INTRODUCTORY CHEMISTRY

Pages 22-40

Introduction to Chemistry The science of structure and interactions

of matter (anything that occupies space and has mass)

Chemical Elements and Atoms

Recall: Chemical elements are substances that

cannot be broken down into a simpler form by ordinary means

Chemical symbols are the one or two letters of the element’s name designated to represent that element

Chemical Elements and Atoms 26 elements found in human body; 4 of

them make-up 96% of the human body Carbon 18% Oxygen 65% Hydrogen 10% Nitrogen 3%

Another 8 make-up 3.8% And the final 14 make up 0.2%, these are

called trace elements

Ions, Molecules, and Compounds

Ion charged particle (atom) that has lost or gained an e-

Example : Ca 2+; has given up two electrons Molecules are formed when two or more atoms

share electrons. Can be same elements sharing or different elements sharing Recall: molecular formulas show number and type of

atoms Example: 2H2O 2 molecules of water composed of 2

atoms of hydrogen; one oxygen atom each A compound is a molecule containing two or

more different elements

Chemical Bonds Forces that bind the atoms of molecules and

compounds together, resisting their separation Chemically stable atoms have 8 electrons in their

outer shells, and unlikely to form chemical bonds Atoms without 8 electrons in their outer shell

form chemical bonds easily because they want eight (octet rule)

Three general types of chemical bonds: Ionic bonds Covalent bonds Hydrogen bonds

Ionic Bonds Force of attraction between ions of

opposite charge

Cation: protons exceed electrons = positively charged atom

Anion: electrons exceed protons = negatively charged atom

Ionic Bonds in Human Body Nnn

Give strength to the tissue

Electrolytes Most other ions in the human body are found

dissolved in body fluids…. Ionic compounds that break down into cations and

anions when dissolved are called electrolytes; they can conduct an electrical current Function examples:

Control water movement within the body Maintain acid-base balances Produce nerve impulses Transport nutrients Support mental function Convert calories into energy

Covalent Bonds No electrons lost or gained; atoms form

molecules by sharing one, two, or three pairs of their outer shell electrons The more pairs shared the stronger the bond Most common type of bonding in human body Do not easily break apart in water (ionic bonds

do)

Types of Covalent Bonds Between Atoms of the Same Element

Single covalent: two atoms share one electron pair

Double covalent: two atoms share two electron pairs

Triple covalent: two atoms share three electron pairs

Types of Covalent Bonds Between Atoms of the Different Elements Nonpolar covalent: atoms share equally

one atom does not attract the shared electrons more strongly than the other atom

Polar covalent: atoms share unequally one atom attracts the shared electron more strongly than the other

Hydrogen Bonds Polar covalent bonds between hydrogen

and other atoms is the third type of chemical bond Hydrogen is slightly positively charged and

attracts another atom with a slightly negative charge; attraction between oppositely charged parts of molecules rather than sharing of electron

These are weak bonds Do not bind atoms into molecules; rather

create a link between molecules or between different parts of a large molecule, like DNA

‘FREE RADICALS’ Defined: ion or molecule with an unpaired

electron in its outermost shell; highly unstable; destructive to other nearby molecules…WHY???

They will steal an electron or give one up to another ion or molecule thus damaging it

Where do free radicals come from?

Produced during metabolic activity How? Exposure to certain substances in our

environment can impede normal metabolic processes during which ions and molecules separate in our cells…

Sunlight Automobile Exhaust Cigarette Smoke Alcohol Consumption Emotional Stress Exposure to Heavy Metals

i.e.: Mercury, Cadium, Lead

Damage Caused by Free Radicals

Body’s defense system in the ‘Battle of the Free Radicals’

ANTIOXIDANTS!!!!!! THEY NEUTRALIZE FREE RADICALS…

The Color of Antioxidants

All Antioxidants Are Not Equal The antioxidants within food are not all the same.

