Chapter 3 (Chemical bases of life )
Organic molecules
They contain carbon
They are abundant in living oraganisms
Macromoleculeis a large, complex organic molecule.
Carbon has 4 electrons on its outer shell. (Needs 4 more electrons to fill the shell)
It can make up to 4 bonds (single or double)(polar or nonpolar)
Functional groups
Groups of atoms with special chemical features that are functionally important.
Each type of functional group exhibits the same properties in all molecules in which it occurs.
Isomers
Two molecules with an identical molecular formula but different structures and characteristics.
Structural isomers
Contain the same atoms but in different bonding relationships.
Steroisomers
Cis-transvisomers
Enantiomers
Positioning around double bound
Mirror image molecules
Formation of macromolecules and organic molecules
Condensation or dehydration
Hydrolysis
Link’s monomers to form polymers
Polymers broken down into monomers
A molecule of water is removed each time a new monomer is added, thus a dehydration reaction
The process repeats to form long polymers
A polymer can consist of thousands of polymers.
Dehydration is catalyzed by enzymes.
A molecule of water is added back each time a monomer is released.
The process repeats to break down long polymer
Hydrolysis is catalyzed by enzymes
Types of organic molecules
Carbohydrates
Lipids
Proteins
Nucleic acids
Composed of C,H and O atoms.
(Cn(H2O)n)
most of the carbon atoms in carbohydrate are linked to a hydrogen atom and a hydroxyl group.
Monosaccharides
-Simplest sugars.
-most common are 5 or 6 carbons.
-pentoses(5C)
Ribose(C5H10O4)
deoxyribose(C5H10O4)
-Hexose
glucose (C6H12O4)
Ways to depict structure
Ring
Linear
Diasaccharides
-Composed of 2 monosaccharides.
-joined by dehydration (glycosidic bond)
-broken down by hydrolysis.
-EXAMPLE:
1)sucrose 2)maltose
3)lactose
Polysaccharides
-Many monosaccharides linked together to form long polymers.
-examples:
1)energy storage: starch(plant), glycogen
(animals).
2)structural: cellulose(plant)
chitin(insects).
Starch is moderately branched.
Glycogen is highly branched
Cellulose is unbranched
-Composed of C,H and some O. -lipids are nonpolar and non soluble in water.
Includes
Fats
Phospholipds
Sterioids
Waxes
-Also know as triglycerides.
-formed by glycerol and 3 fatty acids.
-joined by dehydration;
broken apart by hydrolysis
Fatty acids
Saturated
Unsaturated
All carbons linked by single bonds (tend to be solid at room temperature)
Contains one or more double bonds(tend to be liquid at room temperature-oil-)..(cis is formed naturally but trans is made artificially)
Fats are important for:
1) energy storage: the hydrolysis of triglycerides releases the fatty acids from the glycerol. And these products can be matablized to provide energy.
2) structural: providing cushions that support organs and insulation under the skin that helps.
-formed by one glycerol and two fatty acids and a phosphate group.
-phospholipids are amphipathic molecules.
phosphate head: polar.
fatty acid tail: nonpolar.
-Four interconnected rings of carbon atoms form the skeleton of all steroids.
-usually insoluble in water.
-EXAMPLE: cholesterol.
Tiny differences in structure can lead to profoundly different, specific biological properties.(estrogen vs testosterone)
Composed of C,H,O,N and small amount of sulfur.
-Building blocks are (amino acids)-20 different amino acids -common structure with variable side chain that determines structure and function.
Amino acid structure:
1)amino group.
2)carboxyl group. 3)side chain
Polypeptide formation.
-amino acids joined by dehydration reaction.
(carboxy+amino forms peptide bond)
-Polymers of Amino acids know as polypeptides.
-proteins may be formed from 1 or several polypeptides.
Polypeptides broken down by hydrolysis
An oxygen from the carboxyl goes with 2 H from the amino to form water and peptide bond.
Primary structure
Secondary structure
Tertiary structure
The linear sequence of amino acids is the primary structure.
Certain sequence of amino acids form hydrogen bonds that cause the region to fold into spiral (alpha helix) or sheet (beta pleated sheet)
Secondary structures and random coiled regions fold into a 3-dimensional shape
Quaternary structure
Two or more polypeptides may bond to each other to form structure protein.
Encoded directly by genes
Chemical and physical interactions cause protein folding.
Alpha helix and beta sheet : key determinants of a proteins characteristic.
-Random coiled regions -not a alpha or beta -specific shape and important to function
-Folding gives protein complex 3D shape.-this is the final level of a structure for a single polypeptide chain
-Made up of two or more polypeptides
-individual polypeptide chains are protein subunits.
-proteins can be formed from several copies of the same polypeptide.
-or may be multimetic (composed from different polypeptides)
Five factors that promote protein folding and stability
Hydrogen bonds
Ionic bonds and other polar interactions.
Hydrophobic effects
Van der waals forces
Disulfied bridge
Responsible for the storage, expression and transmission of genetic information.
2 CLASSES:
Deoxyribonucleic acid(DNA)
Ribonucleic acid(RNA)
Stores genetic information encoded in the sequence of nucleotide monomers.
Decodes DNA into instructions for linking together a specific sequence of amino acids to form polypeptide chains
-monomer is nucleotide.
-made up of phosphate group , a five carbon sugar (either ribose or deoxyribose) and a single or double ring of carbon and nitrogen atoms known as base.
-nucleotides are linked into polymer by a sugar phosphate backbone.