Download + H 2 O

Chemistry, Water, and
Biochemsitry
The Organic Molecules
“You are what you eat!”
Biochemistry Preview/Review
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90 naturally occurring elements on Earth’s crust
11 are common to living organisms
20 found in trace amounts
4 elements make up approximately 96.3% of the
total weight of the human body:
 nitrogen
 carbon
 oxygen
 hydrogen
In varying combinations and amounts, these four
elements make up mostly all of the compounds
found in living things
Elements by Mass in the
Human Body
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Oxygen: 65%
Carbon: 18.5%
Hydrogen 9.5%
Nitrogen: 3.3%
Phosphorus: 1.0%
Sulfur 0.3%
Sodium: 0.2%
Magnesium: 0.1%
Silicon: trace
Fluorine: trace
C.H.N.O.P.
Chemical Bonds: Hydrogen Bonds

Hydrogen bonds are a type of weak chemical
bond formed when the partially positive
hydrogen atom participating in a polar covalent
bond in one molecule is attracted to the
partially negative atom participating in a polar
covalent bond in another molecule or in
another part of the same macromolecule
Properties of Water

Water is unique in that it
is the only natural
substance that is found
in all three states —
liquid, solid (ice), and
gas (steam) — at the
temperatures normally
found on Earth.
Properties of Water
 Water is a polar molecule.
 A polar covalent bond is an
attraction between atoms
that share electrons unequally
because the atoms differ in
electronegativity. The shared
electrons are pulled closer to
the more electronegative atom,
making it partially positive.
Properties of Water
 Water freezes at 0oC (32o F) and boils at 100o C (212o F)
at sea level, (but 186.4° at 14,000 feet). In fact, water's
freezing and boiling points are the baseline with which
temperature is measured.
 Water is unusual in that the solid form, ice, is less dense
than the liquid form, which is why ice floats.
 Water expands upon freezing. Water molecules is an
ice crystal are spaced relatively far apart because of
hydrogen bonding. Floating ice insulates the water
below and prevents seas and lakes from freezing solid.
Properties of Water
• Water has a high specific heat
index. Hydrogen bonds absorb
heat when they break, and
release heat when they form,
minimizing temperature changes.
•
•
This means that water can absorb a
lot of heat before it begins to get
hot. This is why water is valuable to
industries and in your car's radiator
as a coolant.
The high specific heat index of
water also helps regulate the rate at
which air changes temperature,
which is why the temperature
change between seasons is gradual
rather than sudden, especially near
the oceans.
Properties of Water
 Water has a very high surface tension. Hydrogen bonds hold
molecules together.
 Water is sticky and elastic, and tends to clump together in drops
rather than spread out in a thin film.
 Surface tension is responsible for capillary action, which allows
water (and its dissolved substances) to move through the roots
of plants and through the tiny blood vessels in our bodies.
 Adhesion: The attraction between different kinds of
molecules.
 Cohesion: The attraction between molecules of the same
kind.
 Cohesion theory of water transport. Theory that the
collective cohesive strength of their hydrogen bonds allows
water molecules to be pulled up through a plant’s xylem in
response to transpiration (evaporation of water) from leaves.
Properties of Water
 Water has a high heat of vaporization.
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Hydrogen bonds must be broken for water to
evaporate.
Evaporation of water cools the surfaces of plants
and animals.
The heat of vaporization is the amount of heat
energy needed to convert one gram of a liquid into
a gas.
Properties of Water
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Water has versatility as a solvent:
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Charged regions of polar water molecules are attracted to
ions and polar compounds.
Water is an effective medium for complex chemical reactions
in organisms
A solution is a liquid consisting of a homogeneous mixture of
two or more substances.
A solvent is the dissolving agent.
 A solute is the substance that is dissolved
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pH
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Water tends to disassociate into H+ and OH- ions. In this
disassociation, the oxygen retains the electrons and only
one of the hydrogens, becoming a negatively charged
ion known as hydroxide.
