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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