1. Augustine Mai, Isaac Mandefro
Period 8
Unit 3 Notes
Organic chemistry is the chemistry of carbon compounds.
Majority of organic molecules found in living organisms can be
classified into one of four types:
- carbohydrates - proteins
- lipids -nucleic acids
Four most common elements found in living things:
-Hydrogen -Carbon
-Nitrogen -Oxygen
Roles:
sulfur -in some amino acids
calcium -cofactor in some enzymes
phosphorous - phosphate groups in ATP
iron- in cytochromes
sodium- in membrane function
Structure of water
Water is the solvent of life
Almost all cells have water within and in surrounding environment.
Hydrogen and oxygen atoms in a water molecule are held together by a polar covalent
bond
Polar covalent bonding results from unequal sharing of electrons
Each oxygen–hydrogen bond is a polar covalent bond. Results in a slight negative charge
at the oxygen end of the molecule and a slight positive charge at the end with the two
hydrogen molecules
Two ends of each water molecule have opposite charges so H2O molecules interact with
each other in different ways.
2. Augustine Mai, Isaac Mandefro
Period 8
Properties of water and living organisms
Thermal Properties
High Specific heat: water can absorb/ give off a lot of heat without changing the
temperature too much
Water is a coolant for the body
Has high heat of vaporization; water absorbs a great deal of heat when it evaporates
Internal body heat turns to perspiration, with evaporates from skin. Heat used to turn
liquid into evaporation so perspiration is a cooling method by lowering temperature.
Cohesive Properties
H2O molecule- highly cohesive
Cohesion: molecules of the same type are attracted to each other
Attraction due to polar covalent bonding
Solvent properties
Excellent solvent of other polar molecules
Most molecules found in/out of the cell are also polar (Includes Carbohydrates,
Proteins, Nucleic Acids)
Most lipids are non-polar
Water is a medium in which biochemistry of a cell occurs
Carbohydrates, Lipids and Proteins
Living things composed of a variety of molecules
Molecule; (Sub-components)
-Carbohydrates; (Monosaccharides); Sub-categories (Monosaccharides, disaccharides,
polysaccharides)
3. Augustine Mai, Isaac Mandefro
Period 8
-Lipids; (Glycerol and fatty acids)
-Proteins(Polypeptide); (Amino Acids)
-Nucleic Acids; (Nucleotides)
All organic molecules contain carbon
Not all carbon containing molecules are organic
Functions of carbohydrates in plants and animals
Carbohydrates among most found biochem molecules in plants/animals
Carbohydrates have different sizes (monosaccharide, disaccharide, etc.)
Animals
Glucose-chemical fuel for cell respiration (mono.)
Lactose-Makes up some solutes in milk (di.)
Glycogen-stores glucose in liver and muscles (poly.)
Plants
Fructose- found in many fruits; makes sweet(Mono.)
Sucrose- often transported from leaves of plants to other locations in plants by vascular
tissue (Di.)
Cellulose- one of primary components in plant cell walls (Poly.)
Role of Lipids
Triglyceride lipids, solid then called fat, liquid then called oil
Excess fat is stored in adipose cells
Efficient for storing energy
Stores twice as much chemical energy as carbohydrates
Important for thermal insulation
Special lipid- phospholipid makes up the double layer of all cell membranes
4. Augustine Mai, Isaac Mandefro
Period 8
Condensation and Hydrolysis Reactions
Foods are chemically digested. The digestive enzymes that accomplish this are
hydrolysing
enzymes.
Each reaction is called a hydrolysis and requires a molecule of water as
a reactant.
Water is always split in hydrolysis
Ex.
-hydrolysis of a disaccharide to two monosaccharides
lactose + water → glucose + galactose
-hydrolysis of a polysaccharide to many monosaccharides;
starch + (many) water → (many) glucose
Condensation reactions are the opposite of hydrolysis reactions
In condensation reactions, the water molecules are products rather than reactants
DNA Structure
Nucleotides are building blocks of DNA
Each nucleotide of DNA is composed of a phosphate, deoxyribose sugar, and base
4 possible nitrogenous bases: adenine, thymine, guanine, cytosine
DNA has double helix shape
Base pairs are adenine, thymine and guanine, cytosine
Adenine and thymine are held together by two hydrogen bonds. Cytosine and guanine
are held together by three hydrogen bonds.
5. Augustine Mai, Isaac Mandefro
Period 8
DNA replication
DNA replication: Cells prepare for a cell division by doubling the DNA content of the cell
Double quantity of DNA + one exact copy of each molecule
Early event of DNA replication is separation of double helix into 2 strands
Enzyme helicase causes separation of strands
In nucleoplasm, there are many free floating nucleotides. Nucleotides available to form
complementary pairs
Formation of a covalent bond between two adjoining nucleotides is catalysed by one of
the DNA polymerase enzymes that's important in the process.
Significance of Complementary base pairings
Pattern of DNA replication ensures 2 identical copies of DNA
Every DNA molecule after replication has a strand that was old, now paired with a
strand that is new
