Carbohydrates Flashcards
What is the general formula for carbohydrates?
(CH20)n
Why are carbohydrates important?
They are essential fro all living organisms
/How are carbohydrates formed
Primarily by photosynthesis
Name the basic unit of carbohydrates?
Monosaccharides
Give examples of some food in which carbohydrates are found
- Bread
- Beans
- Milk
- Popcorn
- Potatoes
Give some common forms of carbohydrates
- Sugars
- Fibres
- Starches
Name the 3 classifications of carbohydrates
- monosaccharides
- Disaccharides
- Polysaccharides
What are monosaccharides?
Simple sugars
What are disaccharides?
Two simple sugars linked by a covalent bond
What are polysaccharides?
They are hundred or thousands of monosaccharides
Give some examples of polysaccharides
- Starch
- Glycogen
- Cellulose
How are monosaccharides commonly found in humans classified?
According to the number of carbons they contain in their backbone structure
How many carbon atoms do the major monosaccharides contain?
4-6
How are carbohydrates formed in plants?
By photosynthesis from carbon dioxide and water in the precise of sunlight
Other than photosynthesis how else can glucose be synthesised?
glucose can be synthesized from other organic molecules in processes of gluconeogenesis
In animals what is glucose synthesis called?
gluconeogenesis
What dos gluconeogenesis usually start with in animals?
Can start with lactate, amino acids or glycerol
How is lactate produced in animals?
produced by anaerobicglycolysis
Where are amino acids derived from in animals?
From the breakdown of protein
How is glycerol produced in animals?
Produced by the breakdown of lipids
What is a glycogenic amino acid?
It is an amino acid that can be converted into glucose through glycogenesis
Give examples of glycogenic amino acid
Alanine Arginine Asparagine Asparticacid Cysteine Glutamicacid Glutamine Glycine.
Name the most commonly occurring monosaccharides
- Fructose
- Glucose
- Galactose
What is fructose found in?
Fruits
Honey
Vegetables
What can fructose be derived from?
Can be derived from the digestion of sucrose
What is glucose found in?
Small amounts are found in some fruits, vegetables and honey
Commonly found in manufactured foods
What can glucose be derived from?
The digestion and conversion of other carbohydrates
What can galactose be derived from?
The digestion of lactose
Are disaccharides taken up by cells?
Disaccharides are not taken up by cells
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
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
Name some nutritionally important disaccharides
- Sucrose
- Lactose
- Maltose
Where is lactose found?
Found exclusively in the milk of mammals
What is lactose made up of?
Consists of a galactose and glucose in a beta-(1-4) glycosidic bond
What is an amino acid that can be converted into glucose called?
A glycogenic amino acid
What is sucrose derived from?
Derived from sugar cane and sugar beet
Where is sucrose found?
- Sweet root vegetables like beetroot an carrots
- Sugar canes and sugar beets
3/ Table sugar - Manufactured food
What is sucrose made up of?
Consists of glucose and fructose in an alpha-(1-2) glycosidic bond
Where is maltose found?
- Malted wheat
- Barley
- Malt extract
- Beer
What is maltose made up of?
Consists of glucose and glucose in an alpha-(1-4) glycosidic bond
What are polysaccharides comprised of?
Multiple monosaccharides joined by glycosidic linkages
Name the predominant monosaccharide found in polysaccharides
D glucose
Name the main polysaccharides
- Glycogen
- Starch
- Cellulose
Name the major form of stored carbohydrates in animals
Glycogen
Which molecules make up glycogen?
A homopolymers of glucose in an alpha-(1-4) linkage
Is glycogen branched or unbranched?
It is highly branched with alpha (1-6) branch linkages occurring every 8-10 residues
Every how many residues does branching occur in glycogen?
Every 8-10 residues
How is glycogen so compact?
Due to coiling of the polymer chains
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
Name the major form of stored carbohydrates in plants
Starch
What is the main difference in the structure of glycogen and starch?
Theres less branching in starch
Every how many residues does branching occur in starch?
Every 20-30 residues
Name the 2 main types of starch
- Amylose
2. Amylopectin
What is the difference between Amylose and Amylopectin
Amylose is unbranched start
Amylopectin is branched starch
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
Can cellulose be digested by humans?
No as humans don’t have an enemy to degrade the beta 1-4 linkage
What is cellulose the principle component of?
dietary fibre (Roughage)
What is Roughage?
It is the fibrous indigestible material in vegetable foodstuffs which aids the passage of food and waste product though the gut
What does roughage aid?
The passage of food and waste product though the gut
What does fibre help with?
Helps to ensure good gut function by increasing the physical bulk in the bowel and stimulating the intestinal transit
What are monosaccharides and disaccharides used for?
- Energy source
- Glycosylation of proteins
- Structural components
- Carbon skeletons fro biosynthesis of amino acids
What are the functions of glucose?
- It is used by all cells as an energy source
- Some glucose is converted to ribose and deoxyribose
- Glucose can be utilised to make the molecule NADPH
- Biosynthesis of lipids and amino acids from Sugar
Which organ redistributed glucose back into the blood?
LIVER
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.
Where does the energy from glucose come from?
Comes from the chemical bond between the carbon atoms
Name the 2 ways glucose can be broken down
- Aerobic respiration
2. Fermentation
How is glucose broken in aerobic respiration?
- Glycolysis of glucose forms Pyruvate
- This relates to ATP molecules
- Pyruvate is oxidised
- Krebs cycle occurs
- Electron transport chain occurs which releases unto 36 ATM molecules
What can glucose be fermented into?
- Alcohol and CO2 (in bacteria and yeast)
2. Lactic acid (in animals)
What aids the passage of food and waste product though the gut?
Roughage
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.
Where is the majority of glycogen stored?
In the muscles and liver
What are ribose and deoxyribose essential for?
They are the essential building blocks of important macromolecules such as RNA, DNA and ATP
When is glucose stored as fat?
When all of the energy, glycogen-storing capacity and building needs of the body are met
What is the raw material for amino acid synthesis obtained from?
Glucose
How many naturally occurring amino acids are therer?
20
What is lipid metabolism associated with?
Associated with carbohydrate metabolism as products of glucose can be converted into lipids
What is a high level of sugar consumption associated with?
Greater risk of tooth decay
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
What is the recommended amount of carbohydrates a person should consume?
Total carbohydrates contributes 50% towards daily energy requirements
How much of your daily energy requirement should come from free sugars?
5% of daily energy requirement
How much of your daily energy requirement should come from natural sugars?
45% of daily energy requirements
What is the recommended dietary fibre intake for an adult
30g/day
What is the average fibre intake in the UK?
12g/day