Cell organelles

2. The organelles of animal and plant cells are similar to each other
except that __________ are present only in animal cells, and
___________ are present only in plant cells.
ORGANELLES
Animal and plant cells
have organelles.
Organelles
compartmentalize
functions within the
cell.

3. MITOCHONDRIA
Electron micrographs of cells show
mitochondria as rod like structures.
0.5μ,m-1 μm in diametre
7 μm in length

4. BIOMEDICAL IMPORTANCE
INNER MEMBRANE
Component of electron transport system.
Impermeable to most ions and large
molecules e.g; H,Na,ATP,GTP
,Pyruvate,Citrate etc.
For transport special carriers are present e.g
Adenine nucleotide carrier system(ATP-
ADP Transport)

5. Complex II,Succinate dehydrogenase
Complex V,ATP Synthetase complex.
OUTER MEMBRANE
Permeable to all ions

6. Matrix
Inclosed by inner mitochondrial
membrane.
Contain enzymes of:
Citric acid cycle
β oxidation of fatty acids
Amino acid oxidation
Urea and heme synthesis

7. NAD
FAD
ADP,Pi
Mitochondrial DNA
Circular DNA,has information for 13
mitochondrial proteins and some RNAs
Mitochondrial cytochrome P450 system

8. P450 system is involved in the hydroxylation
of cholesterol to steroid
hormones(placenta,adrenal cortex,ovaries and
testes)
Bile acid Synthesis (liver)
Vitamin D formation(kidney)
Mitochondria plays a key role in
aging.Cytochrome C component of ETC plays
a main role in cell death and Apoptosis.

9. MITOCHONDRIAL DISEASES.
Fatal infantile mitochondrial myopathy and
renal dysfunction.
MELAS(Mitochondrial encaphalopathy
lactic acidosis and stroke)
Myoclonic epilepsy etc.

10. ENDOPLASMIC RETICULUM

11. BIOMEDICAL IMPORTANCE
ROUGH ER
Biosynthesis of proteins.
Special proteins called CHAPERONS are
present ,involved in proper folding of
proteins.
Protein glycosylation

12. SMOTH ER
Synthesis of lipids,cholesterol and steroid
hormones.
Detoxification of endogeneous and
exogeneous substances
Microsomal cytochrome P450
monoxygenase system(Xenobiotic
metabolism)

13. Elongation of fatty acids
Desaturation of fatty acids
Omega oxidation of fatty acids
Synthesis of other organelles ,peroxisomes
and lysosomes in association with Golgi
Apparatus.

14. _________ ___________GOLGI APPARATUS
Function: Packages, modifies, and
transports materials to different location
inside/outside of the cell.
Appearance: Stack of pancakes
Consists of a stack of curved saccules.
Receives protein and also lipid-filled vesicles
from the ER, packages, processes, and
distributes them within the cell or for export
out of the cell (secretion).
Also encloses digestive enzymes into
membranes to form lysosomes.

15. Golgi complex is the site for the formation
of carbohydrate side chains of
glycoproteins and
mucopolysacchrides(GAGs)
It gives rise to acroblast of spermatozoa
that is converted to acrosome.It contains
lysosomal enzymes and proteinases invoved
in the fertilization of ovum.

16. LYSOSOMES
Extracellular digestion of both intracellular
and extracellular substances.
Single limiting membrane.
Acidic pH 5.
They have group of enzymes called
HYDROLASES.The enzymes destined to
inter lysosomes has mannose at their
ends,which change to manose 6 phosphate
and enter into the lysosomes.

17. BIOMEDICAL IMPORTANCE

18. BONE REMODELING
An osteoclast breaks the bone matrix down
into fragments by means of secreated acid
and lysosomal hydrolases.It completes the
breakdown by endocytosis and lysosomal
digestion of the fragment.

