chapter 4-carbon & diversity of life why carbon makes life diverse types of isomers functional...
TRANSCRIPT
Chapter 4-Carbon & Diversity of Life
Why carbon makes life diverse
Types of Isomers
Functional Groups and Characteristics
Carbon and Diversity
Carbon has four bonding sites This allows for large and complex molecules to be
made with this element They may form flat or tetrahedral molecules and
may also form rings, chains or branched molecules Carbon may also bond with itself as well as other
common elements like Nitrogen, Hydrogen, and Oxygen
These possibilities make a wide variety of organic molecules possible
Types of Isomers
An isomer is a molecule that has the same molecular formula as another molecule but a different structure and thus different properties.
There are a few different types of isomers: Structural Geometric Enantiomers (Chiral carbons)
Structural Isomers
Differ from one another in location of double bonds and arrangement of atoms
Examples are butane and isobutane (see page 56 )
Geometric Isomers
Same covalent bonds but differ in arrangement in space (spatial)
Example is rhodopsin Rhodopsin changes from one geometric
isomer to another to allow sight in darker places (Rods in your retina) and return to vision in bright light
Enantiomers
Mirror images of each other but not superimposable due to an asymmetric carbon
Important in pharmaceutical industry Examples: L-Dopa and Thalidomide
Functional Groups
Groups of atoms commonly part of carbon skeletons that give certain properties to organic molecules
There are a number of functional groups given in your book (see chart on pg. 58)
The Hydroxyl Group -OH
Alcohols (names end in ol) Example: Ethanol Polar Can form hydrogen bonds with sugars
which aids them in dissolving organic compounds such as sugars
Carbonyl Group >CO
Form both Ketones (if it occurs within a carbon skeleton) and Aldehydes(if it occurs at the end of a carbon skeleton)
The simplest ketone is acetone An aldehyde is Propanal Both groups are found in sugars Ketones form ketose sugars and aldehydes form
aldose sugars May be strucural isomers as in acetone and
propanal
Carboxyl Group -COOH
Organic or carboxylic acids Example: Acetic acid (vinegar) Has acidic properties (donates hydrogen
ions) because the bond between hydrogen and oxygen is so polar
Can be found in cells in ionized form (Ex: Acetate ions)
Amino Group -NH2
Consists of a Nitrogen atom bonded to two hydrogen atoms and then to a carbon skeleton
Known as amines Examples are the amino acids like Glycine Generally acts as a base by picking up H+ ions
from the surrounding solution (the aqueous solution in living organisms)
Under cellular conditions it is usually in ionized form. (1+)
Sulfhydryl Group -SH
Consists of a sulfur atom bonded to hydrogen Compounds referred to as Thiols Example: the amino acid Cysteine Two of these groups can form a covalent bond
and cross link to stabilize protein structure These cross-links also determine the
straightness or curliness of hair
Phosphate Group -PO3 2-
A phosphorus atom is bonded to four oxygen atoms One oxygen is bonded to the carbon skeleton while
two carry negative charges Referred to as organic phosphates Ex: Glycerol phosphate which is a backbone for
phospholipids which are the most prevalent molecules in cell membranes
Can react with water to release energy Contributes negative charge to the molecule that
contains it
Methyl Group -CH3
Consists of a carbon atom bonded to three hydrogen atoms
Can be bonded to the carbon or a different atom Referred to as Methylated Compounds Addition of a methyl group to DNA effects gene
expression and arrangement of methyl groups in sex hormones affects their shape and funtion
Ex: 5-Methyl cytidine (part of DNA that has been modified by adding a methyl group