Download Chapter 3 USU - BEHS Science

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.
For Polar Molecules, Water Is a Wonderful Solvent
Dissolving table salt (sodium chloride)
Water Holds Immense Amounts of Heat
Forecasts for San
Diego and Gallup,
1/11/06 – 1/15/06
Water’s high heat
capacity has
profound effects on
climate and ecology.
Water Has High Surface Tension
High surface tension allows long
water columns to be drawn from roots
to leaves – even in a redwood.
Water Is Lighter as Solid than as a Liquid
This means that ice forms
an insulating blanket over
water.
pH Matters
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
Learn to recognize these
chemical groups.
In Biology, Molecular 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 major types of biological molecules.
Molecules of Life
How do you build a cell?
Start with water, add lots of small carbon-containing molecules and …….
use these four major classes of biological molecules.
Monomers, Polymers and Macromolecules
Many biological molecules are macromolecules – huge assemblies of atoms.
Biological macromolecules are formed by linking together a set of building
blocks (monomers) into long chains (a polymer).
Carbohydrates
Carbohydrates are used for energy and to create structures.
The building blocks for carbohydrates are simple sugars.
Three views of glucose, a common simple sugar.
Linking Simple Sugars – the First Step to a Polymer
monosaccharides
a disaccharide
A complex carbohydrate is a long-chain polymer made of simple sugars.
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
Complex Carbohydrates Are Often Used to Create Structures
Cellulose is the most abundant macromolecule on earth – and you’re
probably wearing it now.
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
Molecular Structure of a Fat
Fats are Used in Energy Storage and
Production
The Degree Of
Saturation In A Fat
Affects Its Physical
And Health Properties
Where are the
double bonds?
Cis and Trans
Unsaturated Fats
all cis polyunsaturated
“Good”
Omega-3fatty acids
monoand polyunsaturated
saturated
trans
“Bad”
At a Store Near You
The new line showing
levels of trans fat
Beginning January 1, 2006, the FDA
required that the amount of trans fat be
listed on all food labels.
Sterols
Note the four ring structure
common to all sterols.
Sterols are: 1) essential membrane components and 2) form many hormones.
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.
Phospholipids have a molecular Jekyll and Hyde split personality.
Hydrophilic Head Group And Hydrophobic Tails Are The Keys To
Phospholipid Function
Phospholipids Form Double-Layered 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.
Recently, we’ve learned that RNA also plays
important regulatory roles.
DNA
Nucleotides Are the
Monomers That
Create Polymers of
DNA and RNA
Nucleotides are Important in Their Own Right
Nucleotides fuel the cell
and coordinate its
metabolism.
ATP, the cell’s primary
energy currency.