Slide 2

Chapter 2The Chemical Basis of Life

(BIOCHEMISTRY)

THE BULK OF PHYSIOLOGY INVOLVES CHEMICAL REACTIONS,

BUILDING UP or BREAKING DOWN MOLECULES

UTILIZING ENERGY or PRODUCING ENERGY

Slide 3

Basic Chemistry:

Key terms and concepts ATOMS MOLECULES Elements and compounds Elements in the human body (table 2-1) PROTONS ELECTRONS NEUTRONS Electron shells / energy levels , octet rule,

attractions CHEMICAL BONDS: IONIC, COVALENT,

weak bonds – hydrogen CHEMICAL REACTIONS: SYNTHESIS,

DECOMPOSITION, EXCHANGE: REVERSIBLE

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MORE KEY TERMS: METABOLISM : CATABOLISM vs.

ANABOLISM ENZYMES INORGANIC COMPOUNDS , such as H2O,

O2 ELECTROLYTES ; IONS: ANIONS,

CATIONS ph ACIDS, BASES, BUFFERS, SALTS ORGANIC COMPOUNDS: CARBOHYDRATES LIPIDS PROTEINS (&

Combos) NUCLEIC ACIDS: DNA, RNA,

NUCLEOTIDES ADENOSINE TRIPHOSPHATE (ATP)

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BASIC CHEMISTRY

Element — simple form of matter; a substance that cannot be broken

down into two or more different substances

(PURE) ~118 of them (ref. periodic table)

ex . Hydrogen, oxygen, helium, carbon, gold, silver, copper, sodium,

molybdenum, nitrogen, calcium, phosphorus

Slide 7

Basic Chemistry There are 26 elements in the human body

THERE ARE 11 “MAJOR ELEMENTS,”4 OF WHICH ( OXYGEN, CARBON, HYDROGEN, & NITROGEN ) MAKE UP 96% OF THE HUMAN BODY (water, H2O is 60-80% of the body)

(the others are: sodium, potassium, chlorine,

calcium, phosphorus , sulfur, magnesium)

& There are 15 “trace elements” that make up less than 2% of body weight

Slide 8

Table 2-1:Elements in the human body 11 MAJOR elements:

Oxygen Carbon Hydrogen Nitrogen

Calcium Phosphorus Sodium Chlorine Potassium Sulfur Magnesium

Slide 9

Table 2-1‘trace’elements, but significant roles

Iron blood (Hemoglobin)

Copper many enzymes Iodine thyroid hormone several obscure others

**Basic unit of the elements:

the ATOM **

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BASIC CHEMISTRY Compound—atoms of two or

more elements joined to form chemical combinations -- made up of MOLECULES

atoms MOLECULES

OO

OO

H

H OH

HO

H HH

H

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Basic Chemistry ATOMIC STRUCTURE— ATOMS contain subatomic particles; the most

important are the following:

PROTONS (+ or p)—positively charged particles found in the nucleus

NEUTRONS (n)— neutral subatomic particles found in the nucleus

ELECTRONS (– or e)—negatively charged subatomic particles found in the electron cloud surrounding, moving about the nucleus

Slide 13

Basic Chemistry

Energy levels (cont.) a model resembling planets revolving around the sun,

useful in visualizing the structure of atoms

Exhibits electrons in concentric circles showing relative distances of the electrons from the nucleus

Each ring or shell represents a specific energy level and can hold only a certain number of electrons

Slide 14

Basic Chemistry

Energy levels (Figures 2-3 and 2-4)

The total number of electrons in an atom equals the number of protons in the nucleus (in a stable atom)

Thus, it is ‘neutral’ – has no electrical charge

ie.: Carbon: 6 protons, 6 neutrons, 6 electrons

The electrons form a “cloud” around the nucleus

Slide 15

The NUMBER and arrangement of Electrons

determine whether the atom is chemically active.

In Chemical reactions, it is the electrons in the outer levels which participate in forming CHEMICAL BONDS

If an atom has 8 electrons in the outermost level, it is chemically ‘inert’, or inactive, and ‘unavailable’ .

(octet rule)

Electron energy levels, cont.

Slide 16

Basic Chemistry

Energy levels (cont.)

Octet rule — atoms with fewer (or more) than eight electrons in the outer energy level will attempt to lose, gain, or share electrons with other atoms to achieve stability.

{just like lonely MALE or FEMALE COLLEGE STUDENTS !!!! }

Slide 17

Basic Chemistry THESE Attractions between atoms

result in chemical bonds – (key concept in

Chemistry)

CHEMICAL REACTION — interaction between two or more atoms that occurs as a result of activity between electrons in their outermost energy levels

The result: Formation of: MOLECULES and COMPOUNDS

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BASIC CHEMISTRY

Compound—atoms of two or more elements joined to form chemical combinations -- made up of

MOLECULES atoms

OO

OO

H

HOH

HO

H HH

H

Slide 19

BASIC CHEMISTRY MOLECULES , (COMPOUNDS)

can be

SIMPLE: such as; O2 H2O

CO2

COMPLEX C40H62N10O12

& in between C6H12O6

Slide 21

Basic Chemistry

Chemical bonds — unite atoms into molecules

two major types of chemical bonds:

IONIC BOND: formed by transfer of electrons; strong electrostatic force that binds positively

and negatively charged ions together

COVALENT BOND: formed by sharing of electron pairs between atoms

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Ionic bond: donated electron

Slide 23

Covalent bonds, shared electrons

Hydrogen molecule H2Hh2

Carbon dioxide CO2

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Other types of bonds HYDROGEN BOND

Much weaker than ionic or covalent bonds

Results from unequally shared electrons, and thus unequal charge distribution on molecules, it makes molecules ‘polar’

water is a good example: ( also DNA - has many H

bonds)

HH oO-

o-HH

Etc etc

+HH

+ +

++++

Slide 25

Chemical reactionsCHEMICAL REACTIONS Involve the formation or

breaking of chemical bonds There are three basic types of chemical reactions involved in

physiology:

SYNTHESIS REACTION — combining of two or more substances to form a more complex substance; formation of new chemical bonds: A + B → AB

DECOMPOSITION REACTION — breaking down of a substance into two or more simpler substances; breaking of chemical bonds: AB → A + B

EXCHANGE REACTION — decomposition of two substances and, in exchange, synthesis of two new compounds from them: AB + CD → AD + CB

(so it’s a combo. of the other two Rxn)

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REVERSIBLE REACTIONS — occur in both directions

Most of the metabolic, physiologic chemical reactions of the body can and do take place in either direction,

So, in essence, a synthesis reaction, when reversed, becomes a decomposition reaction

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Metabolism Metabolism — the sum total of all of the

chemical reactions that occur in body cells

Catabolism = decomposition

Anabolism = synthesis

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CATABOLISMChemical reactions that break down complex

compounds into simpler ones and release energy;

HYDROLYSIS is the most common catabolic reaction,,,,,,,, WATER is added to a substance, resulting in its breakdown into smaller compounds

Ultimately, the end products of catabolism are carbon dioxide, water, and other waste products

More than half the energy released is transferred to ATP, which is then used to do cellular work

Slide 29

Metabolism Anabolism

Chemical reactions that join simple molecules together to form more complex molecules

The Chemical reaction most commonly responsible for anabolism is DEHYDRATION SYNTHESIS

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MORE KEY TERMS METABOLISM : CATABOLISM

ANABOLISM

INORGANIC COMPOUNDS , such as H2O, O2

ELECTROLYTES IONS, ANIONS, CATIONS

pH: ACIDS, BASES, BUFFERS, SALTS ORGANIC COMPOUNDS table 2-4 CARBOHYDRATES LIPIDS PROTEINS (&

Combos) ENZYMES NUCLEIC ACIDS DNA RNA

NUCLEOTIDES ADENOSINE TRIPHOSPHATE (ATP)

Slide 33

Organic and Inorganic Compounds ORGANIC MOLECULES

Have at least one carbon atom and at least one C–C or C–H bond in each molecule (they are complex molecules)

