Download Subcellular organelles in Eukaryotic cells

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Subcellular organelles in Eukaryotic cells
Biomolecular Engineering
Mitochondria
 Mitochondria are shaped like sausages, and contains two membranes.
 Mitochondria also contain their own DNA (transferred from mother to their offspring)
 often called the powerhouse of the cell because they make energy for the cell. They produce energy
by turning ADP into ATP in inner membrane.
 Cells that need more energy, such as muscle cells, contain more mitochondria than cells that need less
energy.
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Subcellular organelles in Eukaryotic cells
Biomolecular Engineering
The Endoplasmic
p
Reticulum (ER)
 An interconnected system of flattened, double-layered membranes. The ER is connected to the
nuclear membrane.
 Some parts of the ER contain many ribosomes on their surfaces, giving them a rough appearance
(called rough ER)
ER), Parts of the ER without ribosomes are called smooth ER
ER.
 Ribosome are responsible for proteins synthesis through translation process, so in eukaryotic cells,
translation occurs on the surface of ER not within nuclues.
 Synthesized proteins are delivered to Golgi body in which they move to other parts of cells. So ER is
called mail-man.
Ribosomes
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Subcellular organelles in Eukaryotic cells
Biomolecular Engineering
 The Golgi apparatus,
apparatus also called Golgi body or Golgi complex,
complex
 It looks like a set of flattened sacs.
 The Golgi apparatus packages and transports materials, which are then carried in vesicles through the
cytoplasm to other parts of the cell, or are excreted from the cell (Secretion process). Its nickname is
Post office.
 Many post-translational modification for proteins occurs during transports through ER and Golgi
apparatus
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Subcellular organelles in Eukaryotic cells
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Lysosomes
y
a special type of vesicle that contain digestive enzymes.
Round structures surrounded by membranes.
Lysosomes recycle materials by breaking down worn-out parts of a cell into smaller units
(sweeper in a cell)
cell). They deliver these small materials to the cytoplasm for use in constructing new
proteins (recycling).
 If the membrane of a lysosome breaks, the enzymes released may also destroy the cell itself
(autolysis), giving lysosomes the name "suicide bag".
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Subcellular organelles in Eukaryotic cells
Biomolecular Engineering
Ribosomes are produced in the nucleolus (inside Nucleus).
Nucleus)
Ribosomes are found on the outside of the ER, as well as floating free in the cytoplasm.
Ribosomes contain a small and large subunit, and consist of proteins and rRNA.
Their function is to synthesize proteins by assembling amino acids according to instructions from
mRNA (Translation).
Translation by Ribosome (in Chapter 2)
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Plant cells
Biomolecular Engineering
 Vacuoles are membrane-bound sacs within the cytoplasm of a cell that function in several different ways. In mature
plant
l t cells,
ll vacuoles
l tend
t d to
t be
b very large
l
andd are extremely
t
l important
i
t t in
i providing
idi structural
t t l support,
t as well
ll as serving
i
functions such as storage, waste disposal, protection, and growth. Many plant cells have a large, single central vacuole
that typically takes up most of the room in the cell (80 percent or more). Vacuoles in animal cells, however, tend to be
much smaller, and are more commonly used to temporarily store materials or to transport substances.
 The central vacuole
ac ole in
i plant
l t cells
ll is
i enclosed
l d by
b a membrane
b
termed
t
d the
th tonoplast,
tonoplast an important
i
t t andd highly
hi hl integrated
i t
t d
component of the plant internal membrane network (endomembrane) system.
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Chloroplast (엽록체)
Chloroplasts
 Contains chlorophyll (inside thylakoid membrane),
hence provide the green color.
color
 Double membranes (inner and outer).
 Has its own DNA which codes for redox proteins
involved in electron transport in photosynthesis
 Thylakoid, Stroma, Granum, lumen are included
 Photosynthesis takes place on the thylakoid membrane.
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Biomolecular Engineering
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Classification of Bacteria
According to various criteria
 Shape,
Shape Gram staining,
staining cellular nutrition & energy metabolism
O2 requirement
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Gram staining
Biomolecular Engineering
Gram staining : Bacterial cell staining method developed by the Danish scientist Hans Christian
Gram (1853 – 1938) in 1884
Principle : Different permeability of the cell wall to
“purple colored iodine dye complex”
Brief procedure
1) Fixation of the cell on the slide glass
2) Staining with crystal violet
3) Staining with iodine (potassium iodide)
Crystal violet and iodine treatment produces "purple
colored iodine-dye complexes" inside bacteria
(cytoplasm).
4) Treatment with a decolonizing agent such as 95% ethanol
or a mixture of acetone and alcohol
Under this treatment, the cell wall of Gram (-) cells are
permeable to "purple colored iodine-dye complexes“, so
in this step, Gram (-) cells are decolorized.
5) To visualize decolorized Gram (-) bacteria, a red
counterstain such as safranin is used after decolorization
treatment
treatment.
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Gram staining
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Gram (+) Purple color
(Bacillus anthracis)
Ex)
Bacillus sp., Staphylococcus sp.,
Listeria sp., Streptococcus sp.,
Clostridium sp., Enterococcus sp.
Biomolecular Engineering
Gram (-) Red color
(Escherichia coli)
Ex)
Escherichia coli, Salmonella, Shigella, and
other Enterobacteriaceae, Pseudomonas,
Helicobacter, Bdellovibrio, Legionella
Cyanobacteria, green sulfur and green nonsulfur bacteria.
