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Water, pH and Biological Molecules
What’s so special about water?
It’s a great solvent.
It hold’s tons of heat.
It has high surface tension.
Its less dense as a solid than a liquid.
Water as a Solvent
Dissolving table salt (sodium chloride)
Water Is Lighter as Solid than as a Liquid
This means that ice forms
an insulating blanket over
water.
Water Has High Surface Tension
The attraction of one water
molecule for another also accounts
for ability to hold huge amounts of
heat.
pH is a Big Deal
pH is a measure of
proton (hydrogen ion or
H+) concentration .
Low pH = lots of H+s,
high pH = few H+s.
In biology, keeping H+
levels within a narrow
range is critically
important.
Acids and Bases
An acid produces H+
A base absorbs H+
Carbon’s Cool
Carbon is the central atom of life.
Because carbon contains 4 electrons in its outer shell, it can pair in
many ways with many different atoms in an “attempt” to fill its
outer shell.
Carbon is the Central Atom of Life.
glucose
amino acids
fat
Some Useful
Nomenclature
In Biology, Shape Matters
Its not just chemical formula, it’s the shape of the molecule that lets it
do its “job”.
Never forget the axiom – structure dictates function.
Some biological molecules.
Ah, That Smell!
Once again, shape matters. It’s the good fit between odorant and
receptor molecule that lets us detect aromas.
Molecules of Life
How do you build a cell?
Start with water, add lots of small carbon-containing molecules and
…….
Four Major Classes of Biological Molecules
Rules of the Game
Macromolecules are built by linking a set of building blocks
(monomers) together into long chains (a polymer).
Each hexagon is this figure is a monomeric
building block linked together to form a
polymer.
Macromolecules Are Built By Linking a Set Of Building Blocks
(Monomers) Together Into Long Chains (A Polymer).
Glucose: A Simple Carbohydrate Used For Energy Production and
as a Building Block For Complex Carbohydrates
Linking Simple Sugars – the First Step to a Polymer and the Last
Step to Some Familiar Compounds
Some Familiar and Important Complex Carbohydrates
Note the way complex macromolecule are built by linking simple repeating units.
Carbohydrates are Central Players
in Energy Production and Storage
Lipids are Hydrophobic Molecules That Exist In Three Primary Forms
Sterol
Fat
Phospholipid
Fats Are Made By Linking Fatty Acid Chains to
Glycerol, a Three Carbon Molecule
Space-filling model
of a fat
A fatty acid
Fats are Used in Energy Storage and
Production
The Degree
Of
Saturation
In A Fat
Affects Its
Physical
And
Nutritional
Properties
Where are the
double bonds?
The Degree
Of
Saturation
In A Fat
Affects Its
Physical
And
Nutritional
Properties
saturated
monounsaturated
Where are the
double bonds?
polyunsaturated
Sterols Are Part of Cellular Membranes and Act as Hormones
Note the four ring structure
common to all sterols.
Sterols As Hormones
Estrogen, testosterone,
progesterone, and
corticosteriods (cortisol) are
all steroid hormones.
Sterols As Hormones
“Designer steroids” are major
sporting news where they have been
used illegally in track and field,
baseball, football and countless
other sports.
A heavily muscled Linford
Christie who was disqualified
from international
competition after testing
positive for a banned steroid.
Phospholipids are Building Blocks of Cellular Membranes
The hydrophilic head group and hydrophobic tails are the keys to phospholipid
function.
Hydrophilic Head Group And Hydrophobic Tails Are The Keys To
Phospholipid Function
Phospholipids have a Jekyll and Hyde personality.
Phospholipids Form Biological Membranes
Protein
Proteins are THE key elements of life.
Forget DNA, proteins rule.
Remember the principle - structure determines function.
Since proteins are the key players of the cell, it follows that
protein structure determines cell function.
Some of the Diverse Functions of Proteins
Strands of the Protein Keratin Create Hair
Proteins are Linear Chains of Linked Amino Acids
A Common
Thread and a
Unique
Identity
Amino Acids, Peptide Bonds, Polypeptides, Protein
Proteins are linear chains of 20 different building blocks called amino acids.
Peptide bonds
Amino acids are linked by peptide bonds – a form of
covalent bond.
Proteins are Folded Structures
Whose Shape (and therefore
function) Depends on Amino
Acid Sequence
Nucleic Acids
There are two kinds of nucleic acids,
DNA and RNA. Both are involved in
the storage and flow of information
from gene to gene product.
DNA
Nucleotides are
DNA and RNA
Building Blocks
Nucleotides are Important in Their Own Right
Nucleotides fuel the
cell and coordinate its
metabolism.
ATP, the cell’s
primary energy
currency.