T6 Prokaryotes + Lab blood cell types Flashcards
(95 cards)
1
Q
Prokaryotic microorganisms (2):
A
Archaea
Bacteria
2
Q
Eukaryotic microorganisms (2):
A
Protists
Fungi
3
Q
Eukaryotic macroorganisms (2):
A
Animals
Plants
4
Q
Infectious disease control due to (2 factors):
A
- discovery of antibiotics
- vaccination
5
Q
2 major categories of domain Bacteria:
A
Εubacteria: includes pathogenic bacteria
Cyanobacteria: non-pathogenic;
- have chlorophyll and perform photosynthesis
- live in lakes, oceans, etc
- role in nitrogen fixation (conversion of nitrogen into ammonia => used by the plants)
6
Q
Domain Archaea:
A
extremophiles = live in extreme conditions:
Halophiles -> salty lakes
Methanogens -> digestive tract, anaerobes, produce methane
Thermoacidophiles -> acidous, sulphur rich hot springs w/ optimum temperatures of 70-80° C and pH=2-3
7
Q
Structural & functional properties of prokaryotes (4):
A
- Earth’s first organisms
- unicellular, but some spps can form multicellular colonies
- Prokaryotic cell size: 1–10 µm (vs eukaryotic cells: 10–100 µm)
- Variable morphology: a variety of shapes
8
Q
Morphology of Prokaryotes (3):
A
- Spherical shape (cocci): Staphylococci, Streptococci
- Rod-shaped (rods): bacilli (e.g. E.coli)
- Spiral shape:
- e.g. Vibrio cholerae: shape C or S
- e.g. Spirilla and Spirochetes
9
Q
Differences between prokaryotic and
eukaryotic cells (5):
A
- Smaller in size
- Absence of nuclear membrane
- Absence of membrane-bound organelles
- No organised replicative cell cycle (mitosis), replicate by binary fission instead
- Their cell wall has a different composition (neither chitin nor cellulose)
10
Q
Essential (black, 4) and non-essential (blue, 4) organelles of procaryotic cell (fig)
A
- cell wal: external of PM
- nucleoid - region w/ single circular chromosome
- capsule - externally of cell wall
- fimbriae: look like ciliae, but COMPLETELY DIFF FUNCTION - not for motility, but for attaching bacteria to wall of the cells to infect
- sex pili (pilus): conjugation b/w 2 bacteria
- flagella - as in eukaryotes - f/ cell motility
11
Q
Prokaryotic cell wall funtions (4)
A
- maintains cell shape
- protects the cell
- prevents cell from bursting in a hypotonic environment (osmotic pressure)
- role in cell division
12
Q
Prokaryotic cell wall vs Eukaryotic cell walls
A
Eu: made of cellulose (plant cells) or chitin (fungi)
Bacteria: contains peptidoglycan - network of polysaccharides and polypeptides (NAG, NAM, oligopeptide chains, glycine residues as bridges)
Archaea: contain polysaccharides and
proteins but lack peptidoglycan
13
Q
Gram staining -
A
staining technique used to classify bacteria in 2 major categories based on cell wall composition
- the crystal violet dye used for staining (violet colour)
14
Q
Gram-positive bacteria:
A
Their cell walls mainly consist of peptidoglycan => they absorb crystal violet => purple (violet) colour
exs: Staphylococci, Streptococci, Micrococci
15
Q
Gram-negative bacteria:
A
Their cell walls consist of a small amount of peptidoglycan and large amount of lipopolysaccharides (LPS) => do not absorb crystal violet, b/c outer layer of LPS prevents them => pink colour
SO:
composition of cell wall: peptidoglycan + outer lipopolysaccharide (LPS) membrane, periplasm - Peptidoglycan + lipoproteins - space between inner and outer membrane
composition of outer LPS membrane:
- phospholipids (PE, PG, DPG)
- proteins: glycoproteins, lipoproteins
- lipopolysaccharides (LPS) = lipids + sugars
exs: Escherichia coli, Shigella, Salmonella
16
Q
Functional differences between Gram (+)
and Gram (-) bacteria
A
Gram (+) bacteria: peptidoglycan cell wall
- Resistant to physical stress
