Structure and function of a cell for class VIII

1. CELL- STRUCTURE AND
FUNCTIONS

2. INDEX
1. Introduction
2. Basic structure of cell
3. Discovery of cell
4. Cell theory
5. Unicellular & Multicellular organism
6. Different size of cells
7. Different shapes of cells
8. Structure of cell
8.1Cell membrane
8.2 Cytoplasm
8.3 Nucleus
8.4 Cell organelles
(i)Vacuole
(ii) Mitochondria
(iii) Ribosomes
(iv) Golgi Bodies
9. Prokaryotic and Eukaryotic cells
10. Comparison between plant and animal cell
 Video
 Did you know
 Recapitulation
 Home Assignment

3. Students things around us
are either living or non –
living –do you ever
imagine how these living
things made from, what is
the basic unit which
composed the living
organism.

4. 1.INTRODUCTION
 Cell is the basic unit of any living system.
Like ,Brick is the basic structure unit of a
house, Same as like Cell is the basic
structural unit of a human body.
Onion peel cells under
the microscope.

5. Grouped
to form
Grouped
to form
Organize
d into
And make up
the complete
Do you
know?
Systematic Organization of human body.

7. Who discovered cell and how?
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9. Do you know –
Organisms show Variety
In
 Cell Number
 Shape
Size

10. 1. Unicellular 2.Multicellular
Amoeba , the
single cell
organism.
Animals, the
multicellular
organisms.
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here to
know
more

11. The size of cells in living organisms maybe as small as a millionth of a
meter (micrometer or micron) or may be as large as a few centimeters.
Largest
cell
.
Do
you
know
?

12. Different cells have different shapes .The shape of a cell is related to its
functions and locations.
Round
elongat
ed
shape
Spindle
shape
with
pointed
ends.

14. Cell wall(an outer thick layer
in cells of plants
called cell wall.)
Plasma membrane
Function
This additional layer
surrounding the cell membrane is
required by the plants for protection.
Plant cells need protection against
variations in temperature, high
wind
speed, atmospheric moisture, etc.
Function
•It forms the outer boundary
of cell which is thin and
delicate membrane and gives
the shape and size to the cell.
•It allows only certain selected
substance to enter and leave
the cell.

15. Various
other
componen
ts, or
organelle
s, of cells
are
present in
the
cytoplasm.
These are
mitochond
ria, golgi
bodies,
ribosomes,
etc.
Mitochondri
a
Golgi
bodies
Nucleus
Ribosomes
C
e
l
l
o
r
g
a
n
e
l
l
e
s

16. I am the oval shaped body
floating in the cytoplasm. I am
responsible for the vital
functioning of the cells.
I consist of nuclear membrane,
nucleoplasm, nucleolus,
chromosomes and genes.
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17. 8.4Cell organelles
These are components, small cytoplasmic bodies, or
organelles, of cells that present in the
cytoplasm.These are mitochondria, golgi
bodies, ribosomes, etc.
Mitochondria
Lysosomes
Endoplasmic reticulum
Golgi
Apparatus/bodies
Ribosomes Cell
Organelles
which are
embedded in
the
cytoplasm.

18. I resides only in the
plant cells. The blank-
looking structure in the
cytoplasm is called
vacuole. Large
vacuoles are common in
plant cells.
Vacuoles in animal cells
are much
smaller.

19. I am
powerhouse
of the cell. I
store energy
in the form
of ATP.

20. It helps in protein synthesis.
Protein factory of
cell

21. Its function is the packaging of

22. It helps in the synthesis of food (photosynthesis)due to the
presence of chlorophyll. Green coloured plastids are
called chloroplasts. They provide green
colour to the leaves.

23. Prokaryotic
cells
Eukaryotic
cells
prokaryotes(pro :
primitive; karyon : nucleus) The
cells having
nuclear material without nuclear
membrane are termed
prokaryotic
cells.. E.g.
Eukaryotes(eu :
true; karyon: nucleus)
that contain well
organised nucleus. E.g.
are animal and plant
cells.
flagella
Nuclear material without
nuclear membrane
cytoplasm
Ribosome's

27. .
The cells in the outermost layer of
our skin are dead. An average
adult carries around about 2 kg of
dead skin. Billions of tiny
fragments of the skin are lost every
day. Every time you run your
finger on a dusty table, you shed a
lot of old skin.
DID YOU KNOW?

28. Give the one word answer.
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29. LETS PLAY A CROZZ WORD PUZZLE
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30. 1.A cell requires water, minerals and other
nutrients to survive. It is covered with a
membrane. How do these things reach
inside the cell ?
2.Why are chromosomes called heredity
vehicle?

31. Congratulations, you just finished it. 
QUIT

32. ROBERT HOOK IN 1665
OBSERVED
SLICES OF CORK IN
MICROSCOPE
Robert took thin slices of cork and observed them under a
microscope. He noticed partitioned boxes or compartments in the
cork slice. These boxes appeared like a honeycomb. He also noticed
that one box was separated from the other by a wall or partition.
Hooke coined the term ‘cell’ for each box.

33. Unicellular
(uni : one; cellular :
cell)
• Consist of only one cell.
• A single-celled organism, like amoeba,
captures and digests food, respires,
excretes, grows and reproduces. Similar
Multicellular
(multi :
many; cellular : cell)
• Consist of cells numbering
from few to billions.
• Multicellular organisms like
human beings carried out
functions by groups of
specialized cells forming
different tissues.
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34. Nuclear membrane-It surrounds the
nucleus that controls passage of selected
material in and out of the nucleus.
Nucleoplasm-Dense fluid in the
nucleus.
Nucleolus-It’s a spherical body that
contain RNA( Ribo nucleic acid).
Chromosomes- these a have thread like
structure which are composed of DNA(
Deoxyribo nucleic acid ) which carry
genes(the basic units of hereditary ).
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