Lectures 1-5 Flashcards Preview

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Flashcards in Lectures 1-5 Deck (75):
1

Robert Hooke

Compound microscope
Coined phrase "cells"
Micrographia

2

Van Leeuwenhoek

Simple microscope
Animalcules

3

Aristotle

Abiogensis

4

Francesco Redi

First challenged spontaneous generation

5

John Needham

Argued for life force and vital atoms

6

Lazzaro Spallanzani

Refuted spontaneous generation in the microscopic world

7

Bonnet

Suggested the word 'germs'

8

Pasteur

Conclusively disproved spontaneous generation

9

Robert Kochs Postulates

1) Suspected pathogenic organism must always be present in animals suffering from the disease and should not be present in healthy
2) The organism must be cultivated in pure culture away from the animal body
3) Cells from a pure culture of the suspected organism should cause disease in a healthy animal
4) Organism should be preisolated and shown to be the same as the original
Gold standard, not possible for some diseases. Animal models not useable- cholera

10

Matinus Beijerinck

Enrichment culture - Medium and a set of incubation conditions are established to select for the desired organism from an inoculum
Isolated by N2- fixing Azotobacter

11

Alexander Felming

Discovered penicillium notatum prevented growth of staphylycoccus aureus

12

Edward Jenner

Vaccination
Cowpox didn't get smallpox.

13

Classification of microorganisms

Tree of life- compare nucleic acid. 16S rRNA

14

Will Hennig

Evaluation of traits between organisms
- Identify Homology (Shared ancestry)
- Identify monophyly (Groups based around shared derived characteristics)
-Evaluate and compare character states as a way of identifying relationships
This later became a mathematical operation. Use DNA sequences

15

Carl Linnaeus

Taxonomic classification
- Naming convention to designate where it is grouped within the wider biodiversity of life.
Does not require test of phylogenetic relationships
Uses Synapomorphies to resurrect group- relationships
Possession of the synapomorphy Is used to classify species within groups

16

Problems with Linnaeus classification

Homoplasy ( Convergent evolution of synapomorphic characteristics)
Secondary loss of synapomorphic characters
Species issues - Defined by sexual barriers, but most don't reproduce this way. Some species have many different sexes
Character states are highly variable

17

Woese

Used on Small Subunit RNA. Contains an mRNA binding site

18

Small Subunit RNA gene

rRNA have a range of states of sequence corresponding to the secondary structure of RNA molecule.
Double stranded/ single stranded regions

19

Issues with Molecular phylogenies

Difficult to correct for rate variation
Originally assumed all changes equal.
Some sites don't change
Some change so fast - can't tell what a reversion is. - Mutational saturation

20

Solutions for molecular phylogenies

Model rates and correct
Bigger datasets
Increased sampling
Multiple genes
More character states

21

2 domain tree

50 protein amino acids concatenated alignment.
Sophisticated phylogenetic methods that account for rate variation.
Meta genome discoveries also share this.

22

Cell morphology

Coccus (Circular)
Rod (Rod shaped)
Spirillum ( Curvey rod)
Spirochete (Curvey wavey rod)
Budding and appendaged
Filamentous

23

Cell size

S/V ratio
Faster update of nutrients
More cells per given resource
More cells- more mutations
Drives evolution

24

Cytoplasmic membrane of bacteria

Phospholipid bilayer
Phoshatidylethanolamine
Strengthened by hopanoids
Essiential for mycoplasmas

Bacteria and eukaryotes use Ester bonds
Archea use Ether and (Phytanyl)

25

Cell Wall

Peptidoglycan (Murein). - Made of G acid and M acid

90% of cell is peptidoglycan in gram Positive ( Have inter bridge)
Only 10% in gram negative

26

Gram negative cell wall

Second lipid bilayer
Not just phospholipids
Large polysaccharide - Lipopolysaccharide

27

Gram staining

Gram positive retain crystal violet colour.
Gram negative do not, and are stained pink.

28

Capsules

Can be polysaccharide or protein or both
Play a role in pathogenesis and biofilm formation

29

Biofilms

Predominant bacterial phenotype in nature
May form :
- Solid substrates with water
-Soft tissue surfaces
-Liquid air interfaces
Mainly polysaccharide

30

Fimbriae and Pili

Proteinaceous but can be glyciosylated
Role in pathogenesis biofilms and conjugation
Involved in twitching motility

31

Flagella

Multimeric protein complex, inner and outer membranes
Peritrichous - Everywhere
Polar - 1 at one end
Lophotrichous - Many at one end
Amphitrichous - At both ends
It is helical

32

Endospore

Dormant stage lot lifecycle

33

Cellular structures as antibiotic targets

DNA gyrase - Quinolones ( Nalidixic acid, Ciprofloxacin, Novobiocin)
RNA Elongation - Actinomycin
Lipid Biosynthesis- Platensimycin
tRNA protein synthesis - Mupirocin, puromycin
Folic acid metabolism - Trimethoprim, Sulfonamides

34

Aminoglycosides

Antibiotics contain amino sugars bonded by glycosidic linkage
Eg. Kanamycin, neomycin, amikacin

High neurotoxicity and nephrotoxicity
Reserve antibiotic

35

Macrolides

Contain lactone rings bonded to sugars
E.g erythromycin
Targets 50S subunit

36

Tetracyclines

Contain four rings
Widespread medical use in humans
Inhibits functioning 30S ribosomal subunit

37

Synthetic anti micobial

Quinolones- Inhibition of DNA gyrase
Bind the A subunit of DNA gyrase
Resistance mediated by decreased binding.

