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11 Cards in this Set

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Prokaryotes
-Cells are small 1-5 Um

-Lack membrane bound
organelles

-DNA is circular and organized into a nucleoid mass

-Genetically haploid

-Can have extrachromosomal DNA-plasmids

-One copy of each gene
-Self replicating
Eukaryotes
-Membrane enclosed structures or organelles (nucleus, mitachondria, and chloroplast)

-DNA is linear and organized into chromosomes, usually diploid

-Nucleus divides following mitosis cells divide by mitotic division

-Sexual reproduction occurs following meiosis and gamete fusion.

-Size easier to see
E. Coli Genome
-4,639,221 bp

-4288 protein coding genes

-115 structural RNA's

-A typical cell has 1900 different proteins under any one growth condition.
Homo sapiens
-3.2 Gb (3,200 Mb)

-31,000 protein encoding genes

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Phylogenetics
The study of evolutionary ties between life forms
How do we measure the relatedness of two organisms?
-Morphology
-Metabolic capabilities
-Habitat
-Gene content
-Changes at nucleotide level
Carl Woese
-Mid 1970's revolutionized our thinking about the relationships between organisms
Molecular Chronometers
-Help define phylogenetic relationships

-Something that everything has

-Func'ts needed for something to be a molecular chronometer
a)distribution
b)function
c)comparisons
d)change
16s rRNA as the molecular chronometer
-Needs to be universally distributed

-It should be functionally homologous- have the same function in all cells

-The structure should be sufficently conserved so that sequences can be accurately aligned

-The molecule should change at a rate that is commensurate with the evolutionary distance being measured

-Sequence difference between ribosomal RNA's are an excellent measure of evolutionary change
Constructing a phylogenetic tree
1. Align all sequences this is the most critical step

2. Measure the number of changes between each pair. This is a measure of evolutionary distance, Ed. This number is usually corrected for multiple changes at a single position.

3.Relationships between sequences are plotted graphically where the length of the lines joining each sequence is proportional to the number of changes (or distance) between the sequences.

*Alternative approaches: Parsimony, measures the minimum number of changes needed to diverge two lineages from a commoon ancestor; Maximum likelihood, measures the most probable pairings.
Metabolic Diversity

-Energy can be obtained in three ways
1. Organic Chemicals
~glucose, acetate
~chemoorganotrophs

2. Inorganic Chemicals
~ H2, H2S, Fe2+, NH4-,
~ Chemolithotrophs

3. Light
~Phototrophs