Topic 6: prokaryotes bacteria + archaea Flashcards
(109 cards)
1
Q
Give 3 domains of life
A
1) Bacteria
2) Archaea
3) Eukarya
2
Q
What do bacteria + archaea consist of?
A
Unicellular prokaryotes
3
Q
What do eukarya consist of?
A
- Protists
- Fungi
- Plants
- Animals
4
Q
Give the prokaryotic/eukaryotic micro/macro-organisms
A
MICRO-ORGANISMS:
- Prokaryotic = archaea/bacteria
- Eukaryotic = protists/fungi
MACRO-ORGANISMS:
- Prokaryotic = not existing
- Eukaryotic = animal/plants
5
Q
What did Pasteur do?
A
- Discovered role of pathogenic bacteria in transmitting infectious disease
6
Q
What did Koch do?
A
- Discovered Vibrio cholerae = pathogen causing cholera
7
Q
What did Alexander Fleming do?
A
- Discovered penicillin
8
Q
Give examples of viral pandemics
A
- HIV/AIDS
- Flu pandemics
- Asian flu
9
Q
Give examples of bacterial pandemics
A
- Cholera
- Black death
10
Q
What bacterium caused Black death?
A
Yersinia pestis
11
Q
Describe the 1st antibiotic
A
- Discovered accidentally = mold growing killed Staphylococcus aureus
- 12 years later purified + isolated penicillin drug
12
Q
Describe the properties of prokaryotes
A
- Unicellular microorganism
- 1 prokaryotic cell
- Replicate faster than eukaryotes
- Smaller in size than eukaryotic cell
- Size = 1-10 µm
- Variable morphology
- Domains = bacteria/archaea
- Can thrive in extreme conditions
13
Q
2 types of bacteria
A
1) Eubacteria
2) Cyanobacteria
14
Q
Describe eubacteria
A
- Pathogenic bacteria = causing disease
15
Q
Describe cyanobacteria
A
- Non-pathogenic
- Have chlorophyll = photosynthesize = produce oxygen
- Live in lakes + oceans
- Role = nitrogen fixation
16
Q
Describe archaea
A
- Initially named archaebacteria = morphological similarities to bacteria
- Phylogenetic analysis = revealed molecular similarities to eukaryotes
- Live in extreme conditions
17
Q
3 types of archaea
A
1) Halophiles
2) Methanogens
3) Thermoacidophiles
18
Q
Describe halophiles
A
- In salt lakes
19
Q
Describe methanogens
A
- In digestive track
- Anaerobes
- Produce methane
20
Q
Describe thermoacidophiles
A
- Acidous + sulphur-rich hot springs
- Optimum temp = 70-80° C
- Optimum pH = 2-3
21
Q
How is the nomenclature of microorganisms?
A
- Species name = genus + characteristic property
22
Q
Types of prokaryotic morphology
A
1) Spherical shape = cocci
- Staphyloccoci + streptococci
2) Rod shape = rods
- Bacilli + E.coli
3) Spiral shape
- C/S shape = Vibrio cholerae
- Spirila + Spirochetes
23
Q
Compare prokaryotes/eukaryotes
A
PROKARYOTES:
- Smaller in size
- No nuclear membrane
- No membrane bound organelles
- No replicative cell cycle = bonary fission instead
- Different cell wall composition than eukaryotes
24
Q
Describe the function of a cell wall
A
- Maintain cell shape
- Protects cell
- Prevents cell = bursting in hypotonic environmenet
- Role in cell division
25
What is eukaryotic cell wall made out of?
- Plants = cellulose
- Fungi = chitin
26
What is bacterial cell wall made out of?
- Peptidoglcan = network of polysaccharides + polypeptides
27
What is archaea cell wall made out of?
