Food Ppt (1)

Food Learning Intentions

• State why nutrients are essential

• Describe the 4 major types of biomolecules

Starter

• Food

Importance of Food

Food is necessary for:

1. Energy: Essential for all bodily functions and activities.

2. Growth of New Cells & Repair: Helps in cell regeneration, tissue repair, and organ maintenance.

3. Chemical Production: Needed to produce chemicals for metabolic reactions.

4. (Further context needed)

Composition of Food

• Chemical Elements in Food:

  • Six major elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulfur (S)

  • Salts include Sodium (Na), Magnesium (Mg), Chlorine (Cl), Potassium (K), Calcium (Ca)

  • Trace elements: Iron (Fe), Copper (Cu), Zinc (Zn)

Types of Food

• Elements combine in different ratios to form various food components (biomolecular units):

  • Water

  • Proteins

  • Lipids

  • Carbohydrates

  • Vitamins

  • Minerals

Human Composition by Weight

• Water: 65%

• Protein: 18%

• Fat: 10%

• Carbohydrates: 5%

• Vitamins: 1%

• Minerals: 1%

Task 1

• Information for each biomolecule focusing on:

  • Elements present

  • Structure

  • Sources

  • Roles in metabolic processes

Carbohydrates

Elements in Carbohydrates

• Composed of:

  • Carbon (C)

  • Hydrogen (H)

  • Oxygen (O)

• General formula: Cx(H2O)y

Types of Carbohydrates

1. Monosaccharides:

   • Single sugar molecules, soluble in water (e.g., glucose and fructose found in fruit).

2. Disaccharides:

   • Two monosaccharides (e.g., sucrose from glucose + fructose, maltose from glucose + glucose), soluble and sweet (found in table sugar, milk).

3. Polysaccharides:

   • Many monosaccharides, not soluble, not sweet (e.g., starch, cellulose found in bread, pasta, cereals).

Roles of Polysaccharides

• Structural Role: Cellulose in plant cell walls.

• Metabolic Role: Glucose used for energy production.

Food Tests: Starch

Procedure

1. Label test tubes A-F.

2. Add 2cm³ starch solution in A, water in B (control), food samples in C-F.

3. Add iodine solution (2-3 drops) to each.

4. Observe color change: blue-black indicates starch, yellow for water.

Food Tests: Reducing Sugars

Procedure

1. Label test tubes A-F.

2. Add glucose solution to A, water in B (control).

3. Add 2cm³ of food samples in C-F.

4. Add Benedict's reagent and heat in a water bath.

5. Observe for color changes from blue to red/yellow, indicating reducing sugars.

Lipids

Elements in Lipids

• Contain:

  • Carbon (C), Hydrogen (H), Oxygen (O)

• Types of lipids: fats (solid at room temp.) and oils (liquid at room temp.)

Structure of Lipids

• Triglycerides: Composed of glycerol and three fatty acids.

• Phospholipids: Important for cell membranes.

Sources of Lipids

• Found in:

  • Meat (fat in/on)

  • Butter (80% fat)

  • Cooking oils

Role of Lipids

• Structural Role: Stored energy (twice the energy of carbohydrates) and components of membranes.

• Metabolic Role: Broken down for energy release.

Food Tests: Lipids

Procedure

1. Label pieces of brown paper A-F.

2. Add oil to A, water (control) to B, and additional food samples in C-F.

3. Observe for permanent translucent stains indicating fat presence.

Proteins

Elements in Proteins

• Contain:

  • Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), may also contain Sulfur (S) or Phosphorus (P).

Structure of Proteins

• Made of long chains of 20 types of amino acids.

• Peptides: Chains of fewer than 20 amino acids.

• Polypeptides: Chains greater than 20 amino acids.

• Proteins: Long polypeptides, typically >200.

Sources of Protein

• Found in:

  • Meat, Fish, Eggs, Nuts, Milk, Peas, Beans

Role of Proteins

• Structural Role: Keratin in skin, myosin in muscles.

• Metabolic Role: Enzymes to control reactions, antibodies to fight infections, hormones to regulate body functions.

Food Tests: Proteins

Procedure

1. Label test tubes A-F.

2. Add milk or egg white in A, water (control) in B.

3. Add sodium hydroxide and copper sulfate to each test tube.

4. Observe for color change: the solution turns purple in the presence of protein.

Vitamins

Characteristics

• Essential organic catalysts for metabolism.

• Needed in small amounts and must be supplied continuously.

• Each vitamin differs chemically.

Types of Vitamins

• Water-soluble: Vitamins B & C.

• Fat-soluble: Vitamins A, D, E, K.

Examples of Vitamins and Their Roles

• Vitamin C:

  • Role: Connective tissue maintenance, growth, immune function.

  • Deficiency: Causes scurvy.

• Vitamin D:

  • Role: Calcium absorption.

  • Deficiency: Rickets and Osteomalacia.

Sources of Vitamins

• Vitamin A: Green leafy vegetables, eggs.

• Vitamin B: Lean meat, cereals.

• Vitamin C: Citrus fruits.

• Vitamin D: Milk and sunlight.

• Vitamin E: Vegetable oils.

• Vitamin K: Green leafy vegetables.

Anabolic vs Catabolic Reactions

Anabolic Reactions

• Definition: Energy used to synthesize large molecules from smaller ones (e.g., photosynthesis).

• Example: Formation of glucose from carbon dioxide and water.

Catabolic Reactions

• Definition: Energy released when breaking down large molecules to smaller ones (e.g., respiration).

• Example: Breakdown of glucose into carbon dioxide and water.

Important distinctions

• Catabolism and anabolism are not direct opposites; they involve different chemical pathways.

Minerals

Importance of Minerals

• Needed in small amounts for:

  • Rigid body structures (bones)

  • Soft tissue structures (muscles)

  • Forming salts in fluids (cellular processes)

  • Form biomolecules (e.g., hemoglobin, chlorophyll).

Task 1

• Create a table showing sources and uses of minerals, covering plants and animals.

Water

Importance of Water

• Medium for all metabolic reactions.

• Basis of transport in organisms.

• Habitat for various organisms.

Conclusion and Review Tasks

• Answer review questions about food requirements, carbohydrate types, lipid structure, and tests for proteins.

  • Example: What are polysaccharides? What is the main source of protein?

  • Emphasize practical understanding through experimentation and application of concepts.