Download Cells: The Basic Unit of Life

Cells: The Basic Unit of Life
• Cells are the basic units of organisms
– Cells can only be observed under microscope
• Two basic types of cells:
Animal Cell
Plant Cell
On the following slides, all structures are found in both
plant and animal cells unless stated otherwise.
Cell Biology Animations
Plant Cell
• Cell wall
–Made of cellulose
which forms very thin
fibres
–Strong and rigid
–In plant cells only
Plant Cell
• Cell wall
– Protect and support
the interior of the cell.
– Give shape to the cell
– A dead layer
– Freely permeable
Plant Cell
• Cell membrane
– Lies immediately
against the cell wall
– Made of protein and
lipid Selectively
permeable
Plant Cell
• Cell membrane
– Can control the
movement of
materials into and
out of the cell
– A living layer
– Found in plant &
animal cells
Plant Cell
• Cytoplasm
– Jelly-like substance
enclosed by cell
membrane
– Provide a medium for
chemical reactions to
take place
Plant Cell
• Cytoplasm
– Found in all cells
– Contains organelles
and granules :
•e.g. chloroplast
•e.g. mitochondrion
Organelles
•
very small size – some can only be
observed under electron microscope
•
All organelles have specific functions
•
Found in the cytoplasm
Plant Cell
• Chloroplast
– Only in plant cells.
– Contain the green
pigment chlorophyll
–Chlorophyll traps
light energy, to make
food by
photosynthesis
Plant Cell
• Chloroplast
– Contain starch grains
(products of
photosynthesis)
Plant Cell
• Mitochondrion
( mitochondria )
– Rod shape
– For cellular respiration
(provides energy for the
cell)
Plant Cell
• Mitochondrion
( mitochondria )
– Active cells ( eg.
sperms, liver cells)
have more
mitochondria
Plant Cell
• Non-living
granules
– Starch granules
– Oil droplets
– Crystals of insoluble
wastes
Plant Cell
• Vacuole
– large central vacuole
– Contains cell sap
• a solution of chemicals
(sugars, proteins,
mineral salts, wastes,
pigments)
– Larger in plant cells than
animal cells
Plant Cell
Nucleus
– Control the normal
activities of the cell
– Bounded by a
nuclear membrane
– Contains the genetic material (DNA).
– DNA is organized into threadlike structures
called chromosomes.
Nucleolus
 Contains the
information for the
production of proteins
in the cell.
Not bound by a
membrane
Nuclear Pore
 Allows large
molecules to move in
and out of the nucleus
Different kinds of plant cells
Onion Epidermal Cells
Guard Cells
root hair
Root Hair Cell
Cellular World - YouTube
Animal cell
• No cell wall or
chloroplasts
• Stores glycogen
granules and oil
droplets in the
cytoplasm
Animal Cell
• Endoplasmic
Reticulum (E.R.)
• Found in plant &
animal cells
• Transport of
materials in cell
• Rough and
smooth types
• Rough E.R. has
ribosomes
attached to the
outside.
Endoplasmic Reticulum
mitochondrion
Animal Cell
• Ribosomes
• Found in plant
& animal cells.
• Sites of protein
synthesis.
• Found on rough
E.R. or in the
cytoplasm.
Animal Cell
• Golgi Bodies
• Found in plant &
animal cells.
• Serve as storage,
packaging and
processing
centres for
products released
by the cell.
Animal Cell
• Microtubules
• “Skeleton” of the
cell.
• Found in plant &
animal cells.
• Gives cells shape
and support.
• Found in
centrioles, cilia,
& flagella.
• Composed of
Tubulin.
Animal Cell
• Lysosomes
• Small saclike
structures that
contain digestive
enzymes.
• Found in most
animal and some
plant cells.
Rough E.R.
Different kinds of animal cells
white blood cell
Amoeba
red blood cell
muscle cell
cheek cells
sperm
nerve cell
Paramecium
Journey Into a Cell - YouTube
Similarities between plant cells
and animal cells
Both have a cell membrane surrounding
the cytoplasm.
Both have a nucleus.
Both contain mitochondria, golgi bodies,
E.R. , ribosomes and microtubules.
Differences between plant cells
and animal cells
Animal cells
Plant cells
Relatively smaller in
size
Relatively larger in
size
Irregular shape
Regular shape
No cell wall
Cell wall present
Differences between plant cells
and animal cells
Animal cells
Plant cells
Vacuole small or absent Large central vacuole
No Chloroplasts
Chloroplasts Present
Nucleus at the centre
Nucleus near cell wall