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

Electrophoresis, Electrophoresis is the technique of separating the large ...

Electrophoresis is the technique of separating the large molecules (for instance DNA fragments or proteins) from the mixture of identical molecules. An electric current is passed

Explain the alterations occurring in meat and poultry, Alterations occurrin...

Alterations occurring in meat and poultry Meat, as you already know, is  rich in proteins and contains most of the essential amino acids.  It is also rich in minerals such as c

What do numeric pyramids represent?, What do numeric pyramids represent? ...

What do numeric pyramids represent? The Numeric pyramids represent the number of individuals in each trophic level of a food chain.

Explain about the spinal trauma, Explain about the Spinal Trauma? Spina...

Explain about the Spinal Trauma? Spinal trauma or spinal cord injury, commonly clue to accidents, fills, sports injury can result in serious disabling consequences. The spinal

Neuroglia - organisation of nervous system, Neuroglia - Organisation of Ner...

Neuroglia - Organisation of Nervous System We may refer neuroglia as the connective tissue of the nervous system. It involves all elements of the nervous system other than ne

Explain the types of photoelectric cells, Question 1. State the basic p...

Question 1. State the basic properties of light. Discuss the special features of ultra-microscopy and phase contrast microscopy 2. What are ultrasonic waves? Explain the dif

Define procedure for detection of number of bacteria in milk, Define Proced...

Define Procedure for Detection of Number of Bacteria in Milk? 1. Place a clean, non-greasy slide over the graph paper. 2. Spread 0.01 ml of the milk over an area of 1 cm2 as

Explain obsessive-compulsive disorder, a) Explain obsessive-compulsive diso...

a) Explain obsessive-compulsive disorder? How is it dissimilar from borderline personality disorder? What are the two most common obsessions that affect adolescents?

Cell, The scientist who described cells as “many little boxes” was

The scientist who described cells as “many little boxes” was

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