Plastids Flashcards
(18 cards)
Where are plastids found?
Plastids are found in all plant cells and in euglenoids
Why are they easily visible under a microscope?
They are large in size and thus easily visible
Types of plastids
Leucoplasts, Chromoplasts, Chloroplasts
Leucoplasts are colourless plastids. They occur near the nucleus in non green cells. They have variable size, form and stored nutrients. They are of 3 types.
Amyloplast (starch), Elaioplast (oil), Aleuroplast (flour)
What are Amyloplasts (w/ eg.)
They are starch containing leucoplasts. Eg. Potato tuber, rice, etc.
What are Elaioplasts? (w/ eg.)
They store fats and oils. Eg. Castor.
What are Aleuroplasts? (w/ eg.)
They store protein. Eg. Aleurone cells of maize.
Why do tomatoes or chillies go from green to red when they ripen?
This occurs due to the transformation of chloroplasts to chromoplasts.
What are chromoplasts? (Colour, pigment, formation)
They are yellow, orange or red leucoplasts. The pigment carotene (/carotenoid pigment). They are formed from either leucoplasts or chloroplasts.
What are chloroplasts? (Colour, pigment, function, location)
They are green in colour. They have photosynthetic pigments. Chlorophylls and carotenoids take part in the synthesis of food. Majority of chloroplasts are found in the mesophyll cells of leaves.
Chlorophyll cells vary in size, shape and number. What.
Size: thiccnezz 2-4 mim, length 5-10 mim
Shape: spherical, lens, oval, disc, ribbon
Number: 1 per cell (Chlamydomonas- a green algae) to 20-40 per cell (mesophyll)
Chloroplasts are double membrane bound organelles. They have a outer and inner membrane
The inner membrane is relatively less permeable and thus has more proteins including carrier protein
What is the basic structure of chloroplast?
Stroma is the space enclosed by the inner membrane of the chloroplast.
*Thylakoids * are arranged in flattened membranous sacs in the stroma.
Grana are the stacks of thylakoids.
What are Grana (sing.: Granum) aka?
Intergranal Thylakoid
What is the Stroma Lamellae?
What is a lumen in the chloroplast?
Thylakoids of different grana are connected by flat membranous tubules called stroma lamellae.
The membrane of the thylakoids enclose a space called Lumen.
Contents of the stroma that help in synthesis of carbohydrates and proteins
Stroma contains enzymes and small double-stranded circular DNA molecules and ribosomes.
Compare cytoplasmic ribosomes with ribosomes present in the chloroplast.
Ribosomes of chloroplasts (70S) «_space;Ribosomes of cytoplasm (80S)
Functions of chloroplasts
(a) Photosynthesis- light reactions (thylakoids/grana) and dark reactions (stroma)
(b) Storage of starch
