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Unit 2, Topic 3: The voice of thegenome
Topic 4: Biodiversity and naturalresources
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Preview
Topic 3: The voice of the genome 3. : !nimal cells and
ase"ual
reproduction 3.2: #e"ual reproduction and cell
specialisation
3.3: #tem cells and $eyond 3.4: %"pressing the genome
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!nimal cells &ells 'rst seen over 3(( years ago&ell
theory
! wor) of di*erent scientists
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+irst wor)ing opticalmicroscope
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Light microscope Electron microscope1. The radiation source
(source of illumination) islight, wavelength 400- 00nm
!. Lens is made of glass.". #ot affected $% magnetic
field.4. &a'imum magnification
1 00-!000 times.. esolving power 0.1-0.!
nm.*. +mage is coloured (natural
colour of o$ ect is seen).
1. adiation source iselectrons, wavelength a$out0.00 nm.
!. Lens is electromagnetic.". ffected $% magnetic field.4.
&a'imum magnification 1,
*0,000 to !, 0,000 times.. esolving power !00-"00
nm.*. +mage is $lac and white.
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&ell theory
+our ideas a$out cell theory:. !ll organisms are made up of one
or more
cells , $uilding $loc)s of structures
unicellular or multicellular2. !ll cells carry on activities
chemical
reactions-meta$olism3. /ew cells arise from other living cells
$y
cell division4. &ells contain information for growth,
development and physiological processes
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0iving organisms are classi'ed into twogroups due to structural
di*erences:
Pro)aryotic and %u)aryotic Pro)aryotes $acteria and
cyano$acteria or $lue1green algae %u)aryotes plant, animal,
fungi
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Pro)aryotic cells
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#tructure and functionCellwall 8igid and determines the shape,
protects as uni9ue structures and molecules some of which are
recognised $y the immune system &ontains
peptidoglycan1polysaccharide polymers cross1
lin)ed $y short chains of amino acids ram stain separates
$acteria into gram1positive -purple, layer thic) and gram1negative
-red, cellwall several layersthic)
Pili air1li)e protein structures on the surface of the cell
that
attach to other $acterial cells for con
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Cytoplasm ! gel1li)e su$stance composed mainly of water that
also
contains en7ymes, salts, cell components, and various
organic molecules.Cell Membrane or Plasma Membrane Phospholipid
$ilayer #urrounds the cell>s cytoplasm and regulates the 6ow
of
su$stances in and out of the cellCapsule #urrounds cellwall
elatinous polysaccharide1glycocaly" or slime layer +ound in some
$acterial cells, this additional outer
covering protects the cell when it is engulfed $y
otherorganisms, assists in retaining moisture, and helps the
celladhere to surfaces and nutrients.
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%u)aryotic cells
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%u)aryotic cells
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