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

Explain about the fermentation - methods of food processing, Explain about ...

Explain about the Fermentation - methods of food processing? In contrast to other preservation methods, multiplication of microorganisms and their metabolic activities are enco

What is sodium-potassium pump atpase, What is sodium-potassium pump ATPase?...

What is sodium-potassium pump ATPase?   A.  There is a net flux of sodium from intracellular spaces into luminal spaces through sodium-potassium pump ATPase spanning proteins l

Treatment of congestive cardiac failure, Q. Treatment of congestive cardiac...

Q. Treatment of congestive cardiac failure? A judicious and careful co-ordination between oxygen support, drug therapy and nutrient intake can help in alleviating majority of t

Bovine spongiform encephalopathy, Bovine spongiform encephalopathy The ...

Bovine spongiform encephalopathy The bovine transmissible spongiform encephalopathy (BSE), known as 'mad cow disease'-first noticed in Great Britain in 1986, is similar to scra

Future directions in biodiversity valuation, The methods that can be used f...

The methods that can be used for valuing biodiversity are still evolving at the global level, but studies have been done on how biodiversity values can be incorporated into the pro

Polyphyletic theory, Please I need short notes on polyphylrtic theory

Please I need short notes on polyphylrtic theory

The trp operon, The trp (tryptophan) operon which is shown in the figure wi...

The trp (tryptophan) operon which is shown in the figure will have  five  structural  genes  encoding enzymes  for tryptophan  biosynthesis  with an upstream  Ptrp  (trp promoter)

Isonzerization of glucose-6-phosphate, Isonzerization of glucose-6-phosphat...

Isonzerization of glucose-6-phosphate Isonzerization  of  glucose-6-phosphate :  This step  is  catalyzed  by phosphoglucoisomerase to  form  fructose-6-phosphate.

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