Biology 1001A Lecture Notes - Lecture 1: Reverse Transcriptase, Glyptodont, Georges Cuvier
Document Summary
Lecture 2: characteristics of viruses and why they are not generally considered to be alive . Lack metabolic system to produce their own energy. No cytoplasm enclosed by plasma membrane: why viral infections are usually difficult to treat with drugs, and exceptions to this general principle. Viruses mutate very fast, and become resistant to the drugs. Viruses have no metabolism, so there are no steps to target with drugs. Ex, influenza has 8 pieces of rna that could be arranged in any random order, hard to target: whether viruses are always pathogenic. Help human, protective viruses help interfere with replication or function of pathogenic viruses, and help control insect pests ex, bacteriophages (phages) kill bacteria. Help ecosystem, bacteriophages kill cyanobacteria (release nutrients: hypotheses for the evolutionary origin of viruses. Old hypothesis: fragment of dna escaped from parent cell (transposons), after time, genetic code reduced to only what is needed to reproduce (no more metabolism, etc)