Download Carbon is the most important element to living things

Carbon is the most important element to living things because it can
form many different kinds of bonds and form essential compounds.
LEARNING OBJECTIVES [ edit ]
Explain the properties of carbon that allow it to serve as a building block for biomolecules
Explain why carbon is important for life
Describe the various places carbon is stored on Earth
KEY POINTS [ edit ]
All living things contain carbon in some form.
Carbon is the primary component of macromolecules, including proteins, lipids, nucleic acids,
and carbohydrates.
Carbon's molecular structure allows it to bond in many different ways and with many
different elements.
The carbon cycle shows how carbon moves through the living and non­living parts of the
environment.
TERMS [ edit ]
octet rule
A rule stating that atoms lose, gain, or share electrons in order to have a full valence shell of 8
electrons (has some exceptions).
macromolecule
a very large molecule, especially used in reference to large biological polymers (e.g., nucleic acids
and proteins)
carbon cycle
the physical cycle of carbon through the earth's biosphere, geosphere, hydrosphere, and
atmosphere; includes such processes as photosynthesis, decomposition, respiration and
carbonification
Give us feedback on this content: FULL TEXT [ edit ]
Carbon is the fourth most
abundantelement in the universe and is
the building block of life on earth. On
earth, carbon circulates through the land,
ocean, and atmosphere, creating what is
known as theCarbon Cycle. This global
carbon cycle can be divided further into
two separate cycles: the geological carbon
cycles takes place over millions of years,
whereas the biological or physical carbon
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cycle takes place from days to thousands of years. In a nonliving environment, carbon can
exist as carbon dioxide (CO2), carbonate rocks, coal, petroleum, natural gas, and
dead organic matter. Plants and algae convert carbon dioxide to organic matter through the
process ofphotosynthesis, the energy of light.
Carbon is present in all life
All living things contain carbon in some form, and carbon is the primary component of macromolecules,
including proteins, lipids, nucleic acids, and carbohydrates. Carbon exists in many forms in this leaf,
including in the cellulose to form the leaf's structure and in chlorophyll, the pigment which makes the leaf
green.
Carbon is Important to Life
In its metabolism of food and respiration, an animal consumes glucose (C6H12O6), which
combines with oxygen (O2) to produce carbon dioxide (CO2), water (H2O), and energy,
which is given off as heat. The animal has no need for the carbon dioxide and releases it into
the atmosphere. A plant, on the other hand, uses the opposite reaction of an animal through
photosynthesis. It intakes carbon dioxide, water, and energy from sunlight to make its own
glucose and oxygen gas. The glucose is used for chemical energy, which the plant metabolizes
in a similar way to an animal. The plant then emits the remaining oxygen into the
environment.
Cells are made of many complex molecules calledmacromolecules, which include proteins,
nucleic acids (RNA and DNA), carbohydrates, and lipids. The macromolecules are a subset of
organic molecules (any carbon­containing liquid, solid, or gas) that are especially important
for life. The fundamental component for all of these macromolecules is carbon. The carbon
atom has unique properties that allow it to form covalent bonds to as many as four different
atoms, making this versatile element ideal to serve as the basic structural component, or
"backbone," of the macromolecules.
Structure of Carbon
Individual carbon atoms have an incomplete outermostelectron shell. With an atomic
number of 6 (six electrons and six protons), the first two electrons fill the inner shell, leaving
four in the second shell. Therefore, carbon atoms can form up to four covalent bonds with
other atoms to satisfy the octet rule. The methane molecule provides an example: it has the
chemical formula CH4. Each of its four hydrogen atoms forms a single covalent bond with
the carbon atom by sharing a pair of electrons. This results in a filled outermost shell.
Structure of Methane
Methane has a tetrahedral geometry, with each of the four hydrogen atoms spaced 109.5° apart.