Some antioxidants prevent destruction, while others interrupt the effect of free radicals. Vitamin C, for example, breaks the chain reaction of free radical damage.

Studies have shown that antioxidant supplements do not have the same beneficial effects as a diet full of fruits and vegetables. In fact, there are concerns that the amount of antioxidants, such as beta-carotene, ingested through a daily supplement may be unsafe.

Therefore, it is important to consume a variety of foods with antioxidant qualities rather than take a supplement to get the beneficial effect.

Free Radicals and Aging Many experts believe the aging process is

due to free radicals that damage DNA and decrease organ function

Chemical Reactions Occurs when new bonds form and/or old

bonds break Enables body structures to be built and

functions to be carried out through energy transfers

Forms of Energy and Chemical Reactions

ENERGY capacity to do work Two main forms:

Potential energy: energy stored by matter due to its position Example: sitting at the top of a slide

waiting to go down Kinetic energy: energy of matter in

motion Example: sliding down the slide

CHEMICAL ENERGY IS A FORM OF POTENTIAL ENERGY STORED IN THE BONDS OF MOLECULES

Four Types of Chemical Reactions

Synthesis Reaction (“to put together”) Two or more atoms, ions, or molecules

combine to form new and larger molecules (anabolic)

Decomposition Reaction A molecule is split apart into smaller parts

(catabolic)

Four Types of Chemical Reactions

Exchange Reaction Consists of both synthesis and decomposition

reactions

Reversible Reaction Reactions that can go either way under

different conditions, either building up or breaking down

Chemical Compounds and Life Processes

Chemicals in human body divided into two main classes of compounds: Inorganic compounds

Lack carbon Structurally simple Bonded ionically or covalently

Examples: water, many salts, acids, and bases Exceptions: two-carbon compounds

carbon dioxide and bicarbonate ions Organic compounds; contain carbon and usually

also hydrogen Covalently bonded

Examples: carbohydrates, lipids, proteins, nucleic acids, and ATP (all macromolecules)

Inorganic Compounds Water most important one

physiologically, also most abundant compound in all living systems 55% to 60% of body mass in lean adults

Cells also are mostly composed of water WHY IS WATER THE MOST IMPORTANT???

Water

UNIQUE PROPERTIES….due to its polar covalent bonds and its ‘bent’ shape (can interact with four or more ions or molecules) Solvency

Recall: Solvent liquid or gas in which some other substance can

dissolve Solute substance that is dissolved in a solvent Solution combination of a solvent and a solute

Importance of the property physiologically: Carries nutrients, oxygen, and wastes throughout the body

Water..continued

Water..continued Excellent medium for chemical reactions;

b/c dissolves so many substances Medium for some decomposition and

synthesis reactions Examples:

Digestion decomposition breaks down large nutrient molecules by adding water so they can be absorbed Reaction called hydrolysis

Water..continued Absorbs and releases heat very slowly

Thus regulates body temperature = homeostasis Requires a huge amount of heat to change

form liquid to gas Thus remains liquid sweat long enough to act

cooling mechanism for body Acts as a lubricant

Saliva, mucus, and others Important in thoracic and abdominal cavity, allow

internal organs to touch and slide over one another Needed in joints, so bones, ligaments, and tendons

can run against one another

Inorganic Acids, Bases, and Salts

Acid: breaks apart; disassociates into one or more H+ ions in water

Base: breaks apart; disassociates into one or more OH- ions in water Acids and bases react together to form salts

Example:  NH3 + HCl  → NH3Cl Ammonia + Hydrochloric acid Ammonium chloride

Salt: breaks apart; disassociates into cations and anions in water; neither are H+

ions or OH- ions

Acid-Base Balance: the Concept of pH

Homeostasis maintained through a balance between acid and base quantities in the human body More H+ ions acidic (acidity); More OH- ions basic (alkalinity)

