Download 01 Cells and genomes

Molecular biology
KBC/MBIOG
Textbook:
Alberts et al. Molecular Biology of the Cell, Garland Science, New York
5th ed., 2008
6th ed., 2014
Molecular biology
(KBC/MBIOG)
Ivo Frébort
• 1. Cells and Genomes
A cell contains complete genetic information about the organism
All cells store their hereditary information in the same linear
chemical code - DNA
All cells replicate their hereditary information by templated
polymerization
All cells transcribe portions their hereditary information into
the same intermediary form – RNA
Structure of RNA
All cells use proteins as catalysts
Central dogma of molecular biology
Building of the cell from monomers
All cells translate RNA into protein in the same way
Four steps of the translation
Structure of a ribosome
What is a gene?
ONE GENE is the fragment of
genetic information corresponding to
one protein (in case of transcription
to mRNA) or one non-coding RNA
(in case of of transcription to rRNA,
tRNA, etc.)
All cells are enclosed in a plasma membrane
Nutrients, waste, etc. must pass through the plasma
membrane
Mycoplasma genitalium
the simplest organism
477 genes (580,070 bp)
Procaryotes – the greatest diversity
Procaryotes – big diversity in nutrient usage
Phototropic bacteria
Anabaena cylindrica
Organotrophic bacteria
Escherichia coli
Lithotropic bacteria
Beggiatoa spp.
Tree of life
Bacteria, Archaea ~ 1.000-4.000 genes, Eucaryotes ~ 6.000-30.000 genes
Some genes are conserved throughout species,
others evolve rapidly
Part of rRNA gene
New genes are generated from preexisting genes
Families of evolutionary related genes in Bacillus subtilis
Homologs, orthologs, paralogs …
A complex family of homologous genes
Genes can be transferred between organism
Viral gene transfer (T4 bacteriophage)
Horizontal gene transfer in early evolution – cell promiscuity
Mutations reveal functions of genes
Schizosaccharomyces pombe
The genome of Escherichia coli
Structure of an eucaryotic cell
Eucaryotic cells may have originated as predators
Phagocytosis by human white blood cell
Carnivorous protozoan
Didinium eating other cell
A mitochondrion
The origin of mitochondria
Chloroplasts
The origin of chloroplasts
Comparison of genome sizes
Gene expression as response to extracellular signals
Genetic control of multicellular development
Simplest unicellular eucaryotes – the protists
Yeasts – the minimal model eucaryotes
Saccharomyces cerevisiae
The reproductive cycles of
Saccharomyces cerevisiae
DNA microarray – a tool for studying expression of genes
Interaction map of regulatory proteins in yeast
Model organisms – Arabidopsis thaliana, Drosophila
melanogaster, Caenorhabditis elegans
Genetic redundancy
Xenopus tropicalis
- normal diploid genome
Xenopus laevis
- doubled diploid
genome
Genetic redundancy complicates studies of gene functions
Times of evolutionary divergence of different vertebrates
Phylogenetic tree of eukaryotes (hemoglobin genes)
The Mouse – genetic model for humans
Mutation in the kit gene
A „real passion“ for
Molecular biology
Rhodes Island, Greece
High summer season