Eukaryotic cells contain specialized subcellular structures called organelles that carry out specific functions. The document describes the functions of various organelles including the plasma membrane, cytoplasm, endoplasmic reticulum, ribosomes, Golgi apparatus, lysosomes, mitochondria, chloroplasts, nucleus, nucleolus, cilia, flagella, and vacuoles. It also discusses the cytoskeleton components of microfilaments, microtubules, and intermediate filaments.

1. Eucaryotes

7. Functions of organelles
organelle functions
Plasma membrane Mechanical cell boundary,
semipermeable barrier with transport
system, mediate cell to cell
interaction and adhesion
Cytoplasmic matrix Environment for organelle, location of
metabolic process
ER Transport of materials, proteins and
lipid synthesis
Ribosomes Protein synthesis
Golgi apparatus Packaging and secretion of materials
for various purpose, lysosome
formation

8. Functions of organelles
organelle functions
Lysosome Intracellular digestion
Mitochondria Energy production through TCA cycle & ETC
chloroplast Photosynthesis
Nucleus Control center
Nucleolus Ribosomal RNA synthesis, ribosome
construction
Cilia and
flagella
Cell movement
Vacuole Temporary storage and transport, digestion
(food), water balance(contractile vacuole)

9. Cytoplasmic matrix, Microfilament,
Intermediate filament & Microtubules

10. Cytoplasmic Matrix
Important and complex part of the cell
“Environment” of the organelles
Location for many important biochemical processes
A major component- Cytoskeleton
Vast network of interconnected filaments
Functions-shape and movement

11. Filaments
1. Microfilament,
2. Intermediate filament &
3. Microtubules

12. Microfilament
• Minute protein filament(actin protein)
• 4-7nm
• Scattered
• Or organized into networks and parallel
arrays
• Cell motion-amoeboid movement,
movement of pigment
• Protoplasmic streaming

15. Microtubules
Thin cylinder like
25nm in diameter
Two proteins-
α-tubulin, β-tubulin
4-5nm in diameter
Helical arrangement
13 subunits in one turn

17. Functions of Microtubule
1. Maintain cell shape
2. With microfilament involved in cell
movement
3. Intracellular transport processes
Present in pseudopodia, mitotic spindle,
cilia and flagella

18. Intermediate filament
• Heterogeneous, 10nm in diameter
• Assembled form different groups of proteins
• so show different functions
• Provides support for nuclear envelope
• Link cells to form tissue

20. Endoplasmic Reticulum

23. RER and SER
• Membranous tubules, 40-70nm in
diameter (branching and fusing)
• Flattened sac like structure – cisternae
• Two types- rough ER (on surface
ribosomes are there)-RER
• Smooth ER-SER

24. Functions of ER
• Transportation of proteins, lipids
and other materials
• Protein and lipid synthesis
• Major site of cell membrane
synthesis

25. The Golgi Apparatus

29. Electron micrograph

30. The Golgi Apparatus
• Flattened sac like structure called
cisternae (4-8 in one stack)
• 15-20nm thick separated by other
cisternae by 20-30 nm
• At the edge a complex of tubules and
vesicles
• Cis face and Trans face
• No ribosomes on the surface

31. Functions of the Golgi Apparatus
• Packages materials and prepares them for
secretion
• Participates in the cell membrane development
• Has growth factors

36. Lysosome
• Roughly spherical, enclosed in
single membrane
• 50nm-500nm
• pH-3.5-5.0, involved in
intracellular digestion
• Having variety of enzymes

37. Role of lysosomes
• The biosynthetic- Secretory pathway- move
materials to lysosome to cell membrane or to
exterior
• Synthesis of proteins by ribosomes
• Packed in small buds (vesicles) by ER
• Vesicles face now cis part GC
• Proteins move from cis part to trans part(cisternal
maturation)
• Two times modifications, one in ER and other
during cisternal maturation

38. The biosynthetic- Secretory pathway-
• Delivery of proteins by transport vesicles (in
irregular manner)
• Two types of delivery
• One outside the cell and other called secretory
vesicles keep materials till they receive some
signals
• Proteins which are not folded are destroyed by
proteasome
• Ubiquitin marks such proteins for destruction