Solutions acidity/alkalinity expressed as pH Recall pH scale 0 to 14

pH of 7 is neutral (pure water); H+ ions = OH- ions pH below 7 acidic; H+ ions > OH- ions pH above 7 basic (alkaline); H+ ions < OH- ions

Each whole number change on scale = 10-fold change in number of H+ ions

Maintaining pH: Buffer Systems

pH level limits in body fluids very narrow in scope Examples:

Blood 7.35 - 7.45 Urine 6.5 -7.0 a.m.; 7.5 - 8.0 p.m. Digestive system Lysosomes 4.0 -4.5 Cytosol 7.2 - 7.4 Mitochondrial matrix 7.5 - 7.8

Buffers convert strong acids and bases into weak acids and bases to maintain optimum pH levels in body fluids

Organic Compounds Carbohydrates Lipids Proteins Enzymes Nucleic acids Adenosine triphosphate

A

E

D

C

F

B

Carbohydrates Sugars, glycogen, starches, and cellulose

Contain C, H, and O (1:2:1 ratio; i.e. C6H12O6) Three major groups of carbohydrates:

Monosaccharides, simple sugars Disaccharides, simple sugars Polysaccharides, complex carbohydrates

Monosaccharides Monomer of carbohydrates

Most important one=> glucose; source of chemical energy fro generating ATP

Others => ribose and deoxyribose used to make RNA and DNA

Disaccharides Two monosaccharides bonded together

covalently through dehydration synthesis

Can be broken back down into monosaccharides through hydrolysis

Polysaccharides Contain tens or hundreds of monosaccharides joined

through dehydration synthesis; can be broken down through hydrolysis

Main polysaccharides in human body => glycogen; made entirely of glucose Stored in liver cells Also in skeletal muscles

Why do you think it is composed entirely of glucose; for what purpose????

Plants make starches ; we consume them and break them down to glucose to be used as an energy source

Cellulose is the polysaccharide found in plant cell walls, we cannot digest it… provides us with roughage to aid digestive processes

Lipids Contain C, H, and O Hydrophobic (insoluble in water) because of fewer

polar covalent bonds Includes:

triglycerides (fats; solids and oils; liquids at room temperature) Phospholipids Steroids fatty acids fat-soluble vitamins (A, D, E, and K)

Provide body with chemical signals, insulation, padding and stored energy (two times as much as carbohydrates or proteins)

Large amounts can contribute to heart & blood vessel disease

Triglycerides Most plentiful in human body

Stored in fat tissue called adipose tissue Excess dietary carbohydrates, proteins, fats, and

oils Composed of three fatty acids

(hydrocarbon) & a 3-C glycerol Fatty acids can be saturated,

monounsaturated, or polysaturated

Saturated, Monounsaturated, and Polyunsaturated

Saturated Single covalent bonds between carbons

Allows saturation of hydrogen atoms Found mainly in animal products, mostly fats

Also a few tropical plants: cocoa, palm, coconut Solid at room temperature

Saturated, Monounsaturated, and Polyunsaturated

Monounsaturated (Unsaturated) Contains one double covalent bond between

two carbons Lowers hydrogen atom saturation

Usually liquid at room temperature Examples: olive oil, peanut oil

Saturated, Monounsaturated, and Polyunsaturated

Polyunstaurated More than one double covalent bond Examples: canola oil, corn oil, safflower oil,

sunflower oil, soybean oil

Phospholipids Phospholipids

Glycerol backbone with only two fatty acids attached to two carbons and a phosphate group attached to the third carbon Nonpolar fatty acids are hydrophobic “tails” Polar phosphate group are hydrophilic “heads”

Build body structures, make up cell membranes

Steroids Have complex carbon skeleton with 4

rings Cholesterol – steroid body cells uses to

synthesize other steroids Examples:

Cells in ovaries synthesize estradiol (female sex hormone)

Leydig cells (found in testicles) synthesize testosterone (male sex hormone)

Proteins Contain C, H, O, and N

Some also contain S Make up about ½ the body’s dry mass Serve a multitude of functions:

Structure of body cells; like muscles, tendons, bones, skin, etc.

