Molecular Characteristics Flashcards
1
Q
Nucleic Acid Base Composition
A
- Mol% guanine and cytosine
- determined by Tm (melting temperature)
- more G+C = higher Tm
- conserved within species
2
Q
G+C content between 2 organisms
A
- differs with 10%: organisms are different
- same: no conclusions, may only be by chance that they appear similar
3
Q
compare
Nucleic Acid Hybridization
A
in vitro comparison between the genomes of:
- unknown microbes
- reference microbes
4
Q
Process of Hybridization
A
- DNA denatured
- ssDNA formed
- cooled to 25C below Tm
- complementary strands reassociate and stabilize
- dsDNA formed
5
Q
Monitor rate of reassociation by
A
measuring the absorbance of DNA in solution to calculate the % homology of genomes
6
Q
Organisms are similar when
A
70% homology and <5% difference in Tm
7
Q
ribo
Nucleic Acid Sequencing
A
- to classify taxonomic informative sequences (ribosomal subunits)
- use PCR to amplify the target gene
- phylogenetic tree to see relation
8
Q
Gram-negative Bacteria
A
- stain RED
- thinner cell wall
- all kinds of cell shapes
- binary fission or budding
- phototrophic, chemolithoautotrophic, chemoorganotrophic
- motile or non-motile
- many types of appendages
- no endospores
9
Q
Gram-positive Bacteria
A
- thick cell wall
- sphere, rod, filaments and true branching shape
- binary fission and tip extension
- chemoorganoheterotrophic
- non-motile or petrichous flagella if motile
-may have spores on hyphae - some groups
