Chemistry of Life

Chapter 2.1

C6H12O6 + 6O2 CO2 + H2O

What elements are represented?

What compounds are represented?

How many atoms of each element are represented?

Is it balanced?Which scientific law do balanced chemical equations enforce?

Atoms – The basic unit of matter. Composed of:Protons – positively charged particles in the nucleus of the atom

Neutrons – particles with mass that have no charge; found in the nucleus of the atom

Electrons – negatively charged particles moving around the nucleus in orbits.

Atoms with equal numbers of protons and electrons are “neutral”

Atoms with uneven numbers of electrons and protons = ion

Atoms with more protons than electrons = cation (positive charge)

Atoms with more electrons than protons = anion (negative charge)

Elements – What is an Element?

One or more atoms Cannot be broken down or split

Represented by a one or two letter symbol

ex. Na (sodium)

C (carbon)

Atomic number = number of protons of an element.

Atomic weight = number of protons plus number of neutrons. Ex: Carbon has 6 protons and 6 neutrons; atomic weight is 12

Look at Carbon – CWhat is its atomic mass?

Can we tell how many electrons it has?

How? (hint – look at its atomic number)

Isotope – Atoms of the same element that have different numbers of neutrons. Ex: Carbon can have 6, 7, or 8 neutrons

Radioactive isotope – isotopes with unstable nuclei. Give off radiation

Valence electronsThose electrons that orbit the outer energy level of an atom.

1st energy 2 electrons

2nd energy level 8 electrons

Filled make the element more stable

Unfilled energy levels make the element more reactive with other elements.

Compound – substance formed by the chemical combination of 2 or more elements. Ex: H2O, NaCl, HCl.

Compound usually has different properties than the elements it is composed of

Ex: H2O is a liquid composed of gaseous hydrogen and gaseous oxygen.

Chemical bonds – forces that hold elements of a compound together.

Forces are created by the interaction of each of the element’s valence electrons

Ionic Bond – formed when one or more electrons are transferred from one atom to another.

Ex: Sodium (Na) donates one electron to Chlorine (Cl) to form an ionic bond and make sodium chloride (NaCl – table salt)

Covalent Bond – formed when one or more electrons are shared between elements. This type of bond between elements creates a molecule. Ex: H2O

OH H

Properties of Water

A common molecule with unique characteristics:

Polar – due to the way the hydrogen atoms are arranged around the oxygen atom, water molecules have a (+) end and a (-) end = polar.

OH H

This electrical orientation causes water to be attracted to other charged elements and form hydration spheres around them. This keeps the elements from combining with other charged elements.

Ex: salt placed in water dissolves. In other words, the sodium separates from chlorine & water molecules keep them apart. Water helps keep things dissolved = universal solvent

Has a high heat capacity and heat of vaporization – water absorbs, transports, and releases a great deal of heat without changing its state (ice to water to vapor).

That’s why, on a hot day, you just perspire and not evaporate. The water in your body stays liquid (and not turn into a vapor) while it is carrying the heat to the surface of your skin.

Cohesive - sticks to itself; ex: beading water

Adhesive - sticks to other things

Highly reactive – virtually no chemical reactions occur in living systems without the presence of water

It’s the major component of body lubricants (mucus), protective cushions (amniotic fluid and cerebrospinal fluid), and transport mediums (blood)

SaltsIn living systems, salts are

compounds that dissolve in water and become electrolytes. Electrolytes conduct electricity in the body. Ex: Na, Ca, K, Cl are the major electrolytes. Gatorade has a concentration of these in it.

ACIDSCompounds that give off

hydrogen ions (H+)in solution. Acids read below 7 on the pH scale. The more H+ given off, the lower the number on the pH scale.

BasesCompounds that give

off hydroxide ions (OH-) in solution. Bases read above 7 on the pH scale. The more OH- given off, the higher the pH.

BiochemistryThe Macromolecules of

Life

Chapter 2.3

Organic ChemistryThe study of all compounds that

have bonds between carbon

atoms.

Importance of Carbon

Carbon has 4 valence electrons

It tends to form covalent bonds with other carbon atoms

In doing so, In doing so, carbon can carbon can form a variety form a variety of shapes…of shapes…

…chains…

…rings…

…branches…

…or combinations of chains, rings, and branches.

Macromolecules

Carbon is able to form large and complex molecules called “macromolecules”

Macromolecules are

made by “polymerization”

in which small compounds

(“monomers”) are put

together to make larger

compounds (called

“polymers”)

There are 4 types of organic macro-molecules (organic polymers):

CarbohydratesLipidsProteinsNucleic Acids

Carbohydrates “sugars”

Made of C, H, O in a 1:2:1 ratio; Ex: C6H12O6

Monomer is monosaccharide

ExamplesGlucose-quick energyStarch-plant storageGlycogen- animal storageCellulose-structure in

plantsChitin-exoskeleton

crayfish

Used as the main source of fuel and/or structural purposes

Found in breads, Found in breads, cereals, pasta, potatoes, cereals, pasta, potatoes, corncorn

Lipids: “fats”Made of mostly of C and H

Monomer is glycerol attached to fatty acids

OR

Used to store energy, make cell membranes, waterproof coverings, chemical messengers

Examples: saturated fats, unsaturated fats, polyunsaturated fats, oils, waxes, cholesterol, steroids

Contained in dairy Contained in dairy products, meats, some products, meats, some vegetablesvegetables

Nucleic AcidsMade of C, H, O, N, PMonomers are nucleotides

Used to store and transmit genetic information

Examples include DNA and RNA

Found in anything that contains cells

ProteinsContains C, H, O, N, S, P

Monomers are amino acids

Used to regulate chemical reactions and cell processes, form body structures, transport materials, or fight disease

Examples include enzymes, antibodies, muscle tissue

Contained in meats, legumes, dairy products

Enzymes – special types of proteins

Enzymes are proteins capable of increasing the rate of a reaction without being consumed in the process

Types of reactions enzymes are involved in include:DigestionSynthesis of moleculesStorage and release of energy

Enzymes have the ability to carry out reactions at lower temperatures that would normally require extremely high temperatures

Activation Energy – the energy required to attach enzymes to substrates and cause a change

Substrate – the molecule undergoing a change; also called the reactant.

Activation site – place on the enzyme where a specific substrate attaches

Reactant – in a chemical equation, it is on the left side; what is added together to form products

Product – the end result of the enzyme-substrate reaction; found on the right side of a chemical equation

Optimum – the best conditions for a reaction to occur. In your body, optimum conditions are a pH of 7 and a temperature of 37oC

Denature – to permanently change the shape of an enzyme due to pH or temperature extremes; can prevent the enzyme from functioning properly.

Coenzyme – needs to be present in some enzymes to aid in the reaction. If it is missing the enzyme may not work; vitamins act as coenzymes.

Inhibitors – things that prevent enzymes from working properlyCompetitive inhibitors – compete with the substrate for binding sites on the enzyme; slows down the reaction; ex: ethanol and isopropanol

Noncompetitive inhibitors – irreversible binding to enzymes; stop the reaction permanently Ex: some heavy metals.