Download ANPS 019 Black 09-02

ANPS019
09/02/2011
COVALENT BOND
Atoms share electrons to form a molecule
Very strong
If atoms share electrons equally, nonpolar covalent bond
-equal pull, nonpolar bonds
If atoms share electrons unequally, polar covalent bond
THE STRUCTURE OF WATER MOLEULCES
Polar covalent bond
Two hydrogen atoms each form a covalent bond with the same oxygen atom
Electronegativity: more pull
The oxygen atom is bigger and exerts more pull on the electrons
The electrons spend more time around the oxygen nucleus than around the hydrogen nucleus, thus are
not share equally.
-The oxygen acts more positively, and the hydrogen acts more negatively
The is a polar covalent
HYDROGEN BONDS
(formed all over the body)
Occur when hydrogen bonds covalently with other elements
Unequal sharing of electrons creates a polar molecule
The weakly positive hydrogen atom of a molecule may be attracted to negatively charged atoms of
other molecules
Hydrogen bonds create weak forces that affect the shape and properties of compounds
THE STRUCTURE OF WATER IS BASED ON HYDROGEN BONDING
Individual water molecules are attracted to one another by hydrogen bonds between the oxygen atom
(slight negative charge) of one molecule and the hydrogen atom (slight positive charge) of another
water molecule
Each water molecule is held together by polar covalent bonds
One water molecule is attracted to another by HYDROGEN BONDS
WATER MOLECULES AND SOLUTIONS
The polar water molecule is attracted to any solute with charged atoms
Most ions exist in the body with a shell of water surrounding them
Anything with a charge exists well with water
PROPERTIES OF WATER
Solubility:
-most molecules in body dissolved in water (but not all)
Reactivity
-water is involved in many of the reactions in the body
High Heat Capacity
-water can absorb and retain a great deal of heat
Lubrication:
-little friction between water molecules so water is protective for many interactions between organs
IMPORTANT TERMS
Compounds that interact readily with water hydrophilic
Compounds that do not interact with water are hydrophobic
--example, fatty substances
A CHEMICAL REACTION OCCURS WHEN REACTANTS COMBINE TO GENERATE ONE OR MORE PROFUCTS
(Chemical reactions should go both ways)
All chemical reactions in the body constitutes metabolism
Metabolism provides for the capture, storage and release of energy
All reactions are theoretically reversible
Anabolism = building larger molecules from smaller ones
Catabolism = breaking larger molecules into smaller one
At equilibrium the rates of two opposing reactions are in balance: anabolism = catabolism
ENZYMES
Most enzymes are proteins: organic molecules
Reactants (substrate interact to yield a product by binding to the active site of the enzyme
Enzymes are catalysts that promote chemical reactions
Active site: substrate binds to enzyme
--active sites are unique for each substrate
Enzymes can do reaction repeatedly
ENZYMES AND ACTIVATION ENERGY
Activation energy is the amount of energy needed to begin a reaction
Enzymes make reaction more likely
Most reactions require enzymes
Enzymes reduce energy of activation, making it more likely a reaction will occur
Enzymes are not changed or used up in the reaction, so one enzyme can catalyze the same reaction over
and over in the cell
pH
A measure of concentration of hydrogen ions in a solution
Solutions can be classified by their pH as neutral, acidic (more H+), or basic (less H-)
Lower # is more acidic
7 is neutral
High number is basic
BUFFERS
Acids release hydrogen ions into solution
Bases remove hydrogen ions from solution
Strong acids and strong bases ionize completely; weak acids and weak bases do not ionize completely
*BUFFERS ARE VERY IMPORTANT TO SUSTAINING BODY AND BLOOD pH: Blood pH is maintained over a
very small range (7.35-7.45) because compounds in blood act as weak acids and bases, releasing or
removing small numbers of H+ ions to keep pH stable
NUTRIENTS AND METABOLITES
Nutrients are essential chemical compounds obtained from their diet
Metabolites are molecules synthesized or broken down inside the body
These can be classified as organic or inorganic compounds:
ORGANIC: have carbon and hydrogen as their primary structural component
INORGANIC: not primarily carbon and hydrogen
ORGANIC COMPOUNDS
Usually large, complex molecules containing carbon and usually hydrogen and oxygen
Four major classes of organic compounds
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids
(Found in small amounts)
The structure of the carbon atom gives it unique bonding properties: VERSATILE
Maybe form single bonds, double bonds, triple bond
Bonding pattern influences the shape of molecule: complexity in sizes and shapes due to bending of
bonding
Carbon based molecules can have wide range of sized and shapes
CARBOHYDRATES
*most simple
Key example: GLUCOSE
Sugars and starches, glycogen
Hydrophilic molecules
Important energy source for metabolism
Occur as monosaccharides, disaccharides and polysaccharides
-di and polysaccharides formed from monosaccharides by dehydration synthesis (removal of water
molecule)
THE FORMATION AND BREAKDOWN OF COMPLEX SUGARS
Water is very important with the interaction of sugar molecules
Dehydration synthesis: two molecules, such as two monosaccharides, are joined together by the
removal of a water molecule, to form a disaccharide.
