Lecture 30 Flashcards
What is dihydroorotate dehydrogenase and what are most organisms with this?
Most eukaryotes have mitochondria and are obligate aerobes, this oxygen is needed not just for energy but also for biosynthetic reactions. One part of this is the dihydroorotate dehydrogenase, which requires molecular oxygen to perform the biosynthesis of pyrimidines and is typically found mitochondrially.
What is one way eukaryotes have been able to grow anaerobically?
A few microbial eukaryotes have gained the ability to grow anaerobically (e.g via dihydroorotate dehydrogenase which is cytoplasmic and doesn’t need oxygen, dihydroorotate + fumarate => orotate + succinate). A few yeasts have both forms.
What is the NCBI database? What does it show for our Saccaromyces cerevisiae dihdroorotate dehydrogenase?
The NCBI database contains sequences of many different genomes and includes tools which can be used for comparisons. Its free. This has a table of aligned sequences, in which the closest homology comes first, the quality of the match is given by the e value, this give s the probability of getting a match of this quality by chance. The best match for the Saccaromyces cerevisiae dihdroorotate dehydrogenase studied is other yeast, but closely followed is Lactococcocus lactis (a bacterium), this isn’t expected typically due to its unrelatedness, likely this is due to horizontal transfer.
Why did fungi need to become anaerobic?
L.Lactis is a facultative anaerobe. Fruits are low oxygen, high sugar food sources, this means that anaerobic bacteria could make good use of them, fungi like yeast could not utilise this food source without being anaerobic and as such needed to gain a trait which would allow this to occur. They also had to be able to survive ethanol which was produced as a byproduct of the fermentation of the fruit.
