August 2021 Life Science Jadean Govender 10I
The chemistry of life
atom →molecule→cell→tissue→organ→system→organism→ecosystem
Unit 1: Molecules for life
Organic compounds
Always contain elements:
• carbon
• hydrogen
• oxygen
• nitrogen
• phosphorus
Inorganic compounds
Aren’t mainly composed of carbon and hydrogen. Not normally composed together
Water is an important inorganic compound
Unit 2: Organic compounds
Carbohydrates
Made up of carbon, hydrogen, and oxygen. Main function →provide energy.
Divided into simple carbohydrates and complex carbohydrates.
Monosaccharides (simple)
• Simple single sugars
• Glucose/fructose/galactose
• Test for glucose with Benedict’s solution/Fehling’s solution.
• Solution will turn red-brown if glucose is present.
Disaccharides (simple)
• Simple double sugars
• Sucrose/maltose/lactose
Polysaccharides (complex)
• Large complex carbs- most common as starches and cellulose.
• Glycogen
• Starch is used →store energy in organisms.
Starches→glucose→supply energy
• Starch →stored in plants
Eg. maize, rice etc
• Cellulose is ONLY in plant’s cell wall.
• Cellulose structure is similar to starch.
• Test for starch is to turn iodine solution blue-black
, August 2021 Life Science Jadean Govender 10I
• Test for cellulose is to turn Schultz’s solution purple
Lipids
Lipids are fat and oils. Contain Carbon, hydrogen, and oxygen.
• Phospholipids- contain phosphorus
• Triglycerides-Ester bond
• Steroids- 4 fused rings of carbon
• Waxes- waxes found in ears
These are all insoluble in water- hydrophobic.
Test for lipids with organic solvents.
Importance of lipids
• Store energy
Make some structures e.g., Cell membranes.
• Protection
• Insulation
• Lubrication
Structure of lipids
• 3 fatty acids attached to 1 glycerol (Ester bond)
• Consists of hydrogen, carbon, oxygen.
• Can be solid or liquid depends on bonds. If solid it has single bonds and liquid it has
double bonds.
Saturated and unsaturated fats
• Unsaturated fatty acids- mainly from plants and are liquid at room temp.
• Saturated fatty acids- mainly from animals and are solid at room temp.
• Unsaturated fats are healthier than saturated.
Proteins
• Contain C, H, O and N. Nitrogen differentiates proteins from carbs/lipids.
• Some contain S, P and Fe.
• Test for proteins are the biuret test and Millon’s reagent test.
Importance of proteins
• Important for cell structure/function. Enzymes are made from proteins.
• Makes up most of dry mass.
• Carry oxygen
• Forming antibodies
• Forming hormones that regulate body functions.
• Proteins are sensitive to temp. and pH
Structure of proteins
• Like starches- large molecules
The chemistry of life
atom →molecule→cell→tissue→organ→system→organism→ecosystem
Unit 1: Molecules for life
Organic compounds
Always contain elements:
• carbon
• hydrogen
• oxygen
• nitrogen
• phosphorus
Inorganic compounds
Aren’t mainly composed of carbon and hydrogen. Not normally composed together
Water is an important inorganic compound
Unit 2: Organic compounds
Carbohydrates
Made up of carbon, hydrogen, and oxygen. Main function →provide energy.
Divided into simple carbohydrates and complex carbohydrates.
Monosaccharides (simple)
• Simple single sugars
• Glucose/fructose/galactose
• Test for glucose with Benedict’s solution/Fehling’s solution.
• Solution will turn red-brown if glucose is present.
Disaccharides (simple)
• Simple double sugars
• Sucrose/maltose/lactose
Polysaccharides (complex)
• Large complex carbs- most common as starches and cellulose.
• Glycogen
• Starch is used →store energy in organisms.
Starches→glucose→supply energy
• Starch →stored in plants
Eg. maize, rice etc
• Cellulose is ONLY in plant’s cell wall.
• Cellulose structure is similar to starch.
• Test for starch is to turn iodine solution blue-black
, August 2021 Life Science Jadean Govender 10I
• Test for cellulose is to turn Schultz’s solution purple
Lipids
Lipids are fat and oils. Contain Carbon, hydrogen, and oxygen.
• Phospholipids- contain phosphorus
• Triglycerides-Ester bond
• Steroids- 4 fused rings of carbon
• Waxes- waxes found in ears
These are all insoluble in water- hydrophobic.
Test for lipids with organic solvents.
Importance of lipids
• Store energy
Make some structures e.g., Cell membranes.
• Protection
• Insulation
• Lubrication
Structure of lipids
• 3 fatty acids attached to 1 glycerol (Ester bond)
• Consists of hydrogen, carbon, oxygen.
• Can be solid or liquid depends on bonds. If solid it has single bonds and liquid it has
double bonds.
Saturated and unsaturated fats
• Unsaturated fatty acids- mainly from plants and are liquid at room temp.
• Saturated fatty acids- mainly from animals and are solid at room temp.
• Unsaturated fats are healthier than saturated.
Proteins
• Contain C, H, O and N. Nitrogen differentiates proteins from carbs/lipids.
• Some contain S, P and Fe.
• Test for proteins are the biuret test and Millon’s reagent test.
Importance of proteins
• Important for cell structure/function. Enzymes are made from proteins.
• Makes up most of dry mass.
• Carry oxygen
• Forming antibodies
• Forming hormones that regulate body functions.
• Proteins are sensitive to temp. and pH
Structure of proteins
• Like starches- large molecules
