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Cell Structure by Susanta Kumar Panda Sambalpur for Class IX Students
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Our School
Under the Guidance of
Sanjukta
Mishra
Our Science Teacher
Swasti Panda
Presents……
Definition of Cell…
A cell is the smallest unit that
is capable of performing life
functions.
The Cell Theory…
All living things are made up of cells.
Cells are the smallest working units of all living things.
All cells come from pre-existing cells through cell division.
Examples of Cells
Amoeba Proteus
Plant Stem
Red Blood Cell
Nerve Cell
Bacteria
The Two Major Categories of Cells….
The countless cells on earth fall into two categories:
Prokaryotic cells — Bacteria and Archaea
Eukaryotic cells — plants, fungi, and animals
Prokaryotes and Eukaryotes
PROKARYOTIC
They are the simplest form of life.
No nucleus.
Do not have structures surrounded by membranes (organelles)
Few internal structures
They are unicellular_(One-celled organisms).
Example: Bacteria
ribosomes
cell wall
plasma membrane
food granule
prokaryoticflagellum
cytoplasm
nucleoid (DNA)
are the most complex form of life.
They have nucleus
Contain organelles surrounded by membranes
They are multicellular organisms (composed of many cells).
Most living organisms
Examples: animals and plants.
Eukaryotic
EUKARYOTIC
Plant Animal
Prokaryotes & Eukaryotes…
Similarities & differences
Both surrounded by plasma membrane, but very different
Prokaryotes – Archaebacteria and Eubacteria
Eukaryotes – everything else
“TYPICAL” ANIMAL CELL
“Typical” Plant Cell
Similarities in Plant & Animal Cell…
Both constructed from eukaryotic cells
Both contain similar organelles
Both surrounded by cell membrane
Difference Between Plant & Animal Cells…
Plants haveCell wall – provides strength & rigidityHave chloroplasts, photosynthetic
Animals haveOther organelle not found in plants (lysosomes formed from Golgi)Centrioles, important in cell division
Surrounding the Cell
Plasma (Cell) Membrane
All living cells (eukaryotes and prokaryotes) have cell membranes Made mainly of phospholipids and
proteins▪ Animal cell membranes contain cholesterol
Functions:▪ Separate the cell from the external
environment▪ Controls passage in and out of cell
Cell Membrane
Outer membrane of cell that controls movement in and out of the cell
Double layer
Membrane Structure
Cell Wall
Rigid structure outside cell membrane• Found in plants, fungi, bacteria,
some protists (not animals)• Made of cellulose (plants), chitin
(fungi) or other material (bacteria)• Supports and protects cell
Inside the Cell
ORGANELLESCell Parts
CELL STRUCTURE AND FUNCTION
Cell Organells
nuclearpores
nuclearpore
nuclear envelopenucleolus
histone protein
chromosome
DNANucleus Function
protects DNA Structure
nuclear envelope double membrane membrane fused in spots to create pores
allows large macromolecules to pass through
What kind of molecules need to pass through?
Nucleolus Function
ribosome production▪ build ribosome subunits from rRNA &
proteins▪ exit through nuclear pores to cytoplasm &
combine to form functional ribosomes
smallsubunit
large subunit
ribosome
rRNA &proteins
nucleolus
smallsubunit
largesubunitRibosomes
Function protein production
Structure rRNA & protein 2 subunits combine 0.08mm
RibosomesRoughER
SmoothER
membrane proteins
Types of RibosomesFree ribosomes
◦ suspended in cytosol◦ synthesize proteins that
function in cytosolBound ribosomes
◦ attached to endoplasmic reticulum
◦ synthesize proteins for export or for membranes
Endoplasmic Reticulum (ER)
Function • processes proteins• manufactures membranes• synthesis & hydrolysis of many compounds
Structure• membrane connected to nuclear envelope &
extends throughout cell
Types of ER
Rough ER (RER) – Has ribosomes attached Site of protein synthesis
Smooth ER (SER) Complex molecules built here Continuous with RER
Smooth ER function Membrane production Many metabolic processes
• synthesis synthesize lipids
oils, phospholipids, steroids & sex hormones
• hydrolysis hydrolyze glycogen into glucose
in liver detoxify drugs & poisons
in liver ex. alcohol & barbiturates
Rough ER function Produce proteins for export out of cell
• protein secreting cells• packaged into transport vesicles for export
Golgi ApparatusFunction
finishes, sorts, tags & ships cell productsships products in vesicles
membrane sacsStructure
Stack of flattened membranes“pita bread” like
transport vesicles
secretoryvesicles
Golgi Apparatus
Vesicles Transport…
ER contents pinch off into vesicles - membrane-bound sacs that store and transport substances in cells
vesiclebuddingfrom roughER
fusionof vesiclewith Golgiapparatus
migratingtransportvesicle
protein
ribosome
Bulk Transport & ATP The movement of macromolecules such
as proteins or polysaccharides into or out of the cell is called bulk transport. There are two types of bulk transport, exocytosis and endocytosis, and
both require the expenditure of energy
(ATP).
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
CytoplasmCytosol (cytoplasm)
Cellular fluid surrounding organellesSite of many cellular reactionsFound between cell membrane and nucleus
Lysosomes
Lysosomes – special vesicles that store and transport powerful digestive enzymes and other reactive substances within a cell Double membrane protects cell from being
digested Break down
Food particles Unneeded proteins, carbohydrates, etc.. Disease-causing microorganisms
Vacuoles
Large membranous storage sacs found mainly in plants. Stores water, nutrients, waste products
and pigments○ Give certain plants bright colors (beets,
carrots, flowers)
CILIA AND FLAGELLA…
Hairlike organelles that extend from the surface of the cell
Assist in movement Cilia – short and
present in large numbers
Flagella – long and less numerous
Chromosomes…
In nucleus Made of DNA Contain
instructions for traits & characteristics
Chloroplast
Usually found in plant cells
Contains green chlorophyll
Where photosynthesis takes place
Building Proteins
21/07/2014
video B.avi
21/07/2014
Any Questions!!
Thanks ...For giving Your Valuable Time…