Lecture 1: Microbiology: An introduction Flashcards
Define the term microorganism
a very small living organism that can only be seen through a microscope
What is microbiology
the study of very small living organisms
How are microorganisms classfied?
- bacteria
- archaeans
- protozoa
- molds and yeasts
- viruses
Give some examples of microorganisms that can live under extreme conditions
halophiles - need high salt conditions
thermophiles - can thrive at high temperatures (60°-120°)
cryophiles - grow at cold temps (15° and lower)
acidophile, alkaliphile, xerophile (dry conditions)
light microscopy can go up to what mangification scale
1000x
List the key differences between prokaryotes and eukaryotes
prokaryotes - small, bacteria, haploid, no membrane around nucleus, circular DNA, asexual reproduction by binary fission, simple flagellum, resiprate via cytoplasmic membrane no ER, free ribosomes, cell wall is peptidoglycan
eukaryotes - large, protozoa, algae, fungi, animals and plants, diploid, membrane bound nucleus, strands of DNA, sexual and asexual reproduction, complex flagellum, respirate via mitochondira, complex organelles, cell wall made of chitin (fungi) and pectin (plants)
Name the six different types of microscopes and their functions
- brightfield - gram staining
- darkfield - thin organisms with dark background
- phase contrast - unstained organisms
- fluorescence - immunodiagnostic tool
- SEM - surface 3D
- TEM - organelles, internal structures
List the Biological Hierarchical classification
Species, Genus, Family, Order, Class, Phylum, Kingdom, Domain, Life
Define strain
genetic variant of a species (subtype)
define serotype
subtype (strain) that can be defines using specific antibodies from the serum in blood
define pathovar
subtype with tissue/host specificity
define isolate
pure micorbial sample obtained from infected indivdual
How do bacteria grow/cell division
binary fission; haploid genome, duplication of chroosme, continues cell growth, division into two cells
explain bacterial growth kinetics
lag phase - bacteria getting used to new environemnt, expressing enzymes (“setting the table for dinner”)
growth phase - eating up the nutriens, growing, multiplying
stationary phase - become dormant, no more food
death phase - bacteria start to die off
What is a coccus
round shaped bacteria
what is a bacillus
rod shaped bacteria
what is a vibrio
curved shaped bacteria
what is a coccobacillus
egg shapes bacteria
What is a fusiform bacillus
long oval shaped bacteria
Describe the different arrangements of bacteria
staphylo - triangular
strepto - chain
diplo - two
tetrad - four
What is the morphological difference between Gram positive and Gram negative bacteria
gram positive - thick peptidoglycan wall, crosslinked by peptides, only has cytoplasmic membrane
gram negative - thin peptidoglycan layer, has an outer membrane
What are the external morphological structures of bacteria
- flagella
- fimbriae/pilus
- slime layers and capsule
How do flagella move?
powered by a proton motive force in a whip like motion
What is the structure and function of fibriae (pili)
structure - rigid, adhesin attached to pilus to attach to host cell, no motility
function - pili used for DNA transfer –> conjugation
What is the structure and function of the slime layer of bacteria
structure - not organised, bacteria loosely attached
function - gliding, aggregation - sticks to surface and bacteria sticks with it, colonisation of smooth surfaces
eg. plaque on teeth
What is the structure and function of the capsule
structure - highly organised, bacteria found inside capsule, rigid, bacteria firmly attached
function - bacterial adhesion to surfaces, acts as a defense mechanism against host immunity
what are endospores
resistant to heat, cold, drying and many chemmicals - hard to get rid of them, survive many years
