Chapter 6 Review Chemisty of Life

Elements Matter is made up of elements An element is a substance that cannot be broken down to other substances by chemical reactions Carbon, oxygen, hydrogen, and nitrogen make up 96% of living organisms. Elements found in small amounts are called trace elements. Examples are iron and copper. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Table 2-1 Table 2-1

Structure of Atoms An atom is the smallest particle of an element that has the characteristics of that element. Atoms are the building blocks of matter Atoms are composed of: Protons – positive charged particles Neutrons – particles with no charge Electrons - negatively charged particles

Protons and neutrons are found in the nucleus Protons and neutrons are found in the nucleus. The nucleus has a positive charge. Electrons are found in orbits around the nucleus in regions called electron clouds.

Electrons fill energy levels in order from lowest to higher energy levels.

Sodium Atom 11 Protons 12 Neutrons 11 Electrons

Isotopes are forms of an atom with different numbers of neutrons The number of protons tells you what element you have and does not change. If the proton number changes, it is a different element. Neutron number can change, but it is still the same element.

Using the Periodic Table

Chemical Bonding Atoms must fill their outer energy levels tmore do become stable. They do this by forming bonds with other atoms to fill the outer energy levels. Compounds are substances composed of atoms of two or more different elements that are chemically combined and have different properties that the elements that combined.

Ionic Bonds form by the transfer of electrons Ions are charged atoms.

Covalent bonds are formed by sharing of electrons

Metabolism is the sum of all the chemical reactions that take place in an organism. Reactions break down and build molecules that are important to the functioning of organism.

Mixtures are combination of substances that mix together but retain their individual properties Solutions are mixtures in which one substance is distributed evenly in another. Mixtures can be separated by physical means. The chemical reactions of life take place in solutions. Solvents are substances that dissolve other substances. Solute is the substance that is dissolved.

Chemical reactions depend on the pH of the environment. pH is a measure of how acidic or basic a solution is. The pH scale has 14 units. The pH scale measures the hydrogen ion concentration. pH of 7 is neutral and is the pH of pure water. An acid is a substance that forms hydrogen ions in solutions (H+) has a pH below 7. A base is a substance that forms hydroxide ions (OH-) in solutions and has a pH above 7.

Organic Chemistry is the study of carbon molecules Carbons is able to form many different molecules. Can form 4 strong covalent bonds. It can form bonds with four other elements, four groups of elements, or long chains with itself. Carbon can form single, double, and triple bonds. Carbon can form ring compounds.

Isomers are compounds that have the same chemical formula, but have different structures.

There are four Biomolecules. The four biomolecules are: Carbohydrates Lipids Proteins Nucleic Acids

Carbohydrates Carbohydrates are made up C, H, and O The formula is CH2O – for every carbon, there is a water molecule. Simple sugars are the monomers; long chains of simple sugars combine to produce a polymer.

Two sugars can combine to form a dissacrharide. .A single sugar is called a monosaccharide. Two sugars can combine to form a dissacrharide. FORMATION A BOND BY THE REMOVAL OF WATER IS CALLED DEHYDRATION SYNTHESIS.

Polysaccharides are polymers of glucose. Plants store sugar as starch. Animals store sugar as glycogen. Cellulose is found in plant cell walls.

Lipids are fats, waxes, and oils. Lipids are composed on one glycerol molecule and three fatty acids. Fatty acids are linked to glycerol by dehydration synthesis. Saturated fats have no double bonds between carbon atoms. Unsaturated fats have double bonds between carbon atoms.

Importance of Lipids Long term energy storage. Insulation Protective coverings Main component of cell membranes

Proteins are large, complex polymers composed of carbon, hydrogen, oxygen, and nitrogen. Proteins are chains of amino acids.

Proteins are formed by dehydration synthesis.

Importance of Proteins Structure of living organisms. Chemical messengers - example: hormones Protection - example: antibodies Enzymes - required for chemical reactions to happen fast enough to maintain life. Help transport materials in cells.

Enzymes

Nucleic Acids Nucleic Acids are important in the passage of genetic information from one generation to the next. Nucleic Acids are composed of a five carbon sugar, a nitrogenous base, and a phosphate group. There are two nucleic acids: RNA and DNA.