Chemistry of Life Nature of matter

Atom is the smallest unit of matter that cannot be broken down by chemical means. Atoms typically have 1 electron for each proton, so they are neutral. (Neutral, meaning no electrical charge.

3 Basic Particles of an Atom Charge Location Proton Positive (+) Nucleus Neutron Neutral (0) Electron Negative (-) Electron Cloud

The electrons are located in energy levels located outside of the nucleus where the electrons can move. These energy levels are known as the electron cloud.

An isotope is an atom of an element that has the same number of protons, but a different number of neutrons.

Element is a substance made of only one kind of atom, and it is a pure substance. There are four elements that make up 96% of the human body: Carbon Hydrogen Oxygen Nitrogen

Atoms can bond together. A compound is a substance made of the joined atoms of two or more different elements. Example: Na+ + Cl-  NaCl Sodium ion + Chlorine ion  Sodium Chloride Table Salt

A force that joins atoms is called a bond. There are two types of bonds, that we will study. Covalent Bonds Ionic Bonds Covalent and Ionic compounds are alike in that they both fill outer electron levels.

Covalent bonds are created when two or more atoms share electrons and form a molecule. Molecules are held together by covalent bonds. Examples: H2O, CO2, and O2

Molecules with an unequal distribution of electrical charge are polar molecules. Water has a positive charge on one end and a negative charge on the other. Because of its uneven charge, water is a polar molecule. A hydrogen bond is a weak chemical attraction between polar molecules.

Ionic bonds are formed by the electrical attraction between oppositely charged ions. Ion is an atom that has gained or lost an electron. An ion is a charged atom or molecule.

Ionic Bonds, continued… An atom that has lost electrons is positively charged. An atom that has gained electrons is negatively charged.

Ions of opposite charges may interact to form an ionic bond. Example of an ionic bond: Na+ + Cl-  NaCl Sodium ion + Chlorine ion  Sodium Chloride

Acids & Bases pH is a measure of how acidic or basic (alkaline) a solution is. The pH scale ranges from 0-14 and is used to measure pH.

An acid is any substance that forms hydrogen ions (H+) in water. An acidic solution contains more H+ ions. An acidic solution has a pH < 7.

A base is any substance that forms hydroxide ions (OH-) in water. A basic solution contains fewer H+ ions than OH- ions. A basic solution has a pH > 7.

A pH of 7 indicates a neutral between acidic and alkalinity. Let’s test ourselves: 3.24 9.13 6.9 7.2 8.43

Water & Solutions Water is an inorganic substance which means it is not made from carbon or living things. Water is composed of 1 atom of oxygen and 2 atoms of hydrogen. Water molecules are linked by hydrogen bonds. This causes water to heat up and cool down slowly.

Water & Solutions Water, which is essential for life, stores heat efficiently and binds to itself and other substances. The most abundant inorganic substance in a cell is water.

The hydrogen bonds between water molecules cause the cohesion of liquid water. Cohesion is an attraction between substances of the same kind.

Because of cohesion, water and other liquids form drops and thin films Because of cohesion, water and other liquids form drops and thin films. The thin films allow some insects to stand of the surface of water because water is cohesive and adhesive. This attraction between water molecules (to itself) causes a condition known as surface tension.

Surface Tension

Water molecules are also attracted to many other polar substances. Adhesion is an attraction between different substances. Because water sticks to solids (adhesion), water has the property of capillarity.

Capillarity is the ability to spread through fine pores or to move upward through a tubes (such as the stem of a plant) against the force of gravity. The attraction of water to the walls of the tube sucks the water up more strongly than gravity pulls it down. Example: Graduated Cylinder, meniscus

Capillarity

Water dissolves many substances… Due to water’s polar nature (uneven charge distribution), water makes a good solvent, meaning that it can pull apart other molecules. Nonpolar molecules do not dissolve well in water. When nonpolar substances, such as oil are placed in water the oil forms lumps of beads in the water.

