Cell is basic structural and functional unit of all living organism. Cell is enclosed in a compartment containing aqueous fluid called as Cytosol which is surrounded by a cell membrane called Plasma membrane

1. Cellular classification,
Sub-cellular
organelles
PRESENTED BY
MD ALTAMASH AHMAD
PHARM D 3 RD YEAR

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CELL - definition
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• Cell is basic structural and functional unit of all living organism
• Cell is enclosed in a compartment containing aqueous fluid called as
Cytosol which is surrounded by a cell membrane called Plasma
membrane
Cell = Plasma membrane + cytoplasm
Cytoplasm = Cytosol + Subcellular organelles

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CELL – Classification
(according to cellular structure)
Cellular
organism
Prokaryotes
Archaebacteria
(Methanogens,
Halophiles,
Thermoacidophiles)
Eubacteria
(Bacteria-vibrio,
mycobacterium,
tuberculosis,
staphylococcus)
Cyanobacteria
(Blue-green algae,
e.g.- Nostoc,
Anabaena)
Eukaryotes
Protista
(Protozoans)
Fungi
Animal cell
Plant cell
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Prokaryotes
• Unicellular organisms
• First life form on earth
• Lacks well defined nucleus and membrane bound organelles
• Simpler and smaller than eukaryotic cell
• The genetic material (DNA) consists of single chromosome and is
present in the cytoplasm (no nucleus)
• E.g. – bacteria – Archaebacteria, eubacteria, cyanobacteria
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Figure. Prokaryotic Cell

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Components of prokaryotic cell
A prokaryotic cell has a jelly like cytosol within the cell in which other
cellular components are found -
They consist of –
• Cell membrane
• Cytoplasm
• Ribosomes
• Genetic material (RNA, DNA)
• Plasmids
• Cell wall
• Cell capsule or envelope
• Flagella
• Pilli or fimbriae 6

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Eukaryotic cell
• Mostly multicellular
• Eukaryotic cells have the nucleus enclosed within the nuclear
membrane.
• A cell wall is the outermost layer of the eukaryotic cells.
• The cells divide by a process called mitosis.
• The eukaryotic cells contain a cytoskeletal structure.
• The nucleus contains a single, linear DNA, which carries all the
genetic information.
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8. Figure. Eukaryotic Cell
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Sub-cellular organelles of Eukaryotic cell
• A Eukaryotic cell contains-
1. Plasma membrane
2. Cytosol
3. Subcellular organelles
• Sub-cellular organelles are bathed by cytosol and include –
• Nucleus, Mitochondria, Endoplasmic Reticulum, Ribosomes, Golgi
Apparatus, Lysosomes, Peroxisomes And Cytoskeleton.
• All sub-cellular organelles, except ribosomes and cytoskeleton, are
compartments within the cell, surrounded by their own membrane and
contains aqueous fluid
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Cell membrane (Plasma membrane)
• made up of lipid bilayer, thin hydrophobic sheet in fluid state which
envelopes the cell
• lipid bilayer is made up of amphipathic lipid molecules (having both
hydrophilic or polar part and a hydrophobic or non-polar part)
• Also known as plasma membrane
Function –
• Provides external boundary for cell and its organelles
• Maintain the shape, size and integrity of cell and its organelles
• Flexibility of cell membrane allows in shape changes as growth occurs
• Membrane mediates cell-to-cell communication between adjacent cells by
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Figure. Cell membrane

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Cell membrane – function (contd..)
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• Membrane regulates the flow of information between cell and its
environment
• Cell membrane also helps in exocytosis and endocytosis
• Selectively permeable to molecules
• - as lipid bilayer is hydrophobic so it is permeable only to lipid
soluble substances and impermeable to hydrophilic/polar
substances
• - membranes also have transport systems, to facilitate the transport
of polar substances across the cell
• Membranes regulate the transport of substances like nutrients, ions,
gases, water, various products, wastes into and out of cells and their
organelles

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1. Nucleus
• largest sub-cellular organelle
• double membrane – nuclear membrane, surrounds it.
• The outer and inner membranes are separated by lumen. The outer
membrane of the nuclear envelope is continuous with the endoplasmic
reticulum (ER) membrane
• At intervals nuclear membrane has nuclear pores, permit the passage of
molecules in and out of the nucleus.
• nucleus of eukaryotic cell contains a dense body known as Nucleolus rich
in rRNA.
• Nucleoplasm – ground material of nucleus rich in enzymes such as, DNA
polymerases, RNA polymerases, etc.
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Figure. Nucleus