- Sensitive to lysozyme and penicillin (targets transpeptidase - enzyme that synthesises peptidoglycan => destroys bacterial cell wall)
Gram (-) bacteria: outer lipopolysaccharide layer
- Resistant to lysozyme and penicillin class antibiotics
Many antibiotics (e.g. penicillin) target the
peptidoglycan and damage bacterial cell walls => Gram-negative bacteria are more likely to be antibiotic resistant
17
Q
Capsule -
A
polysaccharide or protein layer that covers some prokaryotes, on the external side of the cell wall
it is associated w/ increased virulence of pathogenic bacteria
18
Q
Virulence -
A
ability of an infectious agent to produce disease => it is a measure of the severity of the disease it causes
19
Q
Capsule function (3)
A
- Protects bacteria from phagocytosis by leukocytes
- Protects bacteria from digestion upon phagocytosis
- Protects them from infection by phages and drying
20
Q
Fimbriae (pili)
A
- Some prokaryotes have fimbriae
- Number: 1-400 per bacterium
21
Q
Fimbriae function:
A
- attachment of bacteria to each other or to other cells that they infect
Sex pili: special type of fimbriae (longer than regular fimbriae) - allow prokaryotes to exchange DNA
22
Q
Conjugation -
A
transfer of genetic material between
prokaryotic cells through the sex pili, unidirectionally: one cell gives the DNA and the other cell receives (donor cell attaches to a recipient by a pilus, pulls it
closer, and transfers DNA); it is used for plasmid transfer from one bacterium to the other
23
Q
Plasmids -
A
small circular extrachromosomal DNA
molecules
24
Q
R plasmids
A
plasmids that carry genes responsible for
antibiotic resistance => bacteria with specific R plasmids are resistant to certain antibiotics.
Natural selection favours the bacteria carrying genes for resistance in a population exposed to antibiotics => Antibiotic-resistant strains of bacteria are becoming more common (ex: MRSA - methicillin resistant staphylococcus aureus) => Treatment of bacterial infections becomes harder => Antibiotics should only be used when truly necessary
25
F plasmid
plasmid required for the production of pili => the bacteria that have it act as DNA donors
26
Antibiotics -
drugs used to kill both prokaryotic and eukaryotic microorganisms (including bacteria), they cannot kill non-cellular pathogens such as viruses
27
Taxis -
ability of bacteria to move toward or away from a stimulus;
***chemotaxis*** - movement toward or away from a chemical stimulus
28
Prokaryotic motility structures (3):
- **Flagella** (most bacteria)
- **Αxial filaments** (in *Spirochetes*)
- **Polysaccharide fibers** (in *Flexibacter polymorphus*)
29
Flagella in euk / prok, fn:
- in eukaryotes 1 flagellum, consists of tubulin
- Helical protein filaments, 3-12 μm long, 0.02 μm in diameter
- 1-100 flagella per bacterium, may be scattered about the surface or concentrated at one / both ends
- used for being propelled, consists of flagellin
- **type of mvmt: CW / CCW**;
30
Categories of bacteria depending on the location of flagella (4):
- **Monotrichous**: 1 flagellum (*ex: Vibria*)
- **Lophotrichous**: multiple flagella located at one end (*ex: Spirilla*)
- **Amphitrichous**: a single flagellum on each of two opposite ends
- **Peritrichous**: have multiple flagella projecting in all directions (*ex: E.coli*, *Clostridium Parabotulinum*)
31
Prokaryotic flagellum structure:
* **Motor**: responsible for rotation of flagellum
- located within cell wall and PM
- E for rotation comes from proton motive force (H+ pump) [bacs don't have mitochondria => pumps f/ E]
* **Hook**: located just outside of cell wall
* **Filament**:
- made by subunits of the protein **flagellin**
- clockwise (CW) or counter-clockwise manner (CCW) rotation
