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Chemical Compounds for Life
All living things are mostly composed of 4
elements: H, O, N, C "honk"
Carbon: The "swiss army
knife" of chemistry.
- Compounds are broken down into 2 general categories:
- Organic compounds
- Contain significant amounts of carbon.
- Often found with common "functional groups"
- Carbon is essential to life for several reasons:
- It can form strong stable (usually nonpolar) covalent bonds
- It can form up to 4 chemical bonds
- It can form multiple bonds
Organic Compounds often form
Long chains of smaller molecules (not atoms)
called monomers, bind to form huge Macromolecules.
Organic Compounds of life:
4 Types: Carbohydrates, Lipids, Proteins & Nucleic acids
- Includes: Sugars, starches, cellulose & glycogen
- Made of Carbon ( C ), Hydrogen ( H ), and Oxygen (O )
- Following ratio of elements
Provide & store energy for cells
- Simple sugars include Glucose & Fructose since these are made of only 1 Carbohydrate molecule they are
known as Monosaccharides.
Monosaccharides can be linked together
through the process of
Sucrose (table sugar) is made of 2 sugars
linked together and these are called Disaccharides
- Water is removed from 2 monocaccharides - resulting in a
covalent bond between the 2 molecules
- Often referred to as transport saccharides
- Require some digestion to be used by cells
Starches are many monosaccharides linked together in a single chain.
These are called Polysaccharides.
- Plants use this for energy storage e.g. Potatoes
- Two types
- Amylose - Long strait unbranched chains
- many linked short Amylose chains
Cellulose is made of long polysaccharide chains
- Plants use this for structure (e.g. Wood) - not very
- Due to the reverse orientation of the monosaccharide
sububnits, digestive enzymes cannot hydrolize the bonds between them
Glycogen is a moderately branched polysaccharide
- Animals use this for energy storage.
Lipids are macromolecules including
- Primary function is energy storage.
- Energy is stored in C-H bonds.
- More efficient in storing energy
- Lipids are made of 2 parts
Glycerol - an alcohol - Serves as backbone of the molecule
3 Fatty acids -
Long hydrocarbon chains
Saturated fats have long chains with no double-bonds
Unsaturated fats have double bonds
Polyunsaturated fats have many double bonds
- Each time a double bond is encountered, the molecule
"Bends" slightly, resulting in a lower density of the lipid. This makes the
molecule more likely to remain liquid at room or body temperatures.
- 4 Major types of biologically important Lipids
Phospholipids - Important for membrane structure
Steroids - eg. Cholesterol & testosterone. Provide membrane
support / serve as hormones
Terpenes - serve as important components of pigments
- appear to act like localized hormones to induce
Proteins are made of
There are 20 different amino acids. Each having a similar
general structure - Differ only in their "R" groups
example amino acids
- Amino acids form proteins via deyhdration sythesis forming
Two amino acids linked together are called dipeptides
More than 2 linked together are called
polypeptides - polypeptides can be thousands of amino acids long
- Protein types include globular proteins which are usually enzymes and
which usually serve for structure (eg. Hair)
- Proteins Exhibit 4 "levels of structure.
of a protein is its sequence of amino acids.
The Sequence (primary structure) causes parts
of a protein molecule to fold into sheets or bend into helix shapes - this is a
The protein then can compact and twist on
itself to form a mass called its Tertiary Structure
Several Proteins then can combine and form a
Various conformations are usually caused by
the formation of hydrogen or disulfide
PH, changes or heat can disrupt these bonds,
permanently denaturing the protein.
Two types of Nucleic acids
DNA (Deoxyribonucleic Acid)
RNA (Ribonucleic acid)
DNA is Formed of in a "Double Helix" - like a spiral staircase.
"double helix" shape
- DNA is formed by Nucleotides
- These are made from 3 components
- A 5-Carbon Sugar
- A Nitrogenous base
- A Phosphate group
Nucleotides form a backbone through linkages
from the OH group of the 3rd carbon to a phosphate group of the adjoining
nucleotide. These are called Phosphodiester bonds
- For DNA There are 4 different Nucleotides
categorized as either Purines (double ring) or
Pyramidines (single ringed). These are usually represented by a letter. These Are:
- Cytosine (C)
- Guanine (G)
- Thymine (T)
Each "Rung" of the DNA
"staircase" is formed by the linking of 2 Nucleotides through Hydrogen Bonds.
These Hydrogen bonds form only between
specific Nucleotides. This is known as
Base Pairing. The rules are as
- Adenine (A) will ONLY bond to Thymine (T)
- Cytosine (C) will ONLY bond to Guanine (G)
- RNA differs from DNA in several important ways.
- It is much smaller
- It is single-stranded
- It does NOT contain Thymine, but rather a new
nucleotide called Uracil which will bind to Adenine.
Comparison of DNA & RNA
ATP is closely related to nucleic acids.
Composed of Ribose, Adenine & a phosphate group
- Phosphate group has ability to bind/release additional
phosphate group allowing it to store or release energy.
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Last Updated: March 11, 2004