Plastids

 TOPIC# 12        PLASTIDS

PLASTIDS

   INTRODUCTION

              Membrane bounded ,mostly pigment containing bodies present in the cytoplasm of cell are called plastids.

These pigment containing bodies are only present in plants cells.(mcq point).

   TYPES OF PLASTIDS

             There are three types of plastids:

  1-CHLOROPLAST:

          Membrane bounded structures containing a light capturing pigment chlorphyll present only in green leaves of plants.

 They are mostly vary in shape like mitichondria but its diameter 4-6 micrometer.

 Chloroplast contain pigment chlorophyll which is organic compound which synthesize food by capturing light means here photosynthesis reaction occur and you know it is the preperation of food reaction in plants cell.Chlorphyll structure is seen by electron microscope It is nitrogenous compound which contain four porphyrin ring these four prophyrin structures are connected by Mg+2 ions.This nitrogenous compound also contain a hydrocarbon tail.

Chlorophyll structure is same like heamoglobin but the heamoglobin contain Fe+2 central atom while chlorophyll contain Mg+2 ion.

COMPOSITION OF CHLOROPLAST:

    It contain proteins,lipids,DNA,RNA and ribosomes 70s.

    It is also self replicating organelle like mitochondria because it also have its own DNA and             ribosomes.

   It is also kitchen of cell because here the food of plants is produce in form of carbohydrates.

   It is also called semiautonomous organelle.

STRUCTURE OF CHLOROPLAST:

  It structure contain 3 components;

A- ENVELOPE:

       The envelope is the double membrane which sorrounds the chloroplast.

B-STROMA:

       It covers most volume of chloroplast .it is the cytoplasm of chloroplast which contains fluid ,ribosomes and proteins and where carbondioxide is fixed to produce sugars(plants food).

C-THYLAKOIDS:

       These are the flattened vesicles which arrange themselves to form coulmn like structure called as Grana.

A  Granum appears to be pile of thylakoids stacked on each other like coins.on average 50 or more thylakoids piled to form one granum.

on the granum upper layers the chlorophuyll molecules is present and therefore it appears green.

Each granum is inter connected with another granum by non green part called as intergranum.

2-LEUCOPLAST:

 These are colorless plastid .

 they are triangular,tubular in shape.

it is present in roots cells.

it is responsible for storing food.

Aminoplast is a type of leucoplast responsible for storage of carbohydrates.

3-CHROMOPLAST:

 These are cholorful plastid other than green in plants.

 They are present in the petals of the flower and in ripened fruits.

They help in pollination and dispersal of seeds.

IMPORTANT MCQS IN THIS TOPIC:

1-The pigment containing bodies found in cytoplasm of plants cell is called:

Answer: PLASTIDS

2-The diamter of chloroplast is:

Answer: 4-6 micrometer

3-The grana contain _thylakoids:

Answer: 50 OR MORE

4-The_ plastid is self replicating organele:

Answer: CHLOROPLAST

5-The colorful pigment other than green is :

Answer: CHROMOPLAST

6-Which plastid help in polllination:

Answer: CHROMOPLAST

7-Which plastid store food;

Answer: LEUCOPLAST

8-;Leucoplast present in:

Answer: ROOTS CELLS

9-The choloroplast contain which type of ribosomes:

Answer: 70s ribosomes

10-Where the carbondioxide is fixed in chloroplast:

Answer: STROMA

11-Cholorphyll colour is:

Answer: GREEN

12-There are _ porphyrin rings in cholorophyll molecule:

Answer: 4

13-The chlorophyll center atom is :

Answer: Mg+2

14-The cholorphyll molecules present in:

Answer:   GRANA

IF YOU LIKE THIS BLOG FOLLOW ME FOR MORE UPDATES AND ALSO DROP A BEAUTIFUL COMMENT