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Nucleus - functions
1. By DNA replication provides genetic information to offspring or daughter
cells during cell division., thus it is blue print of life.
2. By transcription (RNA synthesis) provides information for the synthesis of
all protein molecules of the cell.
3. Both replication and transcription take place in the nucleus.
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2. Mitochondria – powerhouse of the cell
• spherical, oval or rod like bodies.
• have two membranes –
• outer and inner membrane.
• outer membrane is smooth which has a large number of special proteins
known as the Porins, while the inner membrane is for folded to form cristae
• The central cavity of the mitochondrion contains the matrix
• Matrix contains enzymes and chemical intermediates of --
• TCA cycle
• Heme synthesis
• Urea cycle, etc.
•Also present in the matrix are, mitochondrial DNA, RNA and ribosomes.
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Figure. Mitochondria

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Mitochondria - functions
• ETC and oxidative phosphorylation components -- situated in inner
mitochondrial membrane are involved in ATP synthesis, hence mitochondria
are regarded as ‘powerhouse of the cell’
• Some of the major pathways operate in the mitochondria. They are, TCA
cycle, -Oxidation of fatty acid, ketone bodies formation, gluconeogenesis
(partly), urea cycle (partly), heme synthesis (partly), pyrimidine synthesis
(partly).
• Mitochondrial DNA codes for some of the mitochondrial proteins involved in
oxidative phosphorylation
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3. Endoplasmic Reticulum (ER)
• network of membrane-enclosed spaces extends throughout the cytoplasm.
classified into -
• Rough and Smooth ER
1. rough appearance (when observed under electron
microscope) is due to ribosomes attached to the cytoplasmic
side of the membrane.
2. smooth ER does not have ribosomes.
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Functions-
• Rough ER : involved in synthesis of proteins (lipoproteins, glycoproteins)
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Figure. Endoplasmic reticulum

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Functions (contd.. )
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• Smooth ER:
I. Metabolism of drugs and toxic compounds ( CYP450 monooxygenases are
present in liver cell smooth ER)
II. Synthesis of lipids
(TAG, phospholipids, cholesterol)
III. Ca2+ storage in skeletal and cardiac muscle.(note- sarcoplasmic
reticulum of muscle is a modified ER)

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4. Golgi apparatus (Golgi complex)
• group of membrane bound flattened tubes or sacs placed one over
another in a pile or stack.
Functions-
• Main functions of Golgi apparatus are protein sorting, packaging and
secretion.
• newly synthesized proteins are handed over to the Golgi apparatus,
which catalyze the addition of carbohydrates, lipids or sulfate moieties
to the proteins.
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Figure. Golgi apparatus

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5. Lysosomes (suicidal bags of cell)
• membrane bound vesicle containing various hydrolytic enzymes
(hydrolases)
• Lysosomal enzymes are capable of digesting proteins,
carbohydrates, lipids and nucleic acids in case of attack on cell by
foreign substance like any pathogen
• pH inside the lysosomes is less than that of cytosol necessary for
its digestive function
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Figure. Lysosome

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Lysosomes - functions
• hydrolases enzyme breakdown the complex molecules brought into the
cell by endocytosis, phagocytosis or worn-out organelles from the cells
own cytoplasm.
• Lysosomes - termed as ‘suicide-bags’ as their lysis can lead to digestion
and death of the cell
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6. Peroxisomes
• small spherical or oval membranous bodies
• It contain enzymes peroxidases and catalase
Functions
• Catalase and peroxidase enzymes destroys unwanted peroxides and
other free radicals
• as free radicals are capable of damaging cell membranes, tissues, and
genes. These free radicals are also responsible for inflammatory
diseases, ageing process and malignant transformation.
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Figure. Peroxisome

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7. Ribosomes
These are Nucleoproteins present either freely in cytosol or
bound to Endoplasmic reticulum
Function
provide necessary infrastructure for mRNA, tRNA & amino acid to interact
with each other for translation process
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8. Cytoskeleton
Made up of microtubules and actin filaments role in maintaining the
cellular structure, mobility and cell division.

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Figure. Ribosomes

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Summary
Name Definition
1. Cell Basic structural and functional unit of living
organism
2.
Prokaryotes
First and oldest, unicellular life form, without
membrane bound nucleus and other organelles
3.
Eukaryotes
Unicellular or multicellular, complex cellular
organisms, having membrane bound organelles
and well defined nucleus
4. Cell membrane
(plasma
membrane)
Lipid bilayer, gives shape, size and maintain
integrity of cell and its organelles
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Summary
Organelle Function
5. Nucleus Provides genetic information to offspring RNA
transcription, directs protein synthesis
6.
Mitochondria
Energy production from the oxidation of food
substances and the release of adenosine
triphosphate
7.
Endoplasmic
reticulum
Translation and folding of new proteins
(rough endoplasmic reticulum), synthesis
of lipids (smooth endoplasmic reticulum)
8. Golgi
apparatus
Sorting, packaging, and modification of
proteins
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Summary (contd..)
Organelle function
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Lysosome
Breakdown of large molecules, acts as
cell’s own suicidal bag
10.
Peroxisome
breakdown of metabolic hydrogen
peroxide and free radicals
11. Ribosome Translation of RNA to form proteins
12.
Cytoskeleton
Maintaining the cellular, shape, motility
and cell division.
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