MIIM - Introduction to Infectious Agents - Week 1 Flashcards
How have microorganisms imapcted the world in the past? Describe what this process is known as, and why it is so important.
They allowed the process of nitrogen fixation into the soil. These bacteria can be found on the roots of some pants, such as legumes, and allow them to incorporate nitrogen. Herbivores eat these plants, who are then eaten by carnivores, or die naturally. As they decay, their nitrogen content is once again recycled into the soil, air, or water. This is the nitrogen cycle.
Describe nitrogen fixation.
When nitrogen in the air is is fixated into the soil by bacteria.
Describe ammonification.
When decaying organic compunds have their nitrogen content converted to ammonia by decomposers.
Describe nitrification.
The process by which ammonia in the soil is converted to nitrites and nitrates by nitrifying bacteria.
Describe denitrification.
When nitrates are converted to nitrogen gas by denitrifying bacteria.
Describe assimilation.
When nitrates are taken up by plant organisms.
Where do bacteria sit on the food chain, and how do they support it?
They sit at the bottom, and support the entire chain by providing essential nutrients.
How do bacteria support humans?
In the gut, by synthesising essential B vitamins such as thiamine (B1), riboflavin (B2), pantothenic acid (B5), biotin (B7), and folate (B9).
Are the majority of microbes good/neutral, or harmful?
Good/neutral. Only a handful are associated with infectious disease.
Name the 5 types of infectious agents. Note which are acellular.
Bacteria, fungi, parasites, viruses, and prions.
Viruses and prions are acellular.
What is characteristic of prokaryotic organelles vs eukaryotes?
They are free-floating in prokaryotes, and are not membrane-bound, as in eukaryotes.
Compare prokaryotic DNA with eukaryotic DNA (2).
Prokaryotic DNA is closed and circular.
Eukaryotic DNA is linear.
What ribosome density unit do prkaryotes and eukaryotes have?
Prokaryotes use 70S
Eukaryotes use 80S
How do prokaryotes and eukaryotes replicate?
Eukaryotes - mitosis/meiosis
Prokaryotes - binary fission
Which of the following are present in prokaryotes?
Endoplasmic reticulum
Peptidoglycan
Plasma membrane sterols
None except peptidoglycans.
Describe what is meant by site-specific pathogenicity.
Occurs when bacteria appear neutral or beneficial in one location, but when moved to another region, they are pathogenic.
Name 6 factors that can affect a microbiome composition.
Climate/geography
Age
Shared living (family/aged care)
Personal hygiene
Diet
Medical treatment/intervention/hospitalisation
What is the periplasmic space?
The space between the cell wall and the inner cell plasma membrane.
What confers shape to a bacteria?
Cell wall
What term is given to rod-shaped, spherical, and spiral forms of bacteria?
Rods - bacilli
Spherical - cocci
Spiral - spirilla
Do all bacteria have cell walls?
No, such as mycoplasma
Describe the cell wall layers of gram-positive (3), gram-negative (2), and acid fast bacteria (5).
Gram negative have:
Inner plasma membrane
Thinner peptidoglycan layer
Outer membrane
Gram positive have:
Inner plasma membrane
Thicker peptidoglycan layer
Acid fast have:
Outer lipid layer
Thick mycolic acid layer
Arabinogalactan layer
Thin peptidoglycan layer
Inner plasma membrane
What is peptidoglycan also known as, and what 2 subunits are used to form bacterial cell walls?
Murein.
Subunits are N-acetyl muramic acid, and N-acetyl glucosamine.
What structure joins chains of peptidoglycan in bacterial cell walls?
A chain of amino acids extending downwards (L-Ala, D-Glu, L-Lys, D-Ala), connected by a penta-glycine bridge (connecting one D-Ala to another L-Lys).
