Notes 10.01

Notes from class today!! :)

I. Exponential growth vs. logarithmic growth
a. Exponential growth
i. Equation:
1. # Bacteria at a given time = 2^x
a. Where x = # of generations since originally had 1 bacterium
b. Ex. X=1, bacteria = 2
ii. Picture on hand out
b. Logarithmic Growth
i. Only part of bacterial growth curve is exponential
II. How an individual bacterium divides – what are the limits?
a. Replication of chromosome
i. Replicate it’s DNA: single circular chromosome
1. DNA is copied by enzyme DNA polymerase
a. DNA polymerase = enzyme that synthesizes new DNA molecules complementary to template strand
b. **DNA is double-stranded, interacting via complementary bases – (A=T) (C G)
i. A=T – 2 hydrogen bonds holding them together
ii. C & G – 3 hydrogen bonds holding them together
2. Need 2 copies of chromosome: 1 for each cell
a. Each has 2 = 1 original DNA and 1 copied DNA
b. Chromosome is attached to inside of plasma membrane upon replication
b. Elongation of cell
i. From circular to oblong – create more in the middle and pushing ends out farther … o → 0 … New cell envelope in the center
1. Pushes copies to opposite ends of the cell
c. Formation of FtsZ ring at septum
i. Pinches the middle of the cell after chromosomes go to opposite sides
ii. Min proteins stop FtsZ from working; they bounce from one end of cell to the other – interpretive dance in class!
1. They stop the FtsZ from working anywhere except for the center
d. Building of new cell envelope components at septum
i. New cell components are then built in the middle of the cell finishing off each of the cells and finishing the cell.
ii. Build upon the FtsZ ring on the ends of the cell to finish the circular formation of both of the new cells
III. Bacterial Generation Times
a. Vary from one bacteria to another
i. Size of chromosome matters
1. Range in size from ~1 million bps – 8-10 million bps
2. Bps – base pairs (A=T) (C G)
b. E. Coli ~ 15-20 minutes (Speed demon rock star)
i. ~ 5 million bps in chromosome
ii. Have split seconds to copy 1,000’s of genes
c. Staphylococcus ~ 30 minutes
i. In ten hours you would have over a million (1,048,576)
d. Mycobacterium TB ~ 22-23 hours

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License