Post on 21-Jan-2016
CHAPTER 2
CHEMISTRY OF LIFE
Level of organisation
ATOM MOLECULE ELEMENT
COMPOUND SOLUTION
Water
Only 4 of the 90 elements make up more than 96% of the mass of the
human body. They are:
Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)
Mixture and Solutions
When elements combine to form a compound, the elements no longer have their original properties.
A mixture is a combination of substance in which the individual components retain their properties. Ex: Sand and sugar
A solution is mixture in which one or more substances (solute) are distributed evenly in another substance (solvent). Ex: Kool-aid
*The concentration of solute is important to organisms
A suspension is a mixture of water and nondissolved materials
Acids and BasesAcids and Bases
Chemical reactions can occur only when conditions are right; they depend on the pH of the environment
pH is a measure of how acid or basic (alkaline) a solution is
A scale with values ranging from 0 to 14 is used to measure pH
ACID is any substance that forms hydrogen ions (H+) in water. Ex: HCl (H+) and (Cl-) has a pH of below 7
BASE is any substance that forms hydroxide ions (OH-) in water.
Ex: NaOH (Na+) & (OH-) has a pH above 7
H+ OH-
Buffers=dissolved compounds that control pH in the body
( HOMEOSTASIS)Buffers are weak acids or bases that
can react with strong acids or bases to prevent sharp sudden changes in pH.
Importance of Acids and Bases to Biological Systems
Chemical reactions in organisms depend on the pH of the environment
Ex: Pepsidase is an enzyme that works best in the acidic human stomach
Certain organisms require a certain pH environment for optimum (best) growth
Organism A__________
Organism B ---------------
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
4.5 10.5
0-8 6.5-14
Life Substances
1.Organic compounds are derived from living things and contain Carbon, must have Carbon and Hydrogen to be organic
2.Inorganic compounds are derived from nonliving things (ex: Water, Carbon Dioxide)
Carbon compounds: easily form 4 covalent bonds to create chains , rings, or branches
•Polymerization: when a large compound (polymer) is produced from smaller compounds (monomers) as the smaller compounds are joined together. •Macromolecules: large polymers
Condensation Reaction (dehydration synthesis) to make
or build, water is produced Hydrolysis to split, water is
added
1.Carbohydrates2. Lipids
3. Proteins4.Nucleic Acids
Carbohydrates
Composed of C (Carbon), Hydrogen (H), Oxygen (O) in
approximate ratio 1:2:1
Monosaccharide: single (simple) sugar Molecular formula for all 3: C6H12O6
GLUCOSE-Produced by plants through photosynthesis
FRUCTOSE-found in fruits GALACTOSE-found in milk
Disaccharides formed by 2 sugarsC12H22O11
Sucrose = glucose + FructoseMaltose = glucose + GlucoseLactose = glucose + Galactose
Polysaccharides formed by more than 2 sugars
Starch-storage for plants Glycogen-storage for
animals (liver) Cellulose-cell wall of plants
Chitin=cell wall of fungi
What makes them different from one another is the arrangement of the individual atoms (structural formulas)
Isomers – compounds that differ in structure but nor in molecular composition
Synthesis of Dissachharides
Glucose Fructose Sucrose Water
+ +
C6H12O6 C6H12O6C12H22O6 H2O
++
* Dehydration synthesis-water is squeezed out
+ +
Hydrolysis of Disaccharide
WaterSucrose FructoseGlucose
C6H12O6 C6H12O6C12H22O6 H2O
+
+
+
+
+
+
* Hydrolysis-water is added
Lipids: Fatty Compounds
Made of C, H, O w/ a greater # in C:H atoms and a smaller # of O atoms than carbohydrates (No uniform Ratio)Ex: fats, oils, waxes (do Not dissolve
in water)
Many common lipids are constructed of a unit of:
•Glycerol (3-Carbon Alcohol) combined by dehydration synthesis
•3 fatty acids-hydrocarbon chain with an Carboxyl Group -COOH
3 fatty acids-hydrocarbon chain with an Carboxyl Group -COOH
Hydrophilic End (water loving-carboxyl end that is polar)
Hydrophobic End (water fearing-hydrocarbon end that is nonpolar)
Functions: forms much of cell membrane to serve as a barrier between the inside and outside of the cell – energy storage for cells
Ex: waxes, triglycerides
Proteins: Organic Compounds made of C, H, O, N
Polymer made of amino acids (monomers); organisms have thousands of proteins
Amino Acids: 20 different kinds that form proteins-has 5 Groups:
a) Central C atomb) Single H atomc) Carboxyl Group (COOH)
d) Amine Group (NH2)
e) R Group (repeating CH2 + CH2 of different lengths)
Dipeptide: 2 amino acids bound together covalently by condensation reaction (a molecule of H2O is lost)-
held together by peptide bondsa) c)
e)d)
b)
Amino acid Amino acid
Dipeptide
Water
Polypeptide:
A long chain of amino acids held together by peptide bonds
Ex of Proteins: Insulin (hormone), hemoglobin, and enzymes
Nucleic Acids: complex organic Nucleic Acids: complex organic molecules that molecules that store important store important
informationinformation in the cell in the cell
2 important types of nucleic acids are 2 important types of nucleic acids are DNADNA and and RNARNA
1.1.DNA (deoxyribonucleic acid): DNA (deoxyribonucleic acid): stores stores essential info for almostessential info for almost all cell all cell activities-including activities-including cell divisioncell division
2.2.RNA (ribonucleic acid): RNA (ribonucleic acid): stores and stores and transfers info for proteinstransfers info for proteins
Nucleotides: monomers that make up both DNA & RNA-made up of 3 main
components:
Phosphate Group
Five-Carbon Sugar
Nitrogen Base (ring)