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 blood typing, What is blood typing? Blood typing is the determi...

What is blood typing? Blood typing is the determination, by means of tests, of the categorization of a blood sample concerning blood group systems (specially the ABO system and

Non-viral vectors, Non-viral vectors   Viral vectors are highly effici...

Non-viral vectors   Viral vectors are highly efficient but when it comes to large scale production at the commercial level, non-viral serve as a better choice. These methods p

Describe the uses of pupil, Describe the uses of pupil Variation in the...

Describe the uses of pupil Variation in the size, shape or reaction usually indicates some form of disease, disorder or use of medication. The pupil is usually dilated by the u

Metabolism of phenylalanine, The metabolism of phenylalanine will now be ta...

The metabolism of phenylalanine will now be taken in some detail, as two inborn errors of metabolism are known which affect this pathway. The Phenylalanine is 1st hydroxylated by p

Explain administrative dietitian, Explain Administrative dietitian Admi...

Explain Administrative dietitian Administrative dietitian play  a  major  role in  large-scale meal planning  and monitoring the  food  preparation process  by  applying  the

Explain divisions of the angiosperms, Q. What are the two divisions of the ...

Q. What are the two divisions of the angiosperms? The angiosperms are divided into dicotyledonous and monocotyledonous.

Bacterial diseases-pigs, Pigs This is a sub-acute or chronic infection ...

Pigs This is a sub-acute or chronic infection manifested by abortion, sterility, high piglet mortality and orchitis in pigs. Br. suis causes brucellosis among pigs. It is morph

Define the micronutrient deficiencies, Define the Micronutrient Deficiencie...

Define the Micronutrient Deficiencies? In the previous section, we learnt about macronutrient deficiencies i.e. protein energy malnutrition in children. We are now aware that t

Define determinants of food security - food availability, Define Determinan...

Define Determinants of Food Security - Food Availability? It depends on the quantum and quality of crops, livestock, fishery and other food sources, as well as commercial impor

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