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

Why did it not drop more give reason, Mr. Smith read that cholesterol was b...

Mr. Smith read that cholesterol was bad for his health so he eliminated all foods and food products containing this molecule. He later found that his cholesterol level dropped only

Explain about the vitamin a - fat soluble vitamins, Explain about the Vitam...

Explain about the Vitamin A? Vitamin A, one of the fat soluble vitamins, refers to a sub-group of retinoid that possess the biological activity of all-trans-retinol. The term '

When it is said that a bacteria is an obligate anaerobe, What is meant when...

What is meant when it is said that a bacteria is an obligate anaerobe? Obligate anaerobes are the living beings that do not survive in the presence of oxygen. For instance, the

Meaning of diabetes self management education, Q. Meaning of Diabetes Self ...

Q. Meaning of Diabetes Self Management Education? You have learned that the treatment of diabetes depends upon the cooperation of the patient and also on how actively a patient

Drawbacks of lamellar model, Drawbacks of Lamellar model This model ...

Drawbacks of Lamellar model This model does not explain the elasticity of PM. Although this model says that PM is elastic but it also states that head of lipid molecules is

Define interaction with carbohydrate, Define Interaction with carbohydrate,...

Define Interaction with carbohydrate, fats and proteins? Dietary carbohydrates, fats and proteins require water-soluble vitamins for their metabolism and in turn, influence the

What is the senses explain their vision , What is the Senses explain their ...

What is the Senses explain their Vision ? Vision :  The human eye consists of structures which evolved together to focus light on a sensitive area called the retina. Light f

What is microtubule assembly, Microtubule assembly: A) generally originates...

Microtubule assembly: A) generally originates in the centrosome. B) Occurs only during mitosis. C) Occurs randomly throughout the cell. D) Is regulated by myosin. E) Is inhibited d

Explain the bohr''s model, Explain the Bohr's model? Bohr's Model :  ...

Explain the Bohr's model? Bohr's Model :  Electrons move around the nucleus at tremendous speeds and occupy most of the space in an atom. The exact position or location of an

Results of cabg , Results of CABG: In most centres where this operation ...

Results of CABG: In most centres where this operation is routinely conducted the mortality is 1-2 per cent. In high-risk group of patients this may go up to 5 to 10 per cent.

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