The document provides information about the structure and functions of human cells and their organelles. It discusses that cells contain organelles like the cell membrane, nucleus, mitochondria, endoplasmic reticulum, ribosomes, Golgi apparatus, and lysosomes. It describes the roles of these organelles, such as the mitochondria generating energy, the endoplasmic reticulum synthesizing proteins and lipids, and ribosomes producing proteins.

1. GOOD AFTERNOON
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2. Dr.Shazia
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3.  INTRODUCTION.
 THE HUMAN CELL.
 CELL MEMBRANE.
 CELL ORGANELLES.
 ENDOPLASMIC RETICULUM.
 RIBOSOMES.
 GOLGI APPARATUS.
 LYSOSOMES.
 MITOCHONDRIA.
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4.  NUCLEUS.
 PEROXISOMES.
 REFERENCES.
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6.  The word “cell” derived from a latin word “cella” meaning
‘store room’ or a ‘chamber’.
 The term cell was first introduced in biology by a british
scientist- robert hooke (1663)
 CELL is the smallest living unit of organisation in the body
 Cell is the structural and functional unit of the living
matter and is capable of carrying on the processes of life
independently.
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7.  The human body has an estimated cell population of 100
trillion cells.
 Cell is not merely a bag of fluid, enzymes and chemicals. It
also contains highly organized physical structures called
intracellular organelles
 Most mammalian cell lie within the size range 5-50
micrometers in diameter; e.g resting lymphocytes are
amongst the smallest and megakaryocytes of the bone
marrow the largest (200 micrometers).
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9. The main cell structures are:
 Plasma membrane or cell membrane.
 The Cytoplasm and
 The cell organelles.
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10.  Remarkable structure that surrounds the cell.
 Nucleus and cytoplasm are covered by cell membrane.
 Cell membrane consists mainly of phospholipids
and protein molecules.
 Cell membrane is about 7.5nm thick.
 Its function is to take part in the maintenance of the
internal environment by active transport of ions and
nutrients.
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11.  Organelles meaning “little organs”.
 A membrane -bound compartment or structure in
a cell that performs a special function.
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12.  Cell organelles are of 2 types..
 Membranous Organelles:
1. Rough Endoplasmic reticulum.
2. Smooth endoplasmic reticulum.
3. Mitochondria.
4. Golgi.
5. Lysosomes.
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13.  Non membranous Organelles.
1. Ribosomes.
2. Cytoskeletal structures.
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14.  Mitochondria has highly organised molecular
structure.
 Ovoid, elongated thread like structures of 0.5µm to
1µm in diameter and roughly 5µm to 10µm in length
 mitochondria are the only organelles to have their own
genetic material.
 In EM it can be seen that mitochondria are bounded
by double unit membrane.
 These membrane are separated by narrow
intramembranous space
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15.  Inner membrane is four or five times larger than outer
membrane.
 Outer membrane is fairly permeable, inner membrane
is highly selective.
 Interior of the mitochondrian is filled with
mitochondrial matrix of slightly higher electron
density than the surrounding cytoplasm.
 Mitochondria are renewed on a continuous basis
throughout the cell cycle.
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16.  Mitochondria surronded by trilaminar double
membrane, the inner one of which remains folded and
forms number of partitions- Cristae Mitochondriales.
 The number and size of mitochondria give an
indication of the energy requirements.
 Mitochondria primarily concerned with the chemical
process by which energy is made available to the cell in
the form of ATP
 ATP is often referred to as the energy “currency of
cell”
 main site of aerobic respiration.
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18.  This DNA is inherited maternally.
 Mitochondrial matrix contains 2r RNA and 22
tRNA`s used in translation of mRNA (synthesizes
37 proteins of their own).
 encodes 13 enzymes, involved in oxidative
phosphorylation(cytochrome b and 3 subunits of
cytochrome: 7 subunits of NADH dehydrogenase)
 The mutations of mtDNA are more likely to cause
muscular dysfunctions .
