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

Gastrointestinal tract function , Gastrointestinal Tract Function: As...

Gastrointestinal Tract Function: As a result of burn  injury acute gastric dilation occurs, creating abdominal distention and  regurgitations. Malabsorption occurs secondary

What is the importance of the glucose blood level, What is the importance o...

What is the importance of the glucose blood level for human health? The glucose blood level (glycemia) must be kept normal. If it is abnormally low there is not enough glucose

Describe postpartum cardiomyopathy, Q. Describe Postpartum Cardiomyopathy? ...

Q. Describe Postpartum Cardiomyopathy? It is defined as presentation of LV Systolic dysfunction and heart failure in last trimester of pregnancy or within 6 months of delivery.

Antibiotic resistance, Antibiotic resistance is the resistance conferred t...

Antibiotic resistance is the resistance conferred to the host the ability to survive a given antibiotic by the plasmids containing resistance genes. If such kind of plasmid is pre

Are microorganisms directly or indirectly affects our lives, Describe 5 way...

Describe 5 ways that a microorganisms directly or indirectly affects our lives.

Deficiency diseases-selenium and vitamin e deficiency, Selenium and vitamin...

Selenium and vitamin E deficiency Selenium is an essential micro-mineral required for various physiological functions and for immunity against a variety of diseases. It is an i

Define fraction in which calcium in plasma is present, Define Fraction in w...

Define Fraction in which Calcium in plasma is Present? Calcium in plasma is present in three major fractions: Ionized calcium Protein bound calcium Complexed c

What is thigmotropism, What is thigmotropism? Thigmotropism is the move...

What is thigmotropism? Thigmotropism is the movement or growth of the plant in response to mechanical stimuli (touch or physical contact), as when a plant grows around a suppor

Heparin, HE P ARIN It is highly sulphated mucopolysaccharide made ...

HE P ARIN It is highly sulphated mucopolysaccharide made of alternate units of glucosamine and glucuronic acid. Heparin is mainly produced by liver and mast cells. I

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