Viruses & Bacteria Flashcards
Litric cycle vs lysogenic cycle
Lityc - phage DNA injects into bacteria - bacteria makes phage proteins - proteins break up bacterial chromosomes into little pieces - makes copies of new phages
Lysogenic - hides, kinda becomes part of cell as prophage (in chromosome) until ready for lityc cycle
How bacteria exchnges DNA
some bacterium contain plasmids - phenotype produces sex pilus (bridge) - exchanges plasmids
also tranduction (through virus)
also transformation (takes up DNA from environment)
Induction (lactose)
lactose is digested by multiple enzyme
Promoter has operators: Repressor protein w separate gene & own promoter - recognizes sequence & binds downstream of DNA promoter
Lactose binds to regressor protein –> allosteric change –> no longer recognizes operator
Negative feedback loop
high concentration of tryptophan –> binds to active repressor which binds to DNA to prevent gene that codes for synthesis
how many genes do humans have?
30 000 (not proportionate do number of base pairs, they thought 600 000)
Why the extra base pairs?
Introns (vs exons) get snipped out at primary RNA transport
Telomeres buffer chromosome against loosing DNA cuz linear DNA loses ends when replicating
Satellites (highly repetitive DNA in centromeric regions of chromosome) - some indicate where centromere is
Transposable elements - DNA parasites -
RNA processing
Splicing - only in eukaryotes - in primary RNA transcript - loops out
5’ G cap - Guanosine gets attached to 5’ 5’ & doesn’t remove phosphate
Polyadenylation - 100 As at end of any mRNA
DNA transposons
Encode transposase proton - which comes back to look for inverted repeats to find where it is, cuts it out, and moves it elsewhere —> mutation (if germ cell), particularity common in plans
Retrotransposons
move through n RNA intermediate cuz they look like retroviruses
Pseudogenes
lack introns, mRNA can be reverse transcribe & re-inserted into genome
