Organic Compounds

Necessities for Life

What is an organic compound?

In Biology, the word organic means “relating to organisms” NOT food grown without the use of pesticides, antibiotics, or other industrial chemicals.

All organic compounds contain covalently bound carbon.

Organic compounds can also be synthesized in the lab.

The Chemistry of Carbon

Carbon atoms have four valence (outer shell) electrons, allowing carbon to form covalent bonds with many elements including hydrogen, oxygen, phosphorus, sulfur and nitrogen.

Carbon can also bond to other carbon atoms, which gives carbon the ability to form chains that are almost unlimited in length.

These carbon-carbon bonds can be single, double, or triple.

The chains be straight, branched, or even ring-shaped. Therefore, carbon is unique in that it can form millions

of different large and complex structures.

MACROmolecules are giant and are. . .

formed by polymerization, in which large compounds (polymers) are built from joining smaller units (monomers) together.

Four Groups of Organic Compounds

Carbohydrates, lipids, nucleic acids, and proteins are needed by all living things.

Carbohydrates (sugars)

main source of energy for organisms can also be used for structural purposes made of C, H, and O; usually in a 1:2:1 ratio The monomers of carbohydrates are called

monosaccharides, like glucose, fructose (in fruits) and galactose (in milk).

The breakdown of monosaccharides supplies immediate energy.

usually end in –ose.

Carbohydrates cont’d

Extra sugar is stored as macromolecules called polysaccharides.

Polysaccharides are made from monosaccharides.

Uses of Polysaccharides

Many animals store extra sugar as glycogen. Glycogen stored in your muscle supplies energy for contractions. Glycogen stored in your liver is released when glucose in your blood runs low.

Plants store excess sugar as starch. Plants also make cellulose, a strong, rigid

fiber used for support.

Lipids (fats, oils, and waxes)

uses: long-term energy storage, insulation, waterproof covering, part of biological membranes, chemical messengers (steroids)

contain mostly carbon and hydrogen generally not soluble in water

Lipids

Many lipids are formed when a glycerol molecule combines with fatty acids.

If all carbon atoms have only single bonds, the lipid is saturated. It holds as many hydrogen atoms as possible.

Lipids

If there is at least one double bond between carbon atoms, the lipid is unsaturated.

Unsaturated lipids like cooking oils tend to be liquid at room temperature.

Nucleic Acids

store and transmit hereditary, or genetic, information

contain hydrogen, carbon, nitrogen, oxygen, and phosphorus

The monomers of nucleic acids are nucleotides, which contain three parts: a 5-carbon sugar, a phosphate group, and a nitrogen base.

examples: DNA and RNA

Proteins have many functions

They can provide structural support in bones and muscles, form parts of cell membranes, function as hormones to regulate the body, form antibodies to protect against infection, and increase the rate of chemical reactions to name a few.

Proteins are macromolecules.

contain nitrogen, carbon, hydrogen, and oxygen (most also have sulfur)

The monomers of proteins are amino acids. Amino acids contain an amino group, a

carboxyl group, and a variable R-group.

• When the amino acids join, they form a polymer called a polypeptide. The monomers are held together by peptide bonds.

• More than 20 different amino acids are found in nature.

• Since the R-group varies, it allows for much variety. That is why proteins have so many functions.

Proteins have four levels of organization.

• This allows for the unique shape of proteins.

• Shape is very important; if a protein is not the right shape, it will not work.

Enzymes – a special type of protein

Enzymes are biological catalysts, which work to speed up a chemical reaction.

Without enzymes, several reactions in cells would never occur or happen to slowly to be useful.

Enzymes lower activation energy.

Activation energy is the energy needed to get a chemical reaction started.

When activation energy is lowered, the reaction speeds up.

Enzyme Action

Enzymes provide a site where reactants can be brought together to react.

This is site is called the active site.

The reactants are called the substrates.

The shape of an enzyme is so specific that generally only one enzyme will work for one substrate.

Therefore, enzymes are said to fit together like a “lock and key.”

Enzyme Action

Since only the substrate changes during the reaction, the enzyme can be reused again and again.

Enzymes can be turned on and off.

Enzymes work best at specific temperatures and pH.

Heating can change the enzyme shape and the wrong pH affects the binding of the substrate to the enzyme.

Ergo, enzymes in our body work best at 37°C (98.6°F) and at a pH between 6.5 to 7.5.

Also, most cells contain proteins that turn enzymes on or off during critical stages of development.