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CHAPTER 4 : CHEMICAL COMPOSITION OF THE CELL

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LEARNING OUTCOMES

State the element in the cell

List the chemical compounds in

the cell

Explain the importance oforganic compounds in the cell

Explain the importance of waterin the cell

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ELEMENTS IN CELLS

All living & non-living things are made upofelements.

At least 25 elements have been found to be

essential to living organisms. C, O, H & N make up about 96% of thechemical composition of living matter.

Major elements: C, H, N, O, Ca, P, S, K,

Na, Cl & Mg. Trace elements: boron (B), chromium (Cr),cobalt (Co), copper (Cu), fluorine (F),iodine (I), iron (Fe), manganese(Mn),molybdenum (Mo), selenium (Se),silicon

(Si), tin (Sn), vanadium (V),& zinc (Zn).

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Element :a substance, composed of only

one kind of atom which cannot be

broken down into simpler substances by

a chemical reaction.

Types of elements: major elements, trace

elements, ultratrace elements

Chemical compound in the cell :

carbohydrates, lipids, proteins, nucleicacids & water.

Can be divided into two: organic &

inorganic compounds

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IMPORTANCE OF ORGANIC COMPOUNDS IN THE CELLS

CARBOHYDRATES A major common energy sourcein cell. (1gglucose 17kJ) To provide energy during respiration To build cell walls To form external skeleton of insects

(chitin) As food storage (starch in plant cells,glycogen in animal cells)

To be converted to other organiccompounds i.e. amino acids & fats.

To form glycoproteins Mucus lining of human respiratory system to trapdust & microbial spores

In plasma membrane for cell recognition

To produce sugary nectar in some flower

to attract feeding insects (pollination)

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LIPIDS Sources & storage of energy (1g 38kJ) To form lipid bilayer of PM To protect organ & as heat insulator As a stored product in the form of

adipose tissues Solvent for vitamins A,D,E,K Source of energy To produce liver bile : for the digestionof fats

To synthesise steroid hormones To form waxy cuticle To lubricate the skin & reduces waterloss (sebum)

IMPORTANCE OF ORGANIC COMPOUNDS IN THE CELLS

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PROTEINS To form the structure of cell(protoplasm)

To form connective tissues such astendons, ligaments & muscle covering

To form the protein molecules in theplasma membrane

To build up muscles for movement To synthesise enzymes, hormones,antibodies, haemoglobin

To produce new cells

IMPORTANCE OF ORGANIC COMPOUNDS IN THE CELLS

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NUCLEIC ACIDS Contain C, H, O, N P. Its basic unit structure is nucleotidewhich consist of a sugar, a phosphate &a nitrogen base.

Two types : DNA(deoxyribonucleic acid)& RNA(ribonucleic acid)

Importance : Carry genetic information

Direct protein synthesis Determine the traits which are inherited fromthe parents

Control all the core activities thatcharacterise life such as chemical reactions &

growth

IMPORTANCE OF ORGANIC COMPOUNDS IN THE CELLS

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Inorganic compound Importance :

As a major component of protoplasm As a transport medium within cells & betweencells

Allows chemical changes to take place insolution

As a medium for biochemical reactions in thecell

As a universal solvent to dissolverespiratory gases & allow diffusion during

gaseous exchange at alveolus & cells To provide support especially in non-woodyplants when cells are turgid & hydrostaticskeleton in some animals

Component of lubricants & secretion (synovialfluid, digestive juices, mucus & sweat)

IMPORTANCE OF WATER IN THE CELLS

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