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MEH: The basics for years ahead > Session 1 > Flashcards

Session 1 Flashcards

1
Q

What are catabolic processes?

A

Break down of molecules to release energy in the form of reducing power

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2
Q

What are anabolic processes?

A

Use of energy and raw materials to make larger molecules for growth and maintenance

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3
Q

What is the SI unit of food energy?

A

Kilojoule. (4.2kj = 1 Kcal)

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4
Q

What are the 9 essential amino acids? (synonym for it)

A

If Learned This Huge List May Prove Truly Valuable

Isoleucine
Lysine
Threonine
Histidine 
Leucine
Methionine
Proline
Tryptophan
Valine
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5
Q

Which vitamins are fats required for absorption?

A

Vitamins A,D,E & K

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6
Q

Fats provide which essential fatty acids?

A

Linoleic and Linolenic Acids

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7
Q

What are minerals required for?

A
  • Calcium and Phosphorus essential for structure
  • Calcium is an important signalling molecule
  • Enzyme co-factors
  • Electrolytes establish ion gradients across membrane & maintain water balance
  • Iron is an essential component of haemoglobin
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8
Q

What are the main vitamins and their diseases associated with their deficiency?

A 
B12 - Anaemia
C - Scurvy
Folate - Neural tube defects, Anaemia
B6 - Anaemia, Dermatitis
D - Rickets
K - Defective Blood Clotting
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9
Q

What are the sources of dietary fibre?

A
  • Cellulose
  • Lignin
  • Pectins
  • Gums

These cannot be broken down by human digestive enzymes but are essential for normal functioning of GI tract. Found in cereal foods such as beans, bread, fruit and veg.

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10
Q

What is low fibre and high fibre associated with?

A

Low fibre intake associated with constipation and bowel cancer

High fibre is shown to reduce cholesterol and risk of diabetes

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11
Q

What is the daily energy expenditure a sum of?

A
  • Basal metabolic rate (BMR)
  • Diet induced thermogenesis (DIT)
  • Physical activity level (PAL)
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12
Q

What does body weight depend on?

A

Relationship between energy intake and expenditure

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13
Q

What is obesity?

A

Excessive fat accumulation in adipose tissue which impairs health.

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14
Q

What is the BMI calculation and the ranges?

A

kg/m^2 = BMI

<18.5 = underweight
18.5-24.9 = desirable weight
25-29.9 = overweight
30-34.9 = obese
>35 = severely obese
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15
Q

What is the ATP-ADP cycle?

A

Chemical bond energy related by oxidation is conserved in the form of ATP by combining ADP and Phosphate.

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16
Q

What are the risk of a vegetarian diet?

A

Protein from vegetable origin may be deficient in one or more of the essential amino acids so therefore a diet has to include a mixture of vegetables

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17
Q

What is fibre?

A

Indigestible plant material such as cellulose necessary for normal bowel function

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18
Q

Which vitamins and mineral have important antioxidant properties in the body?

A

Vitamin C, Vitamin E and Selenium

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19
Q

What is Marasmus?

What are the signs?

A

Protein-Energy malnutrition commonly seen in children under 5.

Child looks

  • Emaciated with obvious signs of muscle wastage
  • Loss of body fat
  • No oedema
  • Hair is thing and dry
  • Diarrhea is common
  • Anemia may be present
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20
Q

What is kwashiorkor?

What are the sign and symptoms?

A

A disease typically occurring in a young child when displaced from breast milk and fed on a diet with high carbohydrate and low protein content.

  • Apathetic child
  • Lethargic
  • Anorexic
  • Generalised oedema
  • Abdomen may appear distended due to hepatomegaly and/or ascites
  • Anaemia is common
  • Low albumin contributing to oedema (low oncotic pressure and starling forces)
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21
Q

ATP is a store of energy. True/False

A

False.

It is a carrier of free energy and has to be rapidly resyntehsised as ATP concentration is only sufficient for a few seconds of energy.

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22
Q

What are 4 examples of high energy signals?

A

NADH. NADPH, FADH2, ATP

23
Q

What are 5 examples of low energy signals?

A

NAD+, NADP+, FAD, AMP, ADP

24
Q

What are types of monosaccharides?

A

Galactose
Glucose
Fructose

25
Q

What are some important physics-chemical properties of sugars?

A
  • Hydrophilic

- Partially oxidised

26
Q

What are some disaccharide and what forms them?

A

Sucrose - Fructose + Glucose
Maltose - Glucose + Glucose
Lactose - Galactose + Glucose

27
Q

What are the 2 main polysaccharides?

A

Glycogen - Polymer of glucose found in animals

Starch - Polymer of glucose found in plants

Cellulose - Polymer of glucose found in plants that has a structural role and has beta-1,4 linkages which can’t be digested by humans

28
Q

What is the process of metabolism of dietary carbohydrates?

A

-Dietary polysaccharides are hydrolysed by glycosides enzyme to release glucose, maltose and smaller polysaccharides such as dextrins

29
Q

What is the purpose of salivary and pancreatic amylase?

A
  • In the mouth, salivary amylases begin the breakdown of dietary polysaccharides
  • In the duodenum, pancreatic amylase breaks down dietary polysaccharide
30
Q

What are the major enzymes found lining the brush border membranes of the epithelial cells in the duodenum and jejunum?

A

Lactase - Release of galactose and glucose from lactose

Sucrase - Release of fructose and glucose from sucrose

Isomaltase - Release of glucose from maltose

31
Q

What causes lactose intolerance?

