This ppt give an overview of cell the unit of life chapter 8 class XI CBSE.

1. CELL – The Unit of Life
Pushpinderjeet Kaur
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2. Robert Hooke Aton Von
Leeuwenhoek Robert Brown
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3. Cell theory
• Schleiden in 1838 – plants are composed of
different kind of cells.
• Schwann (1839) – reported that cells had a
thin layer.
• Schleiden and Schwann together formulated
cell theory
• Animals and plants are composed of cells.
•Modern Cell Theory
• Rudolf Virchow (1855)- [omnis cellula –e- cellula]
• i) all living organisms are composed of cells and products of
cells.
• (ii) all cells arise from pre-existing cells.
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4. Cells differ in SIZE
• Smallest cell
• 0.3 micro metre
• 3-5 micro metre
• Largest cell –Egg of OSTRICH
• Longest cell – neuron (90-100cm )
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5. Various shapes of cell
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6. Types of cells
PROKARYOTIC CELLS EUKARYOTIC CELLS
Primitive nucleus. Advanced nucleus.
No membrane bound organelle is present. Membrane bound organelles are present.
Eg. Kingdom Monera Kingdom Protista , fungi , plantae and animalia
UNIICELLULAR MULTICELLULAR
Single cell Many cells, division of labour
Amoeba , Paramecium Horse
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7. PROKAYOTIC CELLS
• Represented by bacteria, blue green algae and mycoplasma.
• They are smaller than eukaryotic cells & divide rapidly.
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8. CELL ENVELOPE
• The cell envelope consists of a tightly bound three layered structure i.e.,
• GLYCOCALYX (outermost)
• Slime layer
• Capsule
• CELL WALL
• PLASMA MEMBRANE
• Mesosome
• Flagella
• Pili
• Fimbriae
RIBOSOMES
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11. Mesosomes
• Help in
• Cell wall formation, DNA replication &
distribution to daughter cells
• Respiration , secretion processes
• Increase surface area of plasma membrane
and enzymatic content.
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12. FLAGELLA , FIMBRRIAE & PILI
• Flagella is composed of – filament ,
hook and basal body
• Fimbriae – helps the bacteria to
attach to the rocks in the streams or
host tissues.
• Pili – Elongated tubular structures
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13. RIBOSOMES
• Ribonucleoprotein particles (15-20 nm)
• 70 S ( s- sedimentation coefficient /
Svedberg Unit)
• Larger Subunit – (50 S) – Peptide bond
formation
• Smaller subunit (30 S) – mRNA binding
site
• Polysome or Polyribosome – Many
ribosomes attached on a mRNA is called
Polysome
• Function – Protein Synthesis
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14. Inclusion bodies
• No membrane is present, these
granules lie freely in the cytoplasm
• Phosphate granules – energy and
phosphate reserve
• Cyanophycean granules- Function as
nitrogen reserve composed of arginine
and asparagine
• Glycogen granules – reserve of glucose
• Gas vacuole – allow bacteria to adjust
their buoyancy
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15. DNA
• Small extra chromosomal DNA is
called plasmid
• These carry genes for resistance
against antibiotics.
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17. EUAKRYOTIC CELL
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18. PLASMA MEMBRANE
• Plasma membrane is
composed of lipids
and proteins.
• It is bilipid layer.
• Membrane proteins
are classified into
Peripheral or integral
proteins.
Fluid mosaic Model was
proposed by Singer &
Nicolson in 1972.
- Quasi fluid nature
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20. Importance of plasma membrane
• Cell growth
• Formation of intercellular junction
• Secretion
• Endocytosis process of engulfing large particles of food particles.
• Cell division
• Transport of molecules
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21. ACTIVE & PASSIVE TRANSPORT
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22. CELL WALL
• Cell wall - non living rigid
structure
• plants – Cellulose ,
hemicellulose, pectin and
proteins
• Algae – cellulose, galactans,
mannans and calcium carbonate
• Fungi – chitin
• Monerans – Peptidoglycan (
except mycoplasma)
• Cell wall is composed of -
• Middle lamella
• Primary cell
• Secondary cell wall
• FUNCTION
• Shape to the cell
• Protects from mechanical damage &
infection
• Helps in cell to cell interaction
• Barrier to undesirable macro molecules
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23. ENDOPLASMIC RETICULUM (ER)
• Present in all eukaryotic
cells except for mature
mammalian RBC.
• Absent in Prokaryotic cells.
