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

Describe circulatory system, Circulatory system:  One of the eleven major b...

Circulatory system:  One of the eleven major body organ systems in animals; carbon dioxide, nutrients, transports oxygen, and waste products between the cells and the respiratory s

Endocrine regulation of the cycle - reproduction, Endocrine Regulation of t...

Endocrine Regulation of the Cycle - Reproduction You have learnt above that the reproductive cycles are governed by the interplay of pituitary and gonadal hormones. According

Define the future challenges of spatial processes, Define the Future challe...

Define the Future challenges of spatial processes? Understanding the dynamics of stochastic spatial systems, systems with a multitude of spatial scales, and systems along with

What main idea, What key idea, contained in Malthus's essay on populations,...

What key idea, contained in Malthus's essay on populations, helped Darwin formulates his theory of natural selection?

Phases of karyokinesis, Phases of Karyokinesis: Karyokinesis can furth...

Phases of Karyokinesis: Karyokinesis can further be divided into prophase, metaphase, anaphase and telophase. 1-Prophase: (pro= before) Chromatin: During Interphase (non

Class Pisces, need different types of information about fishes and their pi...

need different types of information about fishes and their pictures

Why binding motifs regulate gene expression, How do leucine zipper binding ...

How do leucine zipper binding motifs regulate gene expression?

Munch pressure flow model, Munch Pressure Flow Model Munch, a German p...

Munch Pressure Flow Model Munch, a German plant physiologist, proposed in 1930, a simple physical model which can be tested in the laboratory for the mechanism of phloem trans

Explain denaturation and coagulation, Explain Denaturation and coagulation ...

Explain Denaturation and coagulation Denaturation and coagulation of the proteins are considered to be the chemical changes, since they involve the unfolding of proteins, whic

Expression of variability, In the previous sub-section we discussed the pos...

In the previous sub-section we discussed the possible ways by which variabiliti can, be generated. We shall now examine one instance that illustrates the consequence of variability

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