1. Atom 2. Nucleus 3. Electron 4. Element 5. Compound 6. Molecule 7. Covalent Bond 8. Ionic Bond 9. Acid 10.Base

Chapter 2

Biochemistry – the study of the chemicals of living things and their changes

Democritus –2500 yrs. Ago

Have subatomic particles: protons (+), neutrons (no charge), and electrons (-)

◦ Particles found in the nucleus = protons and neutrons

◦ Particles found outside the nucleus in energy levels = electrons

One type of Atom A pure substance Atomic # = the number of protons Mass # = the number of protons and

neutrons

Atoms of the same element that have different #’s of neutrons

These atoms have the same chemical properties

Radioactive isotopes = useful and dangerous

The chemical combination of one or more elements in a fixed ratio

◦ Example: H2O = 2Hydrogen: 1Oxygen Physical and chemical properties of these

elements are quite different

These bonds hold atoms in a chemical compound together

Valence electrons = the very outside electrons of an atom that form bonds.

1. Ionic Bonds = One or more electrons are transferred from one atom to another. There is a strong attraction between elements with opposite charged ions.

◦ Ion – atom that has gained or lost electrons◦ Loss (+, more protons), gain (-, more

electrons).◦ Example Na (sodium) loses an electron to Cl

(chlorine) = Na+Cl-

2. Covalent Bonds = One or more electrons are shared from one atom to another.

◦There are single and double covalent bonds

◦These form moleculesExample: H2 , N2

◦The particles that move around the nucleus of an atom are called neutrons. protons. electrons. isotopes.

◦The atomic number of a carbon atom is 6. How many neutrons does the isotope carbon-14 have? 6 8 12 14

◦Which of the following statements about the three isotopes of carbon is true? They are all radioactive. They have different numbers of electrons. They have the same chemical properties but differ

in atomic mass. They have the same number of protons and

neutrons.

◦A chemical compound consists of Electrons mixed with neutrons. two or more elements combined in a definite

proportion. two or more elements combined in any proportion.

at least three elements combined by ionic or covalent bonds.

◦Van der Waals forces are the result of unequal sharing of electrons. ionic bonds. the bonding of different isotopes. the chemical combination of sodium and chlorine.

Water is a Polar Molecule – uneven distribution of electrons between Hydrogen and Oxygen

Water is very cohesive = it is highly attracted to other water molecules◦ This is due to Hydrogen

bonding

A mixture is two or more elements or compounds that are mixed together

2 Types◦ 1. Solution = Compounds are evenly

distributed.Contain solutes = substances being

dissolved, and solvents = the substance in which the solute is dissolved.

◦ 2. Suspensions = mixtures with undissolved materials

pH Scale = the concentration of H+ (hydrogen) and OH- (hydroxide) ions in solution.

Acids = Higher concentration of H+ ions then pure water = pH below 7

Bases = Lower concentration of H+ ions then pure water = pH above 7

H2O H+ + OH−

Water Hydrogen ion + hydroxide ion

Lots of H+ = acid Lots of OH− = base

Measure of H+ in solution The higher the H+ the closer to zero on the

pH scale Scale from 0 – 14

0 – 6.9 = acid 7 = neutral 7.1 – 14 = base

Each step on the pH scale represents a factor of 10◦ An acid with a pH of 4 is ten times stronger than

an acid with a pH of 5◦ How many times more basic is a pH of 10 than a

pH of 8? 100 times more basic (10) (10) = 100

Tools used to measure pH◦ Example: pH paper, litmus paper

Measures amount of H+ and changes color based on the concentration

Weak acid or base that can react with strong acids or bases to help prevent sharp, sudden changes in pH

Buffers are very important for maintaining homeostasis in living things

◦A molecule in which the charges are unevenly distributed is called a polar molecule. cohesive molecule. hydrogen molecule. covalent molecule.

◦A dissolved substance is called a solvent. solution. solute. Suspension.

◦A compound that produces hydroxide ions in solution is called a(an) base. buffer. acid. salt.

◦Hydrogen bonds between water molecules result from adhesion between water molecules. magnetic attractions between water molecules. uneven electron distribution in each water

molecule ionic bonds in the water molecule.

◦On a pH scale, a value of 2 means that the solution has equal concentrations of H+ and OH- ions. the same concentration of H+ ions as pure water.

higher concentration of H+ than in pure water. lower concentration of H+ than in pure water.

Organic Chemistry - Study of all compounds that contain bonds between carbon atoms.

Why is Carbon so important?◦ 4 Valence Electrons = strong covalent bonds

between other atoms ◦ Carbon can bond to other carbon atoms = single,

double, triple bonds

Giant Molecules Created by

Polymerization = Chemical process in which small units of compounds, called monomers, join together to build large units, called polymers

4 groups of carbon based compounds found in living things◦1. Carbohydrates Made up of carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio

Bodies main source of energy (Animals)

Used for structural purposes (plants)

Sugars (immediate energy) and starches (stored energy). Sugar monomers make up starches. Monosaccharides = “single

sugar” molecules. Ex. Glucose Polysaccharides = “many

simple sugar” molecules. Ex. Glycogen (animals) and Cellulose (plants).