- Polysaccharides + proteins
- No peptidoglycans
28
Define gram staining
- Technique = classify bacteria into 2 categories = based on cell wall composition
- Dye used = Crystal violet
29
Define Gram-positive bateria
- Cell walls = peptidoglycan
- Absorb crystal violet = purple
30
Define Gram-negative bacteria
- Cell wall = small amount of peptidoglycan + large amount lipopolysaccharides
- Don't absorb crystal violet = pink
31
Describe the cell wall structure of Gram-negative bacteria
- Periplasm = peptidoglycan + lipoproteins = space between inner + outer membrane
- Outer LPS membrane =
> Phospholipids = PE/PG/DPG
> Proteins = glycoproteins + lipoproteins
> LPS = lipids + sugars
32
Example of Gram-positive bacteria
- Staphylococci
- Streptococci
- Micrococci
33
Examples of Gram-negative bacteria
- Escherichia coli
- Shigella
- Salmonella
34
Describe the functional differences between Gram +/- bacteria
POSITIVE:
- Peptidoglycan wall = resistant to physical stress
- Sensitive to lysozyme + penicillin
NEGATIVE:
- Resistant to lysozyme + penicillin
- More likely to be antibiotic resistant due to LPS layer = antibiotics target peptidoglycan > damage cell wall
35
Describe the capsule
- Polysaccharide/protein layer = covers some prokaryotes
- External of cell wall
- Increased virulence
36
Define virulence
- Ability of infectious agent > produce disease
- Measure of severity of disease
37
Describe the function of the capsule
- Protect from phagocytosis by leukocytes
- Protects from digestion by phagocytosis
- Protects from infection by phages + drying
38
Define fimbriae
- 1-400 per bacterium
- Attach to bacteria/other cells that they infect
39
Define sex pili
- Fimbriae longer than regular = allow prokaryotes to exchange DNA
40
Define conjugation
- Transfer genetic material between cells via sex pili
- Unidirectional = 1 cell gives + other cell receives
- For plasmid transfer
41
Define plasmids
- Small + circular + extrachromosomal DNA
- Carry genes responsible for antibiotic resistance
- Donor cell attaches to recipient via pilus = transfers DNA
42
Types of plasmids
1) R plasmids = antibiotic resistance
2) F plasmids = production of pili = bacteria with pili act as donors
43
Describe antibiotics
- Drugs used to kill microorganisms
- Cannot kill non-cellular pathogens = viruses = not treat cold/flu
- R plasmids = resistant to certain antibiotics
44
Describe antibiotic resistance
- Natural selection = favor bacteria with resistance gene in population exposed to antibiotics
- Treatment of bacterial infections = harder
- Antibiotics should only be used when necessary
- E.g. MRSA = methicillin resistant staphylococcus aureus
45
Define taxis
- Ability of bacteria to move toward/awaay from stimulus
46
Define chemotaxis
- Move towards/away from chemical stimulus
47
Give the prokaryotic motility structures
1) Flagella = most bacteria
2) Axial filaments = Spirochetes
3) Polysaccharide fibes = Flexibacter polymorphus
48
Describe the flagella
- Types of movement = CW/CCW rotation
- Structure = helical protein filaments
- Size = 3-12 μm long + diameter 0.02 μm
- 1-100 per bacteria
49
Types of bacteria based on flagella location
1) Monotrichous = 1 flagellum = Vibria
2) Lophotrichous = multiple flagella on 1 end = Spirilla
3) Amphitrichous = single on 2 opposite ends
4) Peritrichous = multiple in all directions = E.coli + Clostridium parabotulinum
50
Parts of the structure of flagella
1) Motor
2) Hook
3) Filament
51
Describe the motor
- Rotation of flagellum
- Location = cell wall + plasma membrane
- Energy for rotation = from proton motive force
52
Describe the hook
- Location = outside cell wall
53
Describe the filament
- Subunits of protien flagellin
- CW/CCW rotation
54
Describe the axial filaments
- Location = lengthwise between plasma memebrae + outer membrane
- Movement = twisting motion = snake like
55
Describe polysaccharide fibers
- Movement = crawling/sliding
- E.g. Flexibacter polymorphus
56
Describe the cytoplasmic/plasma membrane
- Composition = phospholipids + proteins
- Selectively permeable
57
Give the phospholipds that are part of cytoplasmic membrane
- Phosphatidyl-glycerol (PG)
- Phosphatidyl-ethanolamine (PE)
- Phosphatidic acid (PA)
- Diphosphatidyl-glycerol (DPG)
58
Describe the internal organization in prokaryotic cells
- Lack complex compartmentalization
- No membrane-bound nucleus/organelles
- Have mesosomes
59
Describe mesosomes
- Infoldings of membrane
- Specialized to perform metabolic functions
- Function:
> Cellular respiration in aerobic prokaryotes
> Photosynthesis in cyanobacteria
> Forms diaphragm in cytokinesis
60
Describe prokaryotic ribosomes
- RNA + proteins
- Function = protein synthesis
- Different subunits than eukaryotes = 30S + 50S
61
How does tetracycline work?
