolic Peptide hormone

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17
Q

Where is insulin produced from?

A

beta-cells of the pancreatic islets

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18
Q

What does insulin do to glycogen storage?

A

Promotes it

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19
Q

What does insulin help prevent

A

Hyperglycemia

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20
Q

What is the glucose transporter cell on the liver cell walls?

A

GLUT2

Glucose diffuses DOWN conc gradient from blood to liver.

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21
Q

Glucose diffuses DOWN conc gradient from blood to liver, how is glucose prevented from diffusing back into the blood across the GLUT2 transporter?

A

Insulin binds to insulin receptor on liver cell wall
= ⬆️ conc + activity of glucokinase
= maintains glucose conc between blood + liver cell
= More glucose diffuses from blood to liver

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22
Q

What does glucokinase do?

A

Causes:

Glucose + ATP –> ADP + G-6-P –> Glycogen

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23
Q

What is the brains predominant fuel?

A

Glucose

But can also use ketones. (only if needed)

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24
Q

Why is glucose needed in the brain?

A

Continual turnover of cells

Neurotransmitter synthesis

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25
Q

What % of your body weight is the brain?

A

2%

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26
Q

How much of the glucose we ingest does the brain use?

A

~20%

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27
Q

Is the process of getting glucose into the brain insulin mediated?

A

NO

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28
Q

What transporter does glucose use to cross the blood brain barrier?

A

GLUT1

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29
Q

What are the 2 main types of cells in the brain?

A

Neuron - Main brain functional cell

Astrocyte - support cell

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30
Q

Neuron cells in the brain

What are they?

A

Information messengers

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31
Q

How does glucose enter the neuron from the ECF in the brain?

A

Through GLUT3

P group is attached
= G-6-P

Then oxidised to Pyruvate to enter TCA cycle

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32
Q

How does glucose enter the astrocyte from the ECF in the brain?

A

Through GLUT1

P group is attached = G-6-P

Then oxidised to pyruvate to enter TCA cycle

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33
Q

When is there communication between the neuron + astrocyte cells in the brain?

A

If 1 of them has too much glucose in which case:

Pyruvate is converted to lactate.

Lactate then leaves one of the cells, across ECF then to the other cell.

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34
Q

What can the astrocyte cell in the brain do that the neuron cell can’t?

A

Can put G-6-P through glycogen synthesis to store glycogen.

But ONLY when receiving lactate from the neuron cell.

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35
Q

What is Positron Emission Tomography

A

Imaging technique

Uses radioactive substances to visualise + measure changes in metabolic processes, bf, regional chemical composition + absorption.

When used for radio labelled glucose post meal: shows that brain, heart + bladder uses the most glucose.

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36
Q

Where is the radio activity in Positron Emission Tomography

A

In the darker areas

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37
Q

Where does GLUT4 work?

A

Facilitated transport of glucose into skeletal muscle

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38
Q

Glucose absorption into skeletal muscle

A

Facilitated transport across GLUT4

Insulin binds to insulin receptor on muscle cell wall = stimulates activity of hexokinase

Hexokinase: Glucose + ATP –> ADP + G-6-P

== Maintaining conc. grad. so that glucose can continue to diffuse into muscle cell

G-6-P to Glycogen OR glycolysis

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39
Q

Once a P group has been attached to glucose in the liver it can be removed. Is this the case for skeletal muscle?

A

NO, the P group can’t be removed in skeletal muscle.

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40
Q

Where can more glycogen be stored? Muscle or liver?

A

Muscle

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41
Q

What can insulin do in regards to GLUT4 in the skeletal muscle cell?

A

⬆️ its amount on the membrane

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42
Q

How does insulin ⬆️ amount of GLUT4 on the skeletal muscle cell membranes?

A

Insulin binds to insulin receptor

= IRS-1 + PI-3-Kinase are activated

== Activates translocation of GLUT4 transporters to cell wall = ⬆️ absorption of glucose.

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43
Q

Other than insulin, what is another way to ⬆️ amount of GLUT4 transporters in the skeletal muscle cell membrane?

