Biological Nanostructures

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Biological Nanostructures
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Biolog. Nanostructures
Biochemistry
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Prokaryotic Cell
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Cytoplasm of Prokaryotic Cells
-gt dense gelatinous solution of sugars, amino
acids, and salts
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Different Shape and Size of Prokaryotic cells
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Biological Lipids form Bilayer Structures (self
assembly) -gt Vesicle-like Structures
Membranes are a natural barrier
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All Organelles are protected by membranes (single
or double)
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Major Membrane Lipids
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The Fluid Mosaic Model

• Membranes are 2-dimentional solutions of oriented
  lipids and proteins
• Membrane proteins can diffuse laterial in lipid
  matrix -gt lipid is solvent

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Membrane Fluidity is controlled by fatty acid
composition
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Membrane Composition determines Shape of Membrane
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Biological Membrane
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Membrane Proteins
a-helical protein
ß-barrel protein
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Membrane Anchor Proteins
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Membrane attached protein can be part of receptors
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Receptors can be involved in Intracellular
signaling -gt Signal Transduction
Signal from outside the cell (organel) -gt induces
signal inside
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Photosynthesis
Light drives a proton pump -gt generation of
energy (ATP)
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Cell mobility (Molecular Motors)
Bacteria Flagella
Higher Eukaryotes change in cell shape
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Animal cell
1 Plasma membrane 2 Mitochondria 3 Lysosomes 4
Nuclear envelope 5 Nucleus 6 Chromatin 7 Smooth
Endoplasmic Reticulum 8 Rough Endoplasmic
Reticulum 9 Golgi 10 Secretory vesicles 11
Peroxisomes 12 Cytoskeletal fibers 13
Microvilli 14 plant cell wall 15 Plant
Vacuoles 16 Plant Chloroplasts
Plant cell
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Structures that participate in delivering
material to lysosomes
Endocytosis is a process whereby cells absorb
material (molecules or other cells) from outside
by engulfing it with their cell membranes. It is
used by cells because most substances important
to them are polar and consist of big molecules,
and thus cannot pass through the highly
hydrophobic plasma membrane. Endocytosis is the
opposite of exocytosis, and always involves the
formation of a vesicle from part of the cell
membrane.
Phagocytosis (literally, cell-eating) is the
process by which cells ingest large objects, such
as prey cells or large chunks of dead organic
matter. The membrane folds around the material,
and vesicles are sealed off into large vacuoles.
Lysosomes then merge with the vacuoles, turning
them into a digestive chamber. The products of
the digestion are then released into the cytosol.
Macrophages are cells of the immune system that
specialize in the destruction of antigens
(bacteria, viruses and other foreign particles)
by phagocytosis.
Lysosomes -gt trash bin of the cell !!! -gt acid
organelle, contains degrading enzymes Enzymes
nuceases, hydrolases, proteases,
phosphatases Involved in uptake of material
(endocytosis, phagocytosis) and degradation of
organelles (autophagocytosis) Tay-Sachs disease
defect enzyme to break down gangliosides -gt
accumulation of glycolipids
Autophagy, or autophagocytosis, is a process of
organelle degradation that takes place inside the
cell. It is executed by lysosomes and is part of
everyday normal cell growth and development. Its
main purpose is to maintain a balance between
biogenesis (production) of cell structures, and
their degradation and turnover. For example, a
liver-cell mitochondrion lasts around ten days
before it is degraded and its contents are
reused.
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Peroxisomes
-gt contain oxidative enzymes, such as D-amino
acid oxidase, ureate oxidase, and catalase. -gt
resemble a lysosome -gt self replicating, like
the mitochondria. -gt function to get rid of
toxic substances like hydrogen peroxide, or other
metabolites. They are a major site of oxygen
utilization and are numerous in the liver where
toxic byproducts are going to accumulate.
Diameter 0.2 1 µm
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Cell features for secretion of large amount of
proteins
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Endoplasmatic Reticulum
Smooth ER -gt lacks ribosomes, synthesis of FA
and phospholipids in liver
detoxification of pesticides and
cancerogens Rough ER -gt covered with ribosomes
synthesis of membrane
proteins and secreted proteins
secretion -gt vesicles carry proteins to golgi
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Golgi
-gt processes membrane and secreted proteins
(glycosylation) -gt protein sorting
(membrane secreted transport to different
organelles)
cis-Golgi, medial-Golgi, trans-Golgi Secretory
pathway Vesicles transporting proteins from the
endoplasmic reticulum fuse with the cis-Golgi and
subsequently progress through the stack to the
trans-Golgi via vesicles.
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Plant Vacuole
-gt storage of small molecules (water, ions,
sucrose, amino acids) -gt up to 80 of plant cell
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Nucleus
Duploid set of human chromosomes 46-gt 2 x 22
(XY)
-gt genomic DNA (chromatin) -gt nucleus metabolic
active (Transcription, Replication, rRNA, tRNA)
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Chromatin structure of Chromosomes
Histone proteins
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Mitochondria
-gt Energy factory !! Most ATP production of
nonphotosynthetic, aerobic cells -gt have DNA
(protein production)
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Chloroplast
-gt in plants and algae -gt Photosynthesis (ATP
synthesis) takes place in the Thylakoid membranes
(Chlorophyll ) -gt have DNA (protein production)
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Virus

• Not a living organism ? Parasite
• Invade cells kills cells
• Host specific
• Evolution gene transfer within species
• Can trigger genetic diseases (Cancer)
• Protein cover filled with nucleic acids
• Small genome (RNA DNA)
• Virus - Retrovirus
• Used for - Gene therapy
• - Drug delivery systems

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Viruses
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Viruses
Viruses are build by self assemble -gt building of
nanostructures (wires)
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Virus and Nanotechnology
Scientists at the Massachusetts Institute of
Technology (MIT) have been able to use viruses to
create metallic wires, and they have the
potential to be used for binding to exotic
materials, self-assembly, liquid crystals, solar
cells, batteries, fuel cells, and other
electronics. The essential idea is to use a
virus with a known protein on its surface. The
location of the code for this protein is in a
known location in the DNA, and by randomizing
that sequence it can create a phage library of
millions of different viruses, each with a
different protein expressed on its surface. By
using natural selection, one can then find a
particular strain of this virus which has a
binding affinity for a given material. For
example, one can isolate a virus which has a high
affinity for gold. Taking this virus and growing
gold nanoparticles around it results in the gold
nanoparticles being incorporated into the virus
coat, resulting in a gold wire of precise length
and shape with biological origins. Current
thinking is that viruses will one day be created
which can act as agents on behalf of
bio-mechanical healing devices giving humans or
other animals extended life.