2. Lipids◦ Made up of Carbon and Hydrogen

atoms ◦ Insoluble in water.◦ Fats, oils, steroids, and waxes ◦ Used to store energy.◦ Composed of glycerol and fatty

acids◦ 2 types

1. Saturated = Fatty acid carbon chains are joined by a single bond. These fatty acids contain the max. # of Hydrogen atoms

2. Unsaturated = Contains one carbon-carbon double bond in the fatty acid

Saturated Fat Unsaturated Fat

3. Nucleic Acids◦ Contain hydrogen, oxygen, nitrogen, carbon,

and phosphorous ◦ Polymers assembled from nucleotides = a 5-

carbon sugar, a phosphate group, and nitrogenous base.

◦ Store and transmit hereditary or genetic information

◦ 2 Types DNA – Deoxyribonucleic acid RNA – Ribonucleic acid

4. Proteins◦ Contain Nitrogen, Carbon, Hydrogen, and Oxygen ◦ Polymers of amino acids (a.a.) = one amino

group (NH2) end , one carboxyl group (COOH) end, and a third group called the R-group. Each amino acid has a different R-group.

◦ Most diverse macromolecules = Amino acids (20) have an ability to attach to any other amino acid in nature. Attach at amino and carboxyl groups

◦ All proteins have specific roles◦ Control reaction rates and regulate cell

processes ◦ All have 4 levels of organization: Important!!

Primary = sequence of amino acids. Secondary = twisted and folded

chain of amino acids. Tertiary = Chain is then twisted

itself. Quaternary = The entire protein

maintains a folded, twisted shape due to H-bonds and Van der Waals Forces.

◦Large carbohydrate molecules such as starch are known as lipids. monosaccharides. proteins. polysaccharides.

◦Many lipids are formed from glycerol and fatty acids. monosaccharides. amino acids. nucleic acids.

◦Proteins are among the most diverse macromolecules because they contain both amino groups and carboxyl

groups. they can twist and fold into many different and

complex structures. they contain nitrogen as well as carbon, hydrogen,

and oxygen. their R groups can be either acidic or basic.

◦Which of the following statements about cellulose is true? Animals make it and use it to store energy. Plants make it and use it to store energy. Animals make it and use it as part of the skeleton.

Plants make it and use it to give structural support to cells.

◦A major difference between polysaccharides and proteins is that plants make polysaccharides, while animals make

proteins. proteins are made of monomers, while

polysaccharides are not. polysaccharides are made of monosaccharides,

while proteins are made of amino acids. proteins carry genetic information, while

polysaccharides do not.

Chemical Reaction =◦The changing of one set chemicals into another set of chemicals.

◦It will always involve breaking of bonds in reactants and forming new bonds in the products.

All chemical reactions have 2 parts:◦ 1. Reactants = The chemicals that enter a

reaction ◦ 2. Products = The elements or compounds that

are formed from the reactants chemical interaction

CO2 + H2O H2CO3 + EnergyReactants

Products

Energy in Chemical Reactions = Energy is released (spontaneously) or absorbed (need a source of energy) during a chemical reaction

Living things need sources of energy to continue chemical reactions, and stay alive

Activation Energy = The energy needed to start a chemical reaction

Catalysts = A substance that lowers the activation energy and speeds up the rate of a chemical reaction.

Enzymes = Proteins in living things that act as catalysts. Cells use catalysts to speed up chemical reactions that take place there ◦ Lower the activation energy ◦ Very Specific = catalyze only one reaction

Activation Site = an area on the enzyme where the reactants come in contact and are able to react ◦ Reduces the energy needed ◦ Enzyme catalyzed reactions = Substrates

regulating chemical pathways.making material that cells need.

releasing energy. transferring information.

pH changes, temperature changes, cell regulation, etc.

◦The elements or compounds produced by a chemical reaction are known as reactants. enzymes. products. waste.

◦Chemical reactions always involve changes in energy. enzymes. catalysts. changes in the atomic number of the reactants.

◦The factor that prevents many energy-releasing reactions from occurring at relatively low temperatures is called catalytic energy. chemical bond energy. enzyme energy. activation energy.

◦Which of the following statements is true? All proteins are enzymes. All catalysts are enzymes. All enzymes are catalysts. All catalysts are proteins.

◦What happens to an enzyme after the reaction it catalyzes has taken place? The enzyme is destroyed, and the cell must make

another. The enzyme holds on to the product until another

enzyme removes it. The enzyme is unchanged and ready to accept

substrate molecules. The enzyme changes shape so it can accept a

different kind of substrate.