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BIOC192 2024 > Lecture 23 - Glucose as a fuel molecule #1 > Flashcards

Lecture 23 - Glucose as a fuel molecule #1 Flashcards

1
Q

What is glucose?

A

A hexose simple sugar monosaccharide

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2
Q

What is hexose?

A

6 Carbons

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3
Q

What are the 3 types of drawn conformations of glucose?

A

Ring, Open, Chair

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4
Q

What is the chemical structure of glucose?

A

C6H12O6

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5
Q

What is a carbohydrate?

A

A large macromolecule / polysaccharide

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6
Q

What are sources of glucose from carbohydrates?

A

Starch from plants and glycogen from meat

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7
Q

What is starch?

A

A polymer made up of up to 1 million glucose units joined by glycosidic bonds

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8
Q

What are the two forms of starch?

A

Amylose and amylopectin

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9
Q

What is the structure of amylose?

A

A linear polymer of glucose units

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10
Q

What is the structure of amylopectin?

A

A branched polymer of glucose units

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11
Q

What is glycogen?

A

A branched polymer of glucose units

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12
Q

What is a disaccharide?

A

Two monosaccharides joined by a glycosidic bond

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13
Q

What are some examples of disaccharides?

A

Sucrose, lactose, maltose

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14
Q

What is the structure of sucrose?

A

A glucose bound to a fructose by a glycosidic bond

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15
Q

Where are disaccharides found in the diet?

A

Fruit and raw sugar

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16
Q

What enzyme cleaves glycosidic bonds from polysaccharides to disaccharides?

A

Amylase through hydrolysis

17
Q

What enzymes cleave the glycosidic bonds from disaccharides to monosaccharides?

A

Specific enzymes e.g. sucrase for sucrose

18
Q

What is the end result of digestion of carbohydrates?

A

Glucose in the GI tract

19
Q

Are sugars polar or non polar?

A

Highly polar

20
Q

Are sugars water or lipid soluble?

A

Water

21
Q

How do glucose molecules cross the lipid membrane?

A

through specific transporter proteins anchored in the membrane

22
Q

What are the two types of transport?

A

Active and facilitated transport

23
Q

What is active transport?

A

The movement molecules against a concentration gradient, requiring energy input

24
Q

What is facilitated transport?

A

The movement of molecules down a concentration gradient, not requiring energy input

25
Q

What transporter protein transports glucose via active transport across the apical membrane in the GI tract?

A

The sodium-glucose linked transporter (SGLT)

(facilitative)

26
Q

What moves down their concentration gradient through the SGLT?

A

Na+ (into cell from GIT)

27
Q

What moves up their concentration gradient through the SGLT?

A

Glucose (into cell from GIT)

28
Q

What transporter protein, found on the baso-lateral membrane transports glucose via facilitated transport across the membrane into the interstitial fluid?

A

GLUT2

(facilitative)

29
Q

What transporter protein, located on the baso-lateral membrane, creates the low concentration gradient without the cell?

A

Na+/K+ ATPase

  • Na+ pumped out of cell
  • K+ pumped into cell

(Active) - energy from ATP hydrolysis

30
Q

What happens to the K+ that was pumped into the cell via the Na+/K+ ATPase?

A

returns to interstitial fluid, down concentration gradient, through a channel protein to be used by the Na+/K+ ATPase pump again.

31
Q

How is glucose used as a fuel molecule?

A

It is oxidised in glycolysis (in all organisms) which usually occurs in the cytoplasm in eukaryotes

32
Q

Why is glucose essential as fuel for red blood cells?

A

RBCS do not have mitochondria and can therefore not utilise other pathways

33
Q

What is the energy requirement in the brain?

A

120g of glucose per day

34
Q

Do brain cells have mitochondria?

A

Yes

35
Q

What is the traditional view on why the brain favours glucose?

A

Glucose easily crosses the blood-brain barrier and fats do not

36
Q

What is the modern hypothesis as to why the brain prefers glucose?

A

It is safer, providing a quicker source of ATP without the risk of damage

37
Q

Why is glucose favoured as a energy molecule in the eye cells?

A

High amounts of blood vessels and mitochondria would refract the light, so these are limited and glucose does not require either

38
Q

Which muscle cells use fats as fuel?

A

Red muscle cells, for endurance

39
Q

Which muscle cells use glucose as fuel?

A

White muscle cells, for sprinting

BIOC192 2024 (35 decks)

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