Act as enzymes; speeding up chemical reactions

Aid in muscle contractions Some are antibodies; others are hormones;

gene regulators; components of blood

Amino Acid Structure

Building block (monomer) of proteins Union of two or more amino acids produces a peptide

bond United molecule composed of two amino acids called a

dipeptide Three amino acids united called tripeptide More than three united called polypeptide; these form

proteins Sequence is crucial for proper function

Made of amino group (NH2), carboxyl group (COOH) and one of many side or “R” (radical) groups

20 different varieties of amino acids in human body

Protein function ishighly sensitive to

protein structure!!!

Protein Structure Primary Protein Structure:

sequence of amino acids

Secondary Protein Structure: Sequence of amino acids linked by hydrogen

bonds to form new shape, such as…

Pleated sheath

Helix

Tertiary Protein Structure Folded shape of protein when there are

attractions between alpha helices & pleated sheets

Denaturation occurs when hydrogen bonds holding shape together are broken

DenaturationThe change in the shape of a protein

molecule without breaking peptide bonds

Denaturation Is irreversible!

Changes or halts what the protein does

Is caused by…

Heat, Detergents

Quaternary Protein Structure Protein consisting of more than one amino

acid chain

Model of myoglobin – an oxygen-storing protein found in muscles

Enzymes Enzymes are proteins; usually end in –ase

Named for type of chemical reaction they catalyze

Speed up chemical reactions by increasing the frequency of collisions and by properly orienting the colliding molecules

They are called catalysts because they speed up reactions without being altered themselves and can be used over and over again

Important properties: specificity, efficiency, and control…

Specificity, Efficiency, and Control Specificity: highly specific

Each enzyme catalyzes a particular chemical reaction that involves specific substrates (molecule upon which the enzyme acts) Specific products are produced Enzyme and substrate fit together like a lock-n-key

Efficiency: single enzyme molecule can convert substrate molecules to products at rate of 600,000 per second…

Control: regulated by cell’s genes; sets rate of synthesis by enzymes and their concentration Co factors/ coenzymes: non-protein substances affect rate at

which inactive enzyme forms become active and visa versa Cofactors: ions of iron, zinc, magnesium, or calcium Coenzymes: niacin, riboflavin, derivatives of Vitamin B

Enzymes-Substrate Complex Enzymes are affected by…

Enzymes-Substrate Complex Enzymes are affected by…

Heat pH Concentration of substrate Competitive inhibitors Noncompetitive inhibitors Lack of cofactors Defective genes

Nucleic Acids: Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA)

Contain C, H, O, N, and P Two types of nucleic acid:

DNA (deoxyribonucleic acid); double helix, 2 strands RNA (ribonucleic acid); one strand

Nucleic acid molecule made up of repeating nucleotides DNA nucleotides consists of: four different nitrogenous bases

(adenine, guanine, cytosine, and thymine), 5-C sugar (deoxyribose), and a phosphate group

RNA nucleotides consists of: four different nitrogenous bases (adenine, guanine, cytosine, and uracil), 5-C sugar (ribose), and a phosphate group

Nitrogenous bases are bonded together by hydrogen bonds

These carry genetic materials and transfer energy from food to body functions

Adenosine Triphosphate “Energy Currency” of living organisms Main function: transfer energy from energy-releasing

reactions to energy-requiring reactions that maintain cellular activities Examples: contraction of muscles, movement of chromosomes during cell division, movement of structures within a cell, transport of substances across cell membrane, and synthesis of larger molecules from small ones

Adenosine composition = adenine + ribose Hydrolysis reduces ATP to ADP (adenosine diphosphate)

thus releasing its stored energy ATP synthase and energy from glucose promotes the

addition of a phosphate group to ADP to reenergize it to ATP