This document summarizes a seminar on cell organelles presented by Dr. Simi M. The seminar covered the major cell organelles including the nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, peroxisomes, and ribosomes. It described the structure and functions of each organelle, highlighting their roles in processes like protein synthesis, lipid synthesis, cellular respiration, waste disposal, and more. The history of the discovery of each organelle was also briefly outlined.

1. Seminar on
CELL ORGANELLES
Dr.Simi M
Dept of Physiology
Sree Gokulam Medical College & Research Foundation.
26th August 2011.

2. Introduction
 Discrete organelles that subserve
distinct functions.
 Bounded by limiting membrane
“Membrane-enclosed organelles”
 Contain enzymes.

3. History
 Homogenised by disrupting cell
membrane with Tween 20
 Albert Claude (Nobel Prize 1974)
 Marker enzymes.

4. CELL ORGANELLES
 Nucleus
 Endoplasmic reticulum
 Golgi Apparatus
 Mitochondria
 Lysosomes
 Peroxisome
 Ribosome
 Centrosomes

5. CELL ORGANELLES

8. THE NUCLEUS – stores,replicates &
reads Cell’s Genetic Information.
 Described by Robert Brown (1831)
 First Discovered & Largest organelle
 2-20 µm in diameter

9. Structure of Nucleus
 Sorrounded by double membrane
- outer membrane
- inner membrane
 Space b/w 2 membranes
"Perinuclear Cistern"

10. Structure of Nucleus

11. Structure of Nucleus

12. Structure of Nucleus

13. THE NUCLEUS
Nuclear Pores
“Nuclear Localisation Sequence”
Nuclear Pore Complex
Outer diameter : ~100 nm
Resting State : ~9 nm

15. Nucleus : Storehouse of DNA
 Chromosomal DNA present inside
nucleus
 Chromatin
- Heterochromatin
- Euchromatin
 Transport pathways
-Importins
-Exportins

17. Nucleolus
 described by Gabriel Valentin 1836
 prominent in cells actively
synthesizing proteins
 Function :
- RNA Processing
- Ribosome synthesis

18. ENDOPLASMIC RETICULUM
 Web of Tubules or Saccules
sorrounding the nucleus.
 “ Railway Track Appearance ” - EM
George Palade
(Nobel Prize 1974)
 2 forms : RER & SER

19. RER SER
Granular  Agranular
Ribosome studded Not Ribosome
studded
PROTEIN SYN LIPID &STERIOD SYN
Egs:
Egs: Leydig cells
Nissl Granules Cells of Adrenal
Russel bodies Cortex
Acinar cells

20. Structure of Endoplasmic Reticulum

21. ENDOPLASMIC RETICULUM
 Functions:
1.Synthesis of proteins,Glycoprotein &
Lipoproteins
2.Detoxification of various drugs
3.Major Reservoir of Ca2+ ions
Modified ER (Sarcoplasmic Reticulum)

22. Microsomes :
Formed by automatic reassembly of
disrupted complex ER on cell
fractionation.
Func:
1.Valuable tool for understanding
metabolism of compounds.
2.Study drug – drug interactions

23. MITOCHONDRIA - Site of
Oxidative Energy Production.
 “Power House of the Cell”
 Richard Altman (1886)
 Carl Benda coined the term
 0.5 – 1 µm in diameter &
 7 µm in length.

24. Structure of Mitochondria
 Described as a “Balloon with in a
balloon”
 Cigar shaped organelles/
Sausage shaped organelles
 2 membrane
- outer membrane
- inner membrane (Cristae)
Lollipop shaped globular structures

25.  Define 2 distinct internal compartments
- inter membrane space
- matrix space
 Capable of “Self replication”
 Short Life span

26. Structure of Mitochondria

30. Mitochondrial Enzymes
 A. Membrane enzymes
1.Enzymes of outer membrane
a) Cytochrome b5 & b5 reductase
b) Fatty acid coA synthase
c) Phospholipase A
d) Nucleoside diphosphokinase

31. Mitochondrial Enzymes
 2. Enzymes of inner membrane
a) Cytochrome b,C1,C,a& a3
b) NADPH dehydrogenase
c) Succinate dehydrogenase
d) Electron transferring flavoproteins
e) β-OH-butyrate dehydrogenase
f) Carnitine – palmitoyl transferase
g)All translocases

32. Mitochondrial Enzymes
 B. Enzymes of inter membrane space
a) Adenylate kinase
b) Nucleoside diphoshokinase
c)Sulfite oxidase

33. Mitochondrial Enzymes
 C. Enzymes in the matrix
a) Pyruvate dehydrogenase complex
b) Citrate synthase
c) Isocitrate dehydrogenase
d)Malate dehydrogenase
e) Fatty acid oxidation system
f) Ornithine transcarbamoylase
g) α-oxoglutarate dehydrogenase
h) Aconitase

35. MITOCHONDRIA
 Functions:
 Critical manufacturer of ATP.
 Programmed Cell death (Apoptosis)
intracellular Ca 2+ stores.

