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PMP-101 > Introduction to Microbiology and bacterial structures > Flashcards

Introduction to Microbiology and bacterial structures Flashcards

1
Q

What is a microorganism?

A

The science of microorganisms  Microbiology
Microorganisms (or microbes) are organisms that are too small to be seen with the unaided eye —> require a microscope (except for some moulds)
1030 microbes estimated in different habitats (more than stars in the known Universe)

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2
Q

List the major groups of microbes:

A

Bacteria > Bacteriology
Fungi (yeasts and moulds) > Mycology
Parasites (protozoa, helminths, and ectoparasites) > Parasitology
Micro-algae > Phycology
Viruses and prions > Virology

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3
Q

Microorganism diversity = flow diagram (from moulds)

A

Generally
Moulds > Protozoa > Yeasts > Bacteria > Viruses > Prions

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4
Q

Define cellular:

A

formed by cell(s)
A single cell (monocellular) – e.g. bacteria
more cells (pluricellular) – e.g. moulds

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5
Q

Define Acellular:

A

without a cellular structure (e.g. viruses and prions)

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6
Q

prokaryotic cells

A

barteria

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7
Q

eukaryotic cells

A

protozoa, yeasts, moulds

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8
Q

3 domains of bacteria

A

Bacteria
Archaea
Eukarya

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9
Q

Microorganisms as cellular entities

A

Bacteria / Archea > Bacteriology

Fungi > Mycology

Parasites > Parasitology

Microalgae > Phycology

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10
Q

acteria / Archea > Bacteriology

A

Prokaryotes

Mostly unicellular / monocellular

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11
Q

Fungi > Mycology

A

Eukaryotes

Yeasts > Unicellular

Moulds > Pluricellular

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12
Q

Parasites > Parasitology

A

Eukaryotes

Protozoa > Unicellular

Helminths > Pluricellular

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13
Q

Microalgae > Phycology

A

Mostly eukaryotic

Both unicellular and pluricellular

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14
Q

Do microorganisms that have nonliving agent include cells?

A

NO - not made up of cells

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15
Q

Virus > Virology
Characteristics:

A
  • Acellular (do not have a cellular structure)
  • Small infectious particles consist of nucleic acid surrounded by a protective coat of protein(s)
  • Coat may be enclosed in a lipid envelope
  • They do not divide
  • They need to infect a cell to replicate their particles
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16
Q

Prions > Virology
Made up of?

A

Simpler infectious particles made up of only proteins (no nucleic acids)

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17
Q

What is the Impact of Microbes on the Environment and Human Activities?
(essential for life on earth)

A
  1. Organic waste decomposition
    (e.g. sewage)
  2. Production of food (e.g. cheese, bread, beer by fermentation)
  3. Drugs/enzymes synthesis
    (e.g. penicillin, insulin, etc.)
  4. Digestion and molecule generation (e.g. vitamins, etc)
  5. Oxygen generation (photosynthesis)
  6. Nitrogen fixation (converting atmospheric N2 to ammonia, NH3)
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18
Q

Where are microbes present - human body?

A

present in body and out of body = NORMAL microbiota

> 100 trillions microorganisms harboured per person (≈10X higher human cells)

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19
Q

Less than _% of microbes cause diseases (pathogens)

A

1%

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20
Q

The majority of normal microbiota are not harmful and can be helpful to:

A

a) prevent growth of pathogens

b) produce growth factors (e.g vitamins B and K)

c) breaking down toxic molecules, boosting the immune system and antimicrobial chemicals

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21
Q

What do you call bacteria have one or more shapes?

A

pleomorphic

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22
Q

Arrangements of Bateria:

A

Pairs:
diplococci,
diplobacilli

Clusters
(random planes):
staphylococci

Chains (one plane): streptococci, streptobacilli

Groups of four: tetrads

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23
Q

How to name and classify Microorganisms?

A

Each organism have TWO names - the GENUS and the SPECIES EPITHET

both = written italicised
genus name = CAPITALISED
The specific epithet = lowercase
genus name = can be abbreviated

e.g. Staphylococcus (Genus) aureus (species) – S. aureus (abbreviation)
Escherichia (Genus) coli (species) - E.coli (abbreviation)

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24
Q

Some are named after scientists / or be descriptive: Escherichia coli or E.coli

A

Honors the discoverer, Theodor Escherich
Describes the bacterium’s habitat—the large intestine, or colon

