Chapter 22 – Model Organisms

Reasons to use model organisms in molecular genetics research

Bacteria and Bacteriophages (phages)

-       advantages: small genomes, single cell, grow fast, facile genetics, can grow large quantities for biochemical experiments

-       compare lytic vs. lysogenic phage growth

-       What is a phage plaque?

Budding yeast (Saccharomyces cerevisiae)

-       advantages: simplest eukaryotic model organism, small genome, unicellular, fast generation time, lots of molecular and genetic tools, can grow a lot of cells in order to use for biochemical analyses

-       life cycle either haploid or diploid; mating types of haploid

-       budding and cell cycle

-       relatively easy gene replacement

Nematode worm (C. elegans)

-       advantages: simplest multicellular model organism, relatively simple body plan, rapid development, lots of progeny

-       life cycle

-       used to study programmed cell death (apoptosis), RNAi (RNA interference), genes in aging

Fruit fly (Drosophila melanogaster)

-       advantages: multicellular, many genetic mutants, rapid development, large populations

-       life cycle

-       basic idea behind P element transformation to make transgenic flies

-       used to study embryonic body patterning, growth factor signaling, genetic mapping techniques

Arabidopsis thaliana

-       plant model organism

-       relative small genome for a plant


-       advantages: simplest vertebrate model organism, one favorite organism for developmental biologists, transparent embryo advantageous to watch development, large number of progeny, relatively fast development


-       best mammalian model organism

-       close synteny between mouse and human chromosomes

-       similar physiology and development to humans

-       gene knock-out technology

-       briefly outline two methods to make transgenic mice: pronuclear injection and homologous recombination into mouse ES (embryonic stem) cells