Transcript Primary Structure - LaurensAPBiology

Water, pH and Biological Molecules…
The Chemistry of Life!
RECALL:
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”
Sterols
Note the four ring structure
common to all sterols.
Sterols are: 1) essential membrane components and 2) form many 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.
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
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
Primary Structure
•Conformation:
Linear structure
•Molecular Biology:
each type of protein has a unique
primary structure of amino acids
•Ex: lysozyme
•Amino acid substitution:
hemoglobin; sickle-cell anemia
Secondary
Structure
•Conformation: coils &
folds (hydrogen bonds)
•Alpha Helix:
coiling; keratin
•Pleated Sheet: parallel;
silk
Tertiary Structure
•Conformation:
irregular contortions from
R group bonding
√hydrophobic
√disulfide bridges
√hydrogen bonds
√ionic bonds
Quaternary
Structure
•Conformation:
2 or more polypeptide
chains aggregated into
1 macromolecule
√collagen (connective
tissue)
•√hemoglobin
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.