32
Axial filaments
- in family of ***Spirochetes***
- Located lengthwise between the bacterial plasma membrane and outer membrane (in the periplasmic space) => **endo**flagella
- Movement type: **twisting motion (snake like motion)**
33
Polysaccharide fibers
- in some bacs, for ex, **Flexibacter polymorphus**
- **type of mvmnt: crawling or sliding**
34
Cytoplasmic membrane (PM) (composed of 2:, 4)
* Composition: phospholipids + proteins
* Phospholipids in prokaryotic plasma membrane:
- Phosphatidyl-glycerol (PG)
- Phosphatidyl-ethanolamine (PE)
- Phosphatidic acid (PA)
- Diphosphatidyl-glycerol (DPG)
* X NO X:
- cholesterol
- Phosphatidyl-serine
- Phosphatidyl-choline
- Phosphatidyl-inositol
- Sphingomyelin
* It is selectively permeable (semi-permeable), fluid mosaic structure
35
Internal Organisation and DNA; mesosomes fn (2)
* Prokaryotic cells lack complex compartmentalisation => they don't have a membrane-bound nucleus and membrane-bound organelles
* Mesosomes:
- infoldings of the plasma membrane
- specialised membranes that perform metabolic functions in some prokaryotes => **Function**:
- cellular respiration (in *aerobic prokaryotes*) or photosynthesis (*e.g. in cyanobacteria*)
- Formation of the diaphragm during cytokinesis
36
Prokaryotic ribosomes
Ribosomes = RNA + proteins
Fn: protein synthesis
**polysomes** = many ribosomes + the same mRNA: to enhance the efficiency of translation
Prokaryotic ribosomes consist of different subunits than eukaryotes
- **30S** (small subunit) and **50S** (large) subunits = 70S is the total size => Some antibiotics (*e.g. tetracycline*) inhibit bacterial ribosomes without inhibiting human (eukaryotic) ribosomes
37
Nucleoid and extra-chromosomal elements:
region that contains the prokaryotic chromosome, not surrounded by a nuclear membrane;
may contain **extra-chromosomal elements**:
- Plasmids: small circular DNA molecules, some carry genes responsible for antibiotic resistance (R plasmids)
- Βacteriophages (phages): viruses that infect bacteria (have DNA genome)
38
Prokaryotic chromosome -
double-stranded circular DNA molecule => smaller than eukaryotic genome, no histones, supercoiled to fit the nucleoid region
39
Plasmids: extra-chromosomal elements fig
40
Endospores what and chars (4)
Some prokaryotes are **sporogenic** => they have the ability to form endospores (spores); endospores are formed under harsh conditions (ex: very high or very low temperature, dry environment)
Εndospores:
- metabolically inactive
- remain viable in harsh conditions for years
- resistant to temperature, dryness, UV light, enzymes, chemicals and drugs
- can grow back to the prokaryotic (vegetative) cell once in optimal conditions, such as *human body*
Examples of sporogenic bacteria: *Bacilli, Clostridia*
41
Reproduction and adaptation
* Key features of prokaryotic reproduction:
– They don't have programmed cell cycle and don't undergo mitosis
– They reproduce quickly by **binary fission**
– They have **short generation times (can divide every 1–3 hours)**
* Their short generation time allows rapid evolution of prokaryotes => adaptive evolution of bacteria (adaptation, evolution in specific conditions)
–Example of adaptive evolution of bacteria: *development of antibiotic resistance*
* Prokaryotes are not “primitive” but are **highly evolved**
42
Binary Fission
1. **Chromosome replication begins**. Soon after that, one copy of the origin moves rapidly toward the other end of the cell.
2. **Replication continues**. One copy of the origin is now at each end of the cell.
3. **Replication finishes**. The PM grows inward (mesosomes), and the new cell wall is deposited (cell plate formation).
