Exam 1 Flashcards
(53 cards)
How were microbes first discovered?
In 1684, Antoni van Leeuwnhoek saw them through the first-ever microscope and called them “animalcules”.
What are the types of microscopy?
Light Microscopy Electron Microscopy (Scanning and Transmission)
What is the difference between SEM and TEM?
SEM: Scanning, shows surface by collecting back-scattered electrons, less magnification possible, but is in 3D
TEM: Transmission, electron beam passes through sample to show outside and inside structures, higher magnification possible, but only 2D
What are the three domains of life?
Bacteria - Prokaryotes
Archaea - Prokaryotes
Eukarya - Eukaryotes
Saprophyte
An organism that is important in the decomposition of dead plant matter. Typically fungal.
How much of Earth’s biomass is microbial?
~60%
What is the Germ Theory of Disease?
Louis Pasteur and Robert Koch demonstrated that specific microbial pathogens cause diseases.
What were initial classifications of organisms based upon?
Morphology and feeding (1860s Ernest Haeckel)
What was the first classification scheme of organisms?
Animalia: move and consume food
Planta: dont move, produce food (incl some bact and fungi)
Protista: Everything else (incl some bact and sponges)
What classification scheme supplanted the Animalia/Protista/Plantae scheme?
5 Kingdoms: Plantae, Fungi, Animalia, Protista, Monera. Did not work well for protista or monera because they were the “precursors” to the others.
How do we pick genes for phylogenetic trees?
Must be universally present
No horizontal transfer
Highly Conserved
Sufficiently large to have differences and be useful for statistical analysis
What genes do we typically sequence to compare organisms?
Ribosomal rRNA. Large Subunit: 23S in Bact and Arch, 28S in Euk
Small Subunit rRNA: 16S in Bact and Arch, 18S in Euk.
To what extent are modern phylogenetic trees useful?
Modern trees are MULTIgene trees and are therefore not useful at the species level.
What class of enzymes is required for supercoiling of DNA?
Topoisomerases
How can microbes regulate the shapes of the fatty acids in their membrane lipids to affect physiology?
More saturated/straight chains = more rigid/dense, higher melting point.
Symport
One molecule with conc gradient, other against it, both in same direction
Antiport
One with gradient, one against, but in OPPOSITE directions
Gram-positive Cell Wall
THICK
Has lots of PG
Gram-negative Cell Wall
Thinner
Some, but little PG
Has LPS
How do BACTOPRENOL and AUTOLYSIN function in PG synthesis?
Bactoprenol exports sugars out of cell so that Autolysin can cleave a space for them in the PG molecule
What does PENICILLIN do?
Inhibits synthesis of new PG, therefore stopping bact growth, but not killing existing amount.
How many pores are in each porin?
FOUR. Three in a triangle and one in the center
What are capsules and how do they differ from LPS?
They are thick coats of “slime” (exact composition varies) that are meant to protect the bacterium from hostile environments. LPS can still exist within an encapsulated bacterium, but is not by definition part of a capsule.
How do archaeal cell membranes differ from those of bacteria and Eukarya?
The bonds between glycerol and the hydrophobic side chains on the lipids are ETHER bonds, not Ester. The Ether bond allows them to resist hydrolysis in extreme environments.