Pure water has the same number (or concentration) of
H+ as OH- ions, therefore the pH is 7
Acidic solutions have more H+ ions than OH- ions.
Basic solutions have less H+ ions than OH- ions.
An acid causes an increase in the numbers of H+ ions
and a base causes an increase in the numbers of OHions.
pH
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The pH scale is a logarithmic scale representing the
concentration of H+ ions in a solution.
If we have a solution with one in every ten molecules
being H+, we refer to the concentration of H+ ions as
1/10. Remember from algebra that we can write a
fraction as a negative exponent, thus 1/10 becomes 101. Conversely 1/100 becomes 10-2 , 1/1000 becomes 103, etc.
Logarithms are exponents to which a number (usually
10) has been raised. The log 1/10 (or 10-1)
pH, a measure of the concentration of H+ ions, is the
negative log of the H+ ion concentration.
If the pH of water is 7, then the concentration of H+
ions is 10-7, or 1/10,000,000.
pH
What is polymerization?
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The formation of
larger compounds
from smaller
compounds
The bonding process
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Polymers formed from monomers via
dehydration synthesis
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Where water is removed from the two
joined molecules
Separated via hydrolysis
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Where water is put back in place
Dehydration Synthesis
A + B + C = ABC + 2 molecules of H2O
H2O
H2O
Hydrolysis
In order to reverse the previous reaction
(dehydration synthesis), we need to add
water to the product ‘ABC’.
So:
ABC + 2 molecules of H2O = A + B + C
Example of a
Modular Home
(i.e.,
Macromolecule)
Living Room
Bed
Room
Monomers
Monomers
Kitchen
Bathroom
All of the individual monomers form the single polymer
So What’s In The Foods
You Eat?
Proteins
Fats (a.k.a.- Lipids)
Carbohydrates
Organic v. Inorganic Compounds?
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Contain carbon to hydrogen (C-H) bonds
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Inorganic compounds = NO (C-H) bonds
“Bucky Ball”
Compounds of Life: The
Macromolecules
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There are four groups of organic
macromolecules:
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Carbohydrates
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Sugars, Starches
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Fats, Waxes, Oils
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Amino acids
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RNA, DNA
Lipids
Proteins
Nucleic acids
Carbohydrates
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Commonly referred to as sugars and
starches
Energy stored in the bonds of the
carbohydrate molecule
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1 grams = 4 calories (Kilocalorie)
Bonds easily broken down (water) by the
body so “Carbs” are the body’s First
Choice of Energy!
Carbohydrates
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They consist of Carbon, Hydrogen and
Oxygen atoms in a consistent ratio of
1:2:1 or C1H2O1
The simplest unit/monomer:
monosaccharides
Monosaccharides
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Simple Sugars
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Some examples are glucose, galactose and
fructose
They all have the same chemical
formula, C6H12O6, but they have
different molecular structures
 Called
Isomers
Monosaccharide Isomers
Galactose- Milk Sugars
Glucose- Plant Sugars
O OH H OH OH OH
H
C
C
C
C
C
C
H OH H
H
H
H
H
O OH H
H OH OH
C
C
C
Fructose- Fruit Sugars
OH O
H
C
H
C
H OH OH OH
C
C
C
C
OH H
H
H
H
C
C
C
H OH OH H
H
H
Monosaccharide Isomers
Forming Carbohydrate
Polymers
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Two monosaccharides: glucose & fructose
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Form a disaccharide: Sucrose (Table Sugar)
Put table sugar in a pan and turn on the
heat…what happens?
