Introduction to Bacteria (2) Genetics Flashcards
How do bacteria replicate?
binary fission
What are the offspring like of bacteria?
identical progeny
How is variation created in bacteria?
spontaneous mutation
transfer of DNA (plasmids)(conjugation)
What is bacterial conjugation?
transfer of genetic material between bacterial cells
What do you term a bacteria with and without an F plasmid?
with = donor cell
without = recipient
What does the F plasmid encode?
F pilus
What is the first stage in plasmid transfer?
contact between donor and recipient
How does the donor cell attach to the recipient cell?
the pilis attaches to receptors on the surface of the recipient cell
What happens when the donor and recipient bacteria are attached?
A specific endonuclease cleaves the plasmid at a specific sequence (origin of transfer).
It is replicated via a rolling circle mechanism
What happens when F plus and F minus cells are mixed together?
all cells eventually become F plus
What is a bacteriophage?
A bacteriophage is a type of virus that infects bacteria. In fact, the word bacteriophage literally means ‘bacteria eater’, because bacteriophages destroy their host cells
Describe the structure of a bacteriophage
composed of a nucleic acid molecule that is surrounded by a protein structure.
What is the mechanism of action of a bacteriophage?
A bacteriophage attaches itself to a susceptible bacterium and infects it.
Following infection, the bacteriophage hijacks the bacterium’s cellular machinery to prevent it from producing bacterial components and instead forces the cell to produce viral components. Eventually, new bacteriophages assemble and burst out of the bacteria in a process called lysis.
What molecule is this?
bacteriophage
What is the treatment associated with bacteriophages?
Bacteriophages are being investigated as treatments for infections –known as ’phage therapy’ –particularly where antibiotics have not been effective.
Name structures A-E
What composes a ribosome?
consists of RNA and associated proteins
What is the function of a ribosome?
synthesise proteins
What are the 2 subunits of a ribosome?
30S
50S
(total 70S)
eukaryotes have 90S (60S and 40S)
What is the 16S subunit?
a subunit of the 30S subunit
used to identify bacteria, as they all have it
What is an endospore?
A dormant, tough, and non-reproductive structure produced by certain bacteria.
- Non-sporulating
What bacteria form spores?
Bacillus subtilis
What is a bacterial spore?
the most dormant form of bacteria since they exhibit minimal metabolism and respiration, as well as reduced enzyme production. Typically, Gram-positive bacteria are best known for producing intracellular spores called endospores as a survival mechanism
When stained, what colour are non-sporulating cells?
dark blue
What are the; dark blue, yellow and pink cells?
B. subtilis
non-sporulating cells (dark blue)
cells that have begun spore-formation by dividing asymmetrically (yellow) and small (pink) chambers.
How does sporulation occur?
binary fission
What is binary fission?
a type of asexual reproduction where a parent cell divides, resulting in two identical cells, each having the potential to grow to the size of the original cell.
Describe the process of sporulation
Endospore formation (sporulation) is the prime example of a complex bacterial developmental process. Sporulating bacteria undergo an intricate sequence of cell differentiation events leading to the formation of a highly resistant dormant spore that can germinate when conditions improve.
What are 2 ways you can classify bacteria? (methods)
phenotypically
genotypically
What are examples of phenotypic classification?
Gram stain
Growth requirements eg aerobic, anaerobic, microaerophilic
Serologic
Mass spectrometry (protein profiling)
What are examples of genotypic classification?
Ribosomal RNA sequence analysis
Whole genome sequencing
When is sporulation carried out by bacteria?
sporulation is caused by conditions unfavourable for growth, such as nutrient depletion.
survive nutrient poor conditions
Is streptococcus a genus or species?
genus
In streptococcus pyogenes, is pyogenes the genus or species?
species
