CTY Family Day 2013
Carnegie Institution for Science
Department of Embryology
Recent technological advancements have led to an explosion in the amount of information available about the genes and proteins present in organisms ranging from viruses to bacteria to plants to humans. In this workshop, you will be introduced to some of the publicly accessible tools and genomic databases that allow anyone with an internet connection to explore how genes in fundamental biological processes are conserved between model organisms and man.
- Night and Day: Regulating circadian rhythm with cryptochromes
- A Tight Squeeze: Packing 2 meters of DNA into each cell with histones
- Muscle or Blood: Determining cell fate with transcription factors
- Under Water: Transporting oxygen in blood with hemoglobin
- The Sweet Life: Metabolising sugar with glucosidases
- A Xerox Copier: Ensuring proper genome duplication with PCNA
- [BONUS] Antifreeze Proteins: A Case of Convergent Evolution
Many organisms vary their activities according to the time of day. These circadian (circa- "approximately" -dian "a day") rhythms help find prey and avoid predators. A protein called cryptochrome acts to coordinate circadian rhythms with changes in the daily sunrise and sunset.
It's no small feat to package DNA into a cell! If the DNA from a single human cell were fully stretched out, it would reach 2 meters in length. To fit inside a volume smaller than you can see with your naked eye, the highly negatively charged DNA is spooled around highly positively charged proteins called histones. When you look at chromosomes, you are actually looking at DNA that is tightly wound in protein. In this example, you will compare the combined structure of DNA and histones in frogs versus humans.
How cells become one type rather than another (e.g. muscle vs blood) is determined in part by proteins called transcription factors. The MyoD transcription factor helps make muscle cells by decoding information stored in DNA using a helix-loop-helix domain. Variations of this domain have been adapted for use in other transcription factors over evolution to make other cell types. In this example, you will compare the helix-loop-helix domain bound to DNA in the MyoD and LMO2 transcription factors.
Almost all living organisms need oxygen. Hemoglobin is the protein that transports oxygen in human blood (red blood cells) from lungs to the tissues of the body. A single Hemoglobin can carry four molecules of oxygen! In this example, you will compare the structure of fish and human hemoglobin proteins, and get an appreciation of how similar or different these essential proteins are in different organisms.
Sugar is essential for many processes: storage and source of energy or even signaling within a cell! To go from storage to use, the cell needs to break down large complexes of sugar molecules into basic building blocks. Proteins like rice beta-glucosidase help regulating these processes essential in EVERY organism. In this example, we will compare beta-glucosidase of rice versus human.
DNA contains the genetic code that provides a cell its identity. To propagate their identity, cells duplicate their DNA content prior to division into 2 identical daughter cells. The super compacted DNA opens up and a sliding clamp encircles DNA that is central to DNA replication to form an accesible platform for the copying machinery. PCNA is such a sliding clamp.
Convergent evolution occurs when different species use different proteins to independently evolve the same function (much like evolution of the wing, where flying birds, insects and bats have developed the capacity to fly independently.) By evolving Antifreeze proteins, which inhibit the growth of ice crystals, some fish and animals have independently evolved an incredible capacity to stay alive at freezing temperatures! In this example, you will compare the structure of fish and beetle Antifreeze Proteins, and learn if humans and other organisms have them.
Special thanks to Valeriya Gaysinskaya, Pavol Genzor, Safia Malki, Zehra Nizami, and Gaëlle Talhouarne for devising these examples