Cell: The Unit of Life
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The space limited by the inner membrane of the chloroplast is called
stroma. It contains many organized flattened membranous sacs called
thylakoids.
drop of lipids
Chloroplast DNAribosome
starch granule
outer membrane
inner membrane
granum
thylakoid
lamella
stroma
intermembrane space
Membrane of thylakoids encloses a space called lumen.
Chlorophyll pigments are present in the thylakoids.
Thylakoids are arranged in stacks called grana or the intergranal
thylakoids.
There are flat membranous tubules called the stroma lamellae
connecting the thylakoids of the different grana.
The stroma contains small, double-stranded circular DNA molecules,
ribosomes and enzymes for the synthesis of carbohydrates and
proteins.
The ribosomes of the chloroplasts are smaller (70S) than the
cytoplasmic ribosomes (80S).
6.
Ribosomes
These are the non-membranous granular structures composed of
ribonucleic acid (RNA) and proteins.
It is first observed by George Palade (1953).
Ribosomes are site of protein synthesis so they are called protein
factories.
Eukaryotic ribosome has 2 subunits- 60S (large subunit) and 40S (small
subunit). They together form 80S. Prokaryotic ribosomes are 70S
Ribosomes are site of protein synthesis so they are called protein factories.
7. Cytoskeleton
It is a network of filamentous proteinaceous structures present
in the cytoplasm.
It consists of microtubules, microfilaments and intermediate
filaments.
It provides mechanical support, motility, maintenance of the
shape of the cell etc.