3.3 Carbohydrates Flashcards

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1
Q

What elements do carbohydrates contain?

A

C, H, O

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2
Q

What’s another term for a carbohydrate?

A

Saccharide (sugar)

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3
Q

What is a single sugar unit called?

A

Monosaccharide

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4
Q

State the names of the 3 common monosaccharides.

A

Glucose, fructose, ribose

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5
Q

What do 2 linked monosaccharides form?

A

Disaccharide

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6
Q

State the names of the 2 common disaccharides.

A

Lactose and sucrose

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7
Q

What do 2 or more linked monosaccharides form?

A

Polysaccharides - (Polymer made up of many sugar monomers/monosaccharides)

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8
Q

State the names of the 3 common polysaccharides.

A

Glycogen, cellulose and starch

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9
Q

What is the formula for glucose?

A

C6H12O6

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10
Q

What name would you give glucose in the context of its structure?

A

6-C hexose monosaccharide

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11
Q

How are carbons labelled in molecular structure

diagrams?

A

Clockwise from the oxygen atom

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12
Q

What is the property of glucose? Why is this?

A

Polar + soluble in water - due to H bonds that form between hydroxyl groups + water molecules

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13
Q

Why is the solubility of glucose important?

A

So glucose can be dissolved in the cell cytoplasm

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14
Q

What happens when 2 alpha glucose are next to each other?

A
  • 2 hydroxyl groups react w/ each other
  • 2 H atoms and 1 O is removed in total from both glucoses and join to form water
  • Glycosidic bond forms between carbon 1 of one glucose and carbon 4 of the second glucose, forming 1-4 glycosydic bond
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15
Q

Why is the reaction between 2 alpha glucoses a condensation reaction?

A

Water is produced as a product of the reaction

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16
Q

What disaccharide forms when 2 alpha glucose react?

A

Maltose

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17
Q

Give examples of 2 other hexose monosaccharide sugars.

A

Fructose and galactose

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18
Q

Where is fructose naturally found?

A

Fruit + often with glucose to form sucrose - cane sugar

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19
Q

What do you produce when you combine glucose and fructose?

A

Sucrose, disaccharide

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20
Q

What do you produce when you combine glucose and galactose?

A

Lactose

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21
Q

What is lactose? Where is it commonly found?

A

Lactose is the product of galactose and glucose, commonly found in milk.

22
Q

Compare the sweetness between fructose, glucose and galactose.

A

Fructose is sweeter than glucose.

Glucose is sweeter than galactose.

23
Q

What are pentose monosaccharides?

A

5-C sugars

24
Q

State 2 examples of pentose monosaccharides.

A

Ribose, deoxyribose

25
Q

What’s the name of the sugar in RNA nucleotides?

A

Ribose

26
Q

What’s the name of the sugar in DNA nucleotides?

A

Deoxyribose

27
Q

What is starch?

A

A polysaccharide formed from alpha glucose molecules joined together

28
Q

In plants, what is glucose stored as?

A

Starch

29
Q

What is one of the polysaccharides in starch called?

A

Amylose

30
Q

How is amylose formed?

A

Amylose is formed by alpha glucose molecules joined together by 1-4 glycosidic bonds

31
Q

What does the angle of the 1-4 glycosidic bond joining amylose mean?

A

The long glucose chain twists to form a helix, which is further stabilised by H bonding within the molecule

32
Q

Why is the polysaccharide starch less soluble than the glucose molecules used to make it?

A

The long glucose chain [making up amylose] twists to form a helix, which is further stabilised by H bonding.
This makes the molecule more compact, so it’s less soluble than glucose.

33
Q

What is the second polysaccharide making up starch, with 1-6 bonds?

A

Amylopectin

34
Q

What are the 2 polysaccharides that make up starch?

A

Amylose + amylopectin

35
Q

How is amylopectin formed?

A

Amylopectin is formed by 1-4 glycosidic bonds between alpha glucose molecules + 1-6 glycosidic bonds (formed by condensation reactions between carbon 1 + carbon 6 of 2 glucose molecules)

36
Q

Why does amylopectin have a branched structure?

A

Due to 1-6 glycosidic bonds - 1-6 branching points occur every 25 glucose subunits

37
Q

In animals and fungi, what form is glucose stored in?

A

Glycogen

38
Q

What is glycogen?

A

A branched polysaccharide formed from alpha glucose molecules + a chemical energy store in animals

39
Q

What’s the difference between glycogen and amylopectin?

A

Glycogen is more branched = more compact + less space needed for it to be stored

40
Q

Besides compaction for storage, what other adaptation is there for the branching of glycogen?

A

Due to the branching, there are many free ends where glucose can be added or removed - this speeds up the storage/release of glucose

41
Q

What are the key properties of amylopectin and glycogen?

A

They’re insoluble, branched and compact

42
Q

What must happen to glycogen and starch for them to release glucose?

A

Hydrolysis reactions - the addition of water molecules

43
Q

Why can’t beta join together in the same way as alpha?

A

Hydroxyl/OH groups on carbon 1 and carbon 4 are too far from each other to react

44
Q

What must happen for beta molecules to react?

A

Second beta must be flipped upside down

45
Q

What polysaccharide is formed when 2 beta join? Describe its structure.

A

Cellulose - Straight chain, unable to coil or form branches

46
Q

What is formed when cellulose forms H bonds with each other?

A

Microfibrils

47
Q

What is formed when microfibrils join?

A

Macrofibrils

48
Q

What is formed when macrofibrils join?

A

Fibres

49
Q

Describe the properties of the fibres produced when macrofibrils combine, and state what they’re used to form?

A

Strong and insoluble. Used to form cell walls.

50
Q

What type of sugar are glucose, fructose, ribose?

A

Monosaccharide

51
Q

What kind of sugar are lactose and sucrose?

A

Disaccharide

52
Q

What type of sugar are glycogen, cellulose and starch?

A

Polysaccharide