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Gram staining
Biomolecular Engineering
 Much thicker (multilayered)
peptideglycan structure
 Only one cytoplasmic membrane
(lipid bilayer)
 No periplasmic space
 Lipoteicoic acid (LTA) are found
only
y in Gram ((+))
 Thin peptidoglycan structure
 Two membranes (inner and outer –
same lipid bilayer)
 Periplasmic space between two
membranes.
e b a es.
 Lipopolyscharide (LPS) are found
only in Gram (-)
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Peptidoglycan
Biomolecular Engineering
 Peptidoglycan
ept dog yca : Polymer
o y e by ccrosslinking
oss
g betwee
between N-Acetylglucosamin
N cety g ucosa
and
a d N-Acetylmuramic
N cety u a c acid
ac d
 The structure of the polysaccharide backbone of peptidoglycan is conserved in all bacteria, with only
minor variations.
N-acetylglucosamin
N-acetylmuramic acid
Lysozyme : peptidoglycan-lytic enzyme
(from egg white)
Lysozyme
y y
Loss of
Rigidity &
Cell lysis
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Lipid bilayer
Biomolecular Engineering
Gram (-) bacteria
Phospholipid
p
p
Major components of membrane lipid
Amphiphatic lipid
OM
Peptidoglycan
Periplasm
IM
Cytoplasm
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Lipid bilayer
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Biomolecular Engineering
Phospholipid
p
p
Gram (+) bacteria
Major components of membrane lipid
Amphiphatic lipid
Peptidoglycan
IM
Cytoplasm
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Summary of Gram (-) bacteria
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 Two membranes
b
(inner
(i
andd outer membranes)
b
) consisting
i i off lipid
li id bilayers
bil
 Thin peptidoglycan layer between two membranes
 Outer membrane containing lipopolysaccharide (LPS, which consists of lipid A, core polysaccharide,
and O antigen) outside the peptidoglycan layer
 Periplasmic space between the plasma membrane and the outer membrane
 Example species  Escherichia coli, Salmonella sp., Pseudomonas sp., Shigella sp., Helicobacter sp.,
Bdellovibrio sp., Legionella sp., Cyanobacteria etc
LPS
Outer membrane
Extracellular medium
Peptidoglycan
layer
Periplasm
Chromosome
Cytoplasm
Inner membrane
Flagella
Pili
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Escherichia coli
Biomolecular Engineering
 Escherichia coli
 Nonpathogenic, short, motile, rod-shaped organism
 Cell length: about ~3 μm, diameter: about ~1 μm
 One chromosome – full sequencing was completes in 1997
(4.3 Mb).
 Naturally found in the intestines of humans
 Optimal temperature for cell growth : 37oC,
 One generation time (doubling time) is about 22 min
(The shortest time in all bacteria).
 Aerobically or anaerobically: grown aerobically for the
optimal production of recombinant protein (Facultative
anaerobe)
b )
•The most important/widely used host strain in commercial
production of recombinant proteins/metabolites
 The fastest growth
 High cell density cultivation in large scale culture
 Easy manipulation of cells and many genetic engineering
tools
l
 Deep understanding physiology/metabolism
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Summary of Gram (+) bacteria
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Biomolecular Engineering
 Gram-positive
p
cell
 Have much thicker peptidoglycan layers in cell walls than Gram-negative and so are able to retain a
crystal violet dye during the Gram stain process.
 Do not have an outer membrane, but rather they have a very thick, rigid cell wall (15-80 nm) with
multiple layers of peptidoglycan
 Have only a cytoplasmic membrane (No periplasm)
 Often much better suited to secretion of proteins
• Example species  Bacillus sp., Staphylococcus sp., Listeria sp., Streptococcus sp., Clostridium sp.,
Enterococcus sp.
Peptidoglycan layer
Extracellular medium
Cytoplasm
Cytoplasmic
membrane
Chromosome
Flagella
Pilus
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Eukaryotic cells - Yeast
Biomolecular Engineering
 Saccharomyces
y
cerevisiae (In chapter
p 7)
 Nonpathogenic, single-celled (~ 5 um diameter) yeast
 Sugar ethanol & CO2: used for the production of alcoholic beverage &
bread
 Complete set (16 pairs) of chromosomes entirely sequenced (1996)  first
eukaryotic organism
 Useful host for the production of recombinant proteins from eukaryotic
organisms
 Eukaryotic version of E. coli - widely used for the production of recombinant
proteins
 Other host yeasts for heterologous proteins : Pichia pastoris & Hansenula polymorpha
 Post-translational modification
 Enzymatic addition of compounds to proteins after their synthesis (Translation) in eukaryotic
organisms
 Glycosylation (sugar), phosphorylation (Phosphate), acetylation (acetic acid), sulfation (Sulfur)
etc
 Essential for the proper functioning of the protein in some proteins  EPO,
EPO hTPO (human
thrombopoietin)
 E. coli and other prokaryotes  No ability to perform the protein modifications
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Eukaryotic cells - Yeast
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Glycosylation
Human
Biomolecular Engineering
Bacteria
N-Glycosylated protein
in higher organisms
In bacterial host
(Escherichia coli)
In human or Yeast
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