Carbohydrates Flashcards
1
Q
What is the general formula for carbohydrates?
A
(CH20)n
2
Q
Why are carbohydrates important?
A
They are essential fro all living organisms
3
Q
/How are carbohydrates formed
A
Primarily by photosynthesis
4
Q
Name the basic unit of carbohydrates?
A
Monosaccharides
5
Q
Give examples of some food in which carbohydrates are found
A
- Bread
- Beans
- Milk
- Popcorn
- Potatoes
6
Q
Give some common forms of carbohydrates
A
- Sugars
- Fibres
- Starches
7
Q
Name the 3 classifications of carbohydrates
A
- monosaccharides
- Disaccharides
- Polysaccharides
8
Q
What are monosaccharides?
A
Simple sugars
9
Q
What are disaccharides?
A
Two simple sugars linked by a covalent bond
10
Q
What are polysaccharides?
A
They are hundred or thousands of monosaccharides
11
Q
Give some examples of polysaccharides
A
- Starch
- Glycogen
- Cellulose
12
Q
How are monosaccharides commonly found in humans classified?
A
According to the number of carbons they contain in their backbone structure
13
Q
How many carbon atoms do the major monosaccharides contain?
A
4-6
14
Q
How are carbohydrates formed in plants?
A
By photosynthesis from carbon dioxide and water in the precise of sunlight
15
Q
Other than photosynthesis how else can glucose be synthesised?
A
glucose can be synthesized from other organic molecules in processes of gluconeogenesis
16
Q
In animals what is glucose synthesis called?
A
gluconeogenesis
17
Q
What dos gluconeogenesis usually start with in animals?
A
Can start with lactate, amino acids or glycerol
18
Q
How is lactate produced in animals?
A
produced by anaerobicglycolysis
19
Q
Where are amino acids derived from in animals?
A
From the breakdown of protein
20
Q
How is glycerol produced in animals?
A
Produced by the breakdown of lipids
21
Q
What is a glycogenic amino acid?
A
It is an amino acid that can be converted into glucose through glycogenesis
22
Q
Give examples of glycogenic amino acid
A
Alanine Arginine Asparagine Asparticacid Cysteine Glutamicacid Glutamine Glycine.
23
Q
Name the most commonly occurring monosaccharides
A
- Fructose
- Glucose
- Galactose
24
Q
What is fructose found in?
A
Fruits
Honey
Vegetables
25
What can fructose be derived from?
Can be derived from the digestion of sucrose
26
What is glucose found in?
Small amounts are found in some fruits, vegetables and honey
Commonly found in manufactured foods
27
What can glucose be derived from?
The digestion and conversion of other carbohydrates
28
What can galactose be derived from?
The digestion of lactose
29
Are disaccharides taken up by cells?
Disaccharides are not taken up by cells
30
How are disaccharide formed?
A covalent bond between the anomeric hydroxy of a cyclic sugar and the hydroxyl of a second sugar forms a glycoside
31
What is the covalent bond between the anomeric hydroxy of a cyclic sugar and the hydroxyl of a second sugar called?
Called a glycosidic bond
32
Name some nutritionally important disaccharides
1. Sucrose
2. Lactose
3. Maltose
33
Where is lactose found?
Found exclusively in the milk of mammals
34
What is lactose made up of?
Consists of a galactose and glucose in a beta-(1-4) glycosidic bond
35
What is an amino acid that can be converted into glucose called?
A glycogenic amino acid
36
What is sucrose derived from?
Derived from sugar cane and sugar beet
37
Where is sucrose found?
1. Sweet root vegetables like beetroot an carrots
2. Sugar canes and sugar beets
3/ Table sugar
4. Manufactured food
38
What is sucrose made up of?
Consists of glucose and fructose in an alpha-(1-2) glycosidic bond
39
Where is maltose found?
1. Malted wheat
2. Barley
3. Malt extract
4. Beer
40
What is maltose made up of?
Consists of glucose and glucose in an alpha-(1-4) glycosidic bond
41
What are polysaccharides comprised of?
Multiple monosaccharides joined by glycosidic linkages
42
Name the predominant monosaccharide found in polysaccharides
D glucose
43
Name the main polysaccharides
1. Glycogen
2. Starch
3. Cellulose
44
Name the major form of stored carbohydrates in animals
Glycogen
45
Which molecules make up glycogen?
