Eukaryotic
Cell Organelles
and Organization
J a v a d
F a s a
J a m s h i d i
U n i v e r s i t y
o f
M e d i c a l
S c i e n c e s ,
O c t o b e r
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Eukaryotic Cells Organelles
A eukaryotic cells, membrane-enclosed compartments
Providing increased membrane area to host biochemical
reactions
Form enclosed compartments that are separate from the cytosol
Vary in abundance from cell type to cell type.
Occupy nearly half the volume of a cell
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Eukaryotic Cells Organelles
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Cytosol
Constitutes a little more than half the total volume of the cell
The site of protein synthesis and degradation
Performs most of the cell’s intermediary metabolism
Transport metabolites from their site of production to where
they are used
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Nucleus
Contains the DNA and is the site of transcription of the
DNA into messenger RNA
Inner membrane that defines the nucleus itself, outer
membrane that is continuous with the membrane of the
endoplasmic reticulum
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Nucleus
The nuclear lamina, located on the nuclear side of the
inner nuclear membrane, gives shape and stability to
the nuclear envelope
Composed of intermediate filaments , also regulates
important cellular events
Nuclear pore complexes (NPC) not only define the site of
transport across the nuclear membranes but act as
gatekeepers,
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Nucleolus
Place for transcription of rRNAs and ribosome assembly
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Endoplasmic Reticulum
The largest internal membrane system, about half the total area of
membrane in a eukaryotic cell
The ER also produces most of the lipid for the rest of the cell and
functions as a store for Ca2+ ions.
Sends many of its proteins and lipids to the Golgi apparatus
Smooth endoplasmic reticulum
synthesis of fatty acids and phospholipids, no ribosome
Rough endoplasmic reticulum
synthesis of membrane proteins and proteins that will be secreted out of a
cell
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Golgi apparatus
Consists of organized stacks of disclike compartments
called Golgi cisternae
Receives lipids and proteins from the ER and dispatches
them to various destinations
Modify proteins with sulfate, carbohydrate, lipid, and
somehow address them
Process of the secretory pathway,
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Mitochondria
Generate most of the cell ATP
Aerobic respiration, produce 15 times more ATP
can occupy as much as 25 percent of the volume of the
cytoplasm
The number of mitochondria depends upon the
metabolic requirements of that cell
contain it’s own genomes
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Lysosomes
About 50 different degradative enzymes that can hydrolyze
proteins, DNA, RNA, polysaccharides, and lipids
defunct intracellular organelles
Recycle materials
Low ph=5 , proton pomp , kind of protection
More than 30 different human genetic diseases, which are
called lysosomal storage diseases
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Endosomes
A vesicular compartment involved in the sorting and
transport to lysosomes of material taken up by
endocytosis.
Provide an environment for material to be sorted before
it reaches the degradative lysosome
Comprise three different compartments: early
endosomes, late endosomes, and recycling endosomes
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Peroxisomes
Are small vesicular compartments that contain enzymes
used in various oxidation reactions
Catalysis of proteins and lipids can make H2O2
They contain catalase
Are involved in the:
Catabolism of very long chain fatty acids
Branched chain fatty acids
D-amino acids, and polyamines,
Biosynthesis of plasmalogens
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Ribosomes
Primary site of biological protein synthesis
Read mRNA and attach amino acids
Contain 2 parts
Small ribosomal subunit which reads the RNA
large subunit which joins amino acids
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Ribosomes
50s
Prokaryotic 70s
30s
23s + 5S RNAs
31 Proteins
16s RNA
21 Proteins
60s
Eukaryotic 80s
40s
28s + 5.8s + 5s RNAs
46 Proteins
18s RNA
33 Proteins
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