36.  ETC (innermemb )
 TCA Cycle (matrix )
 β-Oxidation of FA (matrix )
 Ketone body production
 Urea,Heme,Pyramidine syn
 Gluconeogenesis

37. Mitochondrial diseases dt mtdna
mutations
 Leber hereditary optic neuropathy (LHON)
 NARP, Leigh's disease
 MELAS
 MERRF
 Progressive sensorineural deafness
 Chronic progressive external
ophthalmoplegia (PEO)
 Pearson syndrome
 Kearn-Sayre syndrome (KSS)

39. GOLGI APPARATUS – stack of
pancakes/stack of dinner plates
 Also called “Dyctyosome”
 Collection of membrane enclosed sac
(abt 6 sacs )
 Camillo Golgi (Nobel Prize 1906)
 Continuous with ER
 >200 enzymes
 Processing station

40. Structure of Golgi Apparatus

41.  Polarised structure with cis & trans
sides
 Membrane vesicle containing proteins
bud off from ER
↓
 fuse with the cistern on the cis side of
the apparatus.
↓
 passed via other vesicles to the middle
cisterns
↓
finally to the cistern on the trans side,
from which vesicles branch off into the

44. Functions :
 Site for Packaging of proteins
synthesized in ER into vesicles
 Formation of Lysosomal enzymes
 Transport to other organelles
 Glycosylation of proteins

45. LYSOSOMES – Cell’s Trash Incinerato
 Discovered by Rene de Duve (Nobel Prize
1974)
 Large irregular structures bounded by
membrane
 Lysosomes act as “cellular stomachs,”
breaking down bacteria
and the debris from
dead cells that have
been engulfed by a cell.

46. LYSOSOMES
 Proton Pump or H+-ATP ase
acidic interior (ph 5.0)
 40 types of enz
“Acid Hydrolases”
 Specially adapted lys.membrane
Clinical app: Gout(loss of memb
integrity)
 Endocytic Vesicle
 Autophagy : “Multivesicular body”

47. LYSOSOMES
 Particularly abundant in cells involved
in phagocytic activity. (Eg: Neutrophils &
Macrophages)
 3 Forms of lysosomes
Primary
Secondary
Residual Bodies

48. Important Lysosomal Enzymes
Proteolytic 1.Cathepsins 2.Collagenas 3.Elastases
Enzymes es
Lipolytic 1.Lipases 2.Phospholip 3.Fatty acyl
Enzymes ase Esterases
Carbohydrat 1.α- 2. β- 3.Hyaluronid 4.Aryl
e splitting glycosidase galactosidas ase Sulphatase
enzymes e
Nucleic acid 1.Ribonuclea 2.Deoxy
Hydrolysing e Ribonucleas
enzymes e
Other 1.Acid 2.Catalase
enzymes Phosphatse

49. Lysosomal storage diseases
- Congenital absence of Lysosomal
enzymes

50. Disease Enzyme Unique Features
deficiency
Fabry disease α-galactosidase A Cutaneous
Angiokeratomas&
hypohydrosis
Gaucher disease Acid β glucosidase HSM & Skeletal Dysplasia
Niemann - Pick Sphingomyelinase MR,Seizures & Lung
Failure
disease
Tay- Sachs disease β-hexaminidase A MR,Macrocephaly &
Hypercuisis in infants
Hurler disease α-L-iduronidase MR,Coarse facies,CVS inv
Pompe disease Acid α-glucosidase Myocardiopathy

51. Functions of Lysosomes:
 1.Contain enzymes essential for
intracellular digestion
2.Kill & remove foreign bodies
3.Acrosome :- specialised lysosome
4.Autolysis
5.remove IC pdts of metabolism

52. Ribosomes – Sites of Protein
Synthesis.
 Granular structures present on surface
of ER & also as free
 1st observed by George Palade (1953)
 Non membrane bound organelle
 Measure ~ 22 x 32 nm.
 Contain 85% RNA of cell

53. Ribosomes
 Each is made up of a large and a small
subunit
 on the basis of their rates of
sedimentation in the ultracentrifuge, the
60S and 40S subunits
 Polyribosomes(3-5)
 Func
Main Site of Protein Synthesis

54. PEROXISOMES
 also known as microbodies
 “Subcellular respiratory organelles”
 0.5 µm in diameter
 Predominantly present in Hepatocytes &
Tubular Epithelial cells.
 surrounded by a membrane.

