IN THIS I HAVE EXPLAINED ABOUT THE CELL ORGANELLE CALLED PLASTID

1. 11th
grade
PLASTIDS
AND ITS TYPES

2. COME IN!

3. —ARISTOTLE
“Dignity does not consist in
possessing honors but in the
consciousness that we deserve
them ”

4. TABLE OF
CONTENTS
INTRODUCTION
01
CHROMOPLASTS
02
CHLOROPLASTS
03
LEUCOPLASTS
04
05 AMYLOPLASTS
06 ELAIOPLASTS
07 PROTEINOPLASTS

5. INTRODUCTION
❖ THE PLASTID IS A MEMBRANE BOUND ORGANELLE
FOUND IN THE CELLS OF PLANTS, ALGAE AND SOME
OTHER EUKARYOTIC ORGANISM.
❖ PLASTIDS WERE DISCOVERED AND NAMED BY ERNST
HAECKEL BUT A.F.W. SCHIMPER WAS FIRST TO GIVE A
CLEAR DEFINITION.
❖ PLASTIDS ARE THE SITE OF MANUFACTURE AND
STORAGE OF IMPORTANT CHEMICAL COMPOUNDS
USED BY THE CELLS OF AUTOTROPHIC EUKARYOTES.

6. CHROMOPLASTS
❖ Chromoplasts are plastids, heterogeneous organelles
responsible for pigment synthesis and storage in specific
photosynthesis eukaryotes.
❖ The presence of carotenoid pigments makes them
colourful.
❖ Chromoplasts are formed from leucoplasts or
chloroplasts.
❖ Change of colour from green to reddish during the
ripening of tomato and chilli is due to transformation of
chloroplasts to chromoplasts. The orange colour of
carrot roots is due to chromoplasts.

7. ❖ They are the greenish plastids which possess
photosynthesis of food
❖ Majority of the chloroplasts of the green plants are
found in the mesophyll cells of the leaves. They vary in
size, shape and number.
❖ Size = they have variable thickness of 2-4 micrometer
and length of 5-10 micrometer.
❖ Shape = they may be spherical, lens shaped, oval,
discoid or even ribbon-shaped in some plants.
❖ Number = their number varies from 1 per cell in
chlamydomonas, a green alga to 20-40 per cell in the
mesophyll.
CHLOROPLASTS

8. STRUCTURE OF CHLOROPLAST

9. ❖ Like mitochondria, chloroplasts are also double membrane-bound
organelle having outer and inner membrane. The inner membrane is
relatively less permeable to substances than outer membrane and thus,
has more proteins including carrier proteins. The space enclosed by the
inner membrane of the chloroplast is called the stroma. Stroma contains
a large number of organised flattened membranous sacs called
thylakoids which are arranged in the stacks like the piles of coins called
the grana or the integral thylakoids.
❖ The thylakoids of different grana are connected by flat membranous
tubules called the stroma lamellae. The membrane of the thylakoids
enclose a space called lumen
❖ The stroma of the chloroplasts contains enzymes required for the
synthesis of carbohydrates and proteins. It is also contains small,
double-stranded circular DNA molecules and ribosomes. The ribosomes
of the chloroplasts (70S) are smaller than the cytoplasmic ribosomes (80)
STRUCTURE OF CHLOROPLASTS

10. ❖ Photosynthesis = light reaction and dark reaction.
❖ Storage of starch.
Functions of Chloroplasts

11. ❖ They are the colourless plastids which generally occur
near the nucleus in non-green cells. They have variable
size, form and stored nutrients. Granum is absent.
❖ There are three types of leucoplasts:
➢ Amyloplasts : they are starch-containing leucoplasts,
e.g., potato tubers, rice
➢ Elaioplasts : they store fats and oils, e.g., castor
➢ Aleuroplasts : These leucoplast store proteins, eg.,
aleurone cells of maize.
LEUCOPLASTS

12. ❖ Proteinoplasts are specialised organelle found only in
plant cells.
❖ Proteinoplasts belong to a broad category of organelle
known as plastids because they lack pigments,
proteinoplasts are specifically a kind of leucoplasts.
❖ They contain crystalline bodies of protein and can be the
sites of enzymes activity involving those proteins.
PROTEINOPLASTS

13. an AJAY ADITHYA presentation
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