Chemistry of Life
Understanding the essential molecules that constitute all living organisms
In this section, you study the substances that living organisms are made of. For CAPS, the key focus is water, mineral salts, organic compounds, vitamins, and enzymes, together with the functions and tests that learners are expected to know.
1. Inorganic Compounds
Inorganic compounds are simple molecules that are vital for life despite lacking a carbon backbone. The most significant inorganic compound is water.
Water (H2O)
Water is the most abundant molecule in organisms and possesses several key properties:
Good Solvent
Many substances dissolve in water, making it essential for various biological processes including nutrient transport and waste removal.
Temperature Regulation
Water has a high specific heat capacity, helping organisms maintain stable internal temperatures despite external changes.
Transport & Metabolic Reactions
Water is crucial for transporting nutrients and facilitating metabolic reactions within cells.
Mineral Salts
Mineral salts are inorganic ions absorbed from soil or food, playing critical roles in biological functions:
| Mineral | Function | Source |
|---|---|---|
| Calcium (Ca) | Essential for strong bones and muscle contraction | Dairy products, leafy greens |
| Phosphates (PO4) | Important for DNA, RNA, and ATP formation | Meat, dairy, nuts |
| Nitrates (NO3) | Necessary for synthesizing proteins and nucleic acids | Vegetables, soil |
| Iron (Fe) | Essential for hemoglobin in red blood cells | Red meat, spinach |
| Magnesium (Mg) | Needed for chlorophyll in plants | Nuts, whole grains |
| Potassium (K) | Nerve function and muscle contraction | Bananas, potatoes |
| Sodium (Na) | Fluid balance and nerve transmission | Table salt, processed foods |
Quick Check: Inorganic Compounds
1. What property of water makes it an excellent transport medium?
Show Answer
Water is a good solvent - many substances dissolve in it, allowing nutrients to be transported throughout organisms.
2. Which mineral is essential for DNA and ATP formation?
Show Answer
Phosphates (PO4) are important for the formation of DNA, RNA, and ATP.
3. Name two minerals essential for red blood cell function.
Show Answer
Iron (for hemoglobin) and Copper (for red blood cell formation).
2. Organic Compounds
Organic compounds are complex molecules that contain a carbon backbone and are synthesized by living organisms. Understanding their structure, function, and testing methods is essential.
| Compound | Elements | Building Block (Monomer) | Function(s) | Food Test |
|---|---|---|---|---|
| Carbohydrates | C, H, O | Monosaccharides (Glucose) | Primary energy source; short-term energy storage | Iodine solution (Starch - blue-black) Benedict's solution (Glucose - brick-red when heated) |
| Lipids (Fats) | C, H, O | Fatty acids & Glycerol | Long-term energy storage; insulation; cell membranes | Brown Paper Test (translucent spot) Ethanol Emulsion Test (milky white emulsion) |
| Proteins | C, H, O, N, S | Amino acids | Growth and repair; enzymes; hormones; antibodies | Biuret solution (turns violet/purple) |
| Nucleic Acids | C, H, O, N, P | Nucleotides | Genetic material (DNA and RNA) | No Grade 10 test |
Virtual Lab: Food Tests
Interactive GameFood Samples
Tests & Reagents
Tests for starch - blue-black color
Tests for glucose - brick-red when heated
Tests for protein - violet/purple color
Tests for lipids - milky white emulsion
3. Vitamins
Vitamins are organic compounds that are crucial for various bodily functions. Students should be familiar with common vitamins and their associated deficiency diseases.
Vitamin C
Prevents Scurvy
Found in citrus fruitsVitamin D
Prevents Rickets
Sunlight, fatty fishVitamin A
Prevents Night Blindness
Carrots, sweet potatoesVitamin B
Prevents Beriberi or Pellagra
Whole grains, meatVitamin Matching Quiz
Match each vitamin with its deficiency disease. Which is correct?
4. Enzymes
Enzymes are specialized proteins that act as biological catalysts, accelerating chemical reactions in the body without being consumed in the process. They are essential for various metabolic pathways and physiological functions.
How Enzymes Work
Substrate → Enzyme-Substrate Complex → Products
Properties of Enzymes
- Biological catalysts - speed up reactions
- Specific - each enzyme catalyzes one reaction
- Not consumed in reactions - can be reused
- Affected by temperature and pH
- Denature at high temperatures
Examples of Enzymes
- Amylase - breaks down starch
- Protease - breaks down proteins
- Lipase - breaks down lipids
- Catalase - breaks down hydrogen peroxide
Exam Tip
Students should be prepared to describe the detailed procedures for food tests, such as the Biuret test. The Biuret test involves adding Biuret reagent to the sample and observing the color change. A violet or purple color indicates the presence of proteins.
Comprehensive Practice Quiz
1. Which property of water makes it effective for temperature regulation?
2. What is the building block (monomer) of proteins?
3. Which vitamin deficiency causes rickets?
4. Enzymes are described as biological catalysts because they:
5. Which food test would you use to identify the presence of starch?
1. Which mineral is essential for hemoglobin formation?
1. Which elements are found in all organic compounds?
1. Deficiency of vitamin C causes:
1. What happens to enzymes at high temperatures?
Fill in the Blanks
1. The most abundant molecule in living organisms is .
2. Proteins are made up of acids.
3. The Biuret test turns in the presence of protein.
4. is the mineral needed for strong bones and teeth.
5. Enzymes are biological that speed up reactions.
Key Terms
Summary
The Chemistry of Life encompasses both inorganic and organic molecules essential for life. Water and mineral salts form the foundation of inorganic compounds, while carbohydrates, lipids, proteins, and nucleic acids make up the organic molecules. Vitamins are crucial organic compounds that prevent deficiency diseases, and enzymes act as biological catalysts that speed up chemical reactions in living organisms.
- Water is the universal solvent and regulates temperature due to its high specific heat capacity
- Mineral salts like calcium, phosphates, and iron are essential for body functions
- Carbohydrates provide energy; tested with iodine (starch - blue-black) and Benedict's solution (glucose - brick-red)
- Lipids store energy; tested with brown paper and ethanol emulsion (milky white)
- Proteins build structures; tested with Biuret solution (violet/purple color)
- Vitamins prevent deficiency diseases: C (scurvy), D (rickets), A (night blindness), B (beriberi)
- Enzymes are biological catalysts that speed up reactions without being consumed
- Enzymes are specific, reusable, and can be denatured by high temperatures
