بسم الله الرحمن الرحيم
(وَإِنْ تَعُدُّوا نِعْمَةَ اللَّهِ لا تُحْصُوهَا) ابراهيم 34 صدق الله العظيم
Al - Iraqia - university Prof. Dr. Samia –Alshahwani
College of medicine Y1 L6 -2015
Human Biology
P1 Human organization
Ch 2 Chemistry of life
2.3 Molecules of Life
Objectives: By the end the student, should be able to:1- List the four classes of organic molecules that are found in cells.
2- Describe processes by which organic molecules assembled & disassembled.
3- Explain the function of simple carbohydrates and polysaccharides.
4- Describe difference in structure between simple & complex carbohydrate
5-Summarize benefits of fiber in diet.
Organic molecules, carbohydrates, lipids, proteins, & nucleic acids are unique to cells, organic mean contain carbon (C) and hydrogen (H) & is associated with organism. Each type contains subunits, macromolecule, a molecule that contains many subunits; it uses a dehydration reaction, (a type of synthesis reaction). an OH (hydroxyl group) and an H (hydrogen atom), the equivalent of a water molecule, are removed as the molecule forms (Fig. 2.11a). The reaction is reminiscent of a train whose length is determined by how many boxcars it has hitched together. To break down macromolecules, the cell uses a hydrolysis reaction in which the components of water are added during bond breaking between molecules (Fig. 2.11b).
Fig. 2.11 The breakdown & synthesis of macromolecules.
Subunits bond in a dehydration reaction. Water is given off and a macromolecule forms.In the reverse reaction, macromolecules are divided into subunits by hydrolysis
2.4 Carbohydrates
Carbohydrate molecule characterized by presence of atomic grouping H-C-O H, in which the ratio of hydrogen atom (H) to oxygen atom is approximately 2:1this ratio is the same ratio of water
Simple carbohydrates, include monosaccharides & disaccharides.
Monosaccharide:
Pentose means a 5 Carbone sugar;
Hexoes means a 6 Carbone sugar,
Glucose the hexose, body use as immediate source of energy C6H12O6
Other common hexose:
Fructose in fruits
Galactose a constituent of milk
Disaccharide: Made by joining 2 monosaccharide by Dehydration reaction, Maltose, formed by a dehydration reaction between 2 glucose molecules
Sucrose, formed by joining fructose & glucose. known as table sugar
Glucose is a 6-carbon sugar used by cells for quick energy.
Complex carbohydrates: Are polysaccharides containing many glucose unit
Plants store glucose as starch, whereas animals store glucose as glycogen.
Cellulose forms plant cell walls. Cellulose is dietary fiber (fig2.15)
Fiber plays an important role in digestive system heal
Fiber in the Diet
Fiber, (roughage), is undigested carbohydrates pass through digestive system, from plants carbohydrates; include cellulose, pectins, and lignin. Fiber is not truly a nutrient because not used for energy or building cells, but it is an extremely important. Fiber adds bulk to material in the intestine, keeps the colon functioning normally, and it binds many types of harmful chemicals in diet, including cholesterol, & prevents them from being absorbed. There are 2 fiber types:-Insoluble; Provides bulk to fecal material, found in bran, nuts, seeds, & whole wheat foods.
-Soluble: Dissolves in water & acts in binding of cholesterol, found in fruits, oat grains.
Fiber reduces risk of cardiovascular disease, diabetes, colon cancer, & diverticulitis Thanks Samia 2015Your.