The Chemistry of Life
Chapter 2
Water makes up approx 70 to 95 percent of
most organisms.
When the electrons in a covalent bond are not
shared equally they form a polar molecule.
Polar Molecule: unequal distribution of
charge, the molecule has a distinct partial
positive end and a partial negative end.
Universal Solvent: “like dissolves like”
H20 - Polar molecule
Hydrogen
S-
S-
1p+
Hydrogen
6e- 2e-
S+
8p+
8n0
1p+
S+
S+
S+
Oxygen
http://www.youtube.com/watch?v
=DAilC0sjvy0&feature=related
Properties
•High Specific Heat – resists changes in temp.
Water retains its state at temperature levels where other
liquids would begin to turn into gas or evaporate.
•Cohesion – attraction of water molecules,
provides surface tension.
•Adhesion – attraction of water to different
substances….meniscus
Role of Carbon
Carbon has 4 electrons to share and it can share
these electrons in three different ways.
4 Covalent bonds it can form
1. Single
C-C
2. Double
C=C
3. Triple
C C
Carbon-based molecules have three
general types of structures.
Straight
Branched
Ring
ISOMERS
Isomers - compounds that have the
same molecular formula but different
structural formula.
Monomer - singular unit or molecule
Polymer - a group of molecules or units
bonded together.
cellulose
FUNCTIONAL GROUPS
Most organic compounds have functional groups
of atoms that carry out chemical reactions.
FUNCTIONAL GROUPS
-NH2
-PO4
-COOH
-OH
Amine
Phosphate
Carboxylic Acid
Hydroxyl or
Alcohol
Proteins
Nucleic Acids
Fats
Lipids &
Carbohydrates
ENDINGS
-ose
-in
-ase
-ol
Sugars
Proteins
Protein Enzyme
Lipid
(Sucrose)
(Pepsin)
(Amylase)
(Glycerol)
CARBOHYDRATES
- C, H, O
1 Carbon : 2 Hydrogens : 1 Oxygen
1:2:1 ratio
Example:
 Glucose
C6H12O6
CARBOHYDRATE
MONOMERS
Monosaccharides - simplest carbohydrate
Most common arrangement : C6H12O6
Names : Glucose, Fructose, Galactose
CARBOHYDRATE POLYMERS
Disaccharides - 2 monosaccharides
covalently bonded together.
Glucose + Galactose = Lactose (milk sugar)
Glucose + Fructose = Sucrose (table sugar)
Glucose + Glucose = Maltose (malt sugar)
Disaccharides
CARBOHYDRATE POLYMERS
Polysaccharides - long chains
(polymers)
Glycogen- made and stored in animals
…highly branched compared to plant starches
(store food in the liver as glycogen)
Starch – is made and stored by plants
(potatoes)
Cellulose – straight rigid structure that makes
up the cell wall in plants (celery, cotton)
Chitin – rigid structure that makes up
exoskeleton of insects
Polysaccharides
Processes of Forming and
Breaking Bonds
1) Dehydration Synthesis/Condensation - put
monomers together by removing water
(H2O)
2) Hydrolysis - Add H20 to break covalent bonds
http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html
Dehydration Synthesis
Hydrolysis
LIPIDS
- C, H, O
Fats, oils, waxes, cholesterol (steroids),
phospholipids (C57H110O6)
Nonpolar - insoluble in water, make up cell
membrane, energy, used to make hormones,
and Elle’s love for *all* her students.
Fat = 3 Fatty acids + glycerol
(monomers)
(polymer)
 Fatty acid : 1. Chain of C and H atoms
2. Carboxyl group -COOH
 Glycerol : 3 Carbon molecule, backbone of a
lipid.