A

Through contraction during exercise:

SR releases Ca2+

Ca2+ sends signal + causes translocation of multiple GLUT4 to membrane.

PROCESS INDEPENDENT OF INSULIN

44
Q

Enzyme to get glucose to G-6-P in liver

A

Glucokinase

45
Q

Enzyme to get glucose to G-6-P in skeletal muscle

A

Hexokinase

46
Q

Enzyme to get glucose to G-6-P in brain

A

Hexokinase

47
Q

Enzyme used to convert G-6-P to G-1-P

A

Mutase

48
Q

Equation for G-1-P to UDP-Glucose

A

G-1-P + UTP – (UDP-glucose pyrophosphorylase) –> PPi + UDP-Glucose

49
Q

What is the core of a glycogen molecule?

A

Glycogenin protein

where UDP glucose initially attaches to

50
Q

What do you have once 8-10 glucose units have attached to glycogenin?

A

A pro glycogen

Glycogen synthase takes over to prod a macro glycogen.

51
Q

What is glycogen synthase regulated by?

A

Insulin

52
Q

What are the 2 forms in which glycogen synthase is present?

A

Active

Inactive - has a P group attached

53
Q

What does the active form of glycogen synthase do?

A

G-1-P –> glycogen

54
Q

What enzyme is used to convert the inactive form of glycogen synthase to its active form?

What is it stimulated by?

A

Protein phosphatase

  • Stimulated by insulin
55
Q

What does protein phosphatase do to the inactive form of glycogen synthase?

A

Removes its P group + donates it to glycogen

56
Q

What enzyme converts the active form of glycogen synthase back into its inactive form?

What is it stimulated by?

A

Protein Kinase A

  • Stimulated by Ca2+ + adrenaline
57
Q

What enzyme breaks down glycogen into G-1-P?

A

Glycogen phosphorylase

58
Q

There are 2 forms of glycogen phosphorylase: active + inactive form.

Which has the P group attached?

A

Active form

59
Q

How is the inactive form of glycogen phosphorylase converted into the active form? By which enzyme?

A

Glycogen phosphorylase kinase

60
Q

What is the Glycogen phosphorylase kinase enzyme stimulated by?

A

Glucagon

Ca2+

Adrenaline

AMP

61
Q

By what enzyme is the active form of glycogen phosphorylase converted into its inactive form?

By what is it stimulated by?

A

Glycogen phosphorylase phosphatase

Stimulated by insulin

62
Q

What does the glycogen phosphorylase phosphatase do?

A

Removes P group from active glycogen phosphorylase to make it inactive

63
Q

What is glycogen phosphorylase phosphatase inhibited by?

A

High levels of:

ATP + G-6-P

64
Q

What does adrenaline do overall in regards to glycogen?

A

Stimulates its breakdown

65
Q

What does insulin do overall in regards to glycogen?

A

Reduces breakdown

Stimulates storage

66
Q

What does glucagon do overall in regards to glycogen?

A

Stimulates breakdown

Inhibits storage

67
Q

During exercise, what is the main stimulation for glycolysis?

A

Ca2+

Adrenaline

68
Q

Net result of glycolysis?

A

2 mol of ATP

2 mol of NADH

69
Q

Pyruvate dehydrogenase has an active + inactive form.

Which has a P group attached?

A

Inactive form

70
Q

What enzyme converts the inactive form of pyruvate dehydrogenase to its active form?

What is it stimulated by?

A

Pyruvate dehydrogenase phosphatase

Stimulated by:

Ca2+

Mg2+

71
Q

What enzyme converts the active form of pyruvate dehydrogenase to its inactive form?

What is it stimulated by?

A

Pyruvate dehydrogenase kinases (1,2,3,4)

+ ATP

Stimulated by - NADH, ATP + ACoA

72
Q

What does the pyruvate dehydrogenase phosphatase do to the inactive form of pyruvate dehydrogenase?

A

Removes its P group

73
Q

What is the role of the active pyruvate dehydrogenase?

