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BIOLOGY CHAPTER 3: BIOLOGICAL MOLECULES - Coggle Diagram
BIOLOGY CHAPTER 3: BIOLOGICAL MOLECULES
Carbohydrates
Definition: Carbohydrates are organic molecules made up of the elements Carbon Hydrogen and Oxygen. The hydrogen and oxygen atoms are present in a ratio of 2:1
Glucose: c6 h22 o11 Fructose: c12 h22 o11
Sugars
Monosaccharides
Glucose
Found in Plants and Animals
REDUCING SUGAR
Benedicts Test (Presence of REDUCING SUGARS)
1) 2cm^3 food sample into test-tube
2) 2cm^3 benedicts solution
3) Shake mixture and place test - tube in boiling bath for 2 to 3 minutes
4) Record colour of solution
Blue: No reducing sugar present
Green precipitate: Traces of reducing sugar Yellow/ Orange precipitate: Moderate amt of reducing sugar
Brick-Red precipitate: Large amt of reducing sugar
Fructose
Common in Plants, Rare in animals
REDUCING SUGAR
Basic Unit of Carbs. Can pass through cell membranes and be absorbed by cell
Disaccharides
Maltose (glucose + glucose)
REDUCING SUGAR
Sucrose (glucose + fructose)
NOT A REDUCING SUGAR
Two single sugars joined together
Can be split into monosaccharides through enzymes
Complex Carbohydrates (Basic Unit: Glucose)
Starch (plants)
Structure: Made of several thousand glucose molecules
Role: Storage form of carbohydrates found in plants. Can be digested to glucose to provide energy for cell activites
Occurrence: Found in storage organs of plants: Potato tubers and tapioca
Cellulose (plants herbivores)
Structure: Made of many glucose molecules joined together
Role: Cellulose cell wall protects plant from bursting.
Cannot be digested in our intestine. Serve as dietary fibre
Occurrence: Cell walls of plants
Glycogen (mammals)
Structure: Branched molecule made of many glucose molecules
Role: Storage form of carbohydrates in mammals. Digested to glucose to provide energy for cell activites
Occurrence: Stored in liver and muscles
Excess glucose stored in animals as glycogen
Many similar molecules of single sugar joined together to form a large molecule (Long Chains of Glucose)
Glycogen Starch - Suitable storage materials in cells
1) Insoluble in water - dont change water potential of cells
2) Large molecules that cannot diffuse through cell membranes - not lost in cells
3) Easily broken down into glucose when needed - eg: tissue respiration
4) Molecules have compact shapes, so they occupy less space than all individual glucose molecues
Functions: 1) as a substrate for respiration, provide energy for cell activities
2) Form supporting structures - cell wall in plants
3) Converted to other organic compounds - amino acids fats
4) formation of nucleic acid
5) Synthesise lubricants - eg: mucus
6) Synthesise nectar in some flowers