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 hemicellulose, Hemicellulose In plant cell walls, the most abun...

Hemicellulose In plant cell walls, the most abundant compound present is α-cellulose with long fibers embedded in a matrix of cementing compounds (matrix polysaccharides). Thes

Determine number of sucrose molecules in the solution, Determine number of ...

Determine number of sucrose molecules in the solution When a solid is dissolved in a volatile solvent the vapour pressure of the solution is less than the vapour pressure of th

Under which form is nitrogen fixed by living beings, Under which form is ni...

Under which form is nitrogen fixed by living beings? Most living beings cannot use molecular nitrogen to get nitrogen atoms. Producers fix nitrogen mostly from nitrate (NO3-).

Measurement and evaluation of food texture, Q. Measurement and Evaluation o...

Q. Measurement and Evaluation of Food Texture? Kinesthetic characteristics deal with the sense of feel, just like the characteristics of appearance deal with the sense of sight

How is the fluid that fills the nucleus called, The aqueous fluid that fill...

The aqueous fluid that fills the nuclear region is known as karyolymph, or nucleoplasm. In the fluid there are proteins, enzymes and other significant substances for the nuclear me

What is the name of the larva of corals and sea anemones, What is the name ...

What is the name of the larva of corals and sea anemones? What is the biological significance of that larval stage? Sexual reproduction in corals and sea anemones has a larval

Name the skin receptors in humans, Which of the below are skin receptors...

Which of the below are skin receptors in humans which are sensitive to heat? Are they: a) End organs of Krause b) Meissner's corpuscles c) End organs of Ruffini d)

Pharmacological treatment, Diuretic Therapy One of the aims of treatment...

Diuretic Therapy One of the aims of treatment of congestive heart failure is directed toward controlling salt and water retention (central or peripheral edema). Diuretics provid

Neurosecretory systems, Neurosecretory Systems Almost all groups of m...

Neurosecretory Systems Almost all groups of multicellular animals have been investigated to find out if neurosecretory cells are present in them. Such investigations have sho

Diastolic heart failure, Unfortunately, unlike heart failure due to systoli...

Unfortunately, unlike heart failure due to systolic dysfunction, diastolic heart failure has been studied in few clinical trials, so there is little evidence to guide the care of p

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