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3.1 Biological Molecules > 3.1.2 Carbohydrates > Flashcards

3.1.2 Carbohydrates Flashcards

1
Q

EQ What is the reaction catalysed by the enzyme lactase?

A

(Lactose +) Water ->(Glucose +) Galactose

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2
Q

Monosaccharide definition

A

Monomers from which larger carbohydrates are made

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3
Q

What are carbohydrates made out of?

A

Carbon
Hydrogen
Oxygen

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4
Q

carbohydrates

General formula

A

(CH2O)n

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5
Q

Examples of monosaccharides

A

Glucose
galactose
fructose

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6
Q

What is a hexose sugar?

A
  • A monosaccharide
  • Formed from 6 carbon atoms
  • 6 carbon ring
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7
Q

What is a pentose sugar?

A
  • A monosaccharide
  • Contains 5 carbon atoms
  • 5 carbon ring
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8
Q

hexose sugars

examples

A

… Glucose
… Fructose
… Galactose

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9
Q

pentose sugar

examples

A

… Ribose

… Deoxyribose

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10
Q

glucose

feature related to function

A

1) Highly soluble

2) Respiration
3) Main form of transporting carbohydrates around the body

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11
Q

Give 3 features of fructose

A

1) Soluble
2) Sweeter than glucose
3) Main sugar in in fruits and nectar

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12
Q

Give 2 features of galactose

A

1) Not as soluble as glucose

2) Plays an important role in the production of glycolipids and glycoproteins

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13
Q

Disaccharide Definition

A

A carbohydrate composed of 2 monosaccharides

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14
Q

Disaccharide Formation

A

Condensation of 2 monosaccharides

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15
Q

maltose

A

a disaccharide formed by condensation of two glucose molecules

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16
Q

sucrose

A

a disaccharide formed by condensation of a glucose molecule and a fructose molecule

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17
Q

lactose

A

a disaccharide formed by condensation of a glucose molecule and a galactose molecule

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18
Q

Give 3 main stages of forming glycosidic bonds

A

1) The hydroxyl groups bind

2) Condensation reaction
- H₂O molecule is lost

3) A 1-4 glycosidic bond is formed

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19
Q

Give the position of the H in alpha glucose

A

H

OH

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20
Q

Give the position of the H in beta glucose

A

OH

H

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21
Q

1) Glucose exists in different forms of…

2) Which are…

A

1) Structural isomers

2) Molecules with the same atoms, but different arrangements of atoms

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22
Q

how do you distinguish between Alpha and Beta glucose

A

distinguish alpha and beta by looking at the position of the hydroxyl molecule on the last carbon plane.

alpha glucose - Hydroxyl molecule is positioned on at the bottom

Both have the molecular formula C(6)H(12)O(6) and both are hexose sugars.

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23
Q

Polysaccharide Definition

A

A polymer composed of many saccharide units

24
Q

Polysaccharide features

A

Complex sugars.

  • High molecular weight
  • Insoluble in water
  • Tasteless
25
Q

Polysaccharide Formation

A

Condensation of many glucose units

26
Q

Polysaccharide Bonds

A

Glycosidic

27
Q

Polysaccharide Examples

A

glycogen
starch
cellulose

28
Q

Glycogen formation

A

formed by the condensation of α-glucose

29
Q

Starch formation

A

formed by the condensation of α-glucose

30
Q

Cellulose formation

A

formed by the condensation of β-glucose

31
Q

Glycogen location

A

Animals
Muscle, liver
Fungi

32
Q

Glycogen structure

A 
Glycosidic bonds
Branched chain 1,6 links
Contains CHO
Joined by 1,4 links
Made of alpha glucose 
Formed in condensation reaction.
33
Q

Glycogen structure to function

A

Insoluble store of glucose in animals

Insoluble:
→ Water potential of cell is not affected; water doesn’t diffuse into the cells via osmosis.

Large & insoluble:
→ Doesn’t diffuse out of cells.