Polar Molecules & Water

Nonpolar molecules & water

Chemistry of Cells Organic compounds contain carbon. There are 4 types of organic compounds found in living things. Carbohydrates Lipids Nucleic Acids Proteins

Without these compounds, cells could not function. All of these compounds are long repeating units called polymers. Polymers are large molecules formed when many smaller molecules bond together usually in long chains. Each subunit of a polymer is called a monomer (simple molecule).

Carbohydrates Carbohydrates are organic compounds made of carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio. They are the main source of energy for living things, and are found in most foods – like fruits, vegetables, and grains. Most energy that is used in the human body is stored as carbohydrates.

Carbohydrates =

Three Types of Carbohydrates Monosaccharides, or simple sugars, are the building blocks of carbohydrates. Examples of Monosaccharides: Glucose is manufactured by plants during photosynthesis. It is the main source of energy for plants and animals. Fructose is found in fruits and is sweet.

They have the same molecular formula, C6H12O6, but different structural formulas, which makes them isomers.

Three Types of Carbohydrates 2. Disaccharides are two monosaccharide molecules linked together. Example: Sucrose (table sugar) is composed of fructose and glucose linked together.

Three Types of Carbohydrates 3. Polysaccharides are composed of many monosaccharide subunits. Polysaccharides function as storehouses of the energy contained in sugar. Examples: Starch which is made by plants (like potatoes). Energy is passed from potato to the person eating it primarily by the energy stored in starch molecules. Glycogen which is made by animals. Both starch and glycogen are made of hundreds of linked glucose molecules. Cellulose is the polysaccharide that provides structural support for plants. Humans cannot digest cellulose (wood).

STARCH GLYCOGEN IN LIVER CELLS CELLULOSE

Lipids Lipids are nonpolar molecules that are not soluble in water. Lipids are used to store energy (long-term), for insulation, and as protective coatings. Lipids are composed of 3 fatty acids bonded to a glycerol molecule. Examples: fats, phospholipids, steroids, including cholesterol and waxes. FATS STEROIDS CHOLESTEROL WAXES

Lipids The monomers of lipids are fatty acids. Lipids are an important part of the structure and functioning of cell membranes. Phospholipids make up the lipid bilayer of cell membranes. Fats are lipids that store energy. Saturated Fats are solid at room temperature, and they usually come from animals… butter Unsaturated Fats are liquid at room temperature, and they usually come from plants like corn, peanuts, and olives.

The phospholipid bilayer

Lipids Waxes are highly waterproof. In plants, wax forms a protective coating on the outer surfaces, for example on the leaves. In animals, wax forms protective layers, for example ear wax.

Nucleic Acids Nucleic Acids are in all of your cells. The building blocks of nucleic acids are nucleotides. A nucleic acid is a long chain of smaller molecules called nucleotides. A nucleotide has three parts: Sugar Base Phosphate Group

Sugar Phosphate Group Base

Two Types of Nucleic Acids DNA – Deoxyribonucleic Acid DNA consists of 2 strands of nucleotides that spiral around each other. The spiral-staircase shape of DNA is known as the double helix. The two strands of a DNA molecule are held together by hydrogen bonds between the two bases across from one another. Your chromosomes consist of very long strands of DNA, which stores heredity information (or genetic code) that can be used to make proteins. 2. RNA – Ribonucleic Acid RNA consists of a single strand of nucleotides.

Proteins Proteins are long chains of molecules called amino acids that are linked together like parts on a necklace. Amino Acids are the building blocks of proteins. There are 20 different Amino Acids, which bond to each other by peptide bonds (covalent bonds formed between amino acids). Some proteins called enzymes regulate chemical reactions in the body but remain unchanged by the reaction. The complete hydrolysis of a protein would result in the formation of amino acids. Hydrolysis is a chemical reaction which water is used to break down a compound.

Proteins ATP – Adenosine Triphosphate ATP carries energy in cells. ATP is a single nucleotide with two extra energy-storing phosphate groups.