34388551
Membrane Systems and
Organelles of Animal
Cells
- Nucleus
- Largest and most obvious
organelle in cells
- 10-25um in
diameter
- DNA in chromosomes:
contains DNA in close
association with
histones
- Histones: help
support and
protect DNA
- DNA diffusely organised in
a form, chromatin
- Heterochromatin:
Densely packed (dark
under EM)
- Euchromatin: Less
densely packed
(lighter under EM)
- Nucleoli
- 1-3 um
- Under EM, appears darker
than chromatin and is a more
discrete structure
- Contains DNA that codes
for ribosomal RNA (rRNA)
- Makes ribosomes (organelles essential
in the process of protein synthesis
- Once produced, these
are transported out
of the nucleolus,
through the nucleus
and into the
cytoplasm
- Once produced, these
are transported out
of the nucleolus,
through the nucleus
and into the
cytoplasm
- Makes ribosomes (organelles essential
in the process of protein synthesis
- 1-3 um
- Control centre of the
cell
- DNA in chromosomes
codes for the synthesis
of proteins in the
cytoplasm
- Islolating chromosomes (DNA)
from cytoplasm and its
reactions, DNA is protected from
damage
- ‘DNA code’ for protein
synthesis needs to be moved to
cytoplasm where protein
synthesis takes place and other
molecules need to enter
nucleus from cytoplasm (nuclear pores in nuclear envelope)
- Nuclear envelope is a double membrane
- Outer membrane encrusted with ribosomes (site of RER)
- mRNA (carrying genetic code from DNA) passes through nuclear pores into cytoplasm
- mRNA (carrying genetic code from DNA) passes through nuclear pores into cytoplasm
- Outer membrane encrusted with ribosomes (site of RER)
- Nuclear envelope is a double membrane
- ‘DNA code’ for protein
synthesis needs to be moved to
cytoplasm where protein
synthesis takes place and other
molecules need to enter
nucleus from cytoplasm (nuclear pores in nuclear envelope)
- Islolating chromosomes (DNA)
from cytoplasm and its
reactions, DNA is protected from
damage
- DNA in chromosomes
codes for the synthesis
of proteins in the
cytoplasm
- Largest and most obvious
organelle in cells
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