Transcript Molecules of Life

Molecules of Life
Polymers Are Built of Monomers
• Organic molecules are formed by living
organisms
– have a carbon-based core
– the core has attached groups of atoms called
functional groups
• the functional groups confer specific chemical
properties on the organic molecules
Polymers Are Built of Monomers
•
The building materials of the body are known as
macromolecules because they can be very large
•
There are four types of macromolecules:
1.
2.
3.
4.
•
Proteins
Nucleic acids
Carbohydrates
Lipids
Large macromolecules are actually assembled from
many similar small components, called monomers
–
the assembled chain of monomers is known as a polymer
Macromolecule Formation
• There are 4 major categories of organic
molecules in living organisms:
– Carbohydrates
– Lipids
– Protein
– Nucleic acids
Macromolecules
• A macromolecule is built upon repeating
subunits called polymers.
• Macromolecules are large and complex.
• An organic molecule is based on long
chains of carbon with functional groups
on the ends that give the molecule its
unique chemical properties.
Macromolecules
• All four macromolecules consist of a covalent
bond between two subunits..a hydroxyl group
is removed from one end and a hydrogen
group from the other end.
• This process is called dehydration.
• Dehydration requires the action of an enzyme
to facilitate chemical binding.
• Adding of water to the polymer too break them
into subunits is called hydrolysis.
Carbohydrates
• Carbohydrates are energy sources and are
made of polymers of simple carbohydrates.
– Simple carbohydrates include monosaccharides and
disaccharides.
– Complex carbohydrates are polysaccharides formed
from glucose.
• Component of plant cell walls, outer skeletons
of insects.
• Ex.: chitin, cellulose, glycogen, starch.
Carbohydrates
• Carbohydrates are monomers that make up
the structural framework of cells and play a
critical role in energy storage
– a carbohydrate is any molecule that contains the
elements C, H, and O in a 1:2:1 ratio
– the sizes of carbohydrates varies
• simple carbohydrates – consist of one or two monomers
• complex carbohydrates – are long polymers
Carbohydrates
• Simple carbohydrates are small
– monosaccharides consist of only one monomer
subunit
• an example is the sugar glucose (C6H12O6)
– disaccharides consist of two monosaccharides
• an example is the sugar sucrose, which is formed by
joining together two monosaccharides, glucose and
fructose
Formation of sucrose
Carbohydrates
• Complex carbohydrates are long polymer
chains
– because they contain many C-H bonds,
these carbohydrates are good for storing
energy
• these bond types are the ones most often
broken by organisms to obtain energy
– the long chains are called polysaccharides
Carbohydrates
• Plants and animals store energy in
polysaccharide chains formed from glucose
– plants form starch
– animals form glycogen
• Some polysaccharides are structural and
resistant to digestion by enzymes
– plants form cellulose cell walls
– some animals form chitin for exoskeletons
Carbohydrates and their function
Lipids
• Fats and all other biological materials that are
not soluble in water, but are soluble in oil are
lipids.
• Used for long term energy storage.
• Fats:
– Triglycerols are made of glycerol and three fatty
acids.
– Fatty acids may be saturated or unsaturated with
hydrogen along the carbon chain.
Lipids
• Fats are used for:
– Energy storage;
– Components of cell membranes
(phospholipids);
– Message transmission (steroids);
– Pigmentation.
Lipids
• Fatty acids have different chemical properties
due to the number of hydrogens that are
attached to the non-carboxyl carbons
– if the maximum number of hydrogens are attached,
then the fat is said to be saturated
– if there are fewer than the maximum attached, then
the fat is said to be unsaturated
Saturated and unsaturated fats
Proteins
• Proteins may serve as enzymes, play a
structural role, and act as chemical
messengers.
• They are polypeptides made up of amino
acids joined by peptide bonds.
• Act as catalysts.
The formation of a peptide bond
Proteins
• Protein structure:
– The sequence of amino acids within the protein is
called the primary structure.
– Any folding of the primary chain structure is called
the secondary structure.
– Globular shapes are the tertiary structure of a
protein.
– When more than one polypeptide chain composes
the protein, it has quaternary structure.
– The shape of a protein can be denatured (poor
function results).
Proteins
•
There are four general levels of protein
structure
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
Proteins
• Primary structure – the
sequence of amino
acids in the polypeptide
chain
• This determines all
other levels of protein
structure
Figure 4.7 Levels of protein structure:
primary structure
Proteins
• Secondary structure forms
because regions of the
polypeptide that are nonpolar are forced together;
hydrogen bonds can form
between different parts of
the chain
• The folded structure may
resemble coils, helices, or
sheets
Figure 4.7 Levels of protein structure:
secondary structure
Proteins
• Tertiary structure – the
final 3-D shape of the
protein
• The final twists and
folds that lead to this
shape are the result of
polarity differences in
regions of the
polypeptide
Insert Figure 4.7 from TLW 6e
Proteins
• Quaternary structure –
the spatial arrangement
of proteins comprised
of more than one
polypeptide chain
Figure 4.7 Levels of protein structure:
quaternary structure
Protein
• The shape of a protein affects its function
– changes to the environment of the protein
may cause it to unfold or denature
• increased temperature or lower pH affects
hydrogen bonding, which is involved in the
folding process
– a denatured protein is inactive
Nucleic Acids
• Nucleic acids (polynucleotides) store
information for cells.
• DNA (Deoxyribonucleic acid) exists as a double
helix of polynucleotides, using base pairing
within the helix.
– Base pairing dependent upon hydrogen bonding.
– DNA encodes genetic materials and ribonucleic acid
(RNA) is involved in protein synthesis.
The Double Helix
• The reason for DNA to assume its double
helix is because only two base pairs are
possible: Adenine-Thymine and GuanineCytosine.
• The advantage of the double helix is that
it contains two copies of the
information—one the mirror image of
the other.
The DNA double helix