Disaccharide formation
Glucose
Fructose
Sucrose
+
OH
C6H12O6
+
OH
O
C6H12O6
C12H22O11
Water formed from bond between two -OH structures
with an ‘O’, remaining at bond
H2O
Disaccharides
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Other disaccharides are:
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Maltose (malt sugars)
Lactose (milk sugars)
“Di-” & “Poly-” are “complex carbs”
“Mono-” are “simple sugars”
Reversing Disaccharide
formation with Hydrolysis
Sucrose
Glucose
+
Fructose
H2O
O
OH
C12H22O11
C6H12O6
Add Water to Reaction
OH
C6H12O6
Function of Polysaccharides
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Polysaccharides are many (3 or more)
monosaccharides joined together
This is the form of sugar that is stored
in living things
Storage forms of
Polysaccharides
•Glycogen is the animal form of stored
sugar
•It can be hundreds to thousands of
glucose molecules long
•Starch is the plant form of
stored sugar
•It can be hundreds to
thousands of glucose molecules
long
•It does not “branch” like
glycogen
•It also shows a distinctive “branching”
pattern
Starches continued
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Cellulose is a type of starch that plants synthesize
It is the principal component of wood, or the cell
walls of plants
The human appendix is believed to have been used to
break down cellulose tens of thousands of years ago
Humans, as a whole, can no longer break down
cellulose and so it is now considered fiber in our diets
Lipids
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Lipids include
 fats,
 oils
 waxes
**(Fats and waxes are solids at room temperature while oils are
not)
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Lipids have three main functions:
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Energy storage
Forming biological membranes (cell membranes)
Chemical messengers in the body
Lipids
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Energy Storage: Potential Energy
Lipids
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Biological Membranes: Cell Membranes
Lipids
Chemical
Messengers: i.e., Steroids
Lipids
Cholesterol…Good or Bad?
Polymerization of a Lipid
H
H
C
OH
H
C
OH
H
C
OH
H
OH
O
H H
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
Carboxyl
Glycerol
Fatty Acid
Chain
H
H
+ H2O
Saturated v. Unsaturated Fats
H H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
LARD or CRISCO!
H H
H
H
H
Unsaturated Fats: Openings via Carbon to Carbon
double bonds
C
H
C
C
C
C
C
H
H
H
H
H
Saturated Fats: No openings; Hydrogen bonded to
every Carbon.
H
Strong, hard to break bonds.
Bonds now easier to metabolize.
CANOLA OIL, FISH OIL, ETC.
Proteins
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Proteins contain N, O, H and C
Proteins are made from long “chains” of amino
acids
Bonds between amino acids called peptide
bonds.
 Proteins also called polypeptides.
Amino acids have the same basic structure
with the exception of the “R” group: LEGO!
Amino Acid Uses
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Proteins used for building and
maintenance of tissues: i.e., muscle
Not natural
Natural
Amino Acid Uses
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Proteins (amino acid chains) are your last
resort as a food source because they are
difficult to metabolize
Amino Acid Structure
H
H
N
H
C
R
O
Carboxyl Group
C
OH
Carbon
Backbone w/”R”
group
Amino Group
Forming a Polypeptide through
Dehydration Synthesis
H
H
N
H
C
R
O
H
C
H
N
OH
H
H2O
C
R
O
C
OH
Forming a Polypeptide through
Dehydration Synthesis
H
H
N
H
C
R
O
C
H
H
N
C
R
O
+
C
H2O
OH
The result of taking water from the two amino
acids is a polymer, or protein, that has two
monomers connected at a Carbon and a Nitrogen
Nucleic Acids
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2 different nucleic acids:
 RNA-Ribonucleic acid
 DNA-Deoxyribonucleic acid
Both are composed of:
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Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
Nucleic Acids
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Monomers of nucleic acids are called
nucleotides
Nucleotides have three basic parts:
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A special 5-carbon sugar
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A phosphate group
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A nitrogenous base
Nucleic Acids
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The nitrogenous bases contain nitrogen
A nucleotide, depending upon DNA on RNA,
will have one of the following nitrogenous
bases:
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Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
Uracil (U)
Diagram of a Nucleotide
Phosphate
Group
Nitrogenous
Base
5-Carbon
Sugar