1. Monosaccharides Flashcards

1
Q

What are monosaccharide molecules made from?

A

Carbon, hydrogen and oxygen.

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2
Q

What functional group are monosaccharides?

A

Polyhydroxy aldehydes or ketones.

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3
Q

What does polyhydroxy mean?

A

Poly means many, and hydroxy is an −OH group (like those found in alcohols).

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4
Q

Ketones and aldehydes are organic molecules that contain which group?

A

Carbonyl group (C=O).

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5
Q

Like water, monosaccharines contain twice as many what?

A

Hydrogens as oxygens.

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6
Q

Aldehyde monosaccharides are known as what?

A

Aldoses.

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7
Q

Ketone monosaccharides are known as what?

A

Ketoses, with the prefix keto-.

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8
Q

What is this?

A

This monosaccharide has six carbon atoms, and the carbonyl group is at the end of the carbon chain, making it an aldehyde. Therefore, this is an aldohexose.

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9
Q

What is this?

A

The monosaccharide below has five carbon atoms, and the carbonyl group is on the second carbon. Therefore this monosaccharide is a ketone. This is a ketopentose.

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10
Q

As well as their ketone or aldehyde functional group, monosaccharides also have what groups?

A

Hydroxy groups.

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11
Q

Why are monosaccharides highly soluble in water?

A

The hydroxy groups of monosaccharides are polar and can form hydrogen bonds with water. Therefore, because of their many hydroxy groups, monosaccharides are highly soluble in water.

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12
Q

Because of these chiral carbons, monosaccharides will have what?

A

Optical isomers.

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13
Q

Cyclic monosaccharides are often drawn as what?

A

Hawthorn projections.

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14
Q

What is the most abundant monosaccharide?

A

Glucose.

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15
Q

What is produced by plants during photosynthesis?

A

Glucose.

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16
Q

What reaction creates glucose?

A

Carbon dioxide + water.

17
Q

The isomer produced by photosynthesis is always what?

A

D-glucose.

18
Q

Does the isomer L-glucose occur naturally?

A

No.

19
Q

In what form does glucose exist?

A

Both linear and cyclic form.

20
Q

The linear form of glucose is an aldehyde, and can therefore be identified with what?

A

Tollen’s reagent

21
Q

What are the three glucose isomers that exist in equilibrium in an aqueous solution?

A
22
Q

Glucose joins to other monosaccharides to form which disaccharides?

A

Sucrose and lactose.

23
Q

Which 3 monosaccharides make up most of the carbohydrates we eat?

A

Fructose, galactose and glucose.

24
Q

What is the difference between glucose and fructose?

A

Fructose usually forms a five-sided ring, whereas glucose forms a six-sided ring—even though they both have six carbon atoms.

25
Q

In its linear form fructose is a ___, not an ___ like glucose.

A

Ketone, aldehyde.

26
Q

Where is fructose found?

A

Plants, fruit.

27
Q

In many food sources, fructose exists as part of a disaccharide with glucose.

This forms what?

A

Sucrose.

28
Q

Is sucrose sweeter than fructose?

A

It is sweeter than pure glucose. However, pure fructose is nearly twice as sweet as sucrose.

29
Q

What is the difference between glucose and galactose?

A
30
Q

When do we usually consume galactose?

A

It is usually consumed as part of the disaccharide lactose which is the main sugar in milk.

31
Q

Carbohydrates are not the only molecules that taste sweet. What is another?

A

Aspartame, which is a methyl ester of a dipeptide and used to sweeten foods.

32
Q

What is a sugar?

A

A sweet carbohydrate.