Introduction to Microbiology Flashcards
Microbiology
Why study Microbiology?
Microbes cause most common dental diseases (caries, periodontal disease) We need to understand infection to enable effective prevention & treatment. By understanding the basic processes of microbes, we can develop future treatments
What is Microbiology?
Microbiology is the biology of organisms too small to be seen by naked eye.
What are the 4 main classes of microbes?
- TSEs “scrapie-like” agents (Transmissable Spongiform Encephalopathies)
- Viruses.
- Bacteria.
- Eukaryotic microbes: fungi and protozoa
What are TSEs?
There are ‘infective’ proteins. Examples include - Kuru, Scrapie, Creutzfeld-Jacob, Scrapie (dieseses involved with these microbes). They cause sponge-like lesions in the brain by modulating or moderating the conformation of a particular protein.
How does TSEs occur?
TSE occur natural in living organisms; it has a normal confirmation. If it misfolds then it can form amyloid plaques which can lead to large depositions of this protein which cause the destruction of cells.
What are a unique feature of TSEs?
Unique feature of these protein when the abnormally folded protein is mixed with the normally folded protein, they will cause a confirmational change in these proteins and these will also become abnormal.
What are the differences between bacteria, eukaryotes and viruses?
look at lecture notes
What are the features of viruses?
- They infect bacteria, plants and animals.
- Ther are small - only “visible” in electron microscope - 10 to 200 nm.
- They come in different shapes and sizes.
- They are obligate intracellular parasite and metabolically inert.
What is the structure of viruses?
- Nucleic acid packaged in protein: icosohedral or helical
- Genome: DNA or RNA which can be single or double stranded
- Can be naked or enveloped (generated from host proteins)
How does viruses replicate?
- Virus comes in to contact with animal cell. Attached to the surface of the animal cell through recognition of specific receptors the virus enters the cell.
- After gaining entry into the cell release the genome into the cell. Can be released into the cytoplasm or nucleus of the cell.
- Virus uses the host cell machinery to replicates its genome also transcribes it genome to start producing viral proteins.
- Will form new nuclear capsids which will package the viral genome in it. It will either bud off the cells or produce such large numbers the cell will burst. Which will go effect other cells.
How does bacteria replicate?
Bacteria replicate by binary fission. DNA replicates then cells splits in half.
What is the structure of bacteria?
- Membrane lip bilayer – hold the contents of the bacteria
- DNA in chromosome – a single structure of double stranded DNA in one loop
- Plasmids – small circular structures of DNA can range in size.
- Ribosomes – protein manufacturing
- Cell wall – provides rigidity and structure.
look at notes for pictures
How is bacteria defined?
- shape and size
- arrangement of growing bacteria
- Gram stain
- culture requirements
- biochemical reactions
- antigenic structure
- nucleic acid technologies
what is the shape and arrangement of bacteria defined?
- Bacilli – rod like structures eg: E.coli
- Cocci – round, ball shaped eg: S.aureus
- Spirochaetes – complex spiral structures eg: B. burgdorferi lyme disease
- Curved – curved structures eg: V.cholerae
- Streptococci – assemeble in long chains
- Staphylococci – arranged in groups
what are the differences between gram+ and gram- bacteria?
They stain differently due the structures of the cell wall.
Gram + there is a thick peptidoglycan layer. Have a capsule layer helps invading immune responses. The capsule layer is a glomeration of different carbohydrates.
Gram – there is a space between the peptidoglycan layer and the cytoplasmic membrane know as periplasmic space and its thinner. Have a capsule layer helps invading immune responses. They also have a outer membrane layer and have lipoproteins within them. Contains LPS is involved in triggering septic shock.
