17. Bacterial Diversity Flashcards
what are three points of why bacteria is important?
recycling organic material
recyling carbon dioxide
fixing nitrogen
define an autotroph
bacteria that uses photosynthesis for energy
define a heterotroph
bacteria that gets nutrients by consuming other organisms
define a symbiont
bacteria that live in and around eukaryotic hosts
what is a microbiome?
the gut bacteria
define what a pathogen is
bacteria that causes disease by secreting toxins. it can be secreted molecules or outer membrane compartments of gram - negative bacteria
what type and what is the name of the reproduction method of prokaryotes?
asexual reproduction called binary fission
what are the 5 steps of binary fission?
initiation of cell division: DNA of a bacterial chromosome begins to replicate at the origin of replication
origin of replication replicates (so theres two)
one of the origins rapidly makes to the opposite side of cell, while chromosomes replicate and cell grows/elongates
final size will be twice of original, plasma membrane pinches inwards by a tubulin like protein
two new daughter prokaryotes
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why is there such a high level of genetic diversity in bacteria?
because of their very high reproduction rate - a new generation every 20 minutes, means that mutations probablities increase
what are the three horizontal gene transfers? give a description for them
transformation: naked DNA is taken up from the enviorment by bacterial cells
transduction: use of bacteriophages to transfer DNA between cells
conjugation: direct transfer of DNA through plasmids from one bacterial cell to another
what is transformation?
it alters the genotype of a cell (recipient) by the naked DNA (from the donor). occurs when bacteria cells takes up genetic material from its surroundings, which when recombination occurs the DNA will be intergrated into the bacterial choromsome.
used to clone and create insulin
what is transduction?
bacteriophages packing bacterial DNA instead of their own DNA in their capsid during replication in a bacteria donor cell. Prevents new phages being made as the phage has bacterial DNA. When the phage injects the recipient, the bacterial DNA will be released and infected
what is conjugation?
mating between F+ plasmids (male) and F- (female). Involves transfer of the F plasmid from the donor to the recipient via the mating bridge or pilus (unknown which). It results the F- becoming a F+ as it gets a F plasmid
what is the F+
F-
pilus
plasmid
F+ is the donor cell that contains DNA from the F plasmid
F- is the reciever cell that has no F plasmid
pilus are short filamentous projection on bacterial cells
plasmid is a small circular DNA molecule that can replicate indepndanntly of the bacterial chromosome
what are four ways benefit can benefit you?
photosynthesis in plants - energy
digestion in eukaryotes
make you happier - bacteria in soil can raise cerotonin levels
protection from bad bacteria
how do mutaions and rapid reproduction lead to the genetic diversity found in bacteria?
explain what happens and three points of diversity
because bacteria has been around for 3.5 billion years, adaptation have occured and very short generation times - 20 minutes allow gnetic diversity to occur. these contribute to horizontal gene transfer which is accidental to
give new genes
new combinations meaning new novel niches
fast forward evolution
what are two types of genes that can be transferred by horizonal gene transfer?
novel sugar utilisation
anitbiotic resistance genes
what is the antibiotic resistance gene?
natural selection occuring in bacteria. if theres one bacteria thats resistnat to antibiotics, and that person is given antibiotics, natural selection will mean that bacteria survives and reproduces. creating genertions of stronger bacteria
explain how horizonal gene transfer contributes to the rise of antibiotic resistnant bacteria? give a real life example.
in china, there is a very high concentration of pig farming and people. Polymixins are given to pigs as an antibiotic due to the high concentrations, which was proven not to be able to go through HGT.
in 2011, polymixin was proven it could go through HGT. the resistane spread very quickly because of a large amount of usage.
it has spread and is found in humans
