NUR 101: Body Structure and Function

Chemistry of Life Chapter 2

Nov 16, 2004

Angela Watkins-Brooks MSN, RN

Objectives

§ Define atom, element, molecule, and compound

§ Describe the difference between organic and inorganic chemical compounds

§ Discuss the characteristic of water

§ Explain the concept of pH

Objectives

§ Discuss the structure and functions of the following types of organic molecules:

carbohydrate, lipid, protein, and nucleic acid

Chemistry of Life

§ BIOCHEMISTRY is devoted to studying the chemical aspects of life. The basic principles of anatomy and physiology are ultimately based on principles of chemistry.

Levels of Chemical Organization

§ MATTER is any thing that occupies space and has mass.

§ MOLECULES are particles of matter that are composed of one or more smaller units called atoms.

Molecules

Atom

§ ATOMS are composed of several kinds of subatomic particles: protons, electrons, and neutrons

Atom Organization

§ Atom nucleus is the center core of the atom and contains protons and neutrons.

§ Protons are positively charged particles within the nucleus of an atom.

§ Neutrons are electrically neutral particles within the nucleus of an atom.

§ Electrons are negatively charged particles orbiting the nucleus of an atom.

Atom Organization

§ Atomic number-number of protons in the nucleus

§ Atomic mass-the number of protons and neutrons combined

§ Energy levels- the orbitals are arranged into energy levels (shells); the farther an orbital extends from the nucleus, the higher its energy level

Atoms Organization

§ The number of electrons in the outer energy level of an atom determines how it behaves chemically

§ Chemical bonding- joining of one atom with another atom

Levels of Chemical Organization

§ ELEMENTS are pure substances, composed of only one kind of atom

§ MOLECULES are particles of matter that are composed of one or more smaller units called atoms

§ COMPOUNDS are composed of molecules having more than one kind of atom.

Elements in the Body

§ Major elements:

§ Oxygen

§ Carbon

§ Hydrogen

§ Nitrogen

§ Trace elements:

§ Calcium

§ Phosphorus

§ Sodium

§ Potassium

§ Chlorine

§ Iodine

CHEMICAL BONDING

§ IONIC BONDING occurs when one atom donates an electron to another atom and the resulting ions attract each other.

IONIC BONDING

COVALENT BONDING

§ COVALENT BONDING occurs when atoms share electrons

ORGANIC VERSUS INORGANIC

§ Organic compounds are composed of molecules that contain Carbon-Carbon (C-C) covalent bonds or Carbon-Hydrogen (C-H) bonds. Few inorganic compounds contain carbon atoms and none contain Carbon-Carbon or Carbon-Hydrogen bonds.

§ Organic molecules are generally larger and more complex .

TYPES OF INORGANIC MOLECULES

§ Water

§ Acids

§ Bases

§ Salts

Solvent and Solute

§ SOLVENT is a substance in which other substances are dissolved; for example, In saltwater the water is the solvent

§ SOLUTE is substance that dissolves into another substance; for example In saltwater the salt is the solute dissolved in water.

CHEMICAL REACTIONS

§ Dehydration synthesis- reactants combine only after hydrogen and oxygen atoms are removed; thus leftover hydrogen and oxygen come together forming H2O or water

§ Hydrolysis- the reactant, water disrupts in the bonds in large molecules, causing them to be broken down into smaller molecules

Concepts related to PH level

§ PH is a unit expressing relative H+ (hydrogen) concentration

§ Formula used to calculate PH units gives a value of 7 to pure water therefore 7 is a neutral value neither acidic or basic

§ PH values higher than 7 is basic

§ PH values lower than 7 is acidic

§ Normal body function can be maintained only within a narrow range of PH. Normal range 7.35-7.45

PH Scale

Acid – Base Concepts

§ Acid is any substance that when dissolved in water, contributes to an excess of H+ (hydrogen) ions. A lower PH value indicates a higher H+ concentration –acidic Normal range 7.35 to 7.45

§ Base is any substance that when dissolved in water, contributes to an excess of OH- (hydroxide) ion.

Acids and Bases

ACID

§ A solution that has an excess of H+ ions

§ It comes from the Latin word "acidus" which means "sharp„

BASE

• A solution that has an excess of OH- ions

• Another word for base is ALKALI

Acids and bases in our life

TYPES OF ORGANIC MOLECULES

§ Carbohydrates

§ Lipids

§ Triglycerides

§ Phospholipids

§ Cholesterol

§ Proteins

§ Nucleic Acids

§ deoxyribonucleic acid (DNA)

§ ribonucleic acid (RNA)

Carbohydrate Structure and Function

§ Monosaccharide (glucose, galactose, fructose) single monosaccharide unit. Utilized as a primary source of energy and to build other carbohydrates

§ Disaccharide (sucrose, lactose, maltose ) two monosaccharide units. Broken into a monosaccharide for energy

§ Polysaccharide (glycogen, starch) many monosaccharide units. Used to store monosaccharides (thus to store energy)

Lipid Structure and Function

§ Triglycerides are formed by one glycerol unit and three fatty acids. Utilized to store energy in cells

§ Phospholipids are formed by two fatty acids and a phosphorus containing unit. Utilized to form a stable foundation for the cell membrane

§ Cholesterol has four carbon rings at core. Assists in stabilizing the cell membrane and is the basis of steroid hormones

Proteins

§ Large molecules made up of amino acids held together in long folded chains by peptide bonds

§ Can combine with other organic molecules to form glycoproteins or lipoprotiens

Protein Structure and Function

§ Structural proteins (fibers) are amino acids that form essential structures of the body

§ Functional proteins (enzymes, and hormones) are amino acids that facilitate chemical reactions; send signals ; compose some of the hormones cell membrane channels and receptors and enzymes

Enzymes

§ Catalysts-help chemical reactions occur

§ Lock-and-key model- each enzyme fits a particular molecule that it acts on as a key into a lock

Nucleic Acid Structure and Function

§ Nucleic acids are made from nucleotides. Each nucleotide consists of a phosphate unit, a sugar unit and a nitrogen base.

§ Deoxyribonucleic acid (DNA) nucleotide base includes adenine, thymine, guanine, and cytosine. Contains information (genetic code) for making proteins

§ Ribonucleic acid (RNA) nucleotide base includes adenine, uracil, guanine, and cytosine

Serves as a copy of a portion of the genetic code

DNA

§ Composed of:

Deoxyribose

Phosphate

Cytosine=Guanine

Adenine=Thymine

RNA

§ Composed of:

Ribose

Phosphate

Cytosine=Guanine

Adenine=Uracil

Terms

§ Peptide bond

§ Aqueous solution

§ Glycogen

§ Nucleic acid

§ Product

§ Enzymes

Questions and Answers