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

How the needles are classified by thier point geometry, How the needles are...

How the needles are classified by thier point geometry Needles may also be classified by their point geometry; examples include: - taper (needle body is round and tapers smo

Ecology, Ecology Very often a word has a precise well-defined meaning i...

Ecology Very often a word has a precise well-defined meaning in scientific literature but is loosely used in everyday language. It is, therefore, necessary for you to be clear

Can stroke be prevented, Can stroke be prevented Brain experts are conv...

Can stroke be prevented Brain experts are convinced that several strokes can be prevented with proper attention to lifestyle factors which increase risk, including smoking, exc

Explain elephant trunk technique in aortic aneurysm, Explain Elephant Trunk...

Explain Elephant Trunk Technique in Aortic Aneurysm ? Elephant Trunk Technique :  When aneurysm involves arch of the aorta and large portion of descending thor

Explain therapeutic nutrition, Explain therapeutic  nutrition This ne...

Explain therapeutic  nutrition This necessitates dietitian's possessing a wide variety of skills. Beyond the technical knowledge and practical skills dietitians needs to have

Explain the role of calcium ions and tropnin, Explain the role of calcium i...

Explain the role of calcium ions, troponin and F-Actin during contraction in striated muscles of humans?

What is the water cycle, What is the water cycle? The water cycle repre...

What is the water cycle? The water cycle represents the circulation and recycling of water in nature. Liquid water on the planet surface is heated by the sun and turns into

Explain about cloning, What is Cloning Cloning: Somatic (ie 2N) cell fr...

What is Cloning Cloning: Somatic (ie 2N) cell from original female cat removed (nucleus has mutated allele), fertilised egg extracted from another cat, nucleus removed, and egg

Explain the dietary management of sepsis and mods, Explain the Dietary Mana...

Explain the Dietary Management of Sepsis and MODS? Patients suffering from sepsis and/or resultant multiple system organ dysfunctions are critically ill and admitted in the int

Define the fats requirement to avoid underweight problem, Define the Fats r...

Define the Fats requirement to avoid underweight problem?   We know that fats are concentrated source of energy (1g = 9 Kcals). Fats are capable of increasing the energy val

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