19. THYROXIN PRODUCTION.

20. LIPOFUSCIN.
Age pigment wear and tear pigment.
DISEASES OF LYSOSOMES
Release of lysosomal enzymes in response to
ionizing rediations,some carcinogens,silca
particles,dust,hypoxia,heat and certain drugs
leading to cell death, mutaions in genome and
malignancies.
Lysosomal storage diseases

21. PEROXISOMES
First observed by electron microscopy in animal cells
(1950s), then in plant cells (1960s)
Christian deDuve (1965)
Isolated from liver cells by centrifugation
Called them peroxisomes because they generate and
destroy H
2O
2

22. Single membrane
Roughly spherical
0.2 - 1.7mm
Composition varies

23. BIOMEDICAL IMPORTANCE
Rich in enzymes.
50 Enzymes have been demonstrated in them.
Proteins called PEROXINS are involved in the
various stages of their production.
These are involved in the metabolism of lipids
i.e.plasmalogens,cholesterol.
Involved in the β oxidation of very long and
branched chain fatty acids.
Shortens the chain of cholesterol in the
formation of bile acids.

24. Peroxisomes are involved in the production
and detoxification of H ₂O₂
PEROXYSOME PROLIFERATOR
ACTIVATED RECEPTOR(PPARs).
PPARs α:expresses genes hepatic enzymes
for β oxidation and formation of ketone
bodies.

25. PPARsγ:express genes encoding for protein
synthesis involved in lipid synthesis and
storage in the fat cells.
PPARsδ:express genes encoding proteins of
liver and muscles involved in the β
oxidation of fatty acids and dissipation of
free energy as heat.

26. Adrenoleukodystrophy: Deficiency in b-oxidation of
very long-
chain fatty acids
Zellweger syndrome: Defect
in protein import, giving
rise to “ghost peroxisomes”

27. 27
An apparent amorphous mass enclosed by a
nuclear envelope,Literally mean central core of the
body or object.
Within:
Chromosomes
Chromatin
Nuclear matrix
Fibrillar network
Nucleoli
r-RNA and ribosomes
Nucleoplasm
Fluid of the nucleus
NUCLEUS

28. 28
The nuclear envelope
Components:
Two cellular membranes
Barrier to ions, solutes, macromolecules
Membranes fused to form pores
Complex assemblies of proteins
Outer membrane
Ribosomes
Continuous with RER

29. 29
Inner membrane
Bound to nuclear lamina
Filamentous network
Nuclear lamina
Supports envelope
Attachment of chromatin
Nuclear lamina fibers
Proteins – lamins
superfamily – Intermediate filaments of
cytoplasm.

30. 30
The nuclear pore complex (NPC)
Large numbers of proteins – synthesized
in cytoplasm and transported into the
nucleus
RNAs manufactured in nucleus –
transported to cytoplasm

31. NPC is made up of about 50 proteins called
nucleoporins.
Show both selective and non selective
movements of ions and substances.
Larger proteins(RNA polymerases)need special
mechanisms to move from cytoplasm into the
nucleus.Signal system….
Expenditure of energy by GTP hydrolysis.
RNA move from nucleus to cytoplasm through
these pores.

32. The nuclear envelope
Components:

33. The nuclear pore complex (NPC)
Eukaryotic Nucleus - Structure

34. Chromatin
Represents substance of chromosomes.
Each chromatid in a chromosome represents one DNA
molecule that occurs in a highly condensed form.
The nucleic acids present in the chromatin is mostly DNA
but small ammount of RNA is also present.
Chromatin is a combination of DNA and protein.
The most abundant proteins are histones(5
types),NUCLEOSOMES.
Other proteins include enzymes like DNA and RNA
polymerases,Protins involved in the regulation of DNA
transcription and replication.

35. Chromatin occurs in two forms,
 Euchromatin
Stains lightly,partially or completely
uncoiled,active transcription.
 Hetrochromatin
Stains deeply,highly coiled,generally
inactive include noncoding
regions,telomere and centromere.

36. Constitutive heterochromatin
Facultative
X chromosome inactivation, bar b0ody.

37. NUCLEOLUS
Also called micronucleus.
Nucleolonema,network of
Strands containing RNA.
 Size varies depending
upon the activity.

38. Nucleoli are formed around specific genetic
loci called nucleolar organizing regions
(NORs).
Consists of two parts.
Fibrillar part.(site for rRNA
transcription).Genes for 28s,18s and 5.8s are
located there.
Granular part.(assembly of ribosomal
subunits takes place there).