43
Genetic diversity in prokaryotes due to (3)
– Rapid reproduction
– Mutation
– Genetic recombination
Rapid reproduction => accumulation of mutation in a prokaryotic pop => high genetic diversity => rapid evolution
44
Genetic Recombination -
combination of DNA from two sources contributes to genetic diversity
45
Horizontal gene transfer and how (3) -
movement of genes among individuals from **different species**
Prokaryotic DNA from different individuals can be brought together by:
1. Transformation: uptake and incorporation of foreign DNA by prokaryotic cells from their surroundings
2. Transduction: the exchange of DNA between bacteria mediated by bacteriophages (viruses that infect bacteria)
3. Conjugation: transfer of genetic material between prokaryotic cells in direct contact (through sex pili)
46
Prokaryotes are categorized in 4 groups based on their energy and carbon source:
– Phototrophs: obtain energy from light
– Chemotrophs: obtain energy from chemicals
– Autotrophs: require CO2 as a carbon source
– Heterotrophs: require an organic nutrient as a carbon source
47
Four major categories based on mode of
nutrition:
– Photoautotrophs
– Chemoautotrophs
– Photoheterotrophs
– **Chemoheterotrophs - most pathogenic bacteria**
48
Oxygen Metabolism in Prokaryotes (3):
– Obligate aerobes: require oxygen for cellular respiration
– Obligate anaerobes: poisoned by oxygen and use fermentation or anaerobic respiration; if the patient has this type of bacteria, for ex, Micobacterium tuberculosis, treatment includes putting them in a highly oxigenated room.
– Facultative anaerobes: can survive with or without oxygen
49
Nitrogen Metabolism
* Nitrogen is essential for the production of amino acids and nucleic acids
* Prokaryotes can metabolize nitrogen in a variety of ways
* Nitrogen fixation: conversion of atmospheric nitrogen (N2) to ammonia (NH3) by some prokaryotes
50
Phylogenic taxonomy of Prokaryotes (Domain Archaea - 4, Domain Bacteria - 5)
**Domain Archaea** phyla:
Korarchaeotes
Euryarchaeotes
Crenarchaeotes
Nanoarchaeotes
**Domain Bacteria** phyla:
Proteobacteria
Chlamydias
Spirochetes
Cyanobacteria
Gram-positive bacteria
51
Archaea - extremophiles:
Most archaea live in extreme environments:
- Extreme **halophiles**: live in highly saline environments
- Extreme **thermophiles**: thrive in very hot environments
- **Methanogens**: live in swamps, marshes and the digestive tract of mammals, produce methane as a waste product, **obligate anaerobes** (poisoned by oxygen)
52
Archaea resemble...
morphologically - bacteria
molecularly - eukaryotes
53
Rifampicin MODE OF ACTION:
inhibition of bacterial RNA polymerase
54
Streptomycin and chloramphenicol MODE OF ACTION:
inhibit ribosomes
55
Phylum Proteobacteria:
- Gram negative
- contains 5 subgroups: alpha, beta, gamma, delta, epsilon
56
Phylum Proteobacteria, **Subgroup ALPHA proteobacteria**:
* Many species of this subgroup are closely associated with eukaryotic hosts (symbiosis)
***Endosymbiotic theory***: mitochondria have evolved from aerobic alpha-proteobacteria through endosymbiosis
*ex: Agrobacterium: produces tumours in plants and is used in **genetic engineering***
57
Phylum Proteobacteria, **Subgroup BETA proteobacteria**:
- pathogenic!
- Neisseriae:
1. Neisseria meningitidis (aka meningococcus): cause of **meningococcal meningitis**. 85% lethality, septiciaemia
2. Neisseria gonorrhoeae (aka gonococcus): cause of gonorrhea (STD)
- Bordetella pertussis: cause of whooping cough, now is rare due to triple vaccine DTP (starts at 2 m.o.)
