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 type of light-sensitive cell is present in this region, a) Which regio...

a) Which region of the retina gives the most accurate interpretation of the image? b) What type of light-sensitive cell is present in this region?   (a) The fove

Forms of ribosomes, FORM S OF RIBOSOMES (1 )      Bound form - Atta...

FORM S OF RIBOSOMES (1 )      Bound form - Attached to ER. Protein synthesis for secretion purpose occurs on bound ribosomes. (2 )      Free Ribosomes - Occur freely

Spironolactone, Aldosterone mediates myocardial remodeling and fibrosis, as...

Aldosterone mediates myocardial remodeling and fibrosis, as well as sodium retention and potassium loss at the distal tubules. The anti-aldosterone agent, spironolactone   has been

Explain different amino acids found in proteins, How many different protein...

How many different proteins, each composed of 8 amino acids, can be constructed using the 20 different amino acids found in proteins?

Bacterial diseases-actinomyces, Actinomyces Members of the genus Actin...

Actinomyces Members of the genus Actinomyces are facultative anerobic, gram-positive, non acid-fast, non-spore forming, nonhaemolytic rods. All Actinomyces require rich media

Agro industrial-magnesium, Magnesium Magnesium is closely related to c...

Magnesium Magnesium is closely related to calcium and phosphorus in its dispersion and functions in the body. Most of the body’s magnesium is found in bones and muscles. Grass

Show thw cellular structure of protein synthesis, Q. What is the cellular s...

Q. What is the cellular structure to which mRNA molecules bind to start the protein synthesis? To make proteins mRNA molecules essentially associate to ribosomes. Ribosomes hav

Adverse effects of noise pollution, 1.      Effect on general health:  ...

1.      Effect on general health:          Noise pollution increases the rate of heart beat, constriction of blood vessels and blood pressure. Noise also causes anxiety, stres

Drugs derived from plants, A large number of important drugs are derived fr...

A large number of important drugs are derived from plants. For example Tubocuranin, derived from plant-based curare, is used as a muscle relaxant during surgery. Curianol, a Guy

Illustrate about the chemical disinfection, Illustrate about the Chemical d...

Illustrate about the Chemical disinfection Sharp waste may cause injury and person may have diseases like Hepatitis B, Cand HIV/AIDS. Therefore it is important for to understa

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