Can have a bunch of atoms

Often have functional groups attached to the carbon- containing core of the molecule

(ex: of functional groups): hydroxyl carbonyl carboxl amino

phosphate -OH -C=O -COOH -C=NH2 -

O-P=O(OH)2ATP: adenisine triphosphate

Slide 34

INORGANIC COMPOUNDS such as :

H2O O2 CO2electro-lytes: Na+ K+ Cl- Ca++

others

in contrast to organic molecules: inorganic Do not generally have carbon

atoms if so, there are NO C–C or C–H bond, (they are much more simple molecules)

60%-80% of your body is water

Slide 35

INORGANIC COMPOUNDS WaterThe body’s most abundant and important compound: where is water found in the body?:

Intracellular fluid (inside the body) Extracellular fluid (outside the body), to

include blood (intravascular) HOW IS WATER UTILIZED? a Solvent, ( thus a carrier) , for important

substances involved in a vital way in most chemical

reactions

Slide 37

WATER Important Properties of water (Table 2-

2)

Polarity — allows water to act as an effective solvent; ionizes substances in solution (Figure 2-8)

Ionized: to go from a solution to being dissolved The solvent allows transportation of essential

materials throughout the body (Figure 2-12) High specific heat — water can lose and gain large

amounts of heat with little change in its own temperature; ENABLES THE BODY TO MAINTAIN A RELATIVELY CONSTANT TEMPERATURE

High heat of vaporization—water requires absorption of significant amounts of heat to change from a liquid to a gas, ALLOWING THE BODY TO DISSIPATE EXCESS HEAT

Slide 38

Inorganic Compounds Oxygen and carbon dioxide—closely

related to cellular metabolism:

Oxygen —REQUIRED to complete decomposition

reactions necessary for the release of energy in the body

Carbon dioxide —produced as a waste product of

decompensation reactions also helps maintain the appropriate ACID-

BASE balance in the body

Slide 39

Inorganic Compounds Electrolytes

Large group of inorganic compounds, which includes acids, bases, and

salts

Substances that dissociate in solution to form IONS (these are NOT ‘Saturn’ cars,

LOL)

Positively charged ions are cations; negatively charged ions are anions

The major electrolytes are:Sodium (NA+) Potassium (K+) Chloride(CL-)

Carbon Dioxide (CO2) Calcium (Ca++) many others

Slide 40

Inorganic Compounds Electrolytes (cont.)

Acids and bases—common and important chemical substances that are chemical opposites

ACIDSAny substance that RELEASES A HYDROGEN ION (H+)

when in solution; Described as “proton donors”

Level of “acidity” depends on the number of hydrogen ions a particular acid will release

(low pH) pH: 6.9 and below is acidic impt. ex.: HCL hydrochloric acid in the stomach lactic acid builds up in tired muscles

Slide 41

BASESElectrolytes that dissociate to YIELD HYDROXIDE IONS (OH–) or other electrolytes that combine with hydrogen ions (H+)

Described as “proton acceptors”pH: 8.0 and above are basic (high pH) examples: NaOH, NaHCO3 , CaHCO3, Ammonia

Slide 42

pH scale—measuring acidity and alkalinity

pH indicates the degree of acidity or alkalinity of a solution

pH of 7 indicates NEUTRALITY (equal amts of H+ and OH–); a pH of less than 7 indicates ACIDITY;

a pH of more than 7 indicates ALKALINITY

***** ‘normal’ pH of the blood (body) is 7.4 ******

****** this is important !!!!!!!

Slide 44

Inorganic Compounds Buffers

Maintain the constancy of the pHMinimize changes in the concentrations of H+

and OH– ionsAct as a “reservoir” for hydrogen ions

most important buffer for maintaining acid-base balance in the blood is the

carbonic-acid-bicarbonate buffer. H+ + -HCO3 >< H2CO3><

H2O + CO2 Gives up hydrogen ions

Slide 45

Inorganic Compounds

Salts (Table 2-3)Compounds that result from chemical

interaction of an acid and a base

Reaction between an acid and a base to form a salt and water is called a neutralization reaction