58
Neisseria meningitidis (subgroup, Gram, disease, treatment, morphology)
**subgroup**: Beta-Proteobacteria
**Gram** negative
**disease**: meningococcal meningitis; 85% lethality, septiciaemia
**treatment**:
**morphology**: Diplococci
59
Neisseria gonorrhoeae (subgroup, Gram, disease, treatment, morphology)
**subgroup**: Beta-Proteobacteria
**Gram** negative
**disease**: gonococcal urethritis aka gonorrhea, an STD
**treatment**:
**morphology**: Diplococci
60
Bordetella pertussis (subgroup, Gram, disease, treatment, morphology)
**subgroup**: Beta-Proteobacteria
**Gram** negative
**disease**: whooping cough
**treatment**:
**morphology**: rod/coccoid/ovoid
61
Phylum Proteobacteria, **Subgroup GAMMA proteobacteria**:
- Pathogenic bacteria: e.g. Legionella, Salmonella, and Vibrio cholerae
- ***Opportunistic pathogens***, e.g. Escherichia coli: it resides in the intestines of many mammals and is not normally pathogenic but part of the normal flora; however, it can cause opportunistic infections in immunosuppressed patients (e.g. AIDS patients, patients receiving chemotherapy or immunosuppressive drugs
62
Escherichia coli (subgroup, Gram, disease, treatment, morphology)
**subgroup**: Gamma-Proteobacteria
**Gram** negative
**disease**: gastritis, some strains can cause haemorrhagic diarrhoea
**treatment**:
**morphology**: rod
63
strain in bacteria =
subspecies
64
Salmonella entiritidis (subgroup, Gram, disease, treatment, morphology)
**subgroup**: Gamma-Proteobacteria
**Gram** negative
**disease**: food poisoning
**treatment**:
**morphology**: rod
65
Vibrio cholerae (subgroup, Gram, disease, treatment, morphology, toxin)and
**subgroup**: Gamma-Proteobacteria
**Gram** negative
**disease**: cholera - prolonged continuous diarrhoea (5-15 days), **transmission** via contaminated, non-chlorinated water, in undeveloped countries
**treatment**:
**morphology**: curled rod / spiral
**toxin production**: YES, **enterotoxin** => dehydration, death if untreated
66
Phylum Proteobacteria, **Subgroup DELTA proteobacteria**:
no pathogenic spp
67
Phylum Proteobacteria, **Subgroup EPSILON proteobacteria**:
Contains many pathogens:
- Campylobacter: causes food poisoning (complications: blood poisoning)
- Helicobacter pylori: causes stomach ulcers and gastric cancer
68
H. pylori (subgroup, Gram, disease, treatment, morphology)
**subgroup**: Epsilon-Proteobacteria
**Gram** negative
**disease**: asymptomatic chronic gastritis (>80%), chronic atrophic gastritis and gastric / duodenal ulcer (15-20%), gastric cancer (<1%)
**treatment**:
**morphology**: rod
69
Phylum Chlamidias:
Obligate parasites that live within animal cells
70
Chlamydia trachomatis (group, Gram, disease, treatment, morphology)
**group**: Chlamydias
**Gram** negative
**disease**: non-gonococcal urethritis, an STD; !can cause scarring, which blocks fallopian tube, if left untreated, leads to infertility!
**treatment**:
**morphology**: spherical
71
Phylum Spirochetes:
Spiral-shaped bacteria, some of which are parasites
72
Treponema pallidum (group, Gram, disease, treatment, morphology)
**group**: Spirochetes
**Gram** negative
**disease**: syphilis, an STD
**treatment**:
**morphology**: spiral shaped
72
73
Borrelia burgdorferi (group, Gram, disease, treatment, morphology)
**group**: Spirochetes
**Gram** negative
**disease**: Lyme disease, transmitted by ticks; classic symptom - bull's-eye rash (erythema)
**treatment**:
**morphology**: spiral shaped
74
Leptospira (group, Gram, disease, treatment, morphology)
**group**: Spirochetes
**Gram** negative
**disease**: Leptospirosis - zoonosis, transmitted by rodents; typical symptoms: jaundice (due to liver infection), kidney infection
**treatment**:
**morphology**: spiral shaped
75
Phylum Gram-Positive Bacteria
the only bacteria that stain Gram positive, include several pathogenic species
76
Actinomycetes (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** positive
**disease**: actinomycoses - cutaneous infections, ex - acne
as a spp: soil decomposers; source of many antibiotics (e.g streptomycin)
**treatment**:
**morphology**: spiral shaped
77
Bacillus anthracis (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** positive
**disease**: anthrax (biological terrorism)
**treatment**:
**endospores formation**
**morphology**: rods, colonies form chains
78
Clostridium botulinum (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** positive
