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Cell Structure and Functions ppt presentation for Class 9 Students prepared by Susanta Kumar Panda, Sambalpur
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Our School
Presents……
Definition of Cell…
A cell is the smallest unit
that is capable of performing life functions.
The Cell Theory…
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
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” Plant Cell
Difference Between Plant & Animal Cells…
Plants have
Cell wall – provides strength & rigidity
Have chloroplasts, photosynthetic
Animals have
Other organelle not found in plants (lysosomesformed from Golgi)
Centrioles, important in cell division
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
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
nuclearpores
nuclearpore
nuclear envelope
nucleolus
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?
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
Ribosomes
RoughER
SmoothER
membrane proteins
Types of Ribosomes
Free ribosomes
◦ suspended in cytosol
◦ synthesize proteins that function
in cytosol
Bound ribosomes
◦ attached to endoplasmic reticulum
◦ synthesize proteins
for export or
for membranes
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
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
Produce proteins for export out of cell• protein secreting cells
• packaged into transport vesicles for export
Golgi Apparatus
Function finishes, sorts, tags & ships cell products
ships products in vesicles membrane sacs
Structure 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
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).
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
Cytoplasm Cytosol (cytoplasm)
Cellular fluid surrounding organelles
Site of many cellular reactions
Found 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
21/07/2014
v ideo B.av i
21/07/2014
Any Questions!!
Thanks ...For giving Your Valuable Time…