Download Evolution of cells

Evolution of cells

Prof. Dr. Müjgan Cengiz
Evolution of cells
Cells divided to two main class
Procaryotic Cells
Eukaryotic Cells
Some basic molecular mechanisms takes
place in both prokaryotes and eukaryotes
1-Formation of substance
 2-Atomic Evolution
 3-Molecular Evolution
 4-Cellular Evolution
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Life originated .
 3.5-3.8 bilion years
 Ago.
 1 bilion years
 After earth was
 Formed.
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İn 1920 it was tought simple organic
molecules could form
 Spontaneously polymerized into
macromolecules like pirimitive earth
atmosphere.
 At that time there are O2 H2, , H2S ,CO at
the atmosphere
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In this condition by the aid of energy of
sunligt or electricel discharge organic
molecules can form spontaneously.
 In 1950 first demonstration by Stanley
Miller
 Discharge of electrical sparks to the
mixture of Hydrogen, methane, amonia
 And water cause synthesis of organic
molecules.
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The reaction products are amino acids
alanine,aspartic acid,glutamic acid,glycine,
 Some other organic molecules such as
urea,lactic acid,acetic acid,formic acid.
 The other step in evolution was the
formation of macromolecules.
 In the cells there are two informational
maromolecules present(nucleic acids and
proteins)

The nucleic acids can make their own self
replication.
 They can serve as templates of own
sythesis.
 In 1980s Altman found RNA capable of
some chemical reactions(polymerization of
nucleotides)
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RNA is uniquely able to serve a template and
catalyzes its own replication.
The interaction between the RNA and proteins
evolved present day genetic code.
The first genetic material was RNA.
Today after investigaton of reverse transkriptase
enzyme it can be explained how DNA replaced
RNA as the genetic material.
Phospholipids
Main component of membranes
 Phosphate at outside and reacted with
water
 Hydrocarbon tails are inside
 Bilayer
stabilized barier

The first cell formed by enclosing
self replicating RNA by a
membrane
EVOLUTİON OF THE
METABOLİSM
The cells originated from the sea organic
molecules, they were able to obtain the
organic molecules, food from the sea and
environment.
 They need to generate the energy from
environmet and synthetize molecule for
their replication.
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The cells use ATP for
their source of
energy.The
mechanism for
generation of energy
have evolved in 3
stages.
Glycolysis,
photosynthesis and
oxidative metabolism.
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In anaerobic conditions it is assumed that the
first energy generating reactions were like
anaerobic glycolysis, the breakdown of organic
molecules at anaerobic conditions.
Breakdown of glucose to lactic acid generates 2
ATP.
The development of photosynthesis is the
second evolutionary step.
 This allows taking energy from sunligt and
making the energy independently from
organic substances.

The release of O2 as a result of
photosynthesis, changed the environment
and led to development of oxidative
metabolism.
 Complete breakdown of glucose to CO2
and H2O yields energy 36 to 38 ATP.

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Procaryotes are the most different
organisms and they obtain their energy
from inorganic chemicals (for example
from hydrothermal events deep ocean
floor,soil).

DNA sequence comparison showed three
were distinct branch of tree of life.
Archabacteria and bacteria are small
unicelular organisms and have 1000-4000
genes.
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Many of the genes from within a single
organisms show family resemblence.
Family resemblence are seen in 200 gene of
three main acester family of the living world.
There are three lines of
cells(archabacteria,eubacteria and eukaryotes)
Mitochondria and chloroplasts are originated
from endosymbiotic association of aerobic
bacteria and cyanobacteria with the ancestor of
eukaryotes.
Why earth?
Life exists only at earth
 Chemical reactions occurs only at liquid
medium

o
Jüpiter -15 C
o
 Satürn -180 C
o
 Merkür 430 C
o
 Venüs 480 C

The size and mass of earth
 Small planets can not take the
atmosphere
 Big planets have dense atmosphere
 Atmosphere is important for radiation
 Photosynthesis needs visible light
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Evolution and survive of primitive cell
needs energy
Heterotroph
 Takes the energy and building structure
from environment
 All animals
 prokaryotes
 Fungies
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Autotroph
 They can feed themselves
 They synthetize the organic compounds
from simple inorganic substances and
sunlight for the energy need
 All plants
 Some prokaryotes
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Chemosynthetic
 They supply the energy for synthetize
the organic compounds from simple
inorganic reactions

First animals, fungies and single cell
organisms are heterotroph.
 When the number of cells increased,
amount of molecules that need
decreased.
 A competition begin between cells
 Some cells begin to synthetize organic
substances from inorganic substances
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First living primitive cell is
chemosynthetic or photosynthetic
autotroph.
 In marshy place and oceans pirimitive
chemosynthetic bacteria.
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The main topic in
evolution is mutation
(mutation is a
obligation in breeding)
Natural selection
Viruses
Genetic
recombination
Transpozons
Gene duplication