QuestionS on Taxonomy

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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QuestionS on Taxonomy

Post by klapausius » Fri Oct 08, 2010 1:32 pm

i have some question that are bugging me and would like to discuss them here as to get more opinion on my choice, thanx.

The melting temperature from two gram positive bacteria was determined and shown to be the same. This would indicate that the bacteria are:
1. The same species
2. Belong to the same genus
3. Belong to the same phylum
4. None of the above

My choice was (2) this is because variation between genus is <10% when it comes to G+C content

The definition of a species in microbiology can be controversial. Which characteristics best describes what should be considered a species?
1. Gram positive, melting temperature of DNA within 5 C and filamentous growth
2. rRNA with less than 3% divergence, gram negative and sequence similarity based on nucleic acid hybridization of 70%
3. More than 50 characteristics that are identical, rRNA sequence with 2.7% divergence, gram negative
4. 75% similarity in DNA sequence and 98% rRNA gene identity

my choice was (4) as i recall 70% is the cutoff value for species definition when comparing rRNA sequence homology

Which criteria are best suited for distinguishing between subspecies?
1. rRNA sequences
2. DNA-DNA hybridization and G + C contents
3. G + C contents and MLSA
4. rRNA sequences and G + C contents

My choice was (3) MLSA and G+C since these combined together would cover Genus right through Strain (genus species subspecies strain)

A new strain of a pathogenic bacteria has appeared and you are trying to identify the genetic cause for the increased severity. Which approach do you feel is best suited?
2. Whole genome sequencing
3. RFLP analysis
4. SNP analysis

my choice was (2) as the rest would require me to know what its pathogenicity lies in which is impossible since its new

A microorganism has the following characteristics: Gram positive, oxygenic, photosynthesis, GC content of 30%. You are asked to place the microorganism into its appropriate taxonomic rank. Where would you place it?
1. Domain
2. Phylum
3. Class
4. Order

my choice was (4) since this was the lowest i could think of the others were too high in rank

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Post by JackBean » Tue Oct 12, 2010 6:04 am

could be 1., maybe 2.

but there is no 70% ;) Anyway, probably 4. because in all the other possibilities it had to be either G+ or G-

no idea

but wholegenome sequencing is quite expensive and takes long time. Some use of markers would be better ;)

no idea

Cis or trans? That's what matters.

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