Cell inclusions / Ergastic substances

 Cell inclusions / Ergastic substances

• Non-protoplasmic, non-living, metabolically inactive substance formed due to  activity of protoplasm.

3 types

1. Reserve/storage food material:

• Carbohydrate, protein and lipid are reserve material.

Carbohydrate:

• Most abundant monosaccharide is glucose.

• Most sweetest carbohydrate is fructose, also present in honey, semen.

• Sugar present in fruits, honey and nectar is fructose

• Galactose is called nerve sugar.

• Inulin is the fructose units, present in Dahlia. Also, called Dahlia starch.

• Starch = Amylose + Amylopectin

• Aleurone grains are found in the endosoperm of cereals.

• Glycogen: in animal cells and fungi.

Note: Largest starch grain is found in Canna and smallest in rice.

Lipid:

• Cells contain unsaturated fattyacids like oleic acid (C17H33COOH), linoleic acid (C17H31COOH) and linolenic acid (C17H29COOH) 

• Phospholipids are amphipathic in nature

• Waxes are esters of monohydric alcohol and fatty acids.

Protein:

• The building block of protein is amino acid.

• Simplest amino acid is Glycine, most complex Tryptophan, first amino acid to be discovered is Asparagine.

• Sulphur contaning amino acids are cystein, cystine and methionine.

• Proteins are amphoteric in nature oxidized by putrefaction process.

• Most abundant protein is RUBISCO (RUBP-Carboxylase)

• Smallest protein is Adrenocorticotropic hormone (ACTH)

• Zeatin of Maize, Oryzenin of rice, Glutelin and Gliadin of wheat are protein.

2. Secretary products: enzyme, pigment and nectar are the secretary products.

Enzymes

• Term enzymes was coined by 'Kuhne'.

• Buchner reported zymase in yeast.

• Apoenzyme + cofactor = Holoenzyme (Conjugated enzyme) 

• Enzymes have cavity known as active site, where specific substrate is attached during reaction.

Nectar

• Mixture of sucrose, glucose and fructose.

• Attracts insects for pollination.

Pigments

• Yellow colour-xanthophyll, orange colour carotene

• Anthocyanin for purple and pink colours of flower, fruits etc.

3. Excretory products: These are waste of different metabolism and accumulated in 
old leaves, bark, etc. These includes.

A. Alkaloids:

• Nitrogen containing substances, found in storage organ in combination with organic acids.

• Waste of protein metabolism 

• Insoluble in water, sour in taste and poisonous. 

• Sometimes, used in medicine as well.

Examples:

Name of Alkaloid	Obtained From
Atropine	From roots of Atropa belladona
Quinine	From bark of Cinchona
Morphine	From latex of Papaver somniferum (opium or poppy)
Nicotine	From leaves of Nicotiana tabaccum (tobacco leaves)
Reserpine	From Roots of Rauwolfia serpentina [@ R = R] Useful in cure of snakebite
Ephedrine	From shoots of Ephedra (gymnosperm) → Found in sub–alpine climate. → Yaks take it as food
Ergotine	From fungi Claviceps purpurea (Ergot fungi): source of LSD.
Thein	From leaves of Tea (Thea sinensis)
Caffeine	From seeds of coffee (Coffia arabica).
Vasine	From leaves of Adhatoda vasica
Colchicine (is a mutagen)	From corm of Colchicum autumnale (Family- Liliaceae)

Note:

• Colchicine is also called as mitotic poison.

• Inhibits formation of spindle fibres.

• Disturb metaphase stage of cell division.

• Quinine, reserpine and atropine are used for treatment of malaria, high blood pressure and heart disease respectively.

B. Tannins:

• Degradation product of carbohydrates.

• Bitter in taste.

• Found in cell sap. 

• Its percentage is high in young fruits.

• Obtained from heartwood of Acacia catechu, leaves of tea, fruits of Emblica officinalis (amla).

• At maturity, tannin changes to sugar.

C. Latex:

• Yellow/white viscous fluid made of suspensions of main source of proteins, gums, etc. 

• Main source of commercial rubber production

• Latex of papaya contains enzyme papain.

• Papain helps in protein digestion.

• Latex of banana contains Tannins. 

D. Glucosides:

• Degradation products of carbohydrates.

• Control acidity and alkalinity of cell.

Eg: Digitoxin (useful in cure of heart diseases) → source plant → Digitalis purpurea, Saponin (from fruits of Sapindus)

E. Gums: Degradation products of cell wall or cellulose.

• Source of gum Acacia Senegal (Gum tree).

• Process of gum formation is called gumosis.

F. Essential oils:

• These oils evaporate in contact with air. Eg: Leaves of Ocimum, citrus.

G. Resin: Oxidation product of essential oils.

Types:

(i) Oleoresin: eg. Canada balsam → used as a mounting medium for preparation of permanent slide.

• Source plant of Canada balsam → Abies balsamea.

(ii) Gum Resin: Eg: Assafoetida (Hing)

• From roots of Ferula assafoetida.

H. Organic acids:

• Citric acid (in fruits of citrus)

• Malic acid (from apples)

• Oxalic acid (oxalis)

• Tartaric acid (fruit of Tamarindus).

I. Mineral crystals:

• Aggregate crystals of calcium oxalate

(i) Raphids: are needle shaped.

eg. Pistia, Eicchornia.

(ii) Sphaeroraphides/Druses: are star shaped.

eg. Colocasia, Dioscorea.

• Aggregate crystals of calcium carbonate (CaCO3) are called cystoliths → found in leaf cells of Ficus (Banyan tree).

• Crystals of silica → in leaf cells of grasses.

→ Petiole of Atropa belladona (Solanaceae)

→ Equisetum (Horse tail plant) is a pteridophyte.

Note:

• Chloroplast containing spores are found in Funaria, Equisetum.

• Cell walls of grasses and Equisetum are impregnated with silicon.