Biological Nanostructures:

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2Biochemistry

Biolog. Nanostructures

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Prokaryotic Cell

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Cytoplasm of Prokaryotic Cells:-> 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) -> 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:

1. Membranes are 2-dimentional solutions of oriented lipids and proteins2. Membrane proteins can diffuse laterial in lipid matrix -> 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:

α-helical protein

β-barrel protein

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Membrane Anchor Proteins

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Membrane attached protein can be part of receptors

Receptors can be involved in Intracellular signaling -> Signal Transduction

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Signal from outside the cell (organel) -> induces signal inside

Photosynthesis

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Light drives a proton pump -> generation of energy (ATP)

Cell mobility (Molecular Motors)

Bacteria: Flagella Higher Eukaryotes: change in cell shape

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Animal cell

Plant 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

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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. 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. 25

Lysosomes: -> trash bin of the cell !!!

-> acid organelle, contains degrading enzymesEnzymes: nuceases, hydrolases, proteases, phosphatasesInvolved in uptake of material (endocytosis, phagocytosis) and degradation of organelles (autophagocytosis)

Tay-Sachs disease: defect enzyme to break down gangliosides -> accumulation of glycolipids

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Peroxisomes:

-> contain oxidative enzymes, such as D-amino acid oxidase, ureate oxidase, and catalase.

-> resemble a lysosome

-> self replicating, like the mitochondria.

-> 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

Cell features for secretion of large amount of proteins:

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Endoplasmatic Reticulum:

Smooth ER: -> lacks ribosomes, synthesis of FA and phospholipids in liver: detoxification of pesticides and cancerogens

Rough ER: -> covered with ribosomes synthesis of membrane proteins and secreted proteins secretion -> vesicles carry proteins to golgi

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Golgi:

-> processes membrane and secreted proteins (glycosylation)

-> 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.

Plant Vacuole:

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-> storage of small molecules (water, ions, sucrose, amino acids)

-> up to 80 % of plant cell

Nucleus:

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Duploid set of human chromosomes: 46-> 2 x 22 + (XY)

-> genomic DNA (chromatin)-> nucleus metabolic active (Transcription, Replication, rRNA, tRNA)

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Chromatin structure of Chromosomes

Histone proteins

Mitochondria

-> Energy factory !!

Most ATP production of nonphotosynthetic, aerobic cells

-> have DNA (protein production)

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Chloroplast

-> in plants and algae

-> Photosynthesis (ATP synthesis) takes place in the Thylakoid membranes (Chlorophyll )

-> 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 -> building of nanostructures (wires)

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.38