38

B - Lactam Antibiotics

Penicillins, cephalosporins and cephamycins.

39

Penicillins

Effective against gram positive
Some effective against gram negative
Target cell wall synthesis

40

Bacteriostatic

Total cell count and viable stays together

41

Bacteriocidal

Viable cell count decreases, total cell count stays the same

42

Bacteriolytic

Both total cell count and viable cell count decrease

43

Vancomycin

Inhibits cell wall biosynthesis.
Poor bioavailability
Treats C. Difficile

44

Methicillin

Inhibits cell wall biosynthesis

45

How can a bacteria have resistance

-Organism lacks structure antibiotic inhibits
Organism is impermeable to antibiotic
Organism can inactivate the antibiotic
Organism may modify the target of the antibiotic
Organism may be able to pump the antibiotic out (Efflux)

46

How can an organism inactive the antibitoic?

B lactamase (Penicillin)
Phosphorylation or adenylation (streptomycin)
Acetylation ( chloramphenicol)

47

R Plasmid

Consists of a resistance transfer factor that enables conjugation
Congtains genes conferring resistance

48

Gram positive bacteria

Low G+C known as Firmicutes
High G+C known as Actinobacteria
Lactobacillus and steptoccus, produce lattice acid
Rest have other byproducts

49

Lactobacillus - Firmicute

Lacto - Milk
Bacillus - Rod shaped
Variable size.
Used in fermented products
Eg. L. Caseii.
L. Acidophilus

50

Streptococcus - Firmicute

Strepto - Twisted chain
Coccus- Spherical/round
Medically relevent
Subdivied by haemolytic
Eg. S. Pyogenes
S. Mutans
S. Pneumoniae

51

Staphylococcus - Firmicutes

Staphyl - Grape
Coccus - Spherical/round
Medically important pathogens
Eg. S. Aureus
MRSA

52

Bacillus - Firmicute

Rod Shaped.
Endospore forming - Extreme survival
Medically important
B. Anthracis
B. Cereus - Cereals

53

Clostridium - Firmicute

Rod shaped
Endospore orming
Location of spores helps identify
Medically important
C. tetani
C. difficile - Diarrheo
C. Botulinum - Flaccid paralysis

54

Actinomyces - Actinobacteria

Facultative anaerobe
Looks like fungal hyphae
Important for soil ecology

55

Frankia - Actinobacteria

Filamentous
Carry out nitrogen fixation

56

Streptomyces - Actinobacteria

Form mycelium
Produces spores called conidia
Producer of antibiotics
Amphotericin B
Active against gram positive and negative and fungal

57

Gram negative Bacteria - Proteobacteria

Alpha
Beta
Gamma
Delta
Epsilon
Metabiolicaly diverse
Major human pathogens exhibit chemotrophy (glucose)

58

Alpha bacteria - Rhizobiales

Bradyrhizobium/ Rhizobium form symbiosis with plant and N2 fix

59

Beta Bacteria - Neisseriales

Neisseria - Diplococci
Medically important - M Meningitidis
N. Gonorrhoeae

60

Gamma - Enterobacteriales

Largest sub group. Most pathogenic
Shigella/ Salmonella - Food poisoning
Escherichia - Research tool.

61

Delta - Spirilla

Bdelloviobrio - Uses other bacteria as host

62

Epsilon - Campylobacterales

Campylobacter - Motile bacillus curved. Foodborne disease - C. Jejuni
Helicobacter - Multiple flagella. Stomach ulcers

63

How to study non culturable bacteria?

Culture independent analyses -
Fluorescent olignonucleotides that bind to specific DNA
DAPI (400nm)
Acridine orange ( 500nm)
SYBR GREEN (497nm)

FISH - Fluorescent in situ hybridisation -
Different coloured olignucleoides match different 16 S rRNA sequences

64

Ecosystems

Sum of all organisms and abiotic factors in a particular environment

65

Mutualism

Both species benefit

66

Commensalism

One species benefits while the other is neither harmed or benefited
Vitamin K in body

67

Syntrophy

Two or more organism catabolising a nutrients that can not be catabolised by one on its own

68

Species richness

Total number of species present in an ecosystem

69

Species abundance

Proportion of each species in an ecosystem

70

Marine microbial ecosystem

Archae are more suited to extreme conditions below photic zone ( 500m +)

71

Microbial ecology with plants

Legume- root nodule symbiosis
Essential in fixing nitrogen and supplying to plants - rhizobium

72

Colon composition

Firmicutes, bacteriodetes, proteobacteria

73

Role of gut mic

More methanogens in your gut = obese. Low h2 promotes fermentation = nutrients for hosts.

74

Asgard Archae

Share similar cellular systems genes with eukaryotes

75

Part of an Endospore

Exosporium, spore coat, core wall, cortex, DNA