Microbiology Lecture Notes September 30

Lecture
September 30, 2009

1. Why don’t’ bacteria have mitochondria
a. Most bacteria are free-living; they DO NOT live on/in a host/in a host cell
b. A definition is NOT a reason
i. Ex) Prokaryotes don’t have membrane-bounded organelles, and mitochondria are membrane-bounded organelles
c. Because use ATP as energy currency just like ALL OTHER LIVING THINGS do
d. Virtually all bacteria are free living
e. Don’t use the word because
f. Bacteria are like one big mitochondria themselves
g. 1000 nm size of bacteria
h. Mitochondria have their own DNA and replicate on their own time whenever they want to; bacteria act the same way to create ATP
i. Because:
i. Mitochondria have their own DNA
1. Replicate on their own independently of when our cells replicate using the same cell division steps that bacteria do
2. Mitochondria generate ATP like bacteria do
3. Mitochondria can be killed by many abx
4. Mitochondria most likely are descendants of bacteria that were engulfed by or invaded by eukaryotic cells in the past
ii. Biologists think mitochondria re descended from bacteria
1. Symbiotic relationship
2. Mitochondria can be seen as their own separate organisms because they have their own DNA
3. Mitochondria do not have cell walls made of peptidoglycan but are very similar to bacteria in other ways
2. Bacterial Flagellum Article
a. Structures flagellum is similar to:
i. The ATP synthesis set up of Mitochondria and the ATP synthesis of bacteria by proton being pumped by the water-wheel apparatus using electrons
ii. Virulence Factor:
1. Any protein that helps cause symptoms
iii. Type 3 Secretion Systems
1. Works like a hypodermic needle and is also very similar to the setup that spins the bacterial flagellum
2. Similar to bacterial flagellum ATPsynthase
3. Acts like a needle to inject virulence factors into the host cell
4. Need a set of proteins that can cross the envelope of the bacterial cell envelope
3. Review of Wong article:
What is evolution? What is intelligent design? What predictions does evolution make about the origins of any complicated structure? How are these different from the predictions of intelligent design? What evidence do authors of this article use to support their contention that the bacterial flagellum is the product of evolution rather than design?
a. These people are undergrad students
b. How are the predictions of evolution different from the predictions of intelligent design?
i. Intelligent design
1. Things were set up the way they already are
2. Flagellum
a. Bacteria always had the flagellum; wasn’t something that developed over time
b. If you take out the parts of the flagellum it would just fall apart
c. Separate fully functioning things cannot take things away from it or it wont work
ii. Evolution
1. Parts of cells descended from earlier parts of cells and we should see recycling of parts and repetition of parts
iii. Bacteria Flagellum
1. Is the bacterial flagellum similar to other things in the cell?
a. Yes, it is more similar to other things in the cell than just on its own
4. Exponential growth vs. logarithmic growth
a. # of bacteria at a given time = 2 X power (x=# of generations since we just had 1 bacterium)
5. How an individual bacterium divides
a. Replication of chromosome
i. Replicate its DNA
1. Bacteria have a single circular chromosome
2. The DNA is copied by DNA polymerase
3. Need 2 copies of chromosome: 1 for each cell
b. Elongation of cell
i. Happening simultaneously along with DNA replication
ii. New chromosome copies are sent off to either side of the cell
c. Formation of FtsZ ring at septum
i. FtsZ is what pinches the cell at the middle after the chromosome copies have moved to the other ends of the cell
ii. FtsZ pinching in the middle of the cell; chromosomes separate to either side of the cell
d. Building of new cell envelope components at septum
i. New cell envelope components built at the center of the cell

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