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19.  Mitochondria are also significant participants in many
versions of apoptosis, and altered mitochondrial
function appears to be associated with various
cancerous changes in cells.
 In cell hypertrophy- increase in number of
mitochondria in cells
 In cell atrophy- decrease in no. of mitochondrias in
cells.
 Mitochondria are comparatively rare in cancer cells
which derive their energy from anaerobic glycolysis.
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20.  Mega mitochondria seen in liver in alcoholic liver
disease and nutritional deficiency.
 In mitochondrial myopathies- increased no. of
mitochondria, large in size, abnormal cristae,
crystalloids
 Bening tumors found in salivary glands thyroid,
parathyroid, kidneys consists of abundant large
mitochondria giving eosinophilic appearance.
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21.  Mitochondrial damage in βcells- diabetes.
 Dysfunction in heart- cardio myopathy.
 Dysfunction in neurodegenarative diseases-
parkinsons disease..etc
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23.  Also called as claude`s particles.
 Ribosomes are the structures where proteins are made.
 A ribosome is an organelle composed of ribosomal
RNA and ribosomal proteins known as a
Ribonucleoprotein, at which protein synthesis takes
place.
 It has approximately 37 - 62% RNA, and rest are made
up of proteins.
 Ribosomes are tiny particles which are about 200Å.
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24.  They are produced in the nucleolus
 The ribosomes has two categories:
 Those free to roam in the cytoplasm .
 Those bound to endoplasmic reticulum.
Prokaryotes have 70S ribosomes
(large) 50S subunit,and
(Small) 30s subunit .
Eukaryotes have 80S ribosomes
(large) 60S subunit.
(small) 40S
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25.  Ribosomes are composed entirely of rRNA and
ribosomal proteins and are classified under n0n-
membranous organelles as they themselves possess
no membrane component.
 Ribosomes are indistinguishable at LM level
 In EM cytoplasm contains abundance of free
ribosomes.
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26.  Defects in the function of ribosome may cause:
1. Anemia( 5 infants in 1 million are affected)
2. Cartilage hair hypoplasia
3. Shwachman diamond syndrome.(1 child in every
100,000 is born with ribosomal disorder)
4. Dyskeratosis congenita(1 child in 1 million is
affected)
(Williams hematology marshall lichtman, thomas kipps M.D. et al
2010.)
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28.  Garnier named ergastoplasm
 Claude named microsomes.
 Porter named endoplasmic reticulum .
 Endoplasmic- within the cytoplasm.
 Reticulum- strands and vesicles arranged in network.
 Consists of parallel membrane bound channels.
 All the membranes of ER are interconnected with
plasma membrane on one hand and outer nuclear
membrane on the other hand.
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29.  Two morphologically and functionally distinct
differentiation of organelle are identified as
1. Rough endoplasmic reticulum/granular/α-
cytomembranous.
2. Smooth endoplasmic reticulum/agranular/β-cyto
membranous.
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30.  They may serve specialized functions in the cell
including
 protein synthesis,
 sequestration of calcium,
 production of steroids,
 storage and production of glycogen, and
 insertion of membrane proteins.
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32.  Reticulum is studded with osmeophilic granules which
were earlier called as palade granules- ribosomes.
 Large parallel flattened membranous sacs called cisternae
studded with ribosomes.
 It is involved in protein production and protein folding.
 13 million ribosomes are present on RER in an average
liver cell
 RER is found throughout the cell but the density is higher
near the nucleus and golgi.
 In the lumen of RER, quality control checking is carried
out.
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33.  Functions of rough ER:
 Proteins synthesized in the attached ribosomes enter
the lumen of the reticulum, from which they are
ultimately distributed to other organelles.
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34.  Do not possess osmeophilic granules- the ribosome
 Smooth ER is devoted almost exclusively to the
manufacture of lipids e.g.. liver cells and steroid
hormones. e.g.. adrenal cortex and endocrine glands.
