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Biochemistry (MPAS) > Lecture 1: Characteristics of Biomolecules in Health and Disease > Flashcards

Lecture 1: Characteristics of Biomolecules in Health and Disease Flashcards

1
Q

Major biomolecules that play important roles in cellular functions

A 
Water
Carbohydrates (glucose)
Proteins (amino acids)
Lipids (fatty acids, triglycerides) Sodium
Potassium
Calcium
Bicarbonate
Chloride
Lactate
Pyruvate
Acetyl CoA (acetyl coenzyme A
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2
Q

Other major biomolecules

A 
Calcium
Bicarbonate
Chloride
Lactate
Pyruvate
Acetyl CoA
Oxaloacetate
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3
Q

Functions of biomolecules

A
  1. Responsible for producing energy through catabolic reactions
  2. Involved in using up energy for the synthesis of macromolecules through anabolic pathways.
  3. Useful as micronutrients in the maintenance of health and management of
    patients.
  4. Important in cellular functions that maintain life.
  5. Important as structural components.
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4
Q

Biomolecules are vital constituents of the human body and are responsible for

A
  1. Supplying ATP/energy through catabolism of dietary nutrients.
  2. The synthesis of macromolecules through anabolic pathways (e.g. gluconeogenesis) in cells, using the energy derived from the catabolism of nutrients
  3. The metabolism of vitamins and micronutrients.
  4. Maintaining optimal and specific cellular environments
  5. Controlling specific homeostatic mechanisms in cells
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5
Q

Functions of carbohydrates

A

Immediate source of energy

Structural molecules

Interact with proteins (glycoproteins) and lipids (glycolipids)

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6
Q

What happens to excess glucose in hyperglycemic patients?

A

i.e.. diabetes

Excess glucose binds to proteins

Leads to microvascular diseases (atherosclerosis (narrowing and hardening of arteries), nephropathy (kidney disease) and neuropathy (loss of sensation))

= multi-organ failure

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7
Q

What happens when excess glucose binds to hemoglobin in hyperglycemic patients?

A

Affects Hb’s ability to carry oxygen.

Indicated by A1C value, which is a measure of hyperglycaemia

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8
Q

Three main effects of hyperglycemia

A

Osmotic effect

Protein glycosylation

Radical effect

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9
Q

What does osmotic effect cause?

A

Dehydration of cells

Result of movement of water from cells (low concentration, low osmotic pressure) into blood plasma (high concentration, high osmotic pressure)

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10
Q

What happens when there is dehydration of brain cells?

A

Coma

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11
Q

What is osmotic pressure?

A

The pressure that needs to be applied to a solvent to prevent is from moving to another compartment by osmosis

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12
Q

What does osmotic effect cause in diabetic patients with hyperglycaemia?

A

Polyuria (frequent urination)

Thirst

Glycosuria (excess glucose in urine, which leads to excess water excretion in urine as well)

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13
Q

What is the radical effect?

A

Outcome of hyperglycaemia

Excess glucose can produce reactive oxygen species, which damage cell membrane, DNA and other molecules

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14
Q

What can happen to excess glucose?

A

Can be converted to glycogen (glycogenesis) in liver and muscles

This serves as a reserve for when there is not enough glucose

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15
Q

What is glycogenolysis?

A

When the liver breaks down glycogen into glucose to supply extra hepatic tissues with glucose

Liver doesn’t use much glucose itself so that there is some for other organs

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16
Q

When is muscle glucose broken down?

A

During exertion, when energy production is needed

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17
Q

What lipids can glucose be converted into?

A

Triglycerides in liver

Fatty acids

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18
Q

Can fatty acids be converted to glucose?

A

NO (thermodynamic issue)

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19
Q

How does body maintain glucose levels (homeostasis)?

A

Synthesizes it from other molecules during gluconeogenesis

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20
Q

Where do erythrocytes get energy? And what happens if they do not have energy?

A

Depend entirely on glucose

Deficiency of energy = destruction/lysis/breakdown?

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21
Q

Where do brain cells get energy under normal conditions?

A

Entirely from glucose

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22
Q

Where do brain cells get energy during fasting and starvation?

A

Ketone bodies derived from oxidation of fatty acids

Lack of glucose = unconsciousness and eventually coma

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23
Q

What molecules can glucose be synthesized from during gluconeogenesis?

A

Glycerol

lactate

Amino acids

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24
Q

Where does gluconeogenesis occur?

A

Liver and Kidneys only

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25
Q

How are lactate and oxaloacetate produced from glucose?

A

Glucose -> pyruvate

pyruvate -> lactate and oxaloacetate

26
Q

How is acetyl CoA produced from glucose?

A

Glucose -> pyruvate

pyruvate -> acetyl CoA

27
Q

How is glucose produced from pyruvate?

