CHEMISTRY OF LIVING SYSTEMS

6a. Students know that carbon, because of its ability to

combine in many ways with itself and other elements, has a

central role in the chemistry of living organisms.

6b. Students know that living organisms are made of

molecules consisting largely of carbon, hydrogen, nitrogen,

oxygen, phosphorus, and sulfur.

Basic Information about Carbon

Symbol: C Atomic Number: 6 Atomic Mass: 12.0107 amu Melting Point: 3500.0 °C (3773.15 °K, 6332.0 °F) Boiling Point: 4827.0 °C (5100.15 °K, 8720.6 °F) Number of Protons/Electrons: 6 Number of Neutrons: 6 Classification: Non-metal Crystal Structure: Hexagonal Density @ 293 K: 2.62 g/cm3

Color: May be black

Carbon is found in many different

compounds. It is in the food you eat, the

clothes you wear, the cosmetics you use

and the gasoline that fuels your car.

Carbon is the sixth most abundant

element in the universe. In addition,

carbon is a very special element because

it plays a dominant role in the chemistry

of life. Carbon, discovered in prehistory

and was known to the ancients, who

manufactured it by burning organic

material making charcoal. There are

four known isotopes of carbon:

amorphous, graphite, diamond and

fullerene. A new (fifth) isotope of

carbon was recently found. It is a

spongy solid that is extremely

lightweight and, unusually, attracted to

magnets.

Carbon – an element found in every living thing

Covalent Bond – sharing of electrons

Compounds made of Carbon

The simplest organic compounds contain molecules composed of carbon and hydrogen.

The compound methane contains one carbon bonded to four hydrogens (CH4). Ethane is

another example of a simple hydrocarbon. Ethane contains two carbon atoms and six

hydrogen atoms (C2H6)..

You can think of carbon as a bunch of red legos attached together

to form one long chain of legos. Now, you can imagine sticking

yellow, blue and green legos across the tops of the red (carbon)

legos. These other colors represent other elements like oxygen,

nitrogen or hydrogen. As you stick more and more of these

yellow, blue and green legos to the red chain, it would start to

look like a skeleton of legos with a "spine" of red legos and

"bones" of yellow, blue and green legos. This is a lot like the way

that big molecules are made in the body. Without carbon, these big molecules

could not be built.

Now, virtually every part of your body is made up of these big molecules that

are based around chains of carbon atoms. This is the reason we are known as

"carbon based life forms". Without carbon, our bodies would just be a big pile

of loose atoms with no way to be built into a person.

The Elements of Life Hydrogen, carbon, nitrogen and oxygen - comprise more than 95% by weight of

all living matter on Earth. These four elements are also the four most abundant

elements in the universe.

Large Molecules: Small Molecules

DNA *Water

Proteins *Salt

Carbohydrates

Fats

6c. Students know that living organisms have many

different kinds of molecules, including small ones, such as

water and salt, and very large ones, such as carbohydrates,

fats, proteins, and DNA.

DNA – A nucleic acid that carries the genetic

information in the cell and is capable of self-replication

and synthesis of RNA. DNA consists of two long

chains of nucleotides twisted into a double helix and

joined by hydrogen bonds between the complementary

bases adenine and thymine or cytosine and guanine.

The sequence of nucleotides determines individual

hereditary characteristics.

Protein - Any of a group of complex organic

macromolecules that contain carbon, hydrogen,

oxygen, nitrogen, and usually sulfur and are composed

of one or more chains of amino acids. Proteins are

fundamental components of all living cells and include

many substances, such as enzymes, hormones, and

antibodies, that are necessary for the proper functioning

of an organism. They are essential in the diet of animals

for the growth and repair of tissue and can be obtained

from foods such as meat, fish, eggs, milk, and legumes.

Carbohydrate - Any of a group of organic compounds

that includes sugars, starches, celluloses, and gums and

serves as a major energy source in the diet of animals.

These compounds are produced by photosynthetic

plants and contain only carbon, hydrogen, and oxygen,

usually in the ratio 1:2:1.

Fats - A mixture of such compounds occurring widely

in organic tissue, especially in the adipose tissue of

animals and in the seeds, nuts, and fruits of plants.

Water - A clear, colorless, odorless, and

tasteless liquid, H2O, essential for most

plant and animal life and the most

widely used of all solvents. Freezing

point 0°C (32°F); boiling point 100°C

(212°F).

Salt - A colorless or white crystalline

solid, chiefly sodium chloride (NaCl),

used extensively in ground or granulated

form as a food seasoning and

preservative. Also called common salt,

table salt.

DNA

molecule

water

molecule