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MED-109 Biology II ✅ > Topic 6: Prokaryotes ✅ > Flashcards

Topic 6: Prokaryotes ✅ Flashcards

1
Q

3 domains of life

A

Bacteria
Archaea
Eukarya

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2
Q

Eukarya kingdoms

A

Protists
Fungi
Plants
Animals

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3
Q

Where do you find unicellular prokaryotes?

A

Domain Bacteria and Domain Archaea

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4
Q

Prokaryotic Microorgnisms

A

Archaea
Bacteria

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5
Q

Eukaryotic microorganisms

A

Protists
Fungi

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6
Q

Prokaryotic macroorganisms

A

Don’t exist

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7
Q

Eukaryotic macroorganisms

A

Animals
Plants

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8
Q

Micro-organisms definition

A

Microscopic organisms

Consist of either 1 cell (unicellular) or a group of cells (multicellular)

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9
Q

Microorganism categories

A

Bacteria
Archaea
Protists
Fungi
Viruses

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10
Q

Unicellular prokaryotic microorganisms

A

Bacteria

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11
Q

Unicellular prokaryotic microorganisms

A

Archaea

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12
Q

Eukaryotic microorganisms

A

Protists
Eg Protozoa, algae

Fungi
Eg yeasts, mushrooms

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13
Q

Non-cellular pathogens

A

Viruses

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14
Q

What do pathogenic micro-organisms cause?

A

Infectious diseases

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15
Q

Pasteur’s relevance

A

1870

-discovered role of pathogenic bacteria in transmission of infectious diseases

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16
Q

Koch’s relevance

A

1892

-discovered Vibrio cholarae as the pathogen that causes cholera

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17
Q

Which pathogen causes cholera?

A

Vibrio cholerae

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18
Q

Alexander Fleming’s relevance

A

1929

-Discovered the antibiotic penicillin

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19
Q

Examples of outbreaks of pandemics that were viral

A

HIV

Flu pandemic

Asian Flu

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20
Q

Examples of bacterial pandemic outbreaks

A

6th cholera pandemic

Black death

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21
Q

What pathogen caused the plague (aka the Black Death)?

A

Yersinia pestis bacterium

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22
Q

How did Fleming make his discovery?

A

Accidentally discovered a mold growing in his lab

-it was capable of killing the bacterium “staphylococcus aureus”

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23
Q

Ernest Chain and Howard Florey relevance

A

1940ish

Purify and isolate penicillin from its mold

-> life-saving drug

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24
Q

Quarantine word origin

A

From phrase quarantina giorni meaning 40 days

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25
Q

Prokaryotes size relative to eukaryotes

A

Smaller

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26
Q

Domain bacteria categories

A

Eubacteria: includes pathogenic bacteria

Cyanobacteria: non-pathogenic, have chlorophyll & perform photosynthesis

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27
Q

Where do Cyanobacteria live?

A

Lakes, oceans etc

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28
Q

Cyanobacteria role in..

A

In nitrogen fixation

->ie converting nitrogen to ammonia

Also, have chlorophyll and perform photosynthesis ->produce oxygen

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29
Q

Where do archaea live?

A

Extreme conditions

-Halophiles in stately lakes

-Methanogens (anaerobes, produce methane) in digestive track

-Thermoacidophiles in acidous, sulphur-rich hot springs (optimum: 70-80 C, pH 2-3)

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30
Q

Taxonomy

A

Classification of living organisms

Dirty Kevin Periodically Calls Out For Gay Sex

-domain
-kingdom
-phylum
-class
-order
-family
-genus
-species

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31
Q

After Species in taxonomy

A

Subspecies

Variety

Strain (in bacteria)

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32
Q

Binomial Nomenclature

A

Carolus Linnaeus
1707-1778

Species name: genus + characteristic property

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33
Q

Prokaryotic cell size

A

1-10 micro-meter

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34
Q

Eukaryotic cell size

A

10-100 micro-meters

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35
Q

Variable morphology

A

Variety of shapes

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36
Q

Morphology of prokaryotes

A

Spherical shape (cocci) eg staphylcocci, streptococci)

Rod-shaped (rods) eg bacilli (eg E. Coli)

Spiral shape eg vibrio cholerae (C or S shape), Spirilla and Spirochetes

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37
Q

Difference between prokaryotic and eukaryotic cells

A

Prokaryotic:
-smaller

-no nuclear membrane

-no membrane-bound organelles (eg mitochondria, chloroplasts)

-no organized replicative cell cycle (mitosis)

-replicate by binary fission

-cell wall has different composition

-nucleoid, cell wall, cytoplasm, cytoplasmic membrane etc)

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38
Q

Cell wall function in prokaryotes

A

-maintain cell shape

-protects the cell

-prevents cell from bursting in hypotonic environment (osmotic pressure)

-role in cell division

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39
Q

Eukaryotic cell wall composition

A

-Cellulose (plant cells)

Or

-Chitin (fungi)

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40
Q

Bacterial cell walls contain?