- Inhibits bacterial ribosomes without inhibiting human ribosomes
62
Define polysome
- Ribosome + mRNA
63
Describe nucleoid + prokaryotic chromosomes
- Region containing prokaryotic chromosomes = double stranded circular DNA
- No nuclear membrane
- Smaller than eukaryotic genome
- No histones
- Supercoiled DNA to fit into nucleoid
64
Define bacteriophages
- Viruses that infect bacteria = have DNA genome
65
Explain how endospores are formed
- Prokaryotes that are sporogenic
- Under harsh conditions
66
Describe endospores
- Metabolically inactive
- Viable for years
- Resistant to temp/dryness/UV light/enzymes/chemicals/drugs
- Can grow back to prokaryotic cell when back in optimal conditions
- E.g. Bacilli + Clostridia
67
Describe the structure of endospores
1) Cytoplasmic membrane
2) Cortex
3) Coat
4) Exospore
68
Key features of prokaryotic reproduction
- Quickly via binary fission
- Short generation time = every 1-3 hrs = allows rapid evolution
69
Factors for genetic diversity
1) Rapid reproduction
2) Mutation
3) Genetic recombination
70
Define genetic recombination
- Combination of DNA from 2 sourcees
71
Define horizontal gene transfer
- Movement of genes among individuals of different species
72
Give the ways different DNA is combined
1) Transformation = uptake + incorporation of foreign DNA by cells from their surroundings
2) Transduction = exchange of DNA between bacterias via bacteriophages
3) Conjugation = transfer of genetic material between cells in direct contact via sex pili
73
4 energy-based prokaryote groups
1) Phototrophs = energy from light
2) Chemotrophs = energy from chemicals
3) Autotrophs = CO2 as carbon source
4) Heterotrophs = organic nutrient carbon source
74
4 nutrition-based prokaryote groups
1) Photoautotrophs
2) Chemoautotrophs
3) Photoheterotrophs
4) Chemoheterotrophs
75
3 oxygen metabolism-based prokaryote groups
1) Obligate aerobes = require O2 for cellular respiration
2) Obligate anaerobes = poisoned by O2 + fermentation of anaerobic respiration
3) Facultative anaerobes = survive with/without O2
76
Describe the use of nitrogen
- Essential to produce amino/nucleic acids
- Prokaryotes can metabolize nitrogen in many ways e.g. nitrogen fixation = N2 atmosphere> NH3 ammonia
77
Define phylogenetic taxonomy
- Study of evolutionary relationships among groups of organisms
- Using molecular sequencing + morphological data
78
What is the application of molecular systematics in prokaryotic phylogeny investigation?
- Splitting of prokaryotes into = bacteria + archaea by molecular sequencing data
79
Define PCR
- Polymerase chain reaction = rapid sequencing of prokaryotic genomes
- Reveals new groups of archaea
80
5 Major groups of bacteria
1) Proteobacteria
2) Cyanobacteria
3) Chlamydia
4) Spirochetes
5) Gram-positive
81
Describe proteobacteria
- Gram-negative bacteria
1) Alpha
2) Beta
3) Gamma
4) Delta
5) Epsilon
82
Describe alpha proteobacteria
- Many species symbiotic
- Endosymbiotic theory = mitochondria evolved from aerobic alpha via endosymbiosis
- E.g. Rhizobium = form root nodule in legumes + fix atmospheric N2
- E.g. Agrobacterium = form tumors in plants + used in genetic engineering
83
Describe beta proteobacteria
- Pathogenic
- E.g. Neisseriae
1) Neisseria meningitidis = meningococcus = causes meningococcal meningitis
2) Neisseria gonorrhoeae = gonococcus = causes gonococcal urethritis = gonorrhea STD
- E.g. Bordetella pertussis = causes whopping cough
84
Describe gamma proteobacteria
- Pathogenic bacteria = Legionella +Salmonella + Vibrio cholerae
- Opportunistic pathogens = Escherichia coli
85
Describe E.coli
- Location = intestines = part of normal flora + not normally pathogenic
- Opportunistic infections in immunosuppressed patients
- Some strains = haemorrhagic diarrhoea
86
Describe vibrio cholerae
- Causes cholera
- Symptoms = prolonged diarrhoea = 5-15
- Transmission = contamination + non-chlorinated water in undeveloped countries
- Toxin production = dehydration + death
87
Describe delta proteobacteria
- No pathogenic species
- E.g. slime-secreting myxobacteria = soil decomposers
88
Describe epsilon proteobacteria
- Many pathogens
- E.g. Campylobacter = food poisoning + blood poisoning
- E.g. Helicobacter pylori = gastritis + stomach ulcers + gastric cancer
89
Describe chlamydias
- Obligate parasites = live within animal cells
- Chlamydia trachomatis = causes non-gonococcal urethritis = STD
90
Describe spirochetes
- Spiral shaped
- Some parasites
- E.g. Treponema pallidum = syphilis = STD
- E.g. Borrelia burgdorferi = Lyme disease = via ticks
