MODULE 2 PART II:

BIOCHEMISTRY OF MILK:

Introduction to Lipids, Proteins (discussed in Module 1), and

Carbohydrates.

OBJECTIVES:

1. KNOW CHARACTERISTICS OF SOME BIOLOGICAL MOLECULES PRESENT IN MILK

2. KNOW SOME TECHNIQUES IN SEPARATION OF FRACTIONS IN MILK

LAB LAYOUT:LAB LAYOUT:

• Due to time constraints, lecture will be brief today and covered quickly (see web site for lecture presentations).

• BIO 151 builds upon a theme from simple to complex biological processes.

• Essentially, the purpose of Modules 1-3 are to familiarize you with various biological molecules that provide the basis of nutrition and biological reactions in our bodies.

Biological MoleculesBiological Molecules

Lecture Experiments

Module 1: Proteins Proteins

Module 2/3: Lipids and Proteins, Carbohydrates Lipids, and Carbohydrates

Laboratory Objectives:Laboratory Objectives: Fractionate milk into components (dialysate Fractionate milk into components (dialysate

and five fractions)and five fractions)

Describe procedures for separating various Describe procedures for separating various components present in milkcomponents present in milk

Describe various analytical tests to determine Describe various analytical tests to determine the biological molecules present in each of the the biological molecules present in each of the fractionsfractions

Understand the complex nature of milk and Understand the complex nature of milk and know the structure and function of the various know the structure and function of the various biomolecules found in this rich source of food.biomolecules found in this rich source of food.

LIPIDSLIPIDS

Lipids are diverse in structure and function. They are grouped together only because they share one physical property: insoluble in water (hydrophobic).

1. Triglycerides (fats)-• one glycerol and three molecules of fatty acids

joined together by ester linkages through condensation (dehydration) process.

2. Phospholipids-• one glycerol and two molecules of fatty acids (ie.

structurally similar to fats but the third fatty acid is replaced by a phosphate group. Therefore, phospholipids have hydrophobic (non-polar) tails, the fatty acids, and a hydrophilic (polar) head, phosphate group.

What types of lipids are there?

FIGURE: FORMATION OF A FAT MOLECULE FROM 3 FATTY ACIDS AND A GLYCEROL

1. Types of Fats 1. Types of Fats (Triglycerides)(Triglycerides)

– saturated fats [no double bond on their tail] such as lard and butter, solidify at room temperature due to lack of double bond in the fatty acids; thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton

– unsaturated fats [with one or more double bonds on their tail] such as olive oil and peanut oil, liquid at room temperature due to double bonds in the fatty acids).

SATURATED AND UNSATURATED

FATS

2. Phospholipids: • one glycerol and two molecules of fatty acids

(major component of cell membranes).

FIGURE: PHOSPHOLIPID BEHAVIOR

What other components are What other components are found in milk?found in milk?

Lipids, Proteins, ___________ ?Lipids, Proteins, ___________ ?CarbohydratesCarbohydrates

Types of CarbohydratesTypes of Carbohydrates

1. MONOSACHARIDES- single sugar.

2. DISACCHARIDES- two monosaccharides joined by a glycosidic linkage, formed by condensation, a dehydration reaction.

3. POLYSACCHARIDES- complex sugar-are macromolecules with a few hundred monosaccharides joined by glycosidic linkages.

The structure and classification of some The structure and classification of some monosaccharidesmonosaccharides

Sugars may be aldehydes or ketones, depending on the location of the carbonyl group ( -C=O )

Linear and ring forms of glucoseLinear and ring forms of glucose

2. DISACCHARIDES

•two monosaccharides joined by a glycosidic linkage, formed by condensation (dehydration) reaction.

• Maltose= 2 glucose molecules (ingredient for brewing beer)

• Lactose= 1glucose and 1 galactose molecules (major sugar in milk)

• Sucrose= 1 glucose and 1 fructose molecules (table sugar)

Figure 5.2 The synthesis and breakdown of polymersFigure 5.2 The synthesis and breakdown of polymers

Examples of disaccharidesExamples of disaccharides

3. POLYSACCHARIDES- •complex sugar-are macromolecules with a few hundred monosaccharides joined by glycosidic linkages.

• Starch= polymer of glucose (storage polysaccharide found Starch= polymer of glucose (storage polysaccharide found in plants)in plants)

• Glycogen=storage polysaccharide found in animalsGlycogen=storage polysaccharide found in animals

• Cellulose=polymer of glucose, differs from glucose based Cellulose=polymer of glucose, differs from glucose based on different glycosidic linkages (structural polysaccharide).on different glycosidic linkages (structural polysaccharide).

• Chitin=structural polysaccharide found in exoskeleton of Chitin=structural polysaccharide found in exoskeleton of arthropods.arthropods.

Starch and Cellulose Starch and Cellulose Structures ComparedStructures Compared