BIOL 112 Lecture Notes - Lecture 20: Beta-Galactosidase, Pilus, Genetic Recombination
15 Jun 2018
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RNA Viruses: membrane glycoproteins, receptors for hormones, tricks the cell to attach and go in,
releases RNA which tricks the cell again thinking it’s mRNA (viral genome creating new capsids &
glycoproteins) → Undergoes re-programming
Flu Virus: RNA with 8 chromosomes, able to recombine with each other to increase diversity
(H1N1) composed of chromosomes from different virus strains
HIV retrovirus: RNA for genetic material in envelope stolen from host cell, only affects humans
(some monkeys), specific immune cells (cd4 receptor), uses glycoproteins to bind on the cell
surface → super effective for disrupting/killing immune cells
- Reverse transcriptase: specific to virus, RNA into DNA, assembling new glycoproteins
Chicken Pox: affects axon terminus, infection is over; virus hangs out in spinal cords and neurons
for a long time, re-emerges and forms welts in your skin (shingles)
Bacterial Sex: mutants will only grow in certain media (e-coli in methionine), rises by genetic
recombination
Conjugation: mini chromosome (plasmid) that bacteria accumulate, easy to exchange,
o F-plasmid causes them to code genes (can have more than 1 copy), spreads
throughout all populations until there’s only F-plasmids
o High frequency recombination: F-plasmid transfer with chromosomal DNA between
cells, it breaks one strand of DNA which goes through a tube and remaining DNA
makes a copy in the new cell which carries bacterial chromosomes
o Brings bacterial chromosomes into the new cell, becomes double stranded
▪ Linear sequence
▪ Dependent on distance from origin of replication
▪ Facilitates DNA from one bacterium to another
o Sex pilus: transfer DNA from tube from one bacterium to another
Transduction: phage picks up bacterial chromosome and recombines, makes mistakes
Transformation: process whereby bacteria is mixed with DNA; it will suck it up from the
environment, recombine with genome and be stably inherited (bacteria also takes up plasmids)
Gene Regulation:
- Lac Operon: 3 genes; (galactosidase, permease, transacetylase) codes an regulatory gene to
bind to operator sequence, repressor: no beta galactosidase is formed
- Tryptophan: binds to the repressor and becomes active (blocking transcription when
attached to the operator), less trp being formed, once popped off the operator you make
more trp
- Low/High Glucose: proteins that bind to DNA and enhance polymerase to transcribe
EUKARYOTIC GENOMES:
Tetraploids are bigger than diploids because they have big cells, more DNA – big genome – big cell
Comparative Genomics:
find more resources at oneclass.com
find more resources at oneclass.com
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Document Summary
Rna viruses: membrane glycoproteins, receptors for hormones, tricks the cell to attach and go in, releases rna which tricks the cell again thinking it"s mrna (viral genome creating new capsids & glycoproteins) undergoes re-programming. Flu virus: rna with 8 chromosomes, able to recombine with each other to increase diversity (h1n1) composed of chromosomes from different virus strains. Hiv retrovirus: rna for genetic material in envelope stolen from host cell, only affects humans (some monkeys), specific immune cells (cd4 receptor), uses glycoproteins to bind on the cell surface super effective for disrupting/killing immune cells. Reverse transcriptase: specific to virus, rna into dna, assembling new glycoproteins. Chicken pox: affects axon terminus, infection is over; virus hangs out in spinal cords and neurons for a long time, re-emerges and forms welts in your skin (shingles) Bacterial sex: mutants will only grow in certain media (e-coli in methionine), rises by genetic recombination. Transduction: phage picks up bacterial chromosome and recombines, makes mistakes.