A

Peptidoglycan

-a network of polysaccharides and polypeptides

(NAM, NAG, OLIGOPEPTIDE CHAIN AND GLYCINE RESIDUES)

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41
Q

Archaea cell walls contain?

A

Polysaccharides and proteins but not peptidoglycan

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42
Q

Gram staining

A

Staining technique

-used to classify bacteria in 2 major categories (based on cell wall comparison)

Crystal violet dye used

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43
Q

Gram positive bacteria

A

Cell wall consists of mostly peptidoglycan

-absorb crystal violet =>purple colour

44
Q

Gram negative bacteria

A

Cell walls consist of a small amount of peptidoglycan and large amount of lipopolysaccharides (LPS)

-don’t absorb crystal violet=> pink colour

45
Q

Examples of gram+ bacteria

A

Staphylococci
Streptococci
Micrococci

46
Q

Gram+ cell wall structure

A

In peptidoglycan:
-blocky pieces: wall-associated protein
-short & skinny: teichoic acid

47
Q

Gram- bacteria cell wall structure

A

Peptidoglycan and outer LPS membrane

48
Q

Periplasm

A

Peptidoglycan and lipoproteins

Space between inner and outer membrane

49
Q

Gram(-) examples

A

E. Coli, shigell, salmonella

50
Q

Difference between gram+ and gram-

A

(+)
-peptidoglycan cell wall
=>resistant to physical stress
=>sensitive to lysozyme and penicillin

(-)
-outer lipopolysaccharide layer
=>resistant to lysozyme and penicillin
=>many antibiotics (eg penicillin) target the peptidoglycan and damage bacterial cell walls
=>gram(-) bacteria are more likely to be antibiotic resistant

51
Q

Capsule

A

Only on some

Polysaccharide or protein layer that covers some prokaryotes on external of cell walls

Associated with the increased virulence of pathogenic bacteria

52
Q

Virulence

A

Severity to cause disease

53
Q

Capsule function

A

Protects from:

-phagocytosis by leukocytes

-from digestion upon phagocytosis

-from infection by phases and drying

54
Q

Fimbriae

A

Only some have 1-4000 per bacterium

Function is attachment of bacteria to each other or to other cells that they infect

55
Q

Sex pili

A

Special type of fimbriae (longer than regular) that allow prokaryotic DNA exchange

56
Q

Conjugation

A

Genetic material transfer between prokaryotic cells through sex pili

Unidirectional process- one cell gives the DNA the other cell receives

-used for plasmid transfer from one bacterium to the other

The donor cell attaches to a recipient by a pilus, pulls it closer and transfers DNA

57
Q

Plasmids

A

Small circular extrachromosomal DNA molecules

Some carry genes responsible for antibiotic resistance (R plasmids)

58
Q

F plasmid

A

Required for the production pili

Bacteria that have it act as DNA donors

59
Q

R plasmids

A

Carry genes for antibiotic resistance

Bacteria with specific R plasmids are resistant to certain antibiotics

Natural selection favors genes for resistance in population exposed to antibiotics

Antibiotic-resistant strains of bacteria are becoming more common

60
Q

Motility of prokaryotes

A

Taxis: ability of bacteria to move toward or away from a stimulus

Chemotaxis: movement toward or away from a chemical stimulus

Prokaryotic motility structures:
-flagella (most bacteria)
-axial filaments (in spirochetes)
-polysaccharides (in flexibacter polymorphus)

61
Q

Flagella

A

Bacterial motility structure

May be scatter or concentrated on end(s)

Flagella do Bacteria, Archaea and Eukaryotes are composed of different proteins

Movement type: rotation- CW or CCW

62
Q

Category of bacteria depending on location of flagella

A

Monotrichous: 1, eg vibria

Lophotrichous: multiple at 1 end, eg Spirilla

Amphitrichous: single on either end

Peritrichous: multiple flagella projecting in all directions, eg E. Coli, Clostridium Parabotulinum

63
Q

Prokaryotic flagellum structure

A
  1. Motor: responsible for rotation
    -located within cell wall and plasma membrane
    -energy for rotation comes from proton motive force (H+ pump)
  2. Hook: located just outside of cell wall
  3. Filament: subunits of the protein flagellin, CW or CCW rotation
64
Q

Axial filaments

A

In spirochetes

Twisting motion like a snake

In periplasmic space

65
Q

Semipermeable membrane

A

Has phospholipids and proteins like eukaryotes

66
Q

Internal organisation and DNA

A

Prokaryotic cells lack membrane-bound organelles

Have mesosomes
-infoldings of plasma membrane
-specialized membranes that perform metabolic functions in some prokaryotes

