Carbohydrates Flashcards
(62 cards)
1
Q
What are monosaccharides?
A
- monomers from which larger carbohydrates are made
2
Q
What are some examples of monosaccharides?
A
- glucose
- galactose
- fructose
3
Q
What forms a glycosidic bond?
A
- condensation reaction between two monosaccharides
4
Q
What are disaccharides formed by?
A
- condensation of two monosaccharides joined by a glycosidic bond
5
Q
What are the common disaccharides?
A
- maltose
- sucrose
- lactose
6
Q
What is maltose formed by?
A
- condensation of two glucose molecules
7
Q
What is sucrose formed by?
A
- condensation of a glucose molecule and a fructose molecule
8
Q
What is lactose formed by?
A
- condensation of a glucose molecule and a galactose molecule
9
Q
What are the two isomers of glucose?
A
- alpha and beta glucose
10
Q
Describe the structure of alpha glucose
A
- in alpha glucose, in c1, the hydrogen is bonded above the hydroxide
11
Q
Describe the structure of beta glucose
A
- in beta glucose, in c1, the hydroxide is bonded above the hydrogen
12
Q
What are polysaccharides formed by?
A
- formed by the condensation reaction between many glucose monomers
13
Q
What are some examples of polysaccharides?
A
- glycogen
- starch
- cellulose
14
Q
Which polysaccharides are formed by the condensation of alpha glucose?
A
- glycogen and starch
15
Q
Which polysaccharide is formed by the condensation of beta glucose?
A
- cellulose
16
Q
What does starch occur as?
A
- amylose and amylopectin
17
Q
What is the structure of amylose?
A
- unbranched chain of alpha glucose
- 1-4 glycosidic bonds
- coiled in a helix due to hydrogen bonding so is compact
18
Q
What is the structure of amylopectin?
A
- branched chain of alpha glucose
- 1-4 glycosidic bonds
- 1-6 glycosidic bonds
19
Q
Advantage of structure of amylose
A
- coiled due to hydrogen bonds so is compact making it good for storage as you can fit more glucose into a small space
20
Q
Advantage of structure of amylopectin
A
- side branches increase surface area allowing enzymes that hydrolyse the molecule to get at the glycosidic bonds easily so that glucose can be released quickly
21
Q
What is the structure of glycogen?
A
- heavily branched chains of alpha glucose
- 1-6 glycosidic bonds
- 1-4 glycosidic bonds
- more branched than amylopectin
22
Q
Advantage of structure of glycogen
A
- heavily branched allows more hydrolysis to occur more easily so alpha glucose can be released quickly for respiration as animals are more metabolically active
- very compact molecule so good for storage
23
Q
What is the structure of cellulose?
A
- unbranched chains of beta glucose
- 1-4 glycosidic bonds
- every other beta glucose molecules are flipped 180 degrees to form glycosidic bonds and forming cellulose chains
- cellulose chains linked together by hydrogen bonds to form strong fibres called microfibrils
24
Q
Advantage of structure of cellulose
A
- strong fibres called microfibrils from hydrogen bonds between cellulose chains mean cellulose provides structural support for cells
25
What is the shape of amylose?
- unbranched and coiled as helix
26
What is the shape of amylopectin?
- branched
27
What is the shape of glycogen?
- heavily branched
28
What is the shape of cellulose?
- long unbranched straight parallel chains
29
Where is starch (amylose and amylopectin) found?
- plant cells
30
Where is glycogen found?
- animal cell granules in muscle and liver
31
Where is cellulose found?
- plant cell wall
32
What is the function of amylose?
- store product and energy
33
What is the function of amylopectin?
- store product and energy
34
What is the function of glycogen?
- store product in muscle and liver
35
What is the function of cellulose?
- provide structure in cell walls
36
Benedict’s test for reducing sugars
- heat sample with Benedict’s reagent
- if sample stays blue, no reducing sugar is present
- if sample forms green, yellow, orange or brick red precipitate, reducing sugar is present
37
What do reducing sugars include?
- all monosaccharides (glucose, galactose and fructose)
- some disaccharides (maltose and lactose)
38
What is a more accurate way of carrying out Benedict’s test?
- filter solution and weigh precipitate
- remove the precipitate and use colorimeter to measure the absorbency of the remaining Benedict’s reagent
39
What do non reducing sugars include?
- sucrose
40
Benedict’s test for non reducing sugar
- add dilute hydrochloric acid to test solution and heat
- neutralise sample by adding sodium hydrogen carbonate
- heat sample with Benedict’s reagent
- if sample forms green, yellow, orange or brick red precipitate, non reducing sugar is present
41
Why should you add dilute hydrochloric acid to Benedict’s test for non reducing sugar?
- to hydrolyse test solution into monosaccharides
42
Iodine test for starch
- add iodine in potassium iodide solution to test sample
- if test sample changes from browny orange to dark, blue black colour, starch is present
43
What are the properties of disaccharides?
- sweet tasting
- soluble in water
- osmotically active
44
What is the function of sucrose?
- energy transport and storage in plants
45
What is the function of lactose?
- energy transport and storage in mammal milk
46
What is the function of maltose?
- intermediate in starch digestion
47
What are oligosaccharides?
- chains of monosaccharides that are covalently linked to one another by glycosidic bonds containing 3-10 monosaccharides and may be linear or branched
48
What are the properties of polysaccharides?
- osmotically inactive (insoluble/colloidal)
- not sweet tasting
- energy storage or structural functions
- hydrolysed to monosaccharides by amylases or cellulases
49
What is the structure of chitin?
50
Advantage of structure of chitin
51
Draw the structure of alpha glucose
52
Draw the structure of beta glucose
53
Draw the formation of maltose by condensation
54
Draw the hydrolysis of maltose
55
During which processes are polymers hydrolysed in the body into monomers?
- digestion eg. Starch is hydrolysed into glucose
- glycogenolysis is where stores of glycogen is hydrolysed back into glucose when blood sugar levels drop
56
What catalyses hydrolysis in the body?
- enzymes
57
What is the advantage of starch being insoluble?
- won’t affect water potential
58
What is an advantage of cellulose being insoluble?
- won’t affect water potential
59
What is the advantage of glycogen being insoluble?
- won’t affect water potential
60
Why does the colour change occur at the top of the solution first (test for reducing sugars)?
- molecules have more kinetic energy at the top so more successful collisions and faster reaction at the top
61
Define reducing sugars
- these sugars can reduce the copper sulphate (blue) in Benedict’s reagent to copper oxide (brick red)
62
Define non reducing sugars
- reducing group is involved in glycosidic bond in sucrose and therefore, sucrose cannot reduce sopped sulphate to copper oxide
- when sucrose is hydrolysed through boiling with acid, the glycosidic bond is broken and therefore, the reducing group becomes exposed
