Lecture 5Structural organization of biological systems: from

supramolecular complex to cell

Supramolecular complex: structural and functionalMembrane fluidityMembrane functionMolecular machinery: examples

Three Kingdoms: based on rRNA sequencesBacteria (eubacteria)Archaea (archaebacteria)Eukarya (eukaryotes)

Cell culturesTissue culturesCell cycleCell lines

Biological Membrane

Membrane fluidity

Sialic acid bnding sites

Membranes of Eukaryotes and Prokaryotes

Internal Membranes

Molecular Machinery

Molecular Machinery

Three Kingdoms

Prokaryotes and Eukaryotes

Eukaryotic cells

Tissue culture and cell cycle

Fluorescent Activated Cell Sorter

Cell Culture

Subculture and Cloning

Normal and Transformed Cells

Cell Differentiation

Cell Biology

Mycoplasm

Model Organisms

The YeastS. cerevisiae; S.pombe

Genome size: 12 Mb; 13.8Mb

Chromosomes: 16; 3

Number of genes: ~6,000;

4,900

Genes with introns: 5%; 43%

Average gene: 1.5kb,~1 exon;

3kb, ~3 exons

Proteins: 6,217; 5,002

‘Omics

Despite being the only one-tenth the size of a white blood cell, many of the cellular functions of higher species are present in unicellular yeast. Two species of yeast have been pressed into service as model organisms: S.cerevisiae and its distant cousin S.pombe. Each one has nearly 200 genes homologous to human genes involved in disease, with 23 for cancer alone.

The WormC. elegans is a nematode, a smooth-skinned worm with a long, unsegmented, cylindrical body tapered at both ends. Comprising about 1,000 cells, it is the most primitive animal to exhibit characteristics that are important in the study of human biology and disease. Though tiny and transparent, C. elegans contains a full set of differentiated tissues, including a nervous system with a "brain," which allows the study of behavior in a worm that is capable of learning. It is found worldwide in soil and rotting vegetation.

Caenorhabditis elegans

The FlyDrosophila melanogaster,

the diminutive and ubiquitous fruit fly, is the classic organism for the study of animal genetics. It was introduced to the lab early in the 20th century by Thomas Hunt Morgan, for good practical reasons: short life cycle, ease of culture, and high fecundity. Mutant flies, with defects in any of several thousand genes, are now used for the study of genetics, development, behavior, and other topics.

Drosophila melanogaster

The PlantDespite its weedy appearance, A. thaliana, commonly known as thale cress or mouse-ear cress, is the undisputed model plant. Ease of cultivation, rapid life cycle, and high seed production are bolstered by small genome size and ease of transformation. As a result of evolutionary conservation, many of the fundamental advances using Arabidopsis are finding useful application in the improvement of crops such as maize, wheat, and rice.

Arabidopsis thaliana

The FishDanio rerio Small, tropical zebrafish,

native to southeast Asia, have been recruited relatively recently from the pet shop and into the lab. They are easy to look after and breed prodigiously. External fertilization allows easy genetic manipulation and analysis, and the embryo is optically transparent. In addition, the availability of a vast storehouse of mutations means that this model will provide insights into developmental processes for years to come.

Scientists create transparent zebrafish to study human diseases

The MouseNaturally comfortable in fields and in kitchens, M. musculus, for the last century, has been virtually indispensable in the research lab. This animal now appears in all shapes and sizes, as researchers consistently produce new strains. Mouse production is a $200 million-a-year business, with transgenics accounting for a third of the new mice created.

Mus musculus