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25
Vibrio cholerae
Single curved-rod cells (Vibrio) The agent of cholera (cholerae)
26
Vibrio cholerae for info
Single curved-rod cells (Vibrio) The agent of cholera (cholerae)
27
Staphylococcus aureus for info
Arranged in clusters (Staphylo-) Rounded cells (coccus) Describes the gold-colored (aureus) colonies
28
Prokaryotes charictaristics:
Without nucleus Without membrane-bound organelles Simple organisation e.g. Bacteria and Archea
29
Describe the composition of the plasma membrane;
Phospholipid bilayer that encompasses the cytoplasm Fluid mosaic model similar to the eukaryotic cells: 40% lipids (mainly phospholipids), 60% proteins Lacking sterols (cholesterol of human cells) Contain sterol-like molecules (hopanoids)
30
Explain the functions of the plasma membrane;
Serves as a selectively permeable barrier: Controls movements of molecules across the cells
31
What are the infoldings of the plasma membrane called. Why are they present?
mesosomes Site for DNA replication and cellular respiration
32
Functions of the cell wall;
1) Maintain bacterial cell integrity and shape 2) Prevents the cell from bursting when water flows into the cell by osmosis 3) Can contribute to pathogenicity (ability to cause disease)
33
What is the composition of the cell wall?
Structural difference between these two groups Gram+ = purple Gram- = red
34
Why is the cell wall so important?
- Only a few bacteria do not posses cell walls (e.g. mycoplasma) - Target of many antibiotics (anti-bacterial drugs)
35
What is peptidoglycan/ murein?
Essential components of the bacterial cell wall
36
Composition of Peptidolycan?
A rigid multi-layered network made up of linear chains Each chain is a polymer of a repeating identical disaccharide unit (made up of the following 2 monosaccharides) in long rows: N-acetylglucosamine (NAG) N-acetylmuramic acid (NAM) A tetrapeptide chain of 4/5 amino acids is linked to NAM Chains are linked by peptide cross bridges between tetrapeptide side chains of NAMs
37
Name a bacteria that does not incl. peptidoglycan?
Archea
38
The Peptidoglycan formation ; STEP by STEP
1) ubunit: NAG + NAM 2) Repition of the subunit form individual strands/chains 3) Peptidoglycan strands (transpeptidation reaction)
39
How are peptidoglycan strands formed and what enzyme takes part?
peptide cross-link bridges between tetrapeptide of NAMs of peptidoglycan strands Bacterial transpeptidase responsible for links - target of β-lactams (e.g. penicillins) THE link - PEPTIDE bond
40
Cell wall of Gram +ive bacteria
thick structure (several layers) of peptidoglycan, separated from the plasma membrane by a thin periplasmic space
41
Cell wall gram +ive = TEICHOIC ACIDS - what is it made up of?
alcohol and a phosphate group (-ive charge)
42
What is TEICHOIC ACIDS functions?
Bind to and regulate movement of cations into cell Regulate cell growth and prevent cell lysis Linked also to the cell membrane
43
Cell wall of Gram -ive bacteria
Cell wall is thinner, more complex and more susceptible to mechanical breakage
44
Composition of cell wall gram -ive
a thin peptidoglycan layer periplasmic space, containing degradative enzymes and lipoproteins outer membrane (the most external)
45
Composition of the Outer membrane in Gram- bacteria:
Phospholipid bilayer Lipopolysaccharides (LPS): acting as antigen and endotoxin Porins: membrane pores that allow the passage of molecules Lipoproteins
46
What are the funcitons of Outer membrane in Gram- bacteria:
1. Evade phagocytosis and immune system 2. Permeability barrier to antibiotics (penicillin), digestive enzymes, etc
47
What is the process of gram staining?
FIXATION 1) primary staining (crystal violet) 2) Mordant application (Iodine treatment) 3) Decolorisation 4) Counterstaining (counter stain with Safranin) Distinguishing groups of bacteria according to their cell wall structure Staining: for better visual observation, to highlight differences or cell components in bacteria
48
Gram staining - principles +ive
Gram-positive (cells are stained blue due to the crystal violet-iodine complex – the primary stain/mordant) Alcohol dehydrates peptidoglycan (thick layer) forming crystals inside and the dye is retained
49
Gram staining - principles -ive
Gram-negative (cells stain pink as the counterstain – e.g. safranin) Alcohol dissolves outer membrane and leaves holes in peptidoglycan crystal violet-iodine complex washes out; cells are colorless Safranin (pink) added to stain cells
50
External to cell wall
Glycocalix
51
External to cell wall
Glycocalix Some bacteria have an additional viscous layer/coat (called glycocalyx), composed of a network of polysaccharides, lying outside the cell wall
52
Components external to cell wall - Glycocalix
Capsule: thick, well organised and firmly attached Slime layer: thin, unorganised and loosely associated
53
Functions of components external to cell wall e.g. Glycocalix
- Confer pathogenicity (only capsule) - Prevent phagocytosis by host phagocytes - Avoid desiccation by preventing water loss - Aid in attachment to solid surfaces
54
Cytoplasm
Location (inside the plasma membrane) of most biochemical activities
55
Nucleoid
central region containing circular DNA (up to 3500 genes)
56
Plasmids
small, nonessential, circular DNA (5-100 genes; e.g., antibiotic resistance, production of toxins, digest antibiotics) They replicate independently
57
Ribosomes
acterial ribosomes are termed 70S ribosomes (50S + 30S), which distinguish them from the 80S of eukaryotic cells Selective antibiotic target
58
Inclusion bodies
granules as reserve deposits of nutrients in the form of high molecular weight polymers. E.g. glycogen, polymeric phosphates, etc.
59
Name the 5 different classes of antibiotics:
Cell wall Plasma membrane Ribosomes (30S subunits, 50 subunits) Metabolic Pathways DNA synthesis + RNA synthesis
60
Describe the structure of Flagella:
Hairlike filamentous appendages external to the cell Propel bacteria (process requiring ATP) toward or away from stimuli, detected by chemoreceptors May also be a sensory organelle (detecting chemicals, temperature, etc)
61
The composition of Flagella:
3 parts, made of protein flagellin: Filament: outermost region Hook: attaches to the filament Basal body: consists of rod and pairs of rings; anchors flagellum to the cell wall and membrane
62
Flagella and bacteria movements
Flagella rotate to = "run" or "tumble" Direction of flagella determines the movements (tails help movement)
63
Other bacterial appendages 1) Fimbriae (1-500 per bacteria) 2) Sex Pili
1) Thin hairlike appendages that allow for attachment Some types are involved in a twitching motility 2) Hair-like tubular structure Conjugation pili involved in DNA transfer from one cell to another

PMP-101 (53 decks)

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