Hydration synthesis: a complex molecule is broke down by the addition of a water molecule.
Disaccharide to 2 monosaccharides.
POLYSACCHARIDES ARE VERY LARGE CARBOHYDRATES
-straight or high branched
Hydrophilic
Large size makes them ideal molecules to ‘hold” water in the body
LIPIDS
Less oxygen, but same about of carbon as carbohydrates
Includes fats, oils, and waxes
Set of compounds
Hydrophobic
Five classes:
1. Phospholipids and glycolipids: uses in cell membrane
2. Fatty acids: uses in building blocks, energy
3. Glyceridses: uses: fatty acids + glycerol = body fat
4. Steroids: uses cholesterol, some hormones
5. Eicosanoids: uses prostaglandins, etc cell messages
-produced acid released by cell
FATTY ACIDS
Long carbon chains with hydrogen atoms attached
*** -COOH (Carboxylic Acid group)
1. Saturated: all single bonds
2. Unsaturated: double bonds which form kinks
TRIGLYCERIDES
Formed storage fats
Triglycerides = three fatty acids attached by dehydration synthesis to one molecule of glycerol
-energy source
-insulation
-protection
STEROIDS
Cholesterol is critical in cell membrane structure: “structural lipid”
-Four ring structure
Include sec hormones (“sex steroids”) and hormones regulating metabolism (“corticosteroids”)
--help suppress immune system
PROTEINS
Most abundant organic compounds in human body
20% totally body weight
Proteins perform vital functions in the body
1. Structural proteins
2. Contractile proteins: muscles
3. Transport proteins: shovel or move other things in body
4. Enzymes: metabolic activity
5. Buffering proteins: maintain pH
6. Antibodies: fight disease
AMINO ACIDS ARE THE BUILDING BLOCKS OF PROTEINS
Amino acids contain:
-a central carbon atom
-an amino group
-a carboxylic group
-a radical group
--differs between amino acids
--20 different combinations
Amino acids join with peptide bonds to form linear stands of molecules
Hydrophilic
THE FORMATION OF A PEPTIDE BOND INVOLES THE REMOVAL OF A WATER MOLEUCLES BETWEEN TWO
ADJACENT AMINO ACID MOLECULES
INTERACTIONS BETWEEN MOLECULES IN THE CHAIN CUAE THE CHAIN TO BEND, SPIRAL OR FOLD INTO A
UNIQUE SHAPE
1. Primary structure: linear chain of amino acids
2. Second structure: amino acid interactions of either an alpha helix or pleated sheet
3. Tertiary structure: complex folding
4. Quaternary structure: hemoglobin: globular protein or keratin or collage (fibrous protein)
PROTEINS
Long chain of amino acids (1000-100,000)
-short chains are called peptides
Form complex shapes as amino acids in chain react with one another
*Most importantly:
Shape of final protein determines its function
--proteins pushed outside their optimal temperature and pH range become temporarily or permanently
denatured and ill ceases to function-shape changes make proteins nonfunctional!