LIPID
carboxyl
http://users.uma.maine.edu/SusanBaker/tr
iglyceride.html
Triglyceride
Phospholipid
1. Glycerol
2. 2 fatty acids
3. Phosphate head
Steroids
Cholesterol
2 KINDS OF FATS
1. Saturated Fats - single carbon bonds
(solids)
2. Unsaturated Fats - double or triple
carbon bonds (liquids)
PROTEINS
-N, C, H, O sometime S, and always love
made up of amino acids (monomers/basic
building blocks of a protein)
1 amino
group
(-NH2)
1 side chain
(R)
1 Carboxyl group
Amino acids differ in side groups, or R groups.
PROTEINS
PEPTIDE BONDS : bonds formed
between the amino group of one
amino acid and the carboxyl
group of another, with love.
What process allows peptide
bonds to take place?
H R
H R
H - N - C - C - OH + H - N - C - C - OH
H O
H O
Dehydration Synthesis
Proteins differ in the number and order of
amino acids.
– Amino acids interact to give a protein its shape.
Hemoglobin
hydrogen bond
– Incorrect amino acids change a protein’s structure
and function.
PROTEINS
Polypeptides : proteins, long chains of
amino acids
20 different amino acids
NUCLEIC ACIDS
P, N, C, H, O
Hereditary Material
1. DNA
- 2 chains
- deoxyribose sugar
- phosphate backbone
- nitrogeneous base
2. RNA
-
1 chain
ribose sugar
phosphate backbone
nitrogeneous base
NUCLEIC ACIDS
Nucleotides : monomer of a nucleic acid.
Nucleotides are composed of 3 separate
parts
5 Carbon
Sugar
+ PO4 +
Phosphate
Group
Nitrogen Base
S
P
N
Nucleotide
• Nucleic acids are polymers of monomers called
nucleotides.
Nucleotides are made of a sugar,
phosphate group, and a nitrogen base.
A phosphate group
deoxyribose (sugar)
nitrogen-containing molecule,
called a base
DNA Nucleotides
DNA Nucleotides
ATP Nucleotide
NUCLEIC ACIDS
Nitrogen Bases
adenine (purine)
guanine (purine)
cytosine (pyrimidine)
thymine (pyrimidine)
uracil (pyrimidine)
*Only in DNA
*Only in RNA
ENZYMES
Protein catalysts necessary for most of the
chemical rxns that occur in living cells.
Catalysts : a substance that increase the rate
of a chemical rxn.
HOW DO YOU RECOGNIZE
AN ENZYME?
*Enzymes are usually named after the substrate
with an -ase ending.
Substrate : the substance an enzyme acts
upon
EXAMPLES :
Enzyme that splits maltose into 2 glucose molecules is
maltase
Proteins - Protease
Lipids - Lipase
HOW DO ENZYMES WORK?
1. The enzyme shape makes it able to do
work.
Active Site
Enzyme
2. The active site is the place on the enzyme
where the rxn occurs.
3. The substance the enzyme act upon is the
substrate
maltose
* The active site must fit the shape of the substrate
HOW DO ENZYMES WORK?
4. The substrate and the active site of
the enzyme come together briefly to form
the enzyme - substrate complex.
Enzyme
*While temporarily together the enzyme may make or
break bonds within the substrate.
OH
OH
Enzyme
* Note enzymes are
not changed by the rxn
QUESTION
?
* What enzyme broke
the bond between the
disaccharide maltose in
the previous slide?
HYPOTHESIS FOR HOW AN
ENZYME WORKS (2)
1. Lock & Key Hypothesis :
Proposes that the substrate fits exactly into the
active site on the enzyme.
* Key - Active Site unlocks the lock - substrate
2. Induced Fit Hypothesis :
Proposes that the enzyme changes shape slightly to
grasp the substrate at the active site.
* Hand grasping a baseball (molds to shape of
object)
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html
http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/animation__enzy
me_action_and_the_hydrolysis_of_sucrose.html
Diffusion
Diffusion : the net movement of particles
from an area of higher concentration
to an area of lower concentration.
Key factors in the rate of diffusion: concentration, temperature,
and pressure.
What is Equilibrium?
Equilibrium : when concentrations are
equal and the net movement
of particles is equal.