NaOH + HCL >> NaCl + H2O base acid salt water

Slide 46

Organic Molecules (Figure 2-14; Table 2-4) “Organic” describes compounds

that contain C–C or C–H bonds. (complex)

in the Human Body, the key ORGANIC COMPOUNDS are:

CARBOHYDRATES LIPIDS, INCLUDING STEROIDS PROTEINS NUCLEOTIDES, NUCLEIC ACIDS,

ATP

Slide 48

Slide 49

2 East Texas farmers:

#1: MR DUCKS #2: MR KNOT #1: OSAR, CM

WANGS #2 : LIB, MR

DUCKS

Slide 51

***ORGANIC MOLECULES (compounds)***(4 major types in the body

CarbohydratesLipidsProteinsNucleotides

Slide 52

the impt. ORGANIC COMPOUNDS CARBOHYDRATES

a. simple sugars, ie glucose deoxyribose, ribose

( as usable in the cells)

b. disaccharides: sucrose, lactose

(as found in food, must be broken down)

c. polysaccharides: GLYCOGEN (starch) (a large polymer OF GLUCOSE MOLECULES, AS STORAGE)

LIPIDS (TRIGLYCERIDES, PHOSPHOLIPIDS,

STEROIDS, PROSTAGLANDINS)

Slide 53

ORGANIC MOLECULES CARBOHYDRATES—organic

compounds containing carbon, hydrogen, and oxygen; commonly called sugars and starchesMonosaccharides—simple sugars with short

carbon chains; those with six carbons are hexoses (e.g.,

glucose), whereas those with five are pentoses (e.g., ribose, deoxyribose)

Disaccharides and polysaccharides—

two (di-) or more (poly-) simple sugars that are bonded together through a synthesis reaction

Slide 54

MORE ORGANIC COMPOUNDS: LIPIDS

Lipids (Table 2-6)Water-insoluble organic molecules that are critically important biological compounds

Major roles:Energy sourceStructural roleIntegral parts of cell membranes

Slide 55

LIPIDS Lipids : 1) triglycerides, 2)steroids , 3)

prostaglandins

TRIGLYCERIDES, or fats abundant lipids and the most concentrated

source of energy

The building blocks of triglycerides are glycerol (the same for each fat molecule)

and fatty acids (different for each fat, they determine its chemical nature)

Slide 57

More LIPIDS Phospholipids

Fat compounds similar to triglyceride

One end of the phospholipid is water-soluble (hydrophilic); the other end is fat-soluble (hydrophobic)

Phospholipids can join two different chemical environments (Hydrophilic, Hydrophobic)

Phospholipids may form double layers called bilayers that make up cell membranes !!!

Slide 59

Lipids, STEROIDSSteroids Main component is steroid nucleus

Involved in many structural and functional

roles

Slide 60

Lipids : PROSTAGLANDINS

Prostaglandins Commonly called “tissue hormones”; produced by cell membranes throughout the body

Effects are many and varied; however, they are released in response to a specific stimulus and are then inactivated

Slide 61

MOST Proteins are of TWO basic types:

A. STRUCTURAL fundamental components of large portions of the body (muscle)

B. FUNCTIONAL ; involved in the chemical reactions of the body, these proteins are also called ENZYMES

( a few proteins are structural components of the cell, AND have functional capacity as well - they do both)

PROTEINS: POLYMERS OF AMINO ACIDS

Slide 62

PROTEINS

Proteins (Table 2-5) are the Most abundant organic

compoundsChainlike polymers AMINO ACIDS — are the building blocks

of proteins

Amino acids consist of a carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a side chain

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Protein structure PROTEINS are considered

POLYPEPTIDES, because they are long

polymers (chains) Of Amino acids, joined byPEPTIDE BONDS***Peptide bonds join amino acids

together to form proteins.

