Download Mixtures & Organic Compounds

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 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
H+
OH-
 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
 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
Organism A__________
Organism B --------------4.5
10.5
0-8
0
1
2
3
4
5
6.5-14
6
7
8
9
10
11
12
13
 Certain organisms require a
certain pH environment for
optimum (best) growth
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.Carbohydrates
2.Lipids
3.Proteins
4.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 sugars
C12H22O11
 Sucrose = glucose + Fructose
 Maltose = glucose + Glucose
 Lactose = 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
+
C6H12O6 + C6H12O6
+
Water
+
H2O
+
C12H22O6
* Dehydration synthesis-water is squeezed out
Hydrolysis of Disaccharide
Sucrose
+ Water
Glucose
+
C12H22O6
+
Fructose
+
+
H2O
C6H12O6
+
C6H12O6
* 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 fearinghydrocarbon 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 atom
b) Single H atom
c) 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 bonds
b)
a)
d)
c)
e)
Amino acid
Amino acid
Water
Dipeptide
Polypeptide:
 A long chain of amino acids held
together by peptide bonds
 Ex of Proteins: Insulin (hormone),
hemoglobin, and enzymes
Nucleic Acids: complex organic
molecules that store important
information in the cell
 2 important types of nucleic acids are
DNA and RNA
1.DNA (deoxyribonucleic acid): stores
essential info for almost all cell
activities-including cell division
2.RNA (ribonucleic acid): stores and
transfers 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)