Chemical Composition of the Cell

Elements in the Cell
An element is a substance cinsist of only one kind of atom.


Major Elements
Carbon (C), oxygen (0), hydrogen (H) and nitrogen (N) are the most common elements in a human body. There are the major elements of the body.


Ultratrace Elements
Iron
Importance:
Human

1. Important component of haemoglobin in red blood cells.
2. Involved in the synthesis of red blood cells and respiratory enzymes.

Plants

1. Formations of chlorophyll.
2. As an electron carrier during photosynthesis and respiration.

Trace Elements
Some important trace elements found in a human body are

• Sodium (Na),
• magnesium (Mg),
• Calcium (Ca),
• phosphorus (P),
• potassium (K),
• sulphur (S), ) and
• chlorine (Cl)

They make up about 4% of the mass of the human body

Importance of the Trace Elements

Sodium (Na)
Human:

1. Controls osmotic pressure i the cell.
2. Helps in the transmission of nerve impulses.

Magnesium (Mg)
Human
Help in protein synthesis.

Plants
Needed in the synthesis of chlorophyll.

Calcium (Ca)
Human

1. Main component of the bones and teeth.
2. Triggers contraction of muscle cells.
3. Promotes blood clotting.

Plants

1. Formation of cell walls (cellulose).
2. Regulates the semi-permeability of plasma membranes.

Phosphorus (P)
Human

1. Constituent of bones and teeth.
2. Helps in the contraction of muscle cells.
3. Formation of adenosine triphosphate (ATP).
4. Essential constituent of nucleic acids (DNA and RNA).

Plants

1. Involves in cell division.
2. Involves in the formation of ATP and nucleic acids.
3. Induces the formation of flowers and seeds

Potassium (K)
Human

1. Required in muscle contractions
2. Involves in transmission of nerve impulses.

Plants:

1. Formation of carbohydrates.
2. Activates certain enzymes.

Sulphur (S)
Human
Components of some proteins and vitamins in the body.

Plants
Component of some proteins and vitamins.

Chlorine (Cl)
Human

1. Formations of hydrochloric acid in the stomach.
2. Maintains pH value of the stomach.

Plants

1. Photolysis of water during photosynthesis.

Chemical Compounds in the Cell

1. A compound is a substance which consists of two or more elements combined in a fixed ratio.
2. Common elements such as carbon, oxygen, hydrogen, nitrogen, sulphur and phosphorus combined with each other to form various chemical compounds in the cell.
3. The chemical compounds can be divided into two types:
1. Organic compounds which contain the element carbon.
2. Inorganic compounds which do not contain carbon.

Organic Compounds

1. Organic compounds are chemical compounds which contain carbon and hydrogen. They are usually big and complex, present as macromolecules and associated with living organisms.
2. The examples organic compounds found in a cell are carbohydrates, lipids, proteins and nucleic acids.

Inorganic Compounds

1. Inorganic compounds do not contain carbon and usually associated with non-living things.
2. Example of inorganic compound in a cell is water.

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