Highly branched:
→ More ends for enzymes to act on; glycogen can quickly be hydrolysed into α-glucose to be used for respiration.

Compact so can store many glucose molecules in a small space

34
Q

two main components of starch

A

1) Amylose

2) Amylopectin

35
Q

Starch structure

A 
Amylose-
A-glucose molecules
1,4 glycosidic bonds
Unbranched chain 
Helical 
Amypectin- 
A-glucose molecules
1,4 glycosidic bonds 
Branched chain 
1,6 bonds
36
Q

Starch structure to function

A

Energy storage in plants

1) Large molecule
- Doesn’t diffuse out of cells

2) Helical
- Compact,a lot can be stored in a small amount of space.
… Carbohydrate storage molecule

3) Insoluble
- Doesn’t affect water potential
water doesn’t diffuse into the cells via osmosis

Branches have many ends:
→ Can all be acted on simultaneously by enzymes; easily hydrolysed to produce α-glucose, so can be used for respiration.

compact and so can fit lots of molecules in a small space

37
Q

starch formation

A

Formed in condensation reaction.

38
Q

starch location

A

starch is stored by special organelles, or cell subunits, called amyloplasts

39
Q

Cellulose location

A

Plants

Cell walls

40
Q

function of cellulose

A

Used by plants for making cell walls

41
Q

Cellulose structure to function

A
  • Cell walls
    … Strengthens
    … Prevents cells from bursting when they take in too much water

The B-glucose is arranged in a straight chain
└ linked by hydrogen bonds to form microfibrils

42
Q

Cellulose structure

A 
b-glucose molecules 
1,4 glycosidic bonds 
Molecules rotates 180 relative to its neighbour= 
Unbranched, straight chain
Adjacent chains linked by hydrogen bonds
→microfibrils
43
Q

What is the main difference between starch and cellulose?

A

Starch
- Weak

Cellulose
- Strong

44
Q

what are the two classifications of sugars?

A
  • non reducing (e.g sucrose)

- reducing (all monosaccharides e.g glucose and some disaccharides e.g maltose and lactose)

45
Q

What are reducing sugars?

A

A sugar that can donate an electron to a substance to reduce this substance

46
Q

What is benedicts reagent?

A

Copper 2 sulfate

47
Q

Benedicts test- reducing sugars

A

Add Benedicts reagent in excess and heat
Negative result= blue
Positive result= brick red precipitate

48
Q

how can you compare the amount of reducing sugar in different solutions?

A
  1. observing colour change (the darker, the more concentrated)
  2. filter the solution and weigh the precipitate (more accurate)
49
Q

why must you always use benedicts reagent in excess?

A

ensures that all the sugar has reacted

50
Q

what is the colour change of the precipitate formed (for a positive test for reducing sugar) as the concentration of reducing sugar increase?

A

(benedicts reagent) blue - green - yellow - orange - brick red

51
Q

Benedicts test- non reducing sugars

A 
(hydrolysis) heat with dilute HCL/acid
Add hydrolytic enzyme
neutralise using sodium hydrogencarbonate
Add benedicts reagent and heat 
Negative result= blue
Positive result= red precipitate
52
Q

outline the semi quantitative benedict’s test

A

make standards of known concentration
dilution series
compare unknown to standards

53
Q

EQ: Benedicts test for reducing sugars

A
  • Add Benedict’s and
  • Heat
  • for a positive result it will have a red/orange/yellow/green colour
54
Q

EQ: Type of reaction that joins monosaccharides together- definition

A

-condensation

55
Q

EQ: How you would test a sample of food for the presence of starch

A
  • add iodine/potassium iodide solution to the food sample

- blue/black/purple indicates starch is present

56
Q

EQ: The concentration of glucose in the blood rises after eating a meal containing carbohydrates. The rise is slower if the carbohydrate is starch rather than sucrose, why?

A
  • starch is digested by amylase to maltose
  • and then maltose is digested by maltase to glucose
  • whereas sucrose is digested in a single step using sucrose to make glucose

3.1 Biological Molecules (10 decks)

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