A

Converts pyruvate + CoA + NAD+ to:

ACoA
NADH
H+
CO2

74
Q

What are Pyruvate dehydrogenase kinases (1,2,3,4) inhibited by?

A

Pyruvate

NAD+

ADP

CoA

Ca2+

75
Q

What are the stimulators for PFK?

A

ADP

Pi

Low pH

NH4+

76
Q

What are the main functions of the TCA?

A

Decarboxylation of ACoA

ATP prod

FADH2 prod

NADH prod

77
Q

TCA CYCLE

Enzyme for ACoA –> Citrate

A

Citrate synthase

78
Q

TCA CYCLE

Enzyme for isocitrate –> alpha-ketoglutarate

A

Isocitrate dehydrogenase

79
Q

TCA CYCLE

Enzyme for alpha-ketoglutarate to succinylcholine-CoA

A

Alpha KGDH

80
Q

TCA CYCLE

Stimulators for the citrate synthase enzyme

A

High oxaloacetate

Ca2+

ADP

81
Q

TCA CYCLE

Stimulators for isocitrate dehydrogenase

A

ADP

Ca2+

82
Q

TCA CYCLE

Stimulators for alpha-ketoglutarate dehydrogenase

A

ADP

Ca2+

83
Q

TCA CYCLE

Inhibitors for citrate synthase

A

High levels of citrate

84
Q

TCA CYCLE

Inhibitors for isocitrate dehydrogenase

A

ATP

85
Q

TCA CYCLE

Inhibitors for alpha-ketoglutarate dehydrogenase

A

Lots of succinyl-CoA

ATP

NADH

86
Q

How many large protein complexed are there in the ETC?

A

4

87
Q

What is the 1st + foremost reserve for glucose in its postabsroptive state?

A

Liver

88
Q

How many g of glucose does the brain need a day?

A

~100g

89
Q

Where does gluconeogenesis predominantly occur?

A

In liver

But small amount in kidneys

90
Q

Are Pyruvate dehydrogenase and pyruvate kinase reactions reversible?

A

NO, they’re irreversible

91
Q

Can the ACoA from FAs be used to make glucose?

A

NO

92
Q

ACoA can come from pyruvate through oxidation.

Where else can it come from?

A

Beta oxidation

93
Q

What happens when oxaloacetate is converted into malate?

A

Malate is transported OUT of mit through malate-aspartate shuttle.

Then converted back to oxaloacetate to then be converted into phosphoenolpyruvate which can (over a series of steps) be converted back to glucose.

94
Q

What aa broken down from the muscle is a precursor for pyruvate?

A

Alanine

So will enter liver, be converted to pyruvate + follow process to become glucose.

95
Q

What do phosphatases do?

A

Removes a phosphate group from a protein

96
Q

Glycosaminoglycans are made from which macronutrients?

A

CHO & proteins

97
Q

If I wanted to make a milkshake that would give me the impression of having the 
most flavour which type of milk should I use and why?

A

Full fat milk as it has the highest dietary fat content 


98
Q

Other than fat what other functional group is present in sphingolipids?

A

Amino group

99
Q

What does the RNI represent?

A

Reference nutrient intake which tells us that that specific amount is recommended for 97.5% of the population.

100
Q

What dietary assessment method would you use to understand how much processed food all SHS students ate over a year?

A

FFQ

101
Q

Digestive enzymes digest CHO, fat + protein but the wall of the tract is made of 
these nutrients. How does the wall of the tract not get digested as well?

A

Bicarbonate protects, mucus protection from enzymes.

Proteases are released in inactive form when they can pot touch the wall lining.

Also, lining has a high turnover so protects against destruction.


102
Q

What processes allow smooth movement of food through the digestive tract?

A

Peristalsis + segmentation

103
Q

Which macronutrient is going to lead to the largest increase in CCK release?

A

FAT

104
Q

Does CCK make you feel hungry or full?

A

Full

105
Q

How is gastric emptying effected by exercise above 80% VO2 max?

A

Slowed down

Nutrition & Metabolism (17 decks)

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