Function:
-cellular respiration (in aerobic prokaryotes) or photosynthesis (in cyanobacteria)
-formation of diaphragm during cytokinesis

67
Q

Prokaryotic ribosomes

A

RNA + mRNA

Function is protein synthesis

Prokaryotic ribosomes consist of different subunits than eukaryotes
30S (small subunit) and 50S (large) subunits

->antibiotics like tetracycline inhibit bacterial ribosomes without inhibiting human ribosomes

68
Q

Nucleoid

A

Region that contains prokaryotic chromosomes lacking nuclear membrane

69
Q

Polysome

A

Ribosomes + mRNA

70
Q

Prokaryotic chromosome

A

Double-stranded circular DNA molecule

Smaller than eukaryotic genome

-absence of histones
-supercoiled to fit the nucleoid region

Prokaryotes may contain extra-chromosomal regions:
-plasmids
-bacteriophages

71
Q

Plasmids

A

Small circular DNA molecules (R plasmids)

72
Q

(Bacterio)phages

A

Viruses that infect bacteria (have DNA genome)

73
Q

Endospores

A

Sporogenic prokaryotes have the ability to form endospores

Formed under harsh conditions (very high or low temp or dry environment)

Resistant to temp, dryness, UV light, enzymes, chemicals and drugs

Can grow back yo prokaryotic (vegetative) cell once in optimal conditions

74
Q

Eg of sporogenic bacteria

A

Bacilli

Clostridia

Bacillus Atrhus

75
Q

Prokaryote groups based on nutrition

A

Based on energy and carbon source

Phototrophs, chemotrophs, autotrophs, heterotrophs

76
Q

Chemotrophs

A

Obtain energy from chemicals

Chemoautorophs:
-energy source= inorganic chemicals (eg H2S, NH3, FE2+
-carbon source= CO2, HCO3- ETC
-Certain prokaryotes (eg purple-sulphuric bacteria)

Chemoheterotrophs:
-organic compounds
-organic compounds
-many prokaryotes (eg Clostridium) and protists; fungi, animals, some plants

77
Q

Prokaryotic cell structure

A

Cell wall: protect from mechanical damage and osmotic pressure

Cell plasma membrane: semi-permeable so controls what enters ands exits

Capsule (only some): protects bacteria from phagocytosis/ digestion/ drying

Fimbriae (only some): attach bacteria to each other or to host

Sex pili (some): allows prokaryotes to exchange DNA

Flagella (some): motility

Nucleoid: where bacterial chromosome is found

78
Q

Genetic recombination

A

Combination of DNA from 2 sources

Contributes to genetic diversity

79
Q

Horizontal gene transfer

A

Movement of genes among individuals from different species

=>prokaryotic DNA from different individuals can be brought together by

80
Q

Transformation

A

Uptake and incorporation of foreign DNA by prokaryotic cells from their surroundings

81
Q

Transduction

A

Exchange of DNA between bacteria mediated by bacteriophages (viruses that infect bacteria)

82
Q

Conjugation

A

Transfer of genetic material between prokaryotic cells in direct contact

Through six pili

83
Q

Binary fission

A
  1. Chromosome replication begins
    -one copy of the origin moves rapidly towards the other end of the cell
  2. Replication continues
    -one copy of the origin is at each end of the cell
  3. Replication finishes
    -plasma membrane grows inward, new cell wall is deposited
  4. Two daughter cells result
84
Q

Oxygen metabolism

A

Prokaryotes categorized based on ability to metabolize gas

Obligate aerobes
Obligate anaerobes
Facultative anaerobes

Nitrogen is essential

85
Q

Major groups of bacteria

A

Phyla

  1. Protebacteria
  2. Chlamydia
  3. Spirochetes
  4. Cyanobacteria
  5. Gram-positive bacteria (the rest are neg)
86
Q

Group 1

A

Gram(-)

5 subcategories: Alpha, Beta, Gamma, Deta, Epsilon.

Only EPSILON is fully pathogenic, rest have environmental roles

87
Q

Alpha Proteobacteria

A

Subgroup

Many perform symbiosis aka are closely associated with eukaryotic hosts

Mitochondria have evolved from aerobic alpha-proteobacteria through endosymbiosis

88
Q

Beta proteobacteria

A

Non-pathogenic and pathogenic

Pathogenic= Neisseria morphology (diplococci)

-Neisseria meningitidis (meningococcus): causes meningococcal meningitis

-Neisseria gonorrhea (gonococcus): causes gonoccocal urethritis (gonnorrhea STD)

-Bordetella pertussis: causes whooping cough (pertussis)

