Infection Biology and Microbiology

What does Whittakers “Monera” include?

Archaea and Bacteria

Phototroph =

organisms that obtain energy from light

Chemotroph =

organisms that obtain energy from chemical sources

Organotroph =

Organisms that obtain energy (and electrons) from organic compounds

Lithotroph =

organisms that obtain energy (and electrons) from inorganic compounds

Autotroph =

organisms that use inorganic substances (like CO2) as a carbon source

Heterotroph =

organisms that use organic substances (like carbon) as a carbon source

Whats the difference between macro and micro nutrients?

Macronutrients are needed in large amounts, micro in small amounts

Define budding:

a type of asexual reproduction where a new, smaller daughter cell (a bud) grows as an outgrowth from a parent cell, rather than the parent splitting directly in half

What are the 4 phases in the growth of bacteria:

lag phase - adapting to new conditions

log phase - exponential growth

stationary phase - limitation of nutrients and buildup of waste

death - cells lyse

What is haemocytometry?

using a thick glass microscope slide with a laser-etched grid to manually count cells

What is turbidmetry?

measures the cloudiness of a fluid by quantifying the reduction in intensity of a transmitted bean as it passes stright through the solution

What is the standard microbial unit?

colony forming unit (cfu)

What is the difference between selective and differential media?

selctive allows growth of only some types of organism, differential allows identification of organisms based on growth and appearance on the medium

Whats the difference between the surface origin hypothesis and the sub-surface origin hypothesis?

surface suggests evolution started in a primordial soup, sub-surface in hydrothermal vents on the ocean floor

Endosymbiosis theory for evolution of eukaryotes:

key organelles like mitochondria and bacteria incorporated into a host cell

Hydrogen hypothesis for evolution of eukaryotes:

evolution arose from a metabolic partnership - aerobic bacterium produced H2 as a waste product, Archeal host used H2 as energy source

Systematics =

study of the diversity of organisms and their relationships

Define polyphasic bacterial taxonomy:

way of classifying bacteria and archaea using: phenotypic, genotypic, and phylogenetic analysis

Acidophile =

an organism that requires pH under 6

Alkaliphile =

an organism that requires pH above 8

Barophile =

an organism that requires high pressure (e.g. bottom of the ocean)

Halophile =

an organism that requires very salty conditions

Aerobe =

an organism that requires oxygen

Obligate aerobe =

an organism that requires oxygen

Anaerobe =

an organism that doesn’t require oxygen

Facultative anaerobe =

an organism that can live with or without oxygen (often better with)

Obligate anaerobe

an organism that doesn’t tolerate oxygen

Aerotolerate anaerobe =

an organism that can tolerate low oxygen

Microaerophile =

an organism that requires low oxygen

Psychrophile =

an organism that requires a temperature under 15

Mesophile =

an organism that requires temperatures between 15-45

Thermophile =

an organism that requires temperatures above 50

Hyperthermophile =

an organism that requires temperatures over 80

Whats another name for murein?

peptidoglycan

What is glycocalyx?

a sticky outer coating found outside the bacterial cell wall (capsule/slime layer)

What are sterols and hopanoids?

molecules that regulate membrane fluidity, stiffness and permeability (sterols - eukaryotes, hopanoids - bacteria)

What are the 3 components of lipopolysaccharide in gram negative bacteria

O-specific polysaccharide, core polysaccharide, lipid A

Motility =

ability to move spontaneously and independently using metabolic energy

In which direction does a flagellum spin in a run?

anti-clockwise

In which direction does a flagellum spin in a tumble?

clockwise

Aerotaxis =

movement (usually) towards oxygen

Chemotaxis =

movement towards nutrients / away from toxins

Magnetotaxis =

movement along lines of magnetism

Phototaxis =

movement towards light

Which type of bacteria can produce endospores?

gram positive

What is an endospore?

a tough, dormant, and non-reproductive structure produced by certain Gram-positive bacteria when environmental conditions become unfavourable

What is a microbiome?

the community of microorganisms—including bacteria, viruses, fungi, and single-celled organisms—along with their genetic material, that live together in a specific environment

What are 5 challenges faced by the immune system?

rapid viral evolution

antigenic variation/shift

recognition of ‘self’, ‘non-self’ and ‘altered self’

tissue specific responses

appropriate level of response

Cell-mediated immunity =

defence provided by specialised cells in blood and tissues

Humoral immunity =

soluble-phase defence provided by secreted proteins in bodily fluids

What are the 3 types of innate immune defence?

physical barriers

specialised proteins and cells

cell-intrinsic responses

What are defensins?

small positively charged antimicrobial peptides that act as natural antibiotics and play a key role in the body's Innate Immune System

What are tol-like receptors?

a class of transmembrane proteins that play a vital role in the body's Innate Immune System. They act as an early warning system by recognising conserved molecular signatures unique to microbes or cell damage

How does HIV evolve rapidly?

by frequent mutations

How does the flu evolve rapidly?

by recombination