2.1.2 d-g Biological Molecules - Carbohydrates Flashcards

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1
Q

What are the elements present in Carbohydrates?

A

C , H, O

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2
Q

Define monosaccharide

A

a single sugar molecule
monomers of carbohydrates

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3
Q

Define Disaccharide

A

a molecule made of 2 monosaccharides joined by a glycosidic bond

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4
Q

Define polysaccharide

A

a polymer made up of more than 2 monosaccharides joined together

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5
Q

Define pentose sugar

A

a monosaccharide made up of 5 carbons

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6
Q

Define hexose sugar

A

a monosaccharide made up of 6 carbons

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7
Q

Define triose sugar and give an example

A

a monosaccharide made up of 3 carbons
- glyceraldehyde

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8
Q

What a furanose ring?

A

a 5 membered ring
e.g. fructose

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9
Q

What is a pyranose ring?

A

a 6 membered ring
e.g. glucose

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10
Q

Draw a molecule of alpha-glucose

A

hexose
OH group on carbon 1 below the ring

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11
Q

Draw a molecule of beta-glucose

A

hexose
OH group on carbon 1 above the ring

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12
Q

Draw a molecule of ribose

A

pentose - 5 carbon atoms

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13
Q

Define isomer

A

molecules with the same molecular formulae but different structural formulae

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14
Q

What is the difference between alpha and beta glucose?

A

The hydrogen and hydroxyl groups on carbon 1 are reversed

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15
Q

What is the difference between alpha glucose and ribose

A
  • glucose is a pyranose/hexose
  • ribose is a furanose/pentose
  • glucose is used in starch and glycogen
  • ribose is used in RNA
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16
Q

What is the difference between alpha glucose and ribose

A
  • glucose is a pyranose/hexose
  • ribose is a furanose/pentose
  • glucose is used in starch and glycogen
  • ribose is used in RNA
17
Q

Give 3 examples of disaccharides and state which monosaccharides they are composed of

A

Maltose - alpha glucose + alpha glucose
Sucrose - alpha glucose + fructose
Lactose - alpha glucose + galactose

18
Q

State the functions and properties of glucose and where it is found

A

-monosaccharide
- used in respiration
- used to make polymers like starch, glycogen, cellulose

19
Q

State the functions and properties of fructose and where it is found

A
  • hexose sugar
  • found in fruit
20
Q

State the functions and properties of galactose

A
  • hexose sugar
21
Q

Draw a labelled diagram demonstrating how two molecules of glucose form a disaccharide in a condensation reaction, showing the location of a 1,4-glycosidic bond and from where a water molecule is generated

A

condensation reaction
- hydroxyl groups on carbon 1 and 4
water is lost and bond is formed by remaining oxygen atom

22
Q

Describe, using a diagram, how hydrolysis of maltose occurs and why water is needed

A
  • the glycosidic bond is broken by adding water
  • catalysed by enzymes at 35-40 degrees celsius/ or by being boiled with an acid for acid hydrolysis
23
Q

Why does alpha-glucose link together to form starch but beta-glucose links together to form cellulose

A

because of the arrangement of the hydrogen and OH groups on carbon 1

24
Q

What are the two polysaccharides that make up starch?

A
  • amylose (1,4 bonds only - bc unbranched)
  • amylopectin ( 1,4 and 1,6 - bc branches and straight)
25
Q

Explain with use of diagrams why glycosidic bonds are called 1,4 or 1,6

A

depends on whether the glycosidic bonds between the OH groups on carbons 1 and 4 or 1 and 6.

26
Q

What is the structure of a cellulose fibre?

A

Cellulose chains link via hydrogen bonds
- forming strong fibres - called microfibrils
- microfibrils give structural support for cells

27
Q

Describe and explain the properties and functions of starch.

A

STARCH: stores excess glucose in plants
- made up of amylose and amylopectin
- coils into helix
- insoluble (no effect on water potential) + compact - ideal for storage
- amylose - straight, unbranched (1,4 a glucose)
- amylopectin - long branched (1,4 + 1,6 a glucose)
- amylopectin side branches - allow enzymes to hydrolyse into glucose
quickly

28
Q

Describe and explain the properties and functions of glycogen.

A

GLYCOGEN: polysaccharide - stores excess glucose in animals + fungi
- coils into helix
- insoluble (no effect on water potential) + compact - ideal for storage
- similar to amylopectin but v. more branched
- 1,4 + 1,6 a-glycosidic bonds = branched
- more branches - hydroylsed into glucose faster - glucose released quicker - meet high metabolic demands of animals

29
Q

Describe and explain the properties and functions of cellulose.

A

CELLULOSE: makes up cell wall in plants
- long straight
- insoluble (doesnt effect water potential) (permeable to solutes)
- unbranched chains of beta glucose
- doesnt form helix
- forms cellulose molecules from b-glucose which join via hydrogen bonds to form layers of microfibrils
- give strength to cell walls