Cells: 70–95% water
The rest: carbon-based compounds
Remaining major ingredients:
Hydrogen (H)
Oxygen
(O)
Nitrogen (N)
Sulfur (S)
Phosphorus (P)
Organic chemistry
the study of compounds that contain carbon
Vitalism
the idea that organic compounds arise only in organisms
Miller-Urey Experiment
Test whether organic compounds can be made from simple compounds
Electron configuration
the key to an atom’s characteristics.
determines the kinds and number of bonds an atom will form with other atoms
Carbon has how many electrons?
6 : 2 in the first shell, and 4 in the second
With four valence electrons, carbon can form four covalent bonds
with a variety of atoms
This tetravalence makes large, complex
molecules possible
What governs the architecture of living molecules?
The valences of carbon and its most frequent partners (hydrogen, oxygen, and nitrogen)
The electron configuration of carbon gives it covalent compatibility with many different elements
Hydrocarbons are ?
Organic molecules consisting of only carbon and hydrogen
Undergo reactions that release a large amount of energy
Isomers are ?
Compounds with the same molecular formula but different structures
and hence different properties:
Structural Isomers
Cis-Trans
Isomers (Geometric Isomers)
Enantiomers
Structural isomers
different covalent arrangements of their atoms
As the number of Carbons increase, so too do the number of isomers
Cis-Trans isomers (Geometric isomers)
Have the same covalent arrangements but differ in spatial
arrangements
Single bonds allow rotation – Double bonds are NOT
flexible
Conversion from one to the other is important for
biological processes
Enantiomers
are isomers that are mirror images of each other
The middle carbon is “asymmetric” because it has 4 different groups attached
Functional groups
The components of organic molecules that are most commonly involved in chemical reactions
The number and arrangement of functional groups give each molecule its unique properties
The seven functional groups that are most important in the chemistry of life:
Hydroxyl group -OH
Carbonyl group >CO
Carboxyl group
-COOH
Amino group _NH2
Sulfhydryl group -SH
Phosphate
group – OPO32-
Methyl group –CH3
Hydroxyl Group
Polar due to electronegative oxygen. Forms hydrogen bonds with
water.
Compound name: Alcohol
Carbonyl Group
Sugars with ketone groups are called ketoses; those with
aldehydes
are called aldoses.
Compound name: Ketone or aldehyde
Carboxyl Group
Acts as an acid.
Compound name: Carboxylic acid, or organic acid
Amino Group
Acts as a base.
Compound name: Amine
Sulfhydryl Group
Two —SH groups can react, forming a “cross-link” that helps
stabilize
protein structure.
Compound name: Thiol
Phosphate Group
Contributes negative charge. When attached, confers on a molecule the
ability
to react with water, releasing energy.
Compound
name: Organic phosphate
Methyl Group
Affects the expression of genes. Affects the shape and function
of
sex hormones.
Compound name: Methylated compound
Adenosine Triphosphate (ATP)
The primary energy-transferring molecule in the cell
Consists of an organic molecule called adenosine attached to a string of three phosphate groups
ATP becomes ADP
All living things are made up of four classes of large biological molecules
Carbohydrates, lipids, proteins, and nucleic acids
Macromolecules
Are large molecules composed of thousands of covalently connected atoms
Molecular structure and function are inseparable
polymer
is a long molecule consisting of many similar building blocks
dehydration reaction
Occurs when two monomers bond together through the loss of a water molecule
Synthesizing a polymer
hydrolysis
Polymers are disassembled to monomers
a reaction that is essentially the reverse of the dehydration reaction
Breaking down of a polymer
Carbohydrates
Include sugars and the polymers of sugars
Serve as fuel and
building material
Simplest : Monosaccharides, or single sugars
2 monosaccharides
: Disaccharides
Many sugars: Polysaccharides
Monosaccharides
have molecular formulas that are usually multiples of CH2O
Glucose (the most common)
serve as a major fuel for cells and as raw material for building molecules
disaccharide
formed when a dehydration reaction joins two monosaccharides
This covalent bond is called a glycosidic linkage
Polysaccharides
A few hundred to a few thousand monomers!
The structure and function determined by its monomers and the positions of glycosidic linkages
Starch
A storage polysaccharide of plants
Glycogen
Storage polysaccharide in animals
All glucose
Mainly in liver and muscle cells
More branched
than plant starch
Hydrolysis occurs when glucose is needed for energy
Cellulose
forms the tough wall of plant cells
Most abundant organic
compound on earth
Chitin
another structural polysaccharide, is found in the exoskeleton of arthropods
Chitin also provides structural support for the cell walls of many fungi
Lipids
A diverse group of hydrophobic molecules
Do not form polymers
The unifying feature of lipids: little or no affinity for
water
Hydrophobic
Consist mostly of hydrocarbons, which
form nonpolar covalent bonds
The most biologically important lipids are
Fats
Phospholipids
Steroids
triacylglycerol
three fatty acids are joined to glycerol by an ester linkage
The fatty acids can all be the same or different
Hydrogenation
is the process of converting unsaturated fats to saturated fats by adding hydrogen
Fat function -
energy storage
phospholipid
two fatty acids and a phosphate group are attached to glycerol
The two fatty acid tails are hydrophobic, but the phosphate
group and its attachments form a hydrophilic head. (hydrophobic tails
pointing toward the interior)
Enzymes
They are a type of protein that acts as a catalyst to speed up chemical reactions
Polypeptides
are polymers built from the same set of 20 amino acids