 It also plays a pivot role in detoxifying a number of
organic chemicals converting them to safer water
soluble products.eg. In Liver cells smooth ER are found
in larger quantities.
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35.  Smooth ER is very abundant in
1. leydig cells of testies
2. Cells of corpus luteum
3. Parietal cells of gastric mucosa
(Alberts et al,molecular biology of the cell garband
publishing 1994)
 Functions of smooth ER:
 Contains enzymes for fatty acid and steroid synthesis.
 Stores and releases calcium, which controls various
cell activities.
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36.  In 1898, an Italian neurologist Camillo Golgi named
this structure as Golgi apparatus, Golgi complex or
simply as Golgi.
 The structure looks like a network of fine
threads(Golgi network) or irregular granular material
 The main structural unit of Golgi body is a flattened
membranous vesicle described as Golgi saccule
 It is usually located near the nucleus and in the gland
cells found between the nucleus and the apex of the
cell
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37.  Cisternae stack have five functional regions
 Cis golgi network, cis golgi,medial golgi, trans golgi, trans
golgi network.
 Vesicles from ER fuse with the cis golgi network,, travel
upto trans golgi network where they are packaged and sent
to the required destination.
 GERL complex does not appear to be functionally separate
from the Golgi apparatus. (THE JOURNAL OF CELL BIOLOGY " VOLUME
90, 1981)
 Part of the GERL complex : Intracellular stack
of membrane bounded vesicles in which glycosylation
and packaging of secreted proteins takes place.
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38.  3 main structures can be observed under EM :
 Flattened vesicles.
 secretory vesicles.
 Microvesicles.
 The main structural unit of golgi apparatus is flattened
membrane vesicle described as GOLGI SACCULE.
 Golgi saccules arranged in golgi stacks.
 Each stack of saccules in golgi complex possess
1. Forming face(Cis – face)
2. Maturing face(Trans- face)
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39.  Defects in various aspects of golgi function leads
to
1. Congenital glycosylation disorders.
2. Muscular dystrophy.
3. Diabetes.
4. Cancer.
5. Cystic fibrosis.
(UNGAR.D. GOLGI PROTEIN GLYCOSYLATION AND ASSOCIATED
DISEASES, CELL AND DEVELOPEMENTAL BIOLOGY20,762-769(2009)
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41.  Vesicles of 0.5µm in diameter is manufactured in
the Golgi apparatus.
 Size and shape of the lysosomes change with the stage of
their activity.
 pH within the lysosome is distinctly acidic.
 Enzymes of lysosomes are potent enough to digest its own
cellular contents in which it inhabits, (“suicide bag”)
 lysosomes that digest the degenerated mitochondria are
referred to as cytolysosomes,( “digestive bags” )
 Lysosomes hauls away unusable waste and dumping it
outside the cell. (“cellular garbage disposal`s”)
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44.  Contain 50 different hydrolytic enzymes that can
breakdown bacteria and debris that have been taken
into the cell.
 Enzymes found are
 ribonucleus,
 deoxyribonucleus,
 phosphatase,
 collagenase and
 cathepsins
 A lysosome that buds from the trans face of a golgi
stack is termed as primary lysosome.
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45.  The staining reveals a crystal like matrix in spherical
vesicles. The crystalloid matrix is urate oxidase.
 All enzymes of lysosomes are produced in the endoplasmic
reticulum, and transported and processed through the
Golgi apparatus.
 Each acid hydrolase is targeted to lysosome by
phosphorylation.
 Cytochemically, the enzyme alkaline phosphatase(beta-
glyceryle phasphatase) is used as a marker of lysozymes for
light & EM.
 Lysosomes required to digest tails of tadpoles and to
remove the web from the fingers of a 3-6 month old fetus.
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46.  The most common LSDs are:
 Tay sachs diesase
 Niemann- pick disease
 Krabbe`s disease
 Gaucher disease.
 Pompe`s disease.
