Transcript Document

Eucaryotes have a true nucleus and a
number of cellular organelles inside the
cytoplasma.
 The plasma membrane is made of
proteins and phospholipides that form a
bilayer structure.
 One major difference is the presence of
sterols in the cytoplasmic membrane.
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The nucleus of eucaryotic cells contains
chromosomes as nuclear material (DNA molecules
with some closely associated small proteins),
surrounded by a membrane
The nucleolus is in an area in the nucleus and is the
site of ribosome synthesis.
Many chromosomes contain small amounts of RNA
and basic proteins called histones attached to the
DNA.
DNA synthesis
 Nuclear division
 Cell division
 Cell separation
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The M phase consists of mitosis where the nucleus
divides, cytokinesis where the cell splits into
separate doughter cells.
 All of the phases between one M phase and the
next are known as the interphase.
 The interphase is divied into three phases: G1, S,
and G2.
 In the S phase the cell replicates its nuclear DNA.
 Checkpoints exist for entry into the S and M phases
and exit from M phase.
 Cells may also be in a Go state , which is a resting
state where there is no growth.
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Certain procaryotic and eucaryotic organisms
contain flagella- long, filamentous structures that
are attached to one end of the cell and are
responsible for the motion of the cell.
The cytoskeleton refers to filaments that provide an
internal frame work to organize the cells’ s internal
activities and control its shape.
Cilia are flagella like structures. Only one group of
protozoa , called ciliates, contains cilia.
Fungi are heterotrophs.
 larger than bacterial cells
 Two major groups of fungi are yeasts and
molds.
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Yeasts can reproduce by asexual or sexual means
Asexual reproduction is by either budding or fission.
In budding, a small bud cell forms on the cell , which
gradually enlarges and separates from the mother cell.
Asexual reproduction by fission is similat tho that of
bacteria.
In fission, cells grow to a certain size and divide into two
equal sizes.
Sexual reproduction of yeasts involves the formation of
a zygote from fusion of two haploid cells, each having a
single set of chromosomes.
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Molds are filamentous fungi and have a mycelial
structure.
The mycelium is a highly branched system of tubes that
contains mobil cytoplasm with many nuclei.
Long, thin filaments on the mycelium are called
hyphae.
Certain branches of mycelium may grow in the air, and
asexual spores called conidia are formed on these
aerial branches.
Some molds reproduce by sexual means and form
sexual spores. These spores provide resistance against
heat, freezing, drying, and some chemical agents.
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The phycomycetes are algalike fungi ; they don’t posses
chlorophyll and cannot photosynthesize. Aquatic and
terrestrial molds belong to this category.
The ascomycetes form sexual spores called ascospores,
which are contained within a sac. Some molds of the genera
Neurospora and Aspergillus and yeasts belong to thsi
category.
The basidiomycetes reproduce by basidiospores, which are
extended from the stalks of specialized cells called the
basidia. Mushrooms are basidiomycetes.
Only asexually reproducing molds are the deuteromycetes
(fungi imperfecti). Some pathogenic fungi such as
Trichophyton , which causes athlete’ s foot, belong to this
category.
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Algae are unicellular organisms. Some plantlike multicellular
structures are present in marine waters.
All algae are photosynthetic and contain chloroplasts, which
impart the green color to the organisms.
The chloroplasts are the sites of chlorophyll pigments and are
responsible to the photosynthesis.
Some algae contain silica or calcium carbonate in their cell
wall.
Diatoms containing silica in their cell wall are used as filter
aids in industry.
Some algae, such as Chlorella, Scenedesmus, Spirullina, and
Dunaliella, are used for waste water treatment with
simultaneous single-cell protein production.
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Protozoa are unicellular, motile, relatively large eucaryotic
cells that lack cell walls.
Protozoa obtain food by ingesting other small organisms, such
as bacteria, or other food particles.
Protozoa are uninucleate and reproduce by sexual or
asexual means.
They are classified on the basis of their motion.
The amoebae move by ameboid motion, whereby the
cytoplasm of the cell flows forward to form a pseudopodium
(false foot), and the rest of the cell flows toward this lobe.
The flagellates move using their flagella.
Trypanosomes move by flagella and cause of number of
diseases in humans.
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The ciliates move by motion of a large number of small
appendages on the cell surface called cilia.
The sporozoans are nonmotile and contain members that are
human and animal parasites.
Viruses are very small and are obligate parasites of other cells, such
as bacterial, yeast, plant, and animal cells.
 Viruses cannot store free energy and are not functionally active
except when inside their host cells.
 Viruses contain either DNA (DNA viruses) or RNA (RNA viruses) as
genetic material.
 DNA stands for deoxyribonucleic acid, and RNA is ribonucleic acid.
 In free living cells, all genetic information is contained on the DNA,
whereas viruses can use either RNA or DNA to encode such
information.
 This nuclear material is covered by a protein code called a capsid.
 Some viruses have an outher envelope of a lipoprotein and some
do not.
 Viruses infected bacteria are called bacteriophages.
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Some bacteriophages have a hexagonal head, tail, and tail fibers.
Bacteriophages attach to the cell wall of a host cell with tail fibers,
alter the cell wall of the host cell, and inject the viral nuclear
material into the host cell.
Bacteriophage nucleic acids reproduce inside the host cells to
produce more phages.
Host cells lyse or break apart and phase particles are released,
which can infect new host cells. This mode of reproduction of viruses
is called the lytic cycle.
In some cases, phage DNA may be incorporated into the host DNA,
and the host may continue to multiply in this state, which is called
the lysogenic cycle.
REFERANSLAR
Michael L. Shuler and Fikret Kargı, Bioprocess
Engineering: Basic Concepts (2 nd
Edition),Prentice Hall, New York, 2002.
1. James E. Bailey and David F. Ollis,
Biochemical Engineering Fundementals (2 nd
Edition), McGraw-Hill, New York, 1986.