Chapter 2

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Chapter 2 Basic Chemistry

Be Able To

•Differentiate between matter and energy.

•List the major energy forms and provide an example of how each energy form is used.

•Define element and list the 4 major elements of the human body.

•Explain the relationship between atoms and elements.

•Describe the structure of the atom.

•Define radioisotope and describe its use in the diagnosis and treatment of disease.

•Distinguish between organic and inorganic compounds.

•Differentiate between a salt, an acid, and a base.

•List several salts that are important to body functioning.

•Explain the importance of water to homeostasis.

•Explain the concept of pH and state the pH of blood.

Key Terms: matter, kinetic and potential energy, chemical energy, element, atom, atomic symbol, protons, neutrons, electrons, atomic number, atomic mass

number, atomic weight, and radioisotopes.

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Concepts of Matter and Energy

• Matter is anything that occupies space and has mass.

– What are the 3 states of matter?

• Energy is the ability to do work.

– Kinetic energy is energy at work and potential energy is stored energy.

• Chemical energy is stored in the bonds of chemical substances.

• Electrical energy is the result of the movement of charged electrons

(ions).

• Mechanical energy is directly involved in moving matter.

• Radiant energy travels in waves such as light energy.

• Energy conversion is quite inefficient.

• Why are we warm blooded animals?

Human vs a robotic arm made with artificial muscles? Which will generate more mechanical energy?

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Composition of Matter

• Elements are substances that cannot be broken down into simpler substances, e.g. O, Fe, C

• C,H,O,N make up 96% of the body by weight.

• Atoms are the building blocks of an element.

• The nucleus of an atom is

composed of protons (+) and

neutrons (n⁰) that are surrounded by electrons (-).

• Electrons inhabit regions around the nucleus called orbitals.

• The atomic number of an

element is equal to the number of protons in its nucleus.

• The atomic mass number of an element is the sum of protons and neutrons contained in the nucleus.

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Composition of Matter

• The atomic weight of an

element is equal to the mass number of its most abundant isotope.

• Isotopes are structural variations of an element.

• A radioisotope is an isotope that exhibits radioactive behavior.

• Radioactive atoms release particles or electromagnetic energy form the nucleus.

• We use radioisotopes to tag biological molecules so they can be followed through the body.

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Molecules and Compounds

• A molecule is a particle consisting of two or more atoms held

together by chemical bonds.

• A compound is a substance

composed of two or more different elements, the atoms of which are chemically united.

• Chemical bonds involve the

interactions between electrons of the reacting atoms.

• What is the fixed region of space that electrons occupy in an atom?

• More distant electrons are more likely to interact with other atoms than electrons closer to the

nucleus.

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Chemical Bonds and Chemical Reactions

• Bonding behavior is

determined by the electrons in the valence shell.

• Chemically stable elements contain 8 valence electrons.

• Atoms with less than 8 valence electrons tend to gain, lose, or share electrons.

• Ionic bonds form by the

complete transfer of electron(s) from one atom to another.

• Most compounds formed by ionic bonding are salts.

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Chemical Bonds and Chemical Reactions

• A covalent bond involves the sharing of electrons between atoms.

• Each atom in a covalent bond has a full valence shell enough of the time to satisfy its stability needs.

• Nonpolar molecules (CO₂, O₂) share electrons equally.

• Polar molecules (H₂0) do not share electrons equally and take on slight – and + charges.

• Hydrogen bonds are weak

bonds in which a hydrogen atom forms a bridge between two or more electron-hungry atoms.

• Hydrogen bonds are common between water molecules.

Nonpolar molecule

Polar molecule

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Patterns of Chemical Reactions

• Chemical reactions involve the

making or breaking of bonds between atoms.

• Synthesis reactions occur when two or more atoms or molecules combine to form a larger molecule.

– Synthesis reactions absorb energy and underlie all anabolic activities essential to tissue growth and repair.

• Decomposition reactions occur

when a molecule is broken down into smaller molecules, atoms, or ions.

– Decomposition reactions release energy and underlie all catabolic activities.

• Exchange reactions involve both types of reactions in which parts of molecules are switched.

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Biochemistry: The Chemical Composition of Living Matter

• Organic compounds are carbon-containing covalently

bonded compounds of the body, e.g. proteins and lipids.

• Inorganic compounds lack carbon, e.g. water and salts.

• Water is the most abundant

inorganic compound in the body.

