The Chemistry of Life

Objectives

What three subatomic particles make up atoms?

How are all the isotopes of an element similar?What are the two types of chemical bonds?

The Big Idea

Life Depends on chemistryChemical reactions keep you alive

AtomBasic unit of matter

The theory states that these atoms are all individually created and cannot be separated, no matter what scientific procedures are applied.

Subatomic particlesProtons - Neutrons - Electrons

-

Positively charged (+)Not charged (neutral)Negatively charged (-)

Bind together to form the nucleus

Electrons Protons

Neutrons

Nucleus

ElementA pure substance that consists of just one type of atom

6

CCarbon

12.011

Atomic number

An elements Atomic Number = number of protons

IsotopeAtoms of the same element that differ in the number of neutrons they contain

Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14

6 electrons6 protons6 neutrons

6 electrons6 protons8 neutrons

6 electrons6 protons7 neutrons

6

CCarbon12.011 Mass number

The Sum of protons and neutrons in the nucleus of an atom is its MASS NUMBER

The weighted average of the masses of an elements isotope is called its atomic mass

Radioactive isotopesCan be dangerous

Can be used practicallyRadioactive datingTreat cancerKill bacteria

CompoundsA substance formed by the chemical combination of two or more elements in definite proportions

Ex) H2O, NaCl

Sodium – silver colored metal, soft enough to cut with a knife

Sodium reacting explosively in water

Chlorine – poisonous green gas used to kill many people in WWII

Combination of sodium and chlorine

Table Salt

The following periodic chart summarizes the elements of the periodic table, in terms of human composition, and human toxicity. The lesser elements are often referred to as minerals, when referring to human nutrition and health.

Several minerals are required by the human body for proper nutrition. Food supplements may be required to ensure that you are receiving all the nutritional minerals that you need. Major liquid mineral supplements which may be required are calcium supplements, phosphorus supplements, and potassium supplements. Trace mineral supplements often include magnesium supplements, iron supplements, zinc supplements, and selenium supplements.

Yellow Boxes = Top 5 Elements present in the human body

Green Boxes = Second 5 Top Elements present in the human body

Blue Boxes   = Trace elements that are required by the human body

Violet Boxes = Elements that are deleterious to the human body.

Ionic BondsFormed when one or more electrons are transferred from one atom to another

Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-)

Transferof electron

Protons +11Electrons -11Charge 0

Protons +17Electrons -17Charge 0

Protons +11Electrons -10Charge +1

Protons +17Electrons -18Charge -1

If an atom loses an electron it becomes positive

If an atom gains an electron it becomes negative

IonsPositively and negatively charged atoms

Covalent BondsForms when electrons are shared between atoms

MoleculeThe structure that results when atoms are joined together by a covalent bond

Smallest unit of most compounds

Van der Waals ForcesA slight attraction that develops between the oppositely charged regions of nearby molecules due to unequal sharing of electrons

1. Describe the structure of an atom.Atoms are made up of protons and neutrons in a nucleus. Electrons are in constant motion in the space around the nucleus.

2. Why do all isotopes of an element have the same chemical propertiesThey have the same number of electrons

3. What is a covalent bond? A bond formed when electrons are shared between atoms

4. What is a compound? How are they related to moleculesA compound is a substance formed by the chemical combination of two or more elements in definite proportions. A molecule is the smallest unit of most compounds

5. How do Van der Waals forces hold molecules together?When the sharing of electrons are unequal, a molecule has regions that are charged. An attraction can occur between oppositely charged regions of nearby molecules

6. How are ionic bonds and Van der Waals forces similar? How are they different?In both cases, particles are held together by attractions between opposite charges. The difference is that ionic charges are stronger

ObjectivesWhy are water molecules polar?

What are acidic solutions? What are basic solutions?

The Big Idea Much of our planet is covered in water

Water is necessary for life to exist

If life exists on other planets, there most likely is water present

Water has many properties that make life possible

(-)

(+)

The oxygen atom has a stronger attraction for electrons

Hydrogen BondsBecause of waters partial charges, they can attract each other and create hydrogen bonds

Not as strong as covalent or ionic bonds

Waters ability to create multiple hydrogen bonds gives it many special properties

CohesionAttraction between molecules of the same substance

AdhesionAttraction molecules of different substances

MixtureMaterial composed of two or more elements or compounds that are physically mixed but not chemically combined

Ex.) salt & pepper, earths atmosphere

SolutionsMixture of two or more substances in which the molecules are evenly distributed

Ex.) salt waterSettles out over time

Cl-

Water

Cl-

Na+

Water

Na+

SoluteSubstance that is dissolvedEx.) salt

SolventThe substance that does the dissolving

Ex.) Water

SuspensionsMixture of water and non-dissolved materials

Ex.) sugar solution, bloodSeparate into pieces so small, they never settle out

The pH scaleIndicated the concentration of hydrogen ions in a solution

Neutral

Acid

Base

AcidsAny compound that forms H+ (hydrogen) ions in solution

BaseA compound that produces OH- (hydroxide) ions in solution

BuffersWeak acids or bases that can react with strong acids or bases to prevent sharp, sudden pH changes

1. Use the structure of a water molecule to explain why its polarOxygen atom has greater attraction for electrons, therefore the oxygen atom is negative and the hydrogen end is positive

2. Compare acidic and basic solutions in terms of their H+ ion and OH- ion concentrationsAcid have more H+ ions than OH- ions, and bases have more OH- ions than H+ ions

3. What is the difference between a solution and a suspension?In a solution, all components are evenly distributed. In a suspension, un-dissolved particles are suspended

4. What does pH measure?The concentration of H+ ions in a solution

5. The strong acid hydrogen floride (HF) can be dissolved in pure water. Will the pH of the solution be greater or less than 7? less than 7

ObjectiveWhat are the functions of each group of organic compounds?