**disease**: botulism; transmitted through improperly canned food
**treatment**:
**toxin**: YES, neurotoxin botulinum toxin (botox) => paralysis by inhibiting the release of the neurotransmitter acetylcholine at the neuromuscular junction synaptic cleft => death due to **respiratory muscle failure**
**morphology**:
79
Clostridium tetani (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** positive
**disease**: tetanus; **transmission**: bacteria enter through a break in the skin (cut/puncture/wound) by a contaminated object; **symptoms**: convulsive muscle spasms (convulsions of skeletal muscle) and paralysis
**treatment**:
**toxin**: YES, neurotoxin, lethal if untreated
**morphology**:
80
Corynebacterium diphtheriae (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** positive
**disease**: diphtheria; **symptoms**: pseudomembrane formation in the pharynx, trachea
**treatment**: antibiotics, DTP vaccine
**toxin**: YES, Diphtheria toxin, inhibits protein synthesis (translation), EF2 => cell/tissue death and organ damage
**morphology**:
81
Μycoplasma hominis & Ureaplasma urealyticum (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** staining ineffective, Methylene blue
**disease**: non-gonococcal urethritis, STD, if left untreated => infertility
**treatment**:
**toxin**:
**morphology**: NO CELL WALL
82
Mycobacterium tuberculosis (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** staining ineffective, due to a unique lipid-rich (waxy) cell wall (do not have the LPS outer layer that Gram- bacteria have)
**disease**: tuberculosis, characteristic **symptoms**: chronic cough with blood-containing sputum
**treatment**: rifampicin, isoniazid, streptomycin
**morphology**: acid-fast (resistant) Gram-positive bacteria
83
Symbiosis -
An ecological relationship in which two species live in close contact. Prokaryotes often form symbiotic relationships with larger organisms
* Host: the larger organism
* Symbiont: the smaller organism
84
Types of symbiotic relationships (3)
-Mutualism: both symbiotic organisms benefit
-Commensalism: one organism benefits while neither harming nor helping the other organism
- Parasitism: an organism called a parasite harms but does not kill its host; parasites that cause disease are called **pathogens**
85
Beneficial prokaryotes: Mutualistic Bacteria
* Part of our normal flora
* About 500–1000 species of bacteria live in the human intestines
* Many of these break down food that is undigested by our intestines (cannot be digested by our own
enzymes); they also benefit by absorbing nutrients from the gut
86
Pathogenic Bacteria
* Pathogenic prokaryotes cause about 50% of all human diseases
* Pathogenic prokaryotes typically cause disease by releasing toxins
87
Bacterial toxins:
* Exotoxins:
- Products of **bacterial metabolism**
- cause disease even if the prokaryotes that produce them are not present
- Mainly secreted by Gram (+) bacteria
* Endotoxins:
- Lipopolysaccharides (LPS) part of the outer membrane of the Gram (-) bacteria cell wall
- released when bacteria die (due to phagocytosis) and their cell walls break down
88
Staphylococcus aureus (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** positive
**disease**: toxic shock syndrome, food poisoning (gastroenteritis), pneumonia, skin infections
!MRSA! - Methicillin-resistant strain of St. aureus, the main cause of hospital-acquired diseases
**treatment**: penicillin
**morphology**: grape-shaped colonies of cocci
89
Streptococcus pneumoniae aka pneumococcus (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** positive
**disease**: pneumococcal meningitis
**treatment**: penicillin, vaccination
**morphology**: chain-shaped colonies of cocci
90
Mycobacterium leprae (group, Gram, disease, treatment, morphology)
**group**: Gram-positive bacteria
**Gram** staining ineffective, due to a unique lipid-rich (waxy) cell wall (do not have the LPS outer layer that Gram- bacteria have)
**disease**: leprosy
**treatment**: rifampicin, isoniazid, streptomycin
**morphology**: acid-fast (resistant) Gram-positive bacteria
91
Prokaryotes in Research and Technology
Bacteria can be genetically engineered to produce vitamins, antibiotics, and hormones (e.g. insulin production)
92
Prokaryotes used in DNA technology (engineering) (2):
– E. coli is used in **gene cloning**
– Agrobacterium tumefaciens: used to produce transgenic plants (GMOs)
93
Legionella:
Gamma-proteobacteria
Legionnaires' disease (legionellosis)
94
Bacillus cereus:
Gram-positive bacteria
Food poisoning (gastroenteritis)