• Why is water so important?

• Salts are ionic compounds that dissolve readily or disassociate and are involved in many vital body functions, e.g. nerve impulse

conduction.

• All salts are electrolytes which are substances that conduct an

electrical current in solution

Why is water such an universal solvent?

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• Acids, also known as proton donors, are substances that free hydrogen ions when in an aqueous solution.

• Acids in water release hydrogen ions (H+).

• A base, also known as proton

acceptors, is a substance that accepts hydrogen ions.

• When acids and bases are mixed

together they react with each other to form water and salt which is known as a neutralization reaction.

• pH units express the relative

concentration of hydrogen and hydroxyl ions in solution.

• The pH scale runs from 0 to 14, yet one unit change is a tenfold change.

• Buffers are substances that help to stabilize the pH of a solution.

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Chapter 2 Basic Chemistry

Be Able To

•Compare and contrast carbohydrates, lipids, proteins, and nucleic acids.

•Differentiate between fibrous and globular proteins.

•Compare and contrast the structure and functions of DNA and RNA.

•Define enzyme and explain their roles in the body.

•Explain the importance of ATP in the body.

Key Terms: organic and inorganic compounds, salts, electrolytes, proton donors and acceptors, bases,

neutralization reaction, pH units, buffers, carbohydrates, lipids, fatty acids, phospholipids, steroids, proteins, amino acids, fibrous and globular proteins, active site, catalyst, nucleic acids, nucleotides, DNA, RNA, ATP.

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• Carbohydrates are organic compounds composed of

carbon, hydrogen, and oxygen, with a general formula of CH₂O.

• Simple sugars consisting of one single chain or ring structure are monosaccarhides.

• Dissacharides are double sugars constructed of two

monosaccharides by a synthesis reaction.

• Polysaccharides are long branching chains of simple sugars.

• Starch is a storage molecule for plants and glycogen is a

storage molecule for animals

glucose

sucrose

starch

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• Lipids are organic compounds formed of carbon and hydrogen atoms.

• Neutral fats or triglycerides are composed of fatty acid chains and glycerol.

• Saturated fats have carbon chains with single bonds, whereas unsaturated fats have carbon chains with at least one

double bond.

• Neutral fats yield twice as much energy per gram as carbohydrates or proteins.

• Phospholipids have two fatty acid chains and a glycerol group and are both

hydrophobic and hydrophilic, perfect for the cell membrane.

• Steroids are composed chiefly of

hydrogen and carbon atoms arranged in a ring structure.

• Cholesterol is the chief steroid of cell membranes.

Computer model of cholesterol

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• A protein is a complex

nitrogenous substance composed of a chain of amino acids.

• The building blocks of proteins are amino acids which are composed of: a central carbon atom, a

hydrogen atom, amine group, a carboxyl group, and a R-group.

• Amino acid chains less than 50 molecules long are polypeptides.

• 2 types of proteins: fibrous or structural proteins (e.g.

collagen) and globular or functional proteins (e.g.

antibodies and enzymes).

• When the 3-D structure of globular proteins break apart they are

denatured and nonfunctional.

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• Functional proteins, such as enzymes, have a collection of atoms called the active site that interacts chemically with other molecules of a complementary shape and charge.

• Enzymes are functional proteins that act as biological catalysts.

• A catalyst is a substance that increases the rate of a chemical reaction without becoming part of the product.

• Enzymes are reusable and are capable of catalyzing millions of reactions each minute.

Computer model of a lysozyme

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• Nucleic acids are a class of organic compounds that include DNA and RNA.

• The building blocks of nucleic acids are nucleotides which are composed of a sugar, phosphate group, and a nitrogen base.

• DNA provides the instructions for building every protein in the body, whereas RNA carries out the

orders for protein synthesis.

• DNA is a twisted double helix or staircase of 2 strands of

nucleotides joined by

complementary base pairs (A with T and G with C).

• RNA is composed of one strand of nucleotides and exists in 3

varieties: messenger, transfer, and ribosomal RNA.

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• Adenosine triphosphate or ATP is a compound that is the

important intracellular energy source.

• Energy released from the bonds of other compounds, such as glucose, is captured and stored in the bonds between phosphate groups.

• When the bonds between the phosphate groups are broken energy is released and can be used to fuel activities in the cell.

• ATP can be regenerated by cells when a free phosphate group

attaches to ADP, however, this process requires an energy input.