 Slicosis and asbestosis
 Rhematoid arthritis.
 Lysosomes are involved in the pathogenesis of gout
 Tay- sachs disease is the most progressive in the major
group of genetic diseases.
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49.  In cell biology, the nucleus (from Latin nucleus or nuculeus,
kernel) is found in all eukaryotic cells.
 The nucleus was discovered around 1833 by botanist
Robert Brown.
 The nucleus varies in diameter from 11 to 22.25
micrometres
 Usually the nucleus is round and is the largest organelle in
the cell.
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50.  Structure / Components-
 Nuclear envelope- regulate what enters and leaves
nucleus (Nuclear pores)
 Nucleolus-makes ribosomes
 Genetic Material- DNA
 Chromatin – DNA uncoiled, threadlike, Not Divisional
 Chromosomes –DNA is condensed, Divisional
 Nucleoplasm -fluid inside nucleus
 Function
 The nucleus of a eukaryotic cell directs the cell's
activities and stores DNA.
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51.  Nucleolus is a "sub organelle" of the cell nucleus
discovered by Fontana.
 Nucleolus comprises the
Irregular network or rows of fine granules
nucloelonema as seen in EM
 The nucleolus loses its identity during cell division.
 Nucleolus contains still smaller nucleus known as
nucleo-lolus or nucleo-linus or nucleolo-nucleus.
Mark.c.alliegro et al M.C.proc.natl.acad.sci.U.S.A,(2010)
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52.  Defective nucleoli have been implicated in several rare
hereditary diseases, mostly neurodegenerative
disorders such as Alzheimer’s and Huntington’s
disease.
 nucleoli also plays a role in this disease, which is also
known as “shaking palsy”.
 Parkinson’s disease may be caused by oxidative stress
within cells due to defective nucleoli.
The Journal of Neuroscience, January 12, 2011, 31(2):453– 460,
DOI:10.1523/JNEUROSCI.0590-10.2011
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53.  Kennedys disease- mutation of karyopherins.
 Emery dreifuss muscular dystrophy.
 Huntingtons disease.
 Fragile-x-syndrome.
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54.  They are generally less than 1 µm in diameter.
 Unit membrane bound organelles.
 Peroxisomes are also called microbodies.
 Contains the enzymes peroxidase and catalase which
are important in metabolic reactions involving ribose
peroxide.
 Destroy certain products formed from oxygen, notably
hydrogen peroxide that can be toxic to the cell.
 Often seen in kidney and liver cells.
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55.  Peroxisomes ar relatively large in hepatocytes and
kidney cells but very small in intestine cells so called
microperoxisomes
 Peroxisomal disorders:
 Zellweger cerebrohepatorenal syndrome
 Neonatal adreno leukodystrophy.
 Infantile refsum disease.
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57.  Ham`s histology david H .cormark,9th edition
 Human physiology vander sherman luciano 8 th
edition.
 Human physiology volume 1 by dr.c.c. chatterjee
 Review of medical physiology william F. Ganong 17th
edition.
 Robbins pathologic basis of disease 8th edition.
 Concise medical physiology by chaudhari.
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58.  Anthony`s textbook of anatomy and physiology 14th
edition.
 Physiological basis of medical practise 12th edition
B.I.Waverly.
 Moffett schauf- human physiology 2nd edition.
 British society of cell biology.UK
 Guyton text book of medical physiology 9th edition
 Mitochondria as therapeutic targets in diseases, jin
han , shey-shing sheu, seoul national university ,korea
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59.  Neuropathology by dimitri d agamanolis, northeast ohio
medical university.
 Composition and Dynamics of the Nucleolinus, a Link
between the Nucleolus and Cell Division Mark C.
Alliegro, steven Hartson and Mary Anne Alliegro
received December 27, 2011.
 Campbell and rece , book of biology 8th edition.
 Shafers textbook of oral pathology 6th edition.
 Images from Google.
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60. THANK YOU
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