Biochemistry of Cells

ORGANIC MOLECULES: Normally found in living systems Contain C (carbon) Usually in rings or long chains Often attached to other atoms such as Hydrogen, Oxygen and Nitrogen.

Uses of Organic Molecules Canadians consume an average of 140 pounds of sugar per person per year Cellulose, found in plant cell walls, is the most abundant organic compound on Earth

Uses of Organic Molecules A typical cell in your body has about 2 meters of DNA A typical cow produces over 200 pounds of methane gas each year (see video)

Touching on Water About percent of an organism is water Water is used in most reactions in the body Water is called the universal solvent

Carbon-based Molecules Although a cell is mostly water, the rest of the cell consists mostly of carbon-based molecules Organic chemistry is the study of carbon compounds

Carbon is a Versatile Atom It has four electrons in an outer shell that holds eight Carbon can share its electrons with other atoms to form up to four covalent bonds

Hydrocarbons The simplest carbon compounds … Contain only carbon & hydrogen atoms

Carbon can use its bonds to:: Attach to other carbons Form an endless diversity of carbon skeletons

Large Hydrocarbons: Are the main molecules in the gasoline we burn in our cars The hydrocarbons of fat molecules provide energy for our bodies

Shape of Organic Molecules Each type of organic molecule has a unique three- dimensional shape The shape determines its function in an organism

Functional Groups are: Groups of atoms that give properties to the compounds to which they attach Gained Electrons Lost Electrons

Common Functional Groups

Giant Molecules - Polymers Large molecules are called polymers Polymers are built from smaller molecules called monomers Biologists call them macromolecules

Examples of Polymers Proteins Lipids Carbohydrates Nucleic Acids

Most Macromolecules are Polymers Polymers are made by stringing together many smaller molecules called monomers Nucleic Acid Monomer

Linking Monomers Cells link monomers by a process called dehydration synthesis (removing a molecule of water) This process joins two sugar monomers to make a double sugar Remove H Remove OH H 2 O Forms

Breaking Down Polymers Cells break down macromolecu les by a process called hydrolysis (adding a molecule of water) Water added to split a double sugar

Macromolecules in Organisms There are four categories of large molecules in cells: Carbohydrates Lipids Proteins Nucleic Acids

CARBOHYDRA TES 1.Energy 2.Fuel for CNS 3.Fuel for the Muscular System 4.Spare Proteins 5.Supply Dietary Fiber

Carbohydrates Carbohydrates include: Small sugar molecules in soft drinks Long starch molecules in pasta and potatoes

Carb Classification Known as saccharides

Characteristics of Carbohydrates Consist of carbon, hydrogen, & oxygen Energy containing molecules Some provide structure Basic building block is a monosaccharide (CH 2 O) n ; n = 3,5,6 Two monosaccharides form a disaccharide Many form polysaccharides!

Monosaccharides: Called simple sugars Include glucose, fructose, & galactose Have the same chemical, but different structural formulas C 6 H 12 O 6

Monosaccharides Glucose is found in sports drinks Fructose is found in fruits Honey contains both glucose & fructose Galactose is not found in nature

Isomers Glucose & fructose are isomers because they’re structures are different, but their chemical formulas are the same

Rings In aqueous (watery) solutions, monosaccharides form ring structures

Cellular Fuel Monosacchar ides are the main fuel that cells use for cellular work ATP

Disaccharides A disaccharide is a double sugar They’re made by joining two monosaccharides Involves removing a water molecule (dehydration)

Disaccharides Common disaccharides include:  Sucrose (table sugar)  Lactose (Milk Sugar)  Maltose (Grain sugar )

Disaccharides Sucrose is composed of glucose + fructose Maltose is composed of glucose + glucose Lactose is made of galactose + glucose GLUCOSE

Hydrolysis of a Disaccharide:

Polysaccharides Complex carbohydrates Composed of many sugar monomers linked together Polymers of monosaccharide chains

Examples of Polysaccharides Starch Glycogen Cellulose Glucose Monomer

Starch Starch is an example of a polysaccharide in plants Plant cells store starch for energy Potatoes and grains are major sources of starch in the human diet

Glycogen Glycogen is an example of a polysaccharide in animals 2/3 muscles; 1/3 liver Acts as a carb reserve!

Cellulose Cellulose is the most abundant organic compound on Earth It forms cable-like fibrils in the tough walls that enclose plants It is a major component of wood It is also known as dietary fiber

Cellulose SUGARS

Dietary Cellulose Most animals cannot derive nutrition/energy from fiber They have bacteria in their digestive tracts that can break down cellulose

Another important Polysaccharide: CHITIN: Glucose subunits Partly derived from non-sugars (nitrogen) Composes exoskeletons of insects Similar in structure to cellulose

Sugars in Water Simple sugars and double sugars dissolve readily in water They are hydrophilic, or “water- loving” WATER MOLECULE SUGAR MOLECULE

INTERACTIVE CARBOHYDRATES: RECAP: Let’s Take another LOOK! logy/02biologicalmolecules/index.shtmlhttp:// logy/02biologicalmolecules/index.shtml

Carb Digestion: (1-4 hrs) Cracker In the Mouth: Saliva (salivary amylase) hydrolyzing starch to shorter polysaccharides and maltose Do you think much carb digestion takes place in the mouth? In the Stomach: Bolus is continually broken down by acid, but its juices contain no enzymes to digest carbohydrates. Fibers linger in the stomach (satiety) In the Small Intestine – PERFORMS MOST OF THE WORK!! Pancreatic amylase enters and breaks down further.

Digestion cont… On the Outer Membranes of the Intestinal Cells: SPECIFIC ENZMES DISMANTLE DISACCHARIDES! Maltase breaks maltose into _________ +________ Sucrase breaks sucrose into ___________ + _______ Lactase breaks lactose into ___________ + ________ At this point, all polysaccharides and disaccharides are broken down into mono’s – mainly glucose (but some fructose and galactose as well)

Carb Absorption Nutrient absorption takes place in the SI Glucose and galactose leave the cells lining the SI by active transport Fructose leaves by facilitated diffusion, which slows its entry and produces a smaller rise in blood sugar.

Carbohydrate Overview Video Thursday – Carbohydrate Lab Friday – Research Day Monday after March Break – carb overview (begin Lipids) Tuesday after March Break – carb quiz