Chapter 2The Chemistry of Life

Warm-Up

Look at the following words. Place each one in the table below and define if you think you can.atom proton neutron

electron nucleus element

compound

Don’t know the meaning at all

I think the meaning is:

I know the meaning is:

2-1 The Nature of MatterA. Atom – The basic unit of matter

1. 3 types of subatomic particles in an atom– a. proton (+ charge)– b. neutron (no charge)– c. electron (- charge)

• Protons and neutrons are in the NUCLEUS • Electrons are in constant motion around the

nucleus. ---Atoms have a neutral charge!--

B. Elements and Isotopes

1. Element - is a pure substance that consists entirely of one type of atom.

a. Atomic number- number of protons in an atom (C- Carbon 6)

An atom has the same number of protons and electrons.

2. Isotopes – Atoms of the same element that differ in the number of neutrons.

a. Mass number- sum of protons and neutrons

b. Isotopes are named by their mass number

3. Radioactive Isotopesa. Geologists determine age of rocks

b. Radiation for cancer

c. Used as tracers to follow substances in organisms

C. Chemical Compounds

1. A compound is a combination of two or more elements in definite proportions

2. Use chemical formula

D. Chemical Bonds

1. Ionic – valence electrons are transferred (ex: NaCl)

2. Covalent – valence electrons are shared (ex: H20)

3.Van der Waals Forces – When molecules are close together they can develop a slight attraction to the oppositely charged regions of nearby molecules

Warm-up

• Draw a pH scale. Then place the following substances on the scale in the appropriate location according to their pH values.– Dr. Pepper– Fantastik cleaner– Water

Answer:

0 7 14

Dr.P water Fantastik

2-2 Properties of Water

A. Characteristics of Water

- It is the single most abundant

compound in most living things

- A water molecule is neutral

1. Polarity – the oxygen end of the molecule has a slight neg (-) charge and the hydrogen end has a slight pos(+) charge.

There is an uneven distribution of e- between O and H

2. Hydrogen Bonds - attraction between the partial positive and the negative charges of atoms. These bonds are not as strong as ionic or covalent bonds. (EX: Water)

a. Cohesion – attraction between molecules of the same substance

b. Adhesion - attraction between molecules of different substances.

B. Solutions and Suspensions1. Mixture – material composed of two or

more mixed compounds that are physically mixed together but not chemically combined. a. Solutions – all components are evenly

distributed (ex: salt water)1. solute – what is being dissolved2. solvent – substance in which

the solute dissolves b. Suspensions – mixture with non-dissolved particles (ex: blood)

Questions

• 1. How do you know whether a sample is a mixture(physical) or a compound (chemical)?

• Answer: a mixture can easily be separated into the component parts

• 2. Are solutions only in the liquid state?

• Answer: No, solutions can be solids, liquids, or gases

C. Acids and Bases

1. pH Scale – indicates the number of H+

ions in a solution. (Ranges from 1-14)

2. Acids – Contain a higher concentration of H+

ions than pure water and pH values below 7

3. Bases – Contain a lower concentration of H+

ions than pure water and pH values above 7. They also produce OH-

4. Buffers – weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH

Chapter 2-3 Carbon Compounds

What is a Valence Electron?

What is an Organic Compound?

A. Carbon1. 4 Valence Electrons

2. Ability to bond with other elements and itself – millions of structures

3. Compounds containing carbon are considered ORGANIC

B. Macromolecules – “giant molecules”

1. Connecting monomers to make polymers

2. 4 groups of macromolecules

a. Carbohydrates

i. carbon, hydrogen, oxygen – 1:2:1 ratio

ii. main source of energy for organisms

iii. starch – storage molecule

iv. monosaccharides (ex. Glucose) and polysaccharides (glycogen and cellulose)

b. Lipids

i. not soluble in water

ii. fats, oils, and waxes

iii. glycerol + fatty acid

iv. saturated (max # of H bonds) and unsaturated (at least one double bond=)

c. Nucleic acids

i. H, O, N, C, P

ii. Polymers of nucleotides – sugar, phosphate, and nitrogen base

iii. Store and transmit hereditary or genetic information

iv. RNA and DNA

d. Proteins

i. N, C, H, O

ii. Polymers of amino acids

iii.Amino group- NH2 and a carboxyl group – COOH

iv.Proteins control rate of cell reaction(rxn),

regulate cell processes,

form bones and muscles,

transport into and out of cells, and

some fight diseases

4 levels of organization of proteins

Primary- sequence of amino acids in a protein chain

Secondary- amino acid within a chain is twisted or folded

Tertiary- the chain itself is folded

Quaternary- if a protein has more than one chain

Protein Structure

Chapter 2-4 Chemical Reactions and Enzymes

A. Chemical Reactions – process that changes one set of chemicals into another set of chemicals

1. reactants → products

2. breaking of bonds in reactants and forming new bonds in products

B. Energy in Reactions – released or absorbed

1. RXNS (reactions) that release energy are spontaneous – produce heat light and sound

2. RXNS that absorb energy must have a source of energy – plants (sunlight) and animals (food)

3. Activation Energy – energy needed to get reaction started

Catalyzed vs. UncatalyzedReaction

C. Enzymes – (Proteins)

1. Are biological catalysts

2. Catalyst – speed up RXN by lowering activation energy

3. Very specific – only one reaction

D. Enzyme Action

1. Enzyme-Substrate Complex

a. substrates – reactants of enzyme-catalyzed reactions

b. active site – where substrates bind to enzyme (lock and key)

• Catalase. It catalyzes the decomposition of hydrogen peroxide into water and oxygen.

• 2H2O2 -> 2H2O + O2

• One molecule of catalase can break 40 million molecules of hydrogen peroxide each second

Competitive Inhibition

Competitive inhibitionThe necessity for a close, if brief, fit between enzyme and substrate explains the phenomenon of competitive inhibition.

One of the enzymes needed for the release of energy within the cell is succinic dehydrogenase. It catalyzes the oxidation (by the removal of two hydrogen atoms) of succinic acid (a). If one adds malonic acid to cells, or to a test tube mixture of succinic acid and the enzyme, the action of the enzyme is strongly inhibited. This is because the structure of malonic acid allows it to bind to the same site on the enzyme (b). But there is no oxidation so no speedy release of products. The inhibition is called competitive because if you increase the ratio of succinic to malonic acid in the mixture, you will gradually restore the rate of catalysis. At a 50:1 ratio, the two molecules compete on roughly equal terms for the binding (=catalytic) site on the enzyme.

2. Regulation of Enzyme Activity

a. pH values

b. temperature

c. cells regulate - proteins turn enzymes “on” or “off”

• Feedback Inhibition

• If the product of a series of enzymatic reactions, e.g., an amino acid, begins to accumulate within the cell, it may specifically inhibit the action of the first enzyme involved in its synthesis (red bar). Thus further production of the enzyme is halted.