A

Pyruvate -> oxaloacetate

Oxaloacetate -> glucose

28
Q

What can disorders in glucose metabolism (breakdown) lead to?

A

Hypertriglyeridemia (accumulation of triglycerides)

Hepatomegaly (enlarged liver) due to accumulation of glycogen

Lactic acidosis (due to inhibition of oxidative phosphorylation)

29
Q

What are triglycerides?

A

Glycerol + fatty acids

30
Q

Where are triglycerides found?

A

Adipose tissues or chylomicrons

31
Q

Functions of triglycerides

A

Most useful form of storage energy

Energy source in absence of glucose

Membrane structures in lipid bilayer

Interact with proteins and carbohydrates

32
Q

What can the metabolization of fatty acids be used for?

A

To produce energy and ketones

33
Q

When and why do certain organs use ketones for energy?

A

Muscles, brain, liver, kidney

Used during fasting

34
Q

Fatty acids can be converted to…

A

Acetyl CoA (the reverse is true as well)

Triglycerides (interactions with glycerol)

35
Q

What happens when there is a disorder in catabolism of fatty acids?

A

lack of energy

hypertriglyceridemia

fatty degeneration of the liver

during fasting can be fatal because of the lack of glucose.

36
Q

Why is fatty acid oxidation important for glucose synthesis?

A

Oxidation of FAs produces ATP that is used in anabolic pathways for glucose synthesis (gluconeogenesis in liver) from glycerol, amino acids and lactate

If there is no FA oxidation during fasting, glucose cannot be produced and organs will fail

37
Q

Functions of proteins

A

enzymes

hormones

other signaling molecules

38
Q

Are proteins a storage form of energy?

A

NO

But, they can be broken down to amino acids, which can be converted to acetyl coA and metabolized to produce ATP

Proteins can be broken down to amino acids, which can be converted to glucose in the liver.

39
Q

What happens to the blood when Red blood cells lyse?

A

High lactate in the blood

40
Q

What are essential amino acids?

A

provided externally to the body

41
Q

What are non essential amino acids?

A

produced in the body from essential amino acids.

42
Q

Glucogenic amino acids

A

can be converted to glucose only via pyruvate

Other amino acids can be either glucogenic or ketogenic, depending on the physiological conditions.

43
Q

Ketogenic amino acids

A

can be converted to ketones only via acetyl coA

Other amino acids can be either glucogenic or ketogenic, depending on the physiological conditions.

44
Q

Breakdown of proteins

A

Proteins -> amino acids -> ammonia

Ammonia is neurotoxic, and is converted to urea in the liver

45
Q

What excretes urea?

A

Kidneys

46
Q

What happens when someone has a disorder in protein/amino acids metabolism?

A

Can lead to high levels of ammonia (hyperammonaemia), which can adversely affect the central nervous system and causes developmental delays.

47
Q

What is calcium important for?

A

muscle contraction

48
Q

What is calcium phosphate important for?

A

bone formation

49
Q

What are sodium and potassium important for?

A

maintaining the sodium-potassium gradient to propagate action potentials/nerve impulses

50
Q

What are bicarbonate ions important for?

A

act as buffer system to reduce acidity

51
Q

What are Chloride ions important for?

A

allow for osmotic effect and hence flow of water.

52
Q

What are trace elements important for?

A

functions of cellular proteins and processes.

vitamins and minerals are important as cofactors and coenzymes for enzymatic activities

53
Q

What is the central molecule that connects the metabolic pathways of proteins, carbohydrates and lipids?

A

Acetyl CoA

Also, all dietary nutrients and proteins can be converted to acetyl coA

(see figure)

54
Q

What does acetyl-CoA interact with in TCA?

A

Oxaloacetate

Forms carbon dioxide, water, energy and reduced coenzymes (NADH)

55
Q

How is pyruvate linked to the TCA/Krebs cycle

A

Via acetyl CoA

56
Q

How can triglycerides be converted to glucose?

A

Triglyceride is broken down into glycerol and fatty acids, then glycerol is converted to glucose in the liver

57
Q

How does hyperglycemia leads to diabetic foot ulcer?

A

interaction of glucose with proteins leading to glycosylated proteins.

glycosylated proteins produce deleterious effects in different tissues leading to peripheral neuropathy, nephropathy, and optic neuropathy, and cardiovascular diseases.

58
Q

What does fatty degeneration of muscles lead to?

A

Muscle damage

Myalgia (muscle pain)

Myoglobinuria (myoglobin in urine)

Respiratory distress (release of ion from Mb that can radicalize and oxidize proteins)

Kidney stones (precipitates formed by Mb)

59
Q

What does abnormal lipid metabolism cause?

A

Fatty liver disease

Enlarged due to fat deposits

60
Q

What does pyruvate link to gluconeogenesis?

A

Lactic acid

Oxaloacetate

Biochemistry (MPAS) (10 decks)

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