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 are the characteristics of thin gingiva, Characteristics of Thin Gingi...

Characteristics of Thin Gingiva  Highly scalloped soft tissue and bony architecture  Delicate friable soft tissue  Minimal amount of attached gingiva  Thin underlying

Evolution of dental implants, The first evidence of implants dates back to ...

The first evidence of implants dates back to 600 A.D. in the Mayan population. There are reports that the ancient Egyptians attempted intra-osseous implantation of animal teeth or

What is teratology, Teratology: It is the study of abnormal embryos. In ot...

Teratology: It is the study of abnormal embryos. In other words teratology is the study of abnormalities of physiological development. It is often use as the study of birth defect

Medtronic hancock-biological valves, Medtronic Hancock (Standard Model) :  ...

Medtronic Hancock (Standard Model) :  These are gluteraldehyde preserved xenograft aortic valve, which are mounted. The modified orifice version (M-0) is one where the right

What is the importance of biotin, What is the Importance of biotin Biot...

What is the Importance of biotin Biotin is involved in a number of important metabolic reactions, probably as coenzymes. Deficiency symptoms are manifest as degenerative cha

Illustrates the effect of wall movement on earth pressure, Illustrates abou...

Illustrates about the effect of wall movement on earth pressure? Effect of wall movement on earth pressure About fifty years ago Terzaghi conducted a series of tests on larg

Define the flavonoids, Define the Flavonoids? Flavonoids constitute the...

Define the Flavonoids? Flavonoids constitute the largest group of plan1 polyphenols, generally arc the compounds of low molecular weight, bound to sugar molecules. You may be f

Studying the main parts of a flower, Studying the main parts of a flower ...

Studying the main parts of a flower Study specimens of large easy flowers such as tulips or lilies. Count the stamens and observe how they are arranged about the central pistil

Phylum annilida, how we attempt a question of phylum annilida in exam?

how we attempt a question of phylum annilida in exam?

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