Presentation1000000001-BIOCHEMISTRY.pptx

None

1. GROUP 1 BIOCHEMISTRY

2. Occurrence and Function CO₂ + H₂O + solar energy Chlorophyll carbohydrates + 02 Plant Enzymes Carbohydrates are the most abundant class of bioorganic molecules on planet Earth. Although their abundance in the human body is relatively low (Section 1-1), carbo- hydrates constitute about 75% by mass of dry plant materials (Figure 1-2).◄ ,Green (chlorophyll-containing) plants produce carbohydrates via photosynthesis.

3. Plants have two main uses for the carbohydrates they produce. In the form of c ellulose, carbohydrates serve as structural elements, and in the form of starch , they provide energy reserves for the plants. Dietary intake of plant materials is the major carbohydrate source, for humans and animals. The average human diet should ideally be about two-thirds carbohydrate by mass.

4. Carbohydrates have the following functions in humans: Carbohydrate oxidation provides energy. 2. Carbohydrate storage, in the form of glycogen, provides a short-term energy reserve. 3. Carbohydrates supply carbon atoms for the synthesis of other biochemical substances (proteins, lipids, and nucleic acids) 4. Carbohydrates form part of the structural framework of DNA and RNA molecules.

5. 5. Carbohydrates linked to lipids (Chapter 2) are structural components of cell membranes. 6. Carbohydrates linked to proteins (Chapter 3) function in a variety of cell-cell and cell-molecule recognition processes.

6. Classification of Carbohydrates Most simple carbohydrates have empirical formulas that fit the general formula Cn,H2n, On. An early observation by scientists that this general formula can also be writ- ten as Cn(H₂O)n, is the basis for the term carbohydrate that is, "hydrate of carbon."

7. 1. A carbohydrate is a polyhydroxy aldehyde, a polyhydroxy ketone, or a compound that yields polyhydroxy aldehydes or polyhydroxy ketones upon hydrolysis. The carbohydrate glucose is a polyhydroxy aldehyde, and the carbohydrate fructose is a polyhydroxy ketone

8. Carbohydrates are classified on the basis of molecular size as monosaccharides , disaccharides , oligosaccharides , and polysaccharides. 1. A monosaccharide is a carbohydrate that contains a single polyhydroxy aldehyde or polyhydroxy ketone unit. Monosaccharides cannot be broken down into simpler units by hydrolysis reactions. Both glucose and fructose are monosaccharides. Naturally occurring monosaccharides have from three to seven carbon atoms; five- and six-carbon species are especially common. Pure monosaccharides are water-soluble, white, crystalline solids

9. 2. A disaccharide is a carbohydrate that contains two monosaccharide units covalently bonded to each other. Like monosaccharides, disaccharides are crystalline, water- soluble substances. Sucrose (table sugar) and lactose (milk sugar) are disaccharides. Hydrolysis of a disaccharide produces two monosaccharide units. 3. A oligosaccharide is a carbohydrate that contains three to ten monosaccharide units covalently bonded to each other. "Free" oligosaccharides are seldom encountered in biochemical systems. They are usually found associated with proteins and lipids in complex molecules that have both structural and regulatory functions, Complete hydrolysis of an oligosaccharide produces several monosaccharide molecules; a tri- saccharide produces three monosaccharide units, a hexasaccharide produces six mon - osaccharide units, and so on.

10. A polysaccharide is a polymeric carbohydrate that contains many monosaccharide units covalently bonded to each other. The number of monosaccharide units present in a polysaccharide varies from a few hundred units to over 50,000 units. Polysaccharides, like disaccharides and oligosaccharides, undergo hydrolysis under appropriate conditions to produce monosaccharides.

11. The oligo in the term oli - gosaccharide comes from the Greek oligos, which means "small" or "few." The term oligosaccharide is pronounced "OL- ee -go-SACK-uh-ride."

12. Types of carbohydrates are related to each other through hydrolysis. Polysaccharides ↓Hydrolysis Oligosaccharides ↓Hydrolysis Disaccharides ↓Hydrolysis Monosaccharides