Chloroplasts, Biology

Assignment Help:

CHLOROPLASTS

  • Schimper (1883) coined the term chloroplastid for green plastids.
  • Mayer called them Autoplast. Chloroplast name proposed by Erera.
  • Green plastids with chlorophylls and other photosynthetic pigments.
  • Shape of chloroplasts vary in different plants.

Discoidal or oval    -           Higher plants

Girdle shaped        -           Ulothrix

Cup shaped           -           Chlamydomonas

Reticulate              -           Oedogonium

Spiral    -                             Spirogyra

Stellate                  -           Zygnema

  • Largest cell organelle in plants and second largest structure in plant.
  • Double unit membranous cell organelles.
  • Each chloroplast has two parts -

(i) Grana - Made up of Granum lamellae arranged in the form of stacks of coins. Each granum lamella is surrounded by well-defined membrane called Thylakoid (Thylakoid discovered by Menke). Each granum lamella, granular structures called Quantasomes are present. Quantasomes are photosynthetic units. (Quantasomes discovered by Park, Pon and Biggins) Each qunatasome has 230 chlorophyll molecules. Each chlorophyll molecule has two parts - head and tail. Head part is responsible for green colour which is controlled by Mg++. Due to presence of chlorophyll in granum lamellae, the light reaction of photosynthesis takes place in the granum. Lamellae which connects grana are called stroma thylakoids or fret channels (Weier 1966).

1863_chloroplast.png

(ii) Stroma - The non pigmented enzymatic part of chloroplast is called stroma. It is present in form of matrix. Due to presence of enzymes in stroma, dark reactions of photosynthesis take place here. Stroma contains osmophilic droplets called Plastoglobuli. These store lipids. Stoma of chloroplast contains proteins, phospholipids, nucleic acids, ribosome and fewer amounts of enzymes. Ris and Plaut, Ruthe sager discovered DNA in chloroplast, which is called ctDNA or plastidial DNA. Genetic system of chloroplast is called Plastidome. Due to presence of DNA, RNA and ribosomes chloroplast is called semiautonomous unit like mitochondria having a complete protein synthesis apparatus in stroma.


Related Discussions:- Chloroplasts

What is the function other than protection of the ribs, What is the functio...

What is the function, other than protection, of the ribs? The ribs help to alter the volume of the thorax during breathing movements.

Explain milling extraction rate, Explain Milling extraction rate The ch...

Explain Milling extraction rate The chemical composition of the flour depends on the milling extraction rate.  Increasing the rate of flour extraction decreases the proportion

Chronic aortic regurgitation-indications for surgery, Chronic Aortic Regurg...

Chronic Aortic Regurgitation :  Several factors have to be taken into account before recommending surgery. These include severity of symptoms and LV function. With evidence o

Explain the sub-clinical protein energy malnutrition, Explain the Sub-clini...

Explain the Sub-clinical Protein Energy Malnutrition? You have already learnt that clinical forms of PEM represent only a small proportion of the total cases of PEM in a commun

Explain about the term demand, Explain about the term demand. Demand:...

Explain about the term demand. Demand: Potential customers (consumers, buyers or households) of a good or a service into a market, which normally a demand curve is utiliz

A disulfide bond can form between any two amino acids, A disulfide bond can...

A disulfide bond can form between any two amino acids that have sulfur in their side-chain.

Define about fusarium - identification of fungi and yeast, Define about the...

Define about the Fusarium - Identification of Fungi and Yeasts? Classification Kingdom - Mycetae Division - Amastigomycotina Subdivision - Deuteromycotina Class - D

Name the nitrogenous waste excreted in the larval, What benefit does the se...

What benefit does the sea anemone get in the sea anemone-hermit crab facultative mutualism? Give an alternative term for this part of mutualism. Name the nitrogenous wast

Fresh water-types of water found on earth, Fresh Water Water, a univers...

Fresh Water Water, a universal solvent, invariably contains many soluble salts. In fresh water the total salt content remains under 15 percent. Different types of soluble salts

What are the main symptoms of the pulmonary, What are the main symptoms of ...

What are the main symptoms of the pulmonary and of the intestinal phases of the ascaris infestation? In the pulmonary stage the ascaris infestation causes cough, hemoptysis, dy

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd