FUNDAMENTAL UNIT
OF LIFE
CELLS
CELL THEORY
 All living organisms are composed of one or
more cells.
 The cell is the basic unit of structure,
function, and organization in all organisms.
 All cells come from preexisting, living cells.
 Usually credited to Matthias
Schleiden and Theodor Schwann. However,
many other scientist like Rudolf
Virchow contributed to the theory.
ROBERT HOOKE
CELLS WERE FIRST
DISCOVERED BY HIM IN 1665
ROBERT OBSERVED :
 Slice of cork resembled the structure of
the honeycomb consisting of small
compartments. Robert called these little
compartments as cells.
CORK COMES FROM
THE BARK OF THE
TREE
CORK SEEN UNDER THE
MICROSCOPE OF HOOKE
STRUCTURE OF CELL
 Cells come in all shapes and sizes. While
most of the cells are spherical in shape,
cells of various other shapes are also
found. Most of the cells are microscopic in
size, i.e. it is impossible to see them with
naked eyes. Some cells are fairly large, e.g.
a neuron in human body can be as long as
1 meter.
COMPARING CELLS
nerve cells can be 1m long
human egg cell is no bigger than the dot on this
i
human red blood cells is 1/10 the size of a human egg
cell
bacterium are even smaller8000 can fit inside a human egg cell
DIFFERENT CELLS
NERVE CELL
FAT CELL
SPERM
BLOOD CELL
BONE CELL
OVUM
CELL TYPES
PROKARYOTIC
CELLS
no membrane bound
structures
EUKARYOTIC CELLS
membrane-bound
structures
UNICELLULAR ORGANISMS
 ORGANISMS THAT HAVE A SINGLE
CELL- PROKARYOTIC CELLS.
PARAMOECIUM
AMOEBA
CHLAMYDOMONAS
MULTICELLULAR ORGANISMS
 ORGANISMS HAVING MORE THAN
ONE CELL TO PERFORM VARIOUS
FUNCTIONS- EUKARYOTIC CELLS.
PLANTS
ANIMALS
FUNGI
CELL WALL
found in plants, algae, fungi, most bacteria
tough, rigid outer coverings that
protect the cell and give it shape
what makes the cell walls
rigid? Pectin and lignin!
plant cell walls are
mainly made of
cellulose
CELL MEMBRANE
Protective layer around all cells
If a cell has a cell
what does it do? regulate wall, then the cell
interactions between the membrane is
cell and the environment inside of it
water can move
into and out of cell
through the cell
membrane
food particles and some
molecules enter and
waste products leave
through the cell
membrane
CYTOPLASM
Gelatin like substance
that fills cells which is
constantly moving
Cytoskeleton
helps some cells
move
Contains a
framework called the
cytoskeleton - this
helps maintain or
change the shape of
the cell.
cytoskeleton is made up of thin, hollow tubes
of protein and thin, solid protein fibers
ORGANELLES
contained within the cytoplasm
What do organelles do?
★process energy
★manufacture substances needed by the
cell
★move materials
★act as storage sites
★are surrounded by membranes
★nucleus is usually the largest organelle
NUCLEUS
a nucleolus is also within the nucleus
NUCLEUS
ENERGY-PROCESSING ORGANELLES
cells need energy to:
✤process food
✤make new substances
✤eliminate wastes
✤communicate with each
other
PLANTS
๏food is made in green
organelles called
chloroplasts
๏contain green pigment
chlorophyll
๏chlorophyll captures light
energy that is used to make
glucose
ANIMALS
๏energy in food is stored until
it is released by the
mitochondria
๏organelles where energy is
released from the breakdown
of food into carbon dioxide and
water
๏muscle cells are more active,
so they contain more
mitochondria
GOLGI BODIES
proteins are
made and sent
to the Golgi
bodies
Golgi bodies sort proteins and
other cellular substances and
package them into membranebound structures called vesicles
vesicles deliver cellular substances to
areas inside the cell
Refrigerator - cells have membrane-bound spaces
called vacuoles for temporary storage of materials
(water, waste products, food, and other cellular
materials)
RECYCLING ORGANELLES
active cells
break down
and recycle
substances
lysosomes contain
digestive chemicals
that help break down
food molecules, cell
wastes, and worn-out
parts
lysosome
membrane keeps
when a cell dies a lysosome’s
the chemicals from
membrane disintegrates,
leaking into the
releasing digestive chemicals
cell
that quickly breakdown the cell’s
contents
 PRESENTED BY
 LIPIKA BISWAS, TGT
(SCIENCE), K.V. BALLYGUNGE