55.  This membrane contains a no of
peroxisome-specific proteins
 PEROXINS-
the protein Chaperones,various proteins
with specifc signal sequence are directed
to peroxisome.

56. Function:
 Essentially contain two types of Enzymes
:
 Oxidases : which are active in oxidation
of lipid
 Catalase : which act on Hydrogen
Peroxide to liberate Oxygen.

57.  Several years ago, a number of synthetic
compounds were found to cause
proliferation of peroxisomes by acting
on receptors in the nuclei of cells.
 These receptors Peroxisome
Proliferation Activated Receptors
(PPARs)

58. Peroxisome Proliferation
Activated Receptors (PPARs)
• Three PPAR receptors α ,β and γ have been
characterized.
• When activated, they bind to DNA,
producing changes in the production of
mRNAs.
• Mutations of the peroxisome
proliferators' activator receptor γ
(PPARγ) cause insulin resistance

59. Lysosomes Peroxisomes
Larger  Smaller
Formed from Golgi Formed by self-
Apparatus replication or budding
from smooth ER
Digestive organ of cell Detoxifying organ of the
cell
Contain Hydrolases Contain oxidases and
form H2O2
Helps in intracellular Along with
digestion of food, catalase,helps in the
bacteria,damaged cell detoxification of injurious
structures etc substances

60. Applied Physiology
 Perioxisomes protect from oxidative
stress (OS)
 1. Zellweger Syndrome
- peroxisome abnormal or absent
 2. Infantile Refsums Disease
- few proteins are affected
 3.Brown Schilders Disease
-insufficient oxidn of VLCFA by perox

61. Centrosomes –
 Situated near the nucleus
 made up of 2 centrioles
 surrounding amorphous pericentriolar
material.
 centrioles are short cylinders,
arranged at right angles
to each other.

62. Centrosomes –
 Microtubules in groups of 3 ,run
longitudinally in the walls of each
centriole.
 9 of these triplets
are spaced at regular intervals
around the circumference.

64. Centrosomes –
 “microtubule-organizing
centers” (MTOCs) that contain γ-
tubulin.
 Func:
monitor steps in cell division.
regulate chromosome movement

65. References
 1.Walter.F.Boron & Emile .L.Boulpaep
Medical Physiology 2nd edition
 2.Ganong’s Review of Physiology 23
rd
edition
 3.GK Pal Textbook of Medical Physiology
2nd edition
 4.Guyton & Hall Text book of Physiology
12th edition
 5.Vanders Human Physiology 8
th edition

66. References
 6.Sreekumari & Vasudevan Textbook of
Biochemistry 6th edition
 7.Harrison’s Principles of Internal
Medicine 17th edition
 8.Indu Khurana Textbook of Medical
physiology
 9.N Geetha Textbook of Medical Physiology
2nd edition.
 10.A.K Jain Textbook of Physiology
4th edition.

67. RECENT ADVANCES
 Organellar dysfunction in the pathogenesis of
pancreatitis.
 Acute pancreatitis is an inflammatory
disease of exocrine pancreas that carries
considerable morbidity and mortality; its
pathophysiology remains poorly
understood.
 Recent findings obtained on experimental
models, which reveal disordering of key cellular
organelles, namely, mitochondria,
autophagosomes, and lysosomes, in pancreatitis.
 Ref

68. RECENT ADVANCES
 (PPAR) represented by 3 types: PPAR alpha, PPAR
beta, PPAR gamma.
 PPAR alpha is a key regulator of fatty acid beta-
oxidation, participates in development of
inflammatory reaction and atherosclerosis
formation.
 PPAR gamma plays important role in lipid
metabolism, processes of cell differentiation
and growth, participates in glucose utilization
and mechanisms of insulin resistance. Specific
activators of PPAR gamma are glytazones
 Ref :http://www.ncbi.nlm.nih.gov/pubmed/14671562

69. RECENT ADVANCES
 The nuclear (PPAR gamma) in DM,HTN,atherosclerosis
 is a transcription factor that is activated by
polyunsaturated fatty acids and their
metabolites and is essential for fat cell
formation.
 PPAR gamma activators such as the glitazone
drugs lower glucose and lipid levels in patients
with type 2 diabetes and also have
antiatherosclerotic and antihypertensive effects.
 Ref :http://www.ncbi.nlm.nih.gov/pubmed/11395411.

70. Thank You !!!