Life’s backboneMost of the compounds that make up living

things contain carbon. In fact, carbon makes up the basic structure, or “backbone,” of these compounds. Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms.

As a result, carbon atoms can form long chains. A huge number of different carbon compounds exist. Each compound has a different structure. For example, carbon chains can be straight or branching. Also, other kinds of atoms can be attached to the carbon chain.

Section 2-3

Methane Acetylene Butadiene Benzene Isooctane

Macromolecules “giant molecules”Formed by a process called polymerization

MonomersSmaller units

PolymersLinked up monomers

CarbohydratesCompounds made up of carbon, hydrogen, and oxygen atoms usually in a ratio of 1:2:1

Main source of energyThe monomers of starch are sugars

Single sugar molecules are called monosaccharides

The large macromolecules formed from monosaccharides are known as polysaccharides

Starch

Glucose

LipidsMade mostly from carbon and hydrogen atoms

Used to store energy

Glycerol

Fatty Acids

ProteinsMacromolecules that contain nitrogen as well as carbon, hydrogen, and oxygen

Proteins are polymers of molecules called amino acids

General structure Alanine Serine

Carboxyl group

More than 20 different amino acids, can join to any other amino acid

The instructions for arranging amino acids into many different proteins are stored in DNA

Each protein has a specific roleThe shape of proteins can be very important

Amino Acids

Nucleic AcidsMacromolecules containing hydrogen,

oxygen, nitrogen, carbon, and phosphorus

Double Helix

NucleotidesConsists of 3 parts: 5-carbon sugar, phosphate group and nitrogen base

Nitrogen Base

5-Carbon Sugar

Phosphate group

2 kinds of nucleic acidsRNA (ribonucleic acids) – contains sugar ribose

DNA (deoxyribonucleic acid) – contains sugar deoxyribose

1. Name four groups of organic compounds found in living thingscarbohydrate, lipid, protein, nucleic acids

2. Describe at least one function of each group of organic compoundscarbohydrates – energylipids – store energyproteins – form tissuenucleic acids – transmit hereditary information

3. Compare the structures and functions of lipids and starchesLipids are made from carbon and hydrogen. Starches are made of carbon, hydrogen and oxygen. They both can be used to store energy

ObjectivesWhat happens to chemical bonds during chemical reactions?

How do energy changes affect whether a chemical reaction will occur?

Why are enzymes important to living things?

The Big IdeaLiving things are made up of chemical compounds

Everything that happens to an organism is based on chemical reactions

Chemical ReactionsA process that changes or transforms one set of chemicals into another.

ReactantsElements or compounds that enter into a reaction.

Products Elements or compounds produced by a chemical reaction.

Example Reaction: Getting rid of Example Reaction: Getting rid of Carbon DioxideCarbon DioxideIn the blood

In the lungs

CO2 + H20 H2CO3 (carbonic acid)

H2CO3 CO2 + H2OReleased as you breathe

Energy-Absorbing Reaction Energy-Releasing Reaction

Products

Products

Activation energy

Activation energy

Reactants

Reactants

Activation EnergyThe energy that is needed to get a reaction started

EnzymesSome chemical reactions are too slow or have activation energies that are too high to make them practical for living tissue.

These chemical reactions are made possible by CATALYSTS.CATALYSTS.

CatalystSubstance that speeds up the rate of chemical reactions

Work by lowering a reactions activation energy

EnzymeBIOLOGICAL CATALYSTS BIOLOGICAL CATALYSTS Speed up reactions in cellsVery specificNamed for the reaction it catylzes

Enzyme names always end in --asease

Reaction pathwaywithout enzyme Activation energy

without enzyme

Activationenergywith enzyme

Reaction pathwaywith enzyme

Reactants

Products

SubstratesThe reactants of enzyme catalyzed reactions

The active site of the enzyme and the substrate have complementary shapes

Fit like a lock and key

Enzyme – substrate complex

Glucose

Substrates

ATP

Substratesbind toenzyme

Substratesare convertedinto products

Enzyme-substratecomplex

Enzyme(hexokinase)ADP

Products

Glucose-6-phosphate

Productsare released

Active site

Regulation of Enzyme Activity

Enzymes are affected by any variable that affects chemical reactions

1. pH2. Temperature3. Concentration

of enzyme

1. What happens to chemical bonds during chemical reactionsBonds are broken in reactants and new bonds are formed in products

2. Describe the role of energy in chemical reactionssome chemical reactions release energy, and other chemical reactions absorb energy. Energy changes determine how easily a chemical reaction will occur

3. What are enzymes, and how are they important to living things?Enzymes are biological catylasts. Cells use enzymes to speed up virtually every important chemical reaction that takes place in cells

4. Describe how enzymes work, including the role of the enzyme substrate complexSubstrates, the reactants of an enzyme-catylzed reaction, attach to the enzyme at an active site and form an enzyme – substrate complex. Once the complex is formed, the enzyme helps convert substrate into product

5. A change in pH can change the protein. How might a change in pH affect the function of an enzyme such as hexokinase (hint: think about the analogy of the lock and key)A change in pH could change the shape of hexokinase. This change would diminish the ability of glucose and ATP to bind to the active site of the enzyme.

TEST TIME