L1 Microbes Flashcards
Book
Molecular genetics of bacteria
Biomass in plantet
Bacteria accounts for 50% of biomass in the planet, 35% plants, 15% animals
Bacteriophages
viruses that infect bacteria
Microbiome
bacteria that lives within the human body.
Bacteria size
10-20x smaller than eukaryotic cells
Streptomyces
produce 70% antibiotics, they have linear nucleiod. They are non motile
Peptidoglycan
the middle layer of the bacterial cell wall, its the main exoskeleton that prevents bursting/wilting.
Penecilling and derivatives
It inhibits the production of peptidoglycan, hence the bacterial cells burst from osmotic pressure.
Nuceiod
DNA in the bacteria
Bacterial ribosomes
They have smaller protein assembly than eukaryotic
Division
They elongate and cut in half.
DNA packing
Negative supercoiling. This process stores energy. There are multiple sites of which this process happens, so when a strand breaks (nick), only that domain is damaged, but other domains remain intact.
The energy that is within a bacteria is proportional to the amount of repeats of supercoiling.
2 enzymes are involved in supercoiling
DNA Gyrase - responsible for supercoiling
Topoisomerase 1 - unravelling the supercoil
This maintains energy homeostasis for cell division.
DNA replication
Semi-conservative (high N experiment)
DNA polymerase requires a primer
A single site of replication, called oriC
Seperation of strand
DnaG synthesises short strand of RNA primer on the bottom strand.
DNA polymerase will attatch to the 3’ end of the primer and synthesise DNA, not RNA.
oriC:
an AT rich region (easy break)
DnaA is attatched to the oriC. This coils the DNA, and uncoils (breaks AT bonds).
DNA replication moves towards a “replication fork”, at the base there is DnaB, where the helicase unwinds the strands.
For the lagging strand, ligase is used to fill in the gaps.
DNA damage
If DNA is damaged, it cannot replicate.
Termination of DNA replication
opposite side to the oriC, there are buffer sites called Ter.
