6.3 Life Substances

Molecules of Life

Role of Carbon in Organisms

Carbon has four electrons in outer energy level Four covalent bonds fill energy level

Role of Carbon in Organisms

Carbon can bond with other carbon atoms Double bond = each atom shares two electrons Triple bond = each atom shares three electrons

Role of Carbon in Organisms

When carbon atoms bond together they can form chains, branched chains or rings

This makes a huge number of carbon structures possible

Role of Carbon in Organisms

Compounds with the same simple structure can have different forms called isomers

Role of Carbon in Organisms

Carbon compounds can have thousands of carbons

Polymer = a large molecule formed when many smaller molecules bond together

Condensation = large molecule is formed by removing H-O-H

Hydrolysis = large molecule is broken apart by adding H-O-H

Role of Carbon in Organisms

Carbohydrates

Used by cells to store and release energy Organic compound

with carbon, hydrogen2, and oxygen Simple carbohydrate = monosaccharide Two sugar carbohydrate = disaccharide Many sugars = polysaccharide

Carbohydrates

Molecules of Life

Carbohydrates Lipids Proteins Nucleic Acids

Lipids

Used by cells to store energy, insulate and in protective coatings

Organic compound with many more carbon and hydrogen than carbohydrates

For example, beef fat C57H110O6

Not soluble in water because lipids are non-polar

Lipids

2 main types Each made of 3 fatty acids and a glycerol Saturated—bad for you (butter) Unsaturated—good for you (peanut butter)

Lipids

Proteins

Provide structure and carry out cell metabolism Large polymer built of amino acids

Carbon, hydrogen, oxygen, nitrogen, sulfur There are 20 common

amino acids that can build thousands of proteins

Proteins

Amino acids link together in peptide bonds

Number and order of amino acids determines the kind of protein

Proteins

Contract muscle tissue Transport oxygen in bloodstream Provide immunity Carry out chemical reactions Enzyme = protein that changes the rate of a

chemical reaction

Nucleic Acids

Stores cellular information in code Made up of nucleotides Carbon, hydrogen, oxygen, nitrogen

phosphorus Arranged in a base, a sugar, and a

phosphate group

Nucleic Acids

DNA = Deoxyribonucleic acid Contains instructions on how to make

enzymes and proteins Genetic code for how an organism looks Passed from one generation to the next

Nucleic Acids - DNA

Nucleic Acids

RNA = ribonucleic acid Makes copies of DNA

for use in making proteins