A
  • Low activity of lactase is associated with a reduced ability to digest the lactose present in milk products.
  • Lactose stays in the colon where bacteria can break it down
  • Increase in the osmotic pressure due to the persistence of lactose will draw water into the lumen causing the diarrhoea
  • Colonic bacteria can produce hydrogen, CO2 and methane causing feelings of bloating and discomfort.
32
Q

What is the process of sugar transport?

A
  • Glucose, galactose and fructose are actively transported into the absorptive cells lining the gut.
  • Transport from absorptive cells into the blood and from he blood to tissue is by facilitated diffusion via glucose transport protein(GLUT1 - GLUT5)
33
Q

Which tissues have an absolute requirement for glucose?

A
  • Red Blood Cells
  • Neutrophils
  • Kidney Medulla
  • Lens of the Eye
34
Q

What is the purpose of glycolysis?

A
  • Production of pyruvate as an end product
  • 2 ATP net production
  • NADH from NAD+
  • Production of building blocks for anabolism
  • Useful intermediates for specific cell functions
35
Q

What enzyme is required for conversion of glucose to glucose-6-phosphate?

A
  • Hexokinase

- Glucokinase in the liver and pancreas

36
Q

What enzyme is required to convert Fructose-6-Phosphate to Fructose 1,6-Bisphosphate?

A

Phosphofructokinase

37
Q

What enzyme is required to convert phosphoenolpyruvate to pyruvate?

A

Pyruvate kinase

38
Q

What is an example of the clinical application of glycolysis?

A
  • Rate of glycolysis is up to 200 times greater in cancer

- It can be imaged with positrons emission tomography

39
Q

What can be used to phosphorylate glycerol and why is it important?

A
  • Glycerol kinase
  • Glycerol phosphate required for synthesis of TAG in liver and adipose tissue. Glycerol kinase is in the liver so it is less dependent on intermediates from glycolysis for glycerol phosphate. This is the opposite for adipose tissue
40
Q

What is a key regulation of glycolysis?

A

Phosphofructokinase is a key regulator

Allosteric regulation occurs via

  • Stimulation by High AMP
  • Inhibition by High ATP

Hormonal Regulation via

  • Stimulation by insulin
  • Inhibition by glucagon
41
Q

When the supply of oxygen is inadequate and in cells without mitochondria what is pyruvate reduced to and by what enzyme?

A
  • Lactate
  • Via Lactate Dehydrogenase
  • Uses NADH for NAD+
42
Q

When is an elevated lactate seen?

A

Number of physiological and pathological conditions. Higher than 5 mmol/L since this exceeds renal threshold.
-This shows the patient is acutely unwell

43
Q

What is the hexokinase inhibited by?

A
  • Inhibition by glucose-6-phosphate

- Example of product inhibtion

44
Q

What is essential fructosuria?

A

Missing Fructokinase

45
Q

What is fructose intolerance?

A
  • Aldolase is missing
  • Fructose 1 phosphate accumulates in the liver leading to liver damage
  • Treated by removing fructose from the diet
46
Q

What is fructokinase used for?

A

Enzyme used for the conversion of Fructose to Fructose-1-Phosphate.

47
Q

What is aldolase used for?

A

It is an enzyme for the conversion of Fructose-1-Phosphate to Glyceraldehyde and DHAP.

48
Q

What do you need to know about the pentose phosphate pathway?

A

-Starts from glucose-6-phospahte

Important source of NADPH required for

  • Reducing power for biosynthesis
  • Maintenance of GSH levels
  • Detoxification reactions
  • Producing C5-sugar ribose required for synthesis s of nucleotides, DNA and RNA
  • No ATP synthesis and CO2 produced
  • Rate limiting enzymes is Glucose 6-phosphate dehydrogenase
49
Q

What is the effect of G6DP deficiency?

A
  • Reduced activity of the enzyme so low level of NADPH. NADPH is required for reduction of oxidised glutathione back to active reduced form
  • Reduced glutathione is needed for oxidative damage protection
50
Q

Why are red blood cells particularly affected by G6DPH deficiency?

A

The only source of NADPH they have is from the G6DP reaction. This results in haemoglobin cross linkage due to oxidative damage and formation of Heinz bodies. This can result in haemolytic anaemia.

Acute haemolytic episode are precipitated by chemicals that reduce the levels of NADPH such as ANTIMALARIALS, sulphonamides and certain glycosides found in broad beans

51
Q

What is galactosaemia?

A
  • Lack of galactokinase results in accumulation of galactose
  • Lack of Galactose-1-phosphate uridyl transferase enzyme and UDP epimerise enzyme results in increase in Glalactose and Galactose-1-Phosphate.
  • Accumulation of galactose results in the enzyme aldose reductase reducing it to galactitol and depleting NADPH.
52
Q

What is the effect of galactosaemia?

A
  • In the eye it causes cataracts due to lens structure damage via cross linking of proteins by disulphide bonds. There also could be non enzymatic glycosylation of the lens protein due to high lactose which contribute to cataracts
  • There could be increased intra-occular pressure applied on the eye due to accumulation of galactose and galacticol therefore causes glaucoma
  • Damage to liver, brain, kidney due to galactose 1 phosphate accumulation
53
Q

What converts pyruvate to Acetyl CoA?

A

Pyruvate dehydrogenase

MEH: The basics for years ahead (2 decks)

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