89
Q

Diplococci

A

2 spheres in a gram strain

90
Q

Gamma proteobacteria

A

Pathogenic: Legionella, salmonella (rod shaped (EM) and Vibrio Cholera

Opportunistic pathogens: Escherichia Coli is normally part of intestinal flora but it can cause opportunistic infections in immunosuppressed individuals (AIDS)

Vibrio cholera: causes cholera due to toxin production (enterotoxin) -> dehydration then death
-symptoms: prolonged diarrhoea (5-15 days)
Transmitted via contaminated, non-chlorinated water in underdeveloped countries

91
Q

Delta proteobacteria

A

Subgroup

Non pathogenic

92
Q

Epsilon proteobacteria

A

Pathogenic subgroup

Campylobacter: causes food poisoning (complications: blood poisoning)

Helicobacter pylori: causes stomach ulcers and gastric cancer, gastritis

93
Q

Chlamydias

A

Obligate parasites that live in animal cells

Chlamydia trachomatis: causes non-gonococcal urethritis (sexually transmitted disease), if prolonged; scarring of Fallopian tubes ->infertility

94
Q

Spirochetes

A

Leptospirosis

Spiral-shaped bacteria

Borrelia burgdorferi: causes Lyme disease

Treponema pallidum: causes syphilis (STD)

Symptoms of leptospirosis:
-zoonosis: if transmitted by animals (rodents)
-jaundice due to liver infection
-kidney infection

95
Q

Cyanobacteria

A

Non-pathogenic

Endosymbiotic theory: chloroplasts likely evolved from Cyanobacteria by endosymbiosis

96
Q

Gram(+) bacteria

A

Includes several pathogenic species:

-Actinobacteria (Actinomycetes): soil decomposers, cause cutaneous infections

-Bacillus anthracis: causes anthrax (rod and chain morphology)

-Corynebacteriuim diphtheriae: causes diptheria

-Clostridium botulinum: causes botulism (contaminates improperly canned food)

-Clostridium tetani: causes tetanus

-several Staphylococcus and Streptococcus species (eg Staphylococcus aureus, Streptococcus pneumoniae)

-Mycobacteria: Mycobacterium tuberculosis and Mycobacterium leprae

-Mycoplasmas: smallest known cells (no cell wall)

97
Q

Clostridium botulinum

A

Contaminates improperly canned food

Produces the neurotoxin Boulinum toxin (botox)=> causes botulin

Causes paralysis by inhibiting the release of the neurotransmitter acetylcholine at the neuromuscular junction synaptic cleft

Death due to respiratory muscular failure

98
Q

Clostridium tetani

A

Causes tetanus (Greek for stretch)

Symptoms: convulsive muscle spasms (convulsions of skeletal muscle) and paralysis

Due to toxin, can be fatal if untreated

Transmission: bacteria enter through a break in the skin (cut/puncture wound) by a contaminated object

99
Q

Corynebacterium diptheriae

A

Causes diphtheria, a serious upper respiratory tract infection

Characteristic symptoms: Pseudomembrane formation in the pharynx, trachea etc

Diphtheria toxin inhibits protein synthesis (translations) =>cell/tissue and organ damage

100
Q

Mycoplasmas

A

Gram(+) bacteria

Mycoplasma hominis and Ureaplasma urealyticum

Causes non-gonococcal urethritis

101
Q

Mycobacteria and mycoplasmas

A

Both genera include species that are phylogenetically Gram+ but structurally neither gram+ or gram(-) according to the wall

They dont absorb the crystal violet dye

102
Q

Mycoplasmas explanation

A

Don’t have a cell wall so can’t be classified as gram- or + according to the wall

103
Q

Mycobacteria explanation

A

Have a unique lipid-rich (waxy) cell wall

->don’t have LPS outer layer that gram(-) bacteria have

Classified as acid-fast gram+ bacteria due to their lack of an outer LPS layer

Use other dye types like methylene blue to stain

104
Q

Prokaryotes roles in biosphere

A

Chemical recycling

Ecological interactions:
-symbiosis: ecological relationship in which 2 species live in close contact

Types of symbiotic relationship:
-mutualism: both benefit

-commensalism: one benefits while neither harming/helping the other

-parasitism: organism called a parasite harms but doesn’t kill its host
=>parasites that cause diseases are called pathogens

105
Q

Beneficial prokaryotes

A

Mutualistic bacteria

Part of our normal flora

Many break down food that is undigested by our intestines (can’t be digested by our enzymes)

106
Q

Horizontal gene transfer

A

Some pathogenic bacteria are potential weapons of bioterrorism (eg Bacillus athracis)

107
Q

Prokaryotes in DNA technology

A

Engineering

E. Coli used in gene cloning

-Agrobacterium tumefaciens: used to produce transgenic plants (GMOs)

Bacteria can be genetically engineered to produce vitamins, antibiotics, and hormones (eg insulin production)

MED-109 Biology II ✅ (9 decks)

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