Transcript Hydrogen Bonds

Chemistry of
Life
How small is an atom?
 Placed
side by side, 100 million atoms
would make a row only about 1
centimeter long
About the width of your little finger
Atoms- basic unit of matter
Smallest particles of elements
Protons:
Neutrons:
Electrons:
Charge
+
none
-
Weight
Yes
Yes
No
Location
Nucleus
Nucleus
Orbitals
Elements
Cannot be reduced to simpler components
Isotopes
Atoms of the same element that
differ in their numbers of
neutrons
All isotopes of that element still
have the same properties
When will atoms react?
To
gain Electrons
To
lose Electrons
To
share electrons
Molecules
1. Combinations of atoms
2. Joined by chemical bonds - covalent
Types of Chemical Bonds
 Ionic
Bonds – gain or lose e-
 Covalent


Bonds – share e-
Polar
Non-polar
 Hydrogen
Bonds - general attraction between
partial charges of two different molecules
Ionic Bonds : Losing or Gaining
NaCl
e-
Covalent Bonds: Share Electrons
Non-Polar Covalent: neither nucleus exerts
more pull on shared electrons
Polar Covalent Bond
Atoms share electrons unequally
Hydrogen Bonds
(-)
(+)
(-)
(+)
(+)
(+)
Hydrogen Bonds
• Possible with polar molecules
• Easily broken and reformed
• Give water special properties
Cohesion vs. Adhesion
 Cohesion
– the attraction between
molecules of the same substance
 Adhesion
– attraction between molecules
of different substances
Cohesion
 Water
is extremely cohesive b/c of H
bonding
Adhesion
Water – More…
 Found
to be part of a solution – where
one or more substances are evenly
distributed in another substance
 Solute
– the substance that is dissolved
 Solvent – the substance in which the
solute is dissolved
Still more about H2O
 Acids,
Bases, and pH
 pH
– determined by the concentration of
H+ ions
 H2O
H+ +
OH -
A water molecule can react to form ions
pH
 Acid
Solutions – contain more H+ ions (pH < 7)
 Base
Solutions – contain more OH- ions (pH>7)
Organic Compounds (C)
 Carbohydrates
 Lipids
 Nucleic
 Proteins
Acids
Group Name
Chemical Composition
Carbohydrate
s
C:H:O
1:2:1 ratio
Examples
Function in Living Things
Monosaccharide
s- glucose,
fructose
Disaccharide –
sugar
Polysaccharide
– starch,
cellulose
Storing energy
Structure in plants
Lipids
3 fatty acids
1 glycerol
Fats, oils,
waxes, and
steroids
Store energy
Pigments
Cell Membrane
Messages in body
Proteins
Amino
acids
Enzymes
Collagen
Antibodies
Structural component
Chemical reactions
Nucleic
acids
Nucleotides DNA
RNA
Hereditary info
Enzymes and
messages
Saturated vs. Unsaturated Fats
NUCLEIC ACIDS
Nucleic
acids include RNA and DNA
RNA- Ribonucleic Acid
DNA- Deoxyribonucleic acid
Polymers
made up of repeating
monomers called nucleotides.
NUCLEOTIDES
3 Main Components:
 5-Carbon
Sugar
 Phosphate
Group
 Nitrogen-containing
base
Nucleotides: Important Energy
Storage Molecules
 ATP:
acts like cell’s battery, providing
energy for most activities.