Cell Structure
& Function
Cell
Theory
•
All
living things are made up of cells.
•
Cells
are the smallest working units of all living things.
•
All
cells come from preexisting cells through cell division.
•
The study of cells from its basic structure to
the functions of every cell organelle is called Cell Biology. Robert Hooke was
the first Biologist who discovered cells.
Definition
of Cell
A cell is
defined as the smallest, basic unit of life that is responsible for all of
life’s processes.
Characteristics
of Cells
·
Provide structure and support to the body of an
organism.
·
The cell interior is organised into different
individual organelles surrounded by a separate membrane.
·
The nucleus (major organelle) holds genetic
information necessary for reproduction and cell growth.
·
Every cell has one nucleus and membrane-bound
organelles in the cytoplasm.
·
Mitochondria, a double membrane-bound organelle is
mainly responsible for the energy transactions vital for the survival of the
cell.
·
Lysosomes digest unwanted materials in the cell.
·
Endoplasmic reticulum plays a significant role in
the internal organisation of the cell by synthesising selective molecules and
processing, directing and sorting them to their appropriate locations.
Two
Types of Cells
1.
Prokaryotic
(no nucleus) 2. Eukaryotic (contains a nucleus)
Prokaryotic
Cell
·
structures surrounded by membranes
·
Few
internal structures
·
One-celled organisms, Bacteria
·
have no nucleus, in some prokaryotes the genetic
material is freely suspended, this region called nucleoid
·
Cell size ranges from 0.1 to 0.5 µm in diameter.
·
The hereditary material can either be DNA or RNA.
·
Prokaryotes reproduce by binary fission, a form of
sexual reproduction.
Eukaryotic
Cell (Plant and Animal Cell)
·
Contain
organelles surrounded by membranes
·
Most
living organisms
·
Eukaryotic cells are characterised by a true
nucleus.
·
The size of the cells ranges between 10–100 µm in
diameter.
·
This broad category involves plants, fungi,
protozoans, and animals.
·
The plasma membrane is responsible for monitoring
the transport of nutrients and electrolytes in and out of the cells. It is also
responsible for cell to cell communication.
·
They reproduce sexually as well as asexually.
·
There are some contrasting features between plant
and animal cells. For eg., the plant cell contains chloroplast, central
vacuoles, and other plastids, whereas the animal cells do not.
Cell
Structure
Cell found
various components with specific Function, These components include- cell wall,
cell membrane, cytoplasm, nucleus, and cell organelles etc.
Cell
Membrane
•
Outer
membrane of cell that controls movement in and out of the cell
•
Double
layer
Cell
Wall
·
Only
in plant cells & bacteria
·
Outer
membrane that supports & protects cells
·
Made
of cellulose
Nucleus
·
Directs
cell activities
·
Separated
from cytoplasm by nuclear membrane
·
Contains
genetic material – DNA
·
A
structure called the nucleolus is also found in the nucleus.
Nuclear
Membrane
·
Surrounds
nucleus
·
Made
of two layers
·
Openings
allow material to enter and leave nucleus
Nucleolus
- In nucleus
- Made of DNA
- Contain instructions for traits &
characteristics
Cytoplasm
- Inside nucleus
- Contains RNA to build proteins
Chromosomes
·
Gel-like
mixture
·
Surrounded
by cell membrane
·
Contains
hereditary material
Endoplasmic Reticulum
·
Moves
materials around in cell
·
Smooth
type: lacks ribosomes
·
Rough
type (pictured): ribosomes embedded in surface
Ribosomes
·
Each
cell contains thousands
·
Make
proteins
·
Found
on Rough E.R & floating throughout the cell
Mitochondria
·
Produces
energy through chemical reactions – breaking down fats & carbohydrates
·
Controls
level of water and other materials in cell
·
Recycles
and decomposes proteins, fats, and carbohydrates
Golgi Bodies
·
Protein
‘packaging plant’
·
Move
materials within the cell
·
Move
materials out of the cell
Lysosome
·
Digestive
‘plant’ for proteins, fats, and carbohydrates
·
Removes
waste
·
Cell
breaks down if lysosome explodes
Vacuoles
·
Membrane-bound
sacs for storage, digestion, and waste removal
·
Contains
water solution
·
Help
plants maintain shape
·
Found
only in plants
Chloroplast
·
Usually
found in plant cells
·
Contains
green chlorophyll
·
Where
photosynthesis takes place
Cell Structure and Function Notes PPT
