LIFESCI 4 Lecture Notes - Lecture 9: Plasmid, Pilus, Lysozyme
Vid 9
• Bacteria have chromosome and (sometimes) plasmids (chromosomal DNA)
• One plasmid is F plasmid, those with it are F+
- F+ plasmid encodes proteins, can transfer F plasmid from F+ to F- cell
- Conjugation: F+ cell recognizes F- cell -> form pilus -> duplicated F plasmid
transferred
• F plasmid can also insert itself into chromosome
- When it replicates & transfers itself, does so beginning in middle of plasmid -> drag
entire chromosome with it
- These plasmids are HFR plasmids
• HFR Can be used for bacterial mapping
- If transfer interrupted, only genes closest to where plasmid inserts itself are
transferred
- Original cell needs to have + traits for e.g. beta-gal, other cell needs to lack the traits
-> later can tell hih do’t hae taits y goig o edia
Bacteriophage
• Virus of bacteria (protein + DNA)
• 5 things it does
- infecting bacteria
- replicate its DNA
- make phage structural proteins
- assemble phage DNA and proteins
- lyse (kill) the cell
• what phage gene does
- Encode the proteins that replicate the DNA
- Encode the structural proteins
- Encode the lysozyme that lysis the bacteria
- Regulate everything
• Phage gets ATP, machinery (ribosome, enzymes), building blocks from bacteria
• 1 phage infects a bacteria -----30min------> 100 phages
• a phage fos a plaue/leaig o a la of ateia
• phages ae paasiti, a’t go y itself
titration
• want to know how many phages are in solution; pfu/ml (platform unit/ml)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Vid 9: bacteria have chromosome and (sometimes) plasmids (chromosomal dna, one plasmid is f plasmid, those with it are f+ F+ plasmid encodes proteins, can transfer f plasmid from f+ to f- cell. Conjugation: f+ cell recognizes f- cell -> form pilus -> duplicated f plasmid transferred: f plasmid can also insert itself into chromosome. When it replicates & transfers itself, does so beginning in middle of plasmid -> drag entire chromosome with it. These plasmids are hfr plasmids: hfr can be used for bacterial mapping. If transfer interrupted, only genes closest to where plasmid inserts itself are transferred. Original cell needs to have + traits for e. g. beta-gal, other cell needs to lack the traits. > later can tell (cid:449)hi(cid:272)h do(cid:374)"t ha(cid:448)e t(cid:396)aits (cid:271)y g(cid:396)o(cid:449)i(cid:374)g o(cid:374) (cid:373)edia. Bacteriophage: virus of bacteria (protein + dna, 5 things it does infecting bacteria replicate its dna. Assemble phage dna and proteins lyse (kill) the cell: what phage gene does.