- E.g. Leptospira = leptospirosis + jaundice + kidney infections = via zoonosis/rodents
91
Describe cyanobacteria
- Photoautotrophs = make O2 via photosynthesis
- Endosymbiotic theory = chloroplasts evolved from cyanobacteria via endosymbiosis
92
Describe Gram-positive bacteria
- Pathogenic species
1) Actinobacteria = Actinomycetes: soil decomposers + causes cutaneous infections
2) Bacillus anthracis: causes anthrax
3) Corynebacterium diphtheria: causes diphtheria
4) Clostridium botulinum: causes botulism
5) Clostridium tetani: causes tetanus
6) Several types of Staphylococcus/Streptococcus = Staphylococcus aureus + Streptococcus pneumoniae
7) Mycobacteria = Mycobacterium tuberculosis + Mycobacterium leprae
8) Mycoplasmas: the smallest known cells = no cell wall
93
Describe clostridium botulinum
- Contaminates improperly canned food
- Produces = neurotoxin = botulinum = botox = causes botulism
- Causes = paralysis via inhibiting release of neurotransmitter acetylcholine at synaptic cleft
- Causes death = respiratory muscle failure
94
Describe clostridium tetani
- Symptoms = convulsive muscle spasm + paralysis
- Cause = toxin production = fatal if untreated
- Transmission = via break in skin by contaminated object
95
Describe corynebacterium diphtheriae
- Upper respiratory tract
- Symptoms = pseudomembrane = dead tissue in pharynx + trachea
- Toxins = inhibit protein synthesis = organ damage
96
Describe mycoplasmas
- E.g. Mycoplasma hominis + Ureaplasma urealyticum
- Causes = non-gonococcal urethritis
97
Explain why mycobacteria + mycoplasmas not Gram bacteria
- Both phylogenetically Gram+ BUT structurally neither
- Both don't absorb crystal violet
- Mycoplasmas = no cell wall so cannot be classified via wall
- Mycobacteria AKA acid fast G+ bacteria = lipid rich cell wall = no LPS for gram bacteria classification
- Other dyes used = methylene blue
98
Describe archaea
- Morphologically resemble bacteria
- Share traits between bacteria/eukaryotes
99
Types of archaea
1) Halophiles = highly saline environments
2) Thermophiles = very hot environments
3) Methanogens = live in extreme conditions = swaps + marshes + digestive track
- Methane waste product
- Obligate anaerobes = poisoned by oxygen
100
What is the role of prokaryotes in biosphere?
1) Chemical recycling
2) Ecological interaction
101
Explain chemical recycling
- Between living + non-living components of ecosystem
- Decomposers = chemoheterotrophic prokaryotes = breakdown dead organisms + waste products
- Increase availability of N2 + phosphorus + potassium = for plant growth = fertilizers
102
Explain ecological interactions
- Symbiosis: 2 species live in close contact
- Host = larger organism
- Symbiont = smaller organism
- Prokaryotes form symbiotic relationships
1) Mutualism: both benefit
2) Commensalism: 1 benefits with neither harmed + other not benefitting
3) Parasitism: parasite harms NOT kills host
103
Describe beneficial prokaryotes
- Mutualistic bacteria
- Part of normal flora
- 500-1000 species in human intestines
- Function = breakdown food that is undigested by intestines + own enzymes
104
Describe pathogenic bacteria
- Cause 50% all human diseases
- Disease caused by = toxins released = exotoxins + endotoxins
- Horizontal gene transfer can spread genes associated with virulence
- Some potential weapons of bioterrorism
105
Describe exotoxins
- Product of bacterial metabolism
- Will cause disease even if prokaryote not present
- By Gram+ bacteria
106
Describe endobacteria
- Released when bacteria die via phagocytosis + cell wall LPS of Gram- breakas down
107
Give the common pathogenic bacterial species
* Staphylococcus aureus: causes toxic shock
syndrome + food poisoning + gastroenteritis + pneumonia
- MRSA= methicillin-resistant strain of St. aureus
* Streptococcus pneumoniae = pneumococcus: causes pneumococcal meningitis
* Bacillus cereus: causes food poisoning
+ gastroenteritis
* Neisseria meningitidis = meningococcus: causes meningococcal meningitis
* Νeisseria gonorrhoeae = gonococcus: causes gonorrhea STD
* Escherichia coli = E.coli: opportunistic infections
* Mycobacterium tuberculosis: causes tuberculosis
* Mycobacterium leprae: causes leprosy
108
Symptoms of TB
- Lung infection = chronic cough + blood sputum
109
Explain the use of prokaryotes in research + technology
- Used in DNA engineering = E.coli in gene cloning + Agrobacterium tumefaciens used to produce transgenic plants = GMOs
- Bacteria genetically engineered = to produce vitamins + antibiotics + hormones = insulin production
