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 the mandibular ramus, Mandibular Ramus Serves as an intraoral a...

Mandibular Ramus Serves as an intraoral autogenous bone donor site. Cortical bone upto 4mm thickness may be harvested from the ramus. Harvest of bone from this area requires kn

What are pentoses, Pentoses are carbohydrates form of five carbons. Deoxyri...

Pentoses are carbohydrates form of five carbons. Deoxyribose is the pentose that constitutes DNA nucleotides and ribose is the pentose that is part of RNA nucleotides

What is cell biology, What is cell biology? Cell biology is the ...

What is cell biology? Cell biology is the science of studying how cells function like as their reproduction and metabolism, their internal and external anatomy.

Explain the metabolic rate of aerobic organisms, Why can the consumption of...

Why can the consumption of molecular oxygen indicate the metabolic rate of aerobic organisms? Molecular oxygen (O2) consumption has direct relation to the cell metabolic rate i

Illustrate the diabetic contract of the eye, Illustrate the diabetic contra...

Illustrate the diabetic contract of the eye? Diabetic Cataract: 1) Sorbitol Aldose Pathway: In patients with diabetes, there is increase in sugar alcohol which results in

Terrestrial and aquatic ecosystem, Terrestrial and Aquatic Ecosystem W...

Terrestrial and Aquatic Ecosystem What is common between a terrestrial and an aquatic ecosystem. Both have similar type of trophic structure. They possess an autotrophic layer

How much ampicillin can dissolve in 400 ml, How much ampicillin (sodium sal...

How much ampicillin (sodium sal, mw=371.40) would you dissolve in 400 mL of water to make 80 mg/ml solution of ampicillin?

Explain heterologous and homologous immunoglobulins, Q. What is the differe...

Q. What is the difference between heterologous and homologous immunoglobulins? Homologous immunoglobulin is the human from the same species immunoglobulin and In case of inocul

How does temperature affect the action of enzymes, How does temperature aff...

How does temperature affect the action of enzymes upon their substrates? There are explained temperature ranges under which enzymes operate and there is a specific temperature

Phylem porifera, please give us this phylem''s example...

please give us this phylem''s example...

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