A homopolymers of glucose in an alpha-(1-4) linkage
46
Is glycogen branched or unbranched?
It is highly branched with alpha (1-6) branch linkages occurring every 8-10 residues
47
Every how many residues does branching occur in glycogen?
Every 8-10 residues
48
How is glycogen so compact?
Due to coiling of the polymer chains
49
Gives some advantages of glycogen been highly coiled
Means it is compact so a large amount of carbon energy can be stored in a small volume with little effect on cellular osmolarity
50
Name the major form of stored carbohydrates in plants
Starch
51
What is the main difference in the structure of glycogen and starch?
Theres less branching in starch
52
Every how many residues does branching occur in starch?
Every 20-30 residues
53
Name the 2 main types of starch
1. Amylose
| 2. Amylopectin
54
What is the difference between Amylose and Amylopectin
Amylose is unbranched start
| Amylopectin is branched starch
55
How is amylose digested and what are its digestion products?
Enzymes in the digestive tract degrade amylose to generate GLUCOSE
The major product of amylose digestion is maltose
56
Can cellulose be digested by humans?
No as humans don't have an enemy to degrade the beta 1-4 linkage
57
What is cellulose the principle component of?
dietary fibre (Roughage)
58
What is Roughage?
It is the fibrous indigestible material in vegetable foodstuffs which aids the passage of food and waste product though the gut
59
What does roughage aid?
The passage of food and waste product though the gut
60
What does fibre help with?
Helps to ensure good gut function by increasing the physical bulk in the bowel and stimulating the intestinal transit
61
What are monosaccharides and disaccharides used for?
1. Energy source
2. Glycosylation of proteins
3. Structural components
4. Carbon skeletons fro biosynthesis of amino acids
62
What are the functions of glucose?
1. It is used by all cells as an energy source
2. Some glucose is converted to ribose and deoxyribose
3. Glucose can be utilised to make the molecule NADPH
4. Biosynthesis of lipids and amino acids from Sugar
63
Which organ redistributed glucose back into the blood?
LIVER
64
What happens to the majority of glucose entering out body?
About 70 percent of the glucose entering the body from digestion is redistributed (by the liver) back into the blood for use by other tissues.
65
Where does the energy from glucose come from?
Comes from the chemical bond between the carbon atoms
66
Name the 2 ways glucose can be broken down
1. Aerobic respiration
| 2. Fermentation
67
How is glucose broken in aerobic respiration?
1. Glycolysis of glucose forms Pyruvate
2. This relates to ATP molecules
3. Pyruvate is oxidised
4. Krebs cycle occurs
5. Electron transport chain occurs which releases unto 36 ATM molecules
68
What can glucose be fermented into?
1. Alcohol and CO2 (in bacteria and yeast)
| 2. Lactic acid (in animals)
69
What aids the passage of food and waste product though the gut?
Roughage
70
What happens to excess glucose in the body?
Excess glucose is stored as glycogen
If all of the energy, glycogen-storing capacity, and building needs of the body are met, excess glucose can be used to make fat.
71
Where is the majority of glycogen stored?
In the muscles and liver
72
What are ribose and deoxyribose essential for?
They are the essential building blocks of important macromolecules such as RNA, DNA and ATP
73
When is glucose stored as fat?
When all of the energy, glycogen-storing capacity and building needs of the body are met
74
What is the raw material for amino acid synthesis obtained from?
Glucose
75
How many naturally occurring amino acids are therer?
20
76
What is lipid metabolism associated with?
Associated with carbohydrate metabolism as products of glucose can be converted into lipids
77
What is a high level of sugar consumption associated with?
Greater risk of tooth decay
78
What might drinking might sugar beverages lead to?
Weight gain and increased BMI in teenagers and children
| Also increases the risk of developing type 2 diabetes
79
What is the recommended amount of carbohydrates a person should consume?
Total carbohydrates contributes 50% towards daily energy requirements
80
How much of your daily energy requirement should come from free sugars?
5% of daily energy requirement
81
How much of your daily energy requirement should come from natural sugars?
45% of daily energy requirements
82
What is the recommended dietary fibre intake for an adult
30g/day
83
What is the average fibre intake in the UK?
12g/day
