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1: CELL STRUCTURE
• The cell theory was emerged from the work of a German
scientist
• In 1833 Schelidon a botanist suggested that all plants made out
of cells
...


CELL THEORY
• The basic structural and functional unit of life is the
cell
...

• These cells are not visible to the naked eye without aid
...

• There are two types of microscopes : light microscope
Electron microscope

• Both microscopes use radiation in order to create an image of the
specimen
...


Units of measurement
• The basic unit of measuring length is metre
...


Electron microscopy
• Electron microscopy was made to observe objects which cannot
be observed by the light microscope as the specimen is too
small
...

• The maximum resolution of the light microscope is 20 nm
...

• Electron microscope provides black and white images therefore
they should be stained artificially
...

• Can be easily focused using electromagnets as they use electrons

...

• Provides a higher resolution between 3 nm - 20 nm
...

• More detailed images aiding to observe the inside of the
specimen
...
5 nm

differences between light and electron microscopes
Light microscope

electron microscope

• Uses light as radiation

uses electrons for radiation

• Live specimens can be observed

dead specimens are
observed ,dehydration
necessary

• 200 nm resolution

0
...


-contains the colour pigments which define he
colour of petals and the rest of the plant is
defined
...

• Cell walls are thick and freely permeable and present in plants
• Cell membrane is a thin and partly permeable membrane

The ultrastructure of animal cell

Structures and functions of organelles
Nucleus
• The largest cell organelle
• A double membraned structure (nuclear pore )
• Have small pores on the nuclear envelope called nuclear
pores
...

• Proteins which helps to make ribosomes ,nucleotides ,ATP
molecules enter through unclear pores
...

• SER is when no ribosomes are present
• SER produces lipids and steroids reproductive hormones
and cholesterol

Golgi body (Golgi apparatus or Golgi complex )
• these are flattened sacs
• Golgi body collects , processes and sorts molecules ready
to be parts of the cell or out of the cell
...

• Usually has a dimeter of 0
...
5 μm
• Lysosomes contains digestive enzymes and is kept
separately to prevent causing damage to the cell
...
Ex : in mammary glands after lactation
...

• This is usually about 1 μm
...

• The inner membrane contains finger like foldings called
cristea which projects the matrix
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• The outer membrane transports a protein called porin
...

• Mitochondria is responsible for aerobic respiration and in
organs which require higher energy more mitochondria is
present according to the requirement
...

• ATP is known as the universal energy carrier
...

• However at higher magnifications at least about *100 00,
it can be seen to have three layers called trilaminar
...

• These are useful for the absorption in the gut and
reabsorption in the proximal convoluted tube
...

• Microtubules are made out of proteins called tubulin
...

• 13 protofilamnets are joined alongside forming a hollowcenterd structure
• This is a microtubule
• Microtubules also work as a transport system other than
its mechanical function
...

• Centrioles are found at the bases of cilia and flagella
...


• 3-10 μm in longth
• This is a double membraned srtuvutre
• The main function of chloroplast is photosynthesis
...

• The second stage of photosynthesis ; the Calvin cycle
takes place in he solution of stroma
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• Chloroplast do not have their own protein synthesis
including 70 s ribosomes and circular strand of DNA
...
5 - 3 μm in diameter
No nucleus
Circular DNA
May contain several loops of DNA called plasmids

• Eukaryotes :

-

Contains nuclei
DNA present within nuclei
Eukaryotes include animals , plants , fungi , and protists
...

Linear DNA associated with protein forming chromosomes

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