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

Biotic potential of a bacterial population, Q. How different is the growth ...

Q. How different is the growth according to the biotic potential of a viral population from the growth according to the biotic potential of a bacterial population? The growth c

What is ezetimibe, It is a newer agent that inhibits cholesterol absorption...

It is a newer agent that inhibits cholesterol absorption by the enterocyte. It reduces cholesterol absorption by the enterocyte. It reduces cholesterol absorption by 23 per cent-50

Preparation for hospitalization of child - nursing, Preparation for Hospita...

Preparation for Hospitalization   Prevention is a strong component of nursing care. Preparation prior to hospitalization is  essential to make the transition from home to hospi

Define amino acid requirements for human, Define Amino acid requirements fo...

Define Amino acid requirements for Human? Data regarding the essential amino acid requirements of infants, children and adults are given in terms of egg protein and cow's milk

What are the hormones secreted by the neurohypophysis, What are the hormone...

What are the hormones secreted by the neurohypophysis? What are their respective functions? The neurohypophysis secretes oxytocin and the antidiuretic hormone (ADH). Oxytoci

Classification of nephrotic syndrome, Classification of Nephrotic Syndrome ...

Classification of Nephrotic Syndrome In childhood, nephrotic syndrome can be divided into minimal lesion nephrofic syndrome and  significant lesion nephrotic syndrome dependin

What do you mean by the notochord, Q. What is the notochord? How is this st...

Q. What is the notochord? How is this structure formed? The notochord is a rodlike structure that outlines the supporting axis of the embryo and gives birth to the vertebral co

Define the names of some immemorial plants, Define The Names of Some Immemo...

Define The Names of Some Immemorial Plants? From the time immemorial plants have been known by some name, they are common, vernacular or local names given by different persons.

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