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Slide 64

PROTEINS can be either STRUCTURAL AND FUNCTIONAL (sometimes both)

Structural proteins form many of the structures of the body

(such as muscle)

Functional proteins cause chemical changes in the molecules, and are called ENZYMES. Very active in all the chemical reactions of the body

Shape of a protein’s molecules determines its function (Figure 2-21) Denatured proteins have lost their shape and therefore their

function (Figure 2-22) Proteins can be denatured by changes in pH, temperature,

radiation, and other chemicals If the chemical environment is restored, proteins may be renatured

and function normally

Slide 67

Nucleotides and related molecules, nucleic acids, ATP, et alREAD ABOUT IT.

Slide 68

NUCLEOTIDES

NUCLEOTIDES are the building blocks of:

a. The Nucleic acids: DNA, RNA, and b. ATP (Adenosine Tri-

Phosphate)

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Importance of DNA, RNA The Nucleic Acids are POLYMERS of

thousands of smaller molecules called NUCLEOTIDES

a DEOXYRIBONUCLEOTIDE consists of:

1. the pentose sugar: Deoxyribose, 2. a PHOSPHATE group, and 3. a nitrogenous base (one of

four; Adenine, Thymine, Cytosine, or Guanine)

DNA MOLECULES ARE THE LARGEST MOLECULES IN THE BODY

Slide 70

Slide 71

Nucleic acids and related molecules

DNA (deoxyribonucleic acid) Composed of deoxyribonucleotides; that is,

structural units composed of the pentose sugar (deoxyribose), phosphate group, and nitrogenous base (cytosine, thymine, guanine, or adenine)

DNA molecule consists of two long chains of deoxyribonucleotides coiled into double-helix shape

Alternating deoxyribose and phosphate units form backbone of the chains

Slide 72

DNABase pairs hold the two chains of DNA molecule

together (HYDROGEN BONDS)

Specific sequence of more than 100 million base pairs constitute one human DNA molecule;

all DNA molecules in one individual are identical (to each other) and,

they are different from those of ALL other individuals

DNA functions as the molecule of heredity

Slide 73

DNA - THE MOLECULE OF HEREDITY, THE GENETIC LIBRARY Within the DNA molecule is the enormous bank of genetic information which passes traits from one generatin to the next.

DNA acts as the information molecule storing the MASTER CODE , or the Recipes (called GENES) for the formation of RNA, and the thousands of differing protein molecules of the body.

Slide 74

Nucleic acids and related molecules (cont.)

RNA (ribonucleic acid) a single stranded molecule Composed of the pentose sugar (ribose),

phosphate group, and a nitrogenous base

Nitrogenous bases for RNA are adenine, uracil, guanine, or cytosine (uracil replaces thymine compared to DNA)

Some RNA molecules are temporary copies of segments (genes) of the DNA code and are involved in synthesizing proteins (later : mRNA, tRNA, rRNA)

Slide 75

OTHER NUCLEOTIDES - ATP Nucleotides have other important roles in

the body

ATP Adenosine triphosphateComposed of

(A) Adenosine: A. Ribose—a pentose sugar , and B. Adenine—a nitrogen-containing molecule

C. ( TP) Three phosphate subunits

ATP

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IMPORTANCE OF ATP High-energy bonds present between phosphate

groups

Cleavage of high-energy bonds releases energy during catabolic reactions

Energy stored in ATP is used to do the body’s work

ATP often called the ENERGY CURRENCY of cells

ATP is split into adenosine diphosphate (ADP) and an inorganic phosphate group by a special enzyme

Slide 78

OTHER NUCLEOTIDESNAD and FAD (Figure 2-31)

Used as coenzymes to transfer energy-carrying molecules from one chemical pathway to another

cAMP (cyclic AMP) Made from ATP by removing two

phosphate groups to form a monophosphate

Used as an intracellular signal

Slide 79

Combined formsExamples:

Adenosine triphosphate (ATP)—two extra phosphate groups to a nucleotide, important ‘energy’ molecule

Lipoproteins—lipid and protein groups combined into a single molecule (important ones are HDL and LDL -- the way CHOLESTEROL is carried in the bloodstream

Glycoproteins—carbohydrate (glyco, “sweet”) and protein (cellular markers