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22 Cards in this Set
- Front
- Back
Classification
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To group similar things together.
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Hierarchial scheme of classification
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1. Classification system based on the scheme of assigning individuals to groups
2. Assigning these groups to a progressively larger and more inclusive assemblages. |
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Taxonomy
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BIOLOGICAL classification
Science of classifying organisms |
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Kings are playing chess on fine grains of sand
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Kingdom
Phylum Class Order Family Genus Species |
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Diff btwn
Artificial Natural system of biological classification |
Linnaeus's grouped organisms on the basis of VISIBLE SIMILARITIES (Artificial)
Natural based on EVOLUTIONARY RELATEDNESS |
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How are eukaryotic species defined?
Bacteral? |
def: euka species is a group of organisms that share a common pool of genes.
Bacterial defined by similarities of its members. |
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What is a strain?
Microo belonging to the same species can be divided into strains. |
def: Clones that are presumed or known to be genetically different.
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On what basis are viral species defined?
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1. Grouped into genera and genera into families
2. Given English names 3.No higher taxa used 4.Viral species also divided into strains. |
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Why aren't viruses included in biological classificaton schemes?
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Because we don't have an evolutionary history to guide us.
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How is an organism classified according to numerical taxonomy?
IT GIVES EQUAL WEIGHT TO ALL CHARACTERS(Properties) of organisms |
Tries to express the evolutionary distance btwn organisms in a number.
Similarity coefficient (S) |
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TRADITIONAL METHOD
Morphology Biochemistry Physiology |
1. Shape/Arrangement/Flagella
2. Gram stain divides into groups w/or w/out outer membrane 3. Conditions that will support growth(Carbon Source used) 4. End products formed/enzymes produced |
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TRADITIONAL METHOD
Serology Phage typing |
1.Anti-bodies contained in serum are very specific/ helps to distinguish btwn/ closely related strains and species
2. Determining the pattern of bacterial strains attacked by phage |
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GENOMIC METHOD
% of G+C Closely related organisms have similar % of G +C values But values vary and similarities do not prove relatedness. |
Mole % of cystosine/guanine
expressess the percentage of G-C's vs A-T's. GCCTTTATAC= 4 G-C's,6 A-T's G-C's= 40% A-T's=60% |
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DNA Hybridization
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1. Heat DNA strants to separate strands
2. Single strands from different sources mixed 3. Same species DNA will anneal DNA Strand 1= How they hybridize(2 strands anneal makes a hybrid) DNA Strand 2= Will tell you if they are related |
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DNA Sequencing
def: determines the sequence of bases in DNA Ultimate tool of taxonomy Genome sequencing most accurate Large #'s 4.5 million base pairs in E.coli |
Small ribosimal subunit(SSU tRNA)is highly conserved thus tRNA of even distantly related organisms is enough so we can count the # of differences and calculaate evolutionary distance btwn them.
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What is a dichotomous key?
Advantages? Disadvantages? |
A series of questions about characters that offer only two (2) alternatives.
Answers lead to identifying unknown proka. Using a small number of characters lead to generalization 94% of E.coli yes but that means that 6% of E.coli no. |
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Traditional Methods
Biochemical and Physiological characters |
Based on growth requirements (o2, pH, Temp)
End products formed and enzymes produced Fermentation properties Acids, gases produced during fermentation Carbon source that support growth oxidation/reduction measurement Tetrazoluim dye |
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Traditional Method
Phage Typing Determing the pattern of bacterial strains attacked by specific phage |
Bacteriphages are viruses that infect bacteria
Host range of phage is narrow Phages use receptions on surface to know which cells to attack ie. CD4 cells HIV |
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Traditional /Gemonmic Method
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Traditional focus on END PRODUCT
Genomic depends on DNA melting point of DMA(H2 bonding) |
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Classification of viruses
Host specific means plants are infected by plant viruses |
1. What is the kind of nucleic acid?
2. Single stranded or double? 3.What is the apperance under the EM? 4. Is it surrounded by a membrane? 5. Host range and serology |
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GENOMIC METHOD
Probe Small or large signal tells relatedness ie. 100% signal means bacterial is identical |
Probe is tagged
dye, chemiluminescent molecule or radioactive Specific for certain organism Cell DNA lysed Anneal in certain regions Amount of annealing is determed by genetic relatedness. |
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Tell how tetrazolium dye works. Large database
Purpose: Identify the carbon source that supports growth |
1. Plastic plate w/96 wells
containing dye and diff carbons sources 2. Put in organism 3. If the carbon is used up, the dye is reduced and changes in color 4. The color pattern read by machine/put into computer 5. Computer tells what the organism is |