Biology Chapter 2 Chemistry of Life Atom-Smallest unit of matter that cannot be broken down by chemical means!!!! So small scientist have developed models like the one below. Atoms consist of three kinds of particles. Electrons-negatively charged particles Protons-positively charged particles Neutrons-neutrally charged particle What makes up the center of the atom? The NUCLEUS What make up the nucleus? Protons and neutrons!! What are wickedly fast outsiders? Electrons!!!! Atoms typically have one electron for each proton, so they have no electrical charge.

Elements Oxygen, Sulfur, Helium Pure substance made of only one kind of atom. Elements differ from the number of protons they have in the nucleus. Let’s go over your periodic table!!!

More on elements….. There are approximately 118 elements, more are being discovered or are man-made Some elements of the same type may contain different numbers of neutrons and are called isotopes Examples are Carbon, Carbon- 12, Carbon-14, these isotopes can be radioactive.

Chemical Bonding Atoms can join with other atoms to form stable substances. It is a force that joins atoms is called a chemical bond. Compound-Is a substance made of the joined atoms of two or more different elements. Example-NaCl-sodium and chlorine bonded together C 6 H 12 O 6 -sugar, Carbon, Hydrogen and Oxygen bonded together.

Three types of bonds Covalent bonds-Form when two or more atoms share electrons to form a molecule. Example-CO 2, H 2 O, or O 2 Hydrogen bonds-A weak chemical attraction between polar molecules. Examples are water! Read page 29. Ionic bonds-An atom or molecule that has gained or lost one or more electrons. Example-NaCl or salt! They may have an electric charge because they contain an unequal number of electrons and protons END OF SECTION 1

Water and Solutions 70% of our body is water Most cellular functions take place within water. Water helps move nutrients and other substances in and out of your cells. Storage of heat Water helps cells maintain homeostasis Water heats more slowly and retains heat longer than other substances.

Cohesion and Adhesion Cohesion is an attraction between substances of the same kind. Because of this water and other liquids form thin film and drops, like dew. This phenomena is known as surface tension.

Capillary action Adhesion-Is an attraction between different substances. Adhesion powers a process called capillary action, blood going up a capillary tube. Have you seen this happen? Another example would be how sugars, nutrients, and water make it through a plant. Aqueous solutions Solutions-A mixture in which one or more substances are evenly distributed in another substance. See this solution to the right? Sugar water is a solution, can easily move W ithin cells!!!!

Polarity The polarity of water (or slight charge on the water molecule) makes it possible for substances to dissolve in water.  Important when dissolving ionic substances such as salt (NaCl), what is an ion? Look it up, will be on the test!!!  When non-polar substances are placed in water, such as oil, water does not dissolve them, it actually pushes the non-polar substances together, which is why oil forms clumps or beads on water.

Acids and Bases While the covalent bond (form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms)that form a water molecule are fairly strong, sometimes they break to form H+ and OH-formchemical bondingelectronsatoms – Compounds that form hydrogen ions (H+) when dissolved in water are called acids. – Compounds that form hydroxide ions (OH-) are called bases. – Let’s name some acids and bases. Leave some space in your notes for these.

pH scale Is a value between 0 and 14. Pure water has a pH of 7 (sometimes not), it is considered neutral. Acids have a value between 0 and 7, while bases have a pH value between For each number increase on the pH scale, increases or decreases by a factor of 10 times.

Chemistry of Cells Your body is made up of….. – Organic compounds(containing carbon), they are generally covalently bonded to other elements such as, hydrogen, oxygen, and other living things. Carbohydrates-Organic compounds – Monosaccharides-Single sugars C6h12O6-Glucose Produce energy in the form of ATP – Disaccharides-Are single sugars joined together. Examples-table sugar – Polysaccharides-Is a large molecule made up of many sugars put together Examples-Starch and glycogen-made up of hundreds of linked glucose molecules. – Starch is made from plants – Glycogen is made from animals.

Lipids Nonpolar molecules that are not soluble or mostly insoluble in water. – Includes fats, phospholipids, steroids, and waxes. Fats-Lipids that store energy. Contains three fatty acids bonded to a glycerol molecule backbone. A fatty acid contains a long chain of Carbon atoms.

Saturated and Unsaturated Fats Saturated fats-All of the carbon molecules to two hydrogen atoms. – Examples are animal fats such as butter, and lard (good to cook with, bad for you) – Solid at room temperatures Unsaturated fats-Carbon atoms are linked by a double covalent bond, with only ONE hydrogen bond. – Examples are plant oils such as peanut oil, sesame oil, and olive oil – Liquid at room temperatures

Proteins A large molecule linked together by smaller molecules called amino acids. (We will learn much more about these later) – Amino acids are the building blocks of proteins. 20 different amino acids are found in proteins, with some being polar and others nonpolar. Proteins fold into compact shapes and due to their shape, perform different functions. – Some are enzymes and promote chemical reactions – Some have structural functions, such as skin and ligaments – Some are antibodies that defend your body against infection – Some form muscles that allow you to move – Some form hemoglobin, which carries oxygen from you lungs to your body

Some proteins and their 3-dimensional structures!!!!!

Nucleic Acids All of our cells contain nucleic acids, which is a long chain of smaller molecules called nucleotides. – A nucleotide has three parts-A sugar, base and a phosphate group – There are two types of nucleic acids: DNA or RNA DNA or deoxyribonucleic acid consists of two helical strands and stores your hereditary information (chromosomes). RNA or ribonucleic acid consists of a single strand and is important in the manufacturing of proteins. Is also acts as an enzyme. ATP-adenosine triphosphate-Temporary storage for energy.

DNA and RNA structures!!!