40. Endocytosis
• To bring materials into the cell from the outside

41. Endocytosis
Two types
1. Clathrin- dependent
2. Caveolae -dependent

42. Endocytic pathway-endocytosis

43. Clathrin dependent endocytosis
•Also called receptor mediated
endocytosis
•Used to ingest hormone,
growth factors, iron etc

44. Caveolae –dependent endocytosis

45. Caveolae –dependent endocytosis
• Caveolae-tiny flask shaped invagination of PM
• Enriched with cholesterol and membrane protein
caveolin
• Transport of small molecules such as folic acid and
macromolecules
• Cavelae fuse with early endosome
• These get mature to become late endosome
• Finally lysosome

46. Autophagy
• Recycling of cell organelles
• Autophagosomes
• Fuses with late endosomes
• Lysosomes are formed
• Digestion
• Little digestive materials released in cytoplasm
• Lysosome with undigested materials – residual
body

47. Mitochondria

50. Mitochondria
• Powerhouse of the cell
• ATP generation by oxidative phosphorylation and
ETC
• Cylindrical
• 1-1000 per cell or even more
• Outer membrane and inner membrane
• Inter membrane space
• Outer membrane with porin
• Inner with folds called crista- plate like , disk like

51. Mitochondria
• Tubular is very common, vesicle
• Dense matrix-ribosome, DNA, large calcium
phosphate
• DNA closed circle and linear
• Ribosome-70s, synthesize its own protein
• Enzymes of TCA cycle in matrix
• Enzymes and electrons carrier of ETC in
inner membrane

52. chloroplast

54. Chloroplast
• Type of plastid having pigment- chlorophyll
• Site of photosynthesis
• Oval usually
• Two membranes, matrix-stroma(DNA, ribosome,
lipid, starch
• Sac like structures- thylokoids
• Stack of thylakoids-grana
• Pyrenoid in algal chloroplast-protein surrounded
by starch- site of polysaccharide synthesis

56. Nucleus

60. Nucleus
• Prominent organelle
• Discovered by Robert Brown 1831
• Control center and repository for the cell’s genetic
information
• Membrane bound spherical body, 5-7nm in
diameter
• Dense fibrous material-chromatin,
• dispersed
• Present in nucleoplasm-it is DNA
• In dividing cells chromatin get condensed-
chromosome

61. Nucleus
• Inner and outer membranes called envelope
• perinuclear space- 15-75nm
• The envelope is continuous with ER
• Nuclear pore in the envelope-70nm in diameter
• Occupy 10-25 % of the nuclear space
• Fibrous and granular materials at the edge of pore
called annulus (complex ring like)
• Functions-transport route
• Types- euchromatin and heterochromatin

62. Nucleolus

63. Nucleolus
• Complex organelle
• Not membrane bound
• Has granular and fibrillar region
• Present in non-dividing cells
• Functions- synthesis of ribosome (rRNA)
• Combine with proteins
• Immature ribosomes
• Come to cytoplasm and get mature

64. Cilia & Flagella

65. Ultra structure of cilia and Flagella

68. Cilia and Flagella
• Whip like structure
• Help in movement
• Membrane bound cylinders- 0.2 micrometer in
diameter
• Located in matrix, complex structure, axoneme
and the basal body
• 9+2 pattern of microtubule
• Subtubules A and B, -doublet microtubule, Dynein
arm
• Radial spoke from subtubules

69. Plasma membrane

70. Difference between prokaryotic and
eukaryotic cell
Property Prokaryote Eukaryote
Nuclear
membrane
no yes
Histone no yes
Chromosome one circular many, linear
Plasmid very common rare
Nucleolus no yes
Mitochondria no yes

71. Difference between prokaryotic and
eukaryotic cell
property prokaryote eukaryote
ribosome 70s 80s
Gas vesicle yes no

72. Difference between prokaryotic and
eukaryotic cell
Property Prokaryote Eukaryote
chloroplast no yes
Plasma
membrane lipid
hapanoid sterol
flagella One protein fibre 20 microtubule,9+2
pattern
ER no yes
peptidoglycan yes no
GC no yes