• Compartmentalise cells
into
• Luminal
• Extra luminal
• Components of ER
1. Cisternae
2. tubules
3. Vesicles
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24. SMOOTH ENDOPLASMIC RETICULUM ROUGH ENDOPLASMIC RETICULUM
Ribosomes is absent Ribosomes are attached on the tubules with
the help of ribophorin protein
Mainly composed of tubules Mainly composed of cisternae
Major site for lipid synthesis Actively engaged in protein synthesis &
secretion
Adipose tissue, Glycogen storing cells in
liver, animal cells secreting steroidal
hormones
Liver , pancreas and goblet cells
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25. GOLGI APPARATUS
• Camillo Golgi (1898)
first observed densely
stained reticular
structures near the
nucleus.
• They consist of many
flat, disc-shaped sacs
or cisternae
• Convex – cis face
• Concave -trans face
• Golgi body performs
functions of packaging
and delivering the
materials –
intracellular target or
secreted outside cell
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27. LYSOSOMES (lyso = digestive , soma=body)
• Membrane bound vesicular
structure
• Formed by process of packaging in
the golgi apparatus
• Rich in hydrolytic enzymes
• (lipases, proteases, carbohydrases)
• Active at the acidic pH.
• Function
• Autophagy – destruction of
intracellular cell organelles
• Digestion of foreign material
• Digestion of aged cell
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28. Vacuoles
• It is membrane bound space
found in the cytoplasm.
• It contains water , sap,
excretory & other material not
useful for cells.
• Vacuole is bound by tonoplast.
• Types
• Contractile vacuole
• Food vacuole
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29. ENDOMEMBRANE SYSTEM
• Endoplasmic reticulum
• Golgi apparatus
• Lysosomes
• Vacuoles
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30. MITOCHONDRIA
• Double membrane bound structure
• The number of mitochondria per cell
is variable depending on the physiological
activity of the cells.
• Consists of outer & inner membrane
• Inner membrane forms infoldings called
cristae.
• Both posses specific enzymes
• Contain Circular DNA, ribosomes 70 S, few
RNA molecules and other components
required for protein synthesis.
• It divided by binary fission
• Function
• Site of aerobic respiration
SEMI AUTONOMOUS ORGANELLE
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31. PLASTIDS
• Found in all plant cells
and euglenoids
• 1- Chlamydomonas
• Many in higher plants
• Can be ribbon like,
horse shoe shaped or
oval shape
• Classified based on
pigments
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32. CHLOROPLAST
• It id double membranous structure.
• Outer membrane is more permeable than
inner membrane
• Inner membrane consists of stroma.
• flattened membranous sacs called the
thylakoids
• Thylakoids are arranged in stacks called
grana
• flat membranous tubules called the
stroma lamellae
• The membrane of the thylakoids enclose
a space called a lumen
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33. RIBOSOMES
• Ribosomes are the granular
structures first observed under
the electron microscope as
dense particles by George
Palade (1953)
• composed of ribonucleic acid
(RNA) and proteins
• Not surrounded by any
membrane.
• ‘S’ (Svedberg’s Unit) stands for
the sedimentation coefficient; it
is indirectly a measure of
density and size.
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34. CYTOSKELETON
• microtubules,
microfilaments and
intermediate filaments
• functions
• Mechanical support
• motility
• maintenance of the
shape of the cell.
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35. CILIA & FLAGELLA
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36. CILIA & FLAGELLA
• Core is made up of
AXONEME.
• 9- Peripheral doublet
microtubules
• 2- central microtubules,
covered by central sheath.
• Radial spoke arises from
peripheral microtubule
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37. Centrioles & Centrosomes
• Centrosome is an organelle usually containing two cylindrical structures called centrioles.
• They are surrounded by amorphous pericentriolar materials.
• Both the centrioles in a centrosome lie perpendicular to each other.
• Nine evenly spaced peripheral fibrils of tubulin protein
Hub
Spoke
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38. Nucleus
• Nucleus as a cell organelle was first described by Robert Brown.
• Later the material of the nucleus stained by the basic dyes was given the name chromatin by
Flemming
Robert Brown Flemming
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39. Nucleus
• Chromatin
• Nucleoplasm
• Perinuclear space
• Nucleolus
• Nuclear Pore
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40. CHROMOSOME
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43. "p" stands for "petit", "small" in French. The letter "q" was selected to signify the
long arm merely because "q" is the next letter in the alphabet.
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44. MICROBODIES
• Membrane bound vesicles
• Present on both animal and plant cell
• Peroxisome (occurs only in animal cells)
contain catalase enzyme which converts
peroxide H2O2 to water and oxygen.
• Glyoxysome- occurs only in plant cells fatty
seeds. Glyoxyate cycle takes place in which
fats is converted to carbohydrates.
• Contain enzymes used in variety of oxidative
reactions
• Breakdown of lipids
• Destroy toxic molecule
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47. SCIENTIST THEIR WORK
Rudolf Virchow
Camillo Golgi
Flemming
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