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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
Q

Vibrio cholerae

A

Single curved-rod cells (Vibrio)
The agent of cholera (cholerae)

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26
Q

Vibrio cholerae
for info

A

Single curved-rod cells (Vibrio)
The agent of cholera (cholerae)

27
Q

Staphylococcus aureus
for info

A

Arranged in clusters (Staphylo-)
Rounded cells (coccus)
Describes the gold-colored (aureus) colonies

28
Q

Prokaryotes charictaristics:

A

Without nucleus
Without membrane-bound organelles
Simple organisation

e.g. Bacteria and Archea

29
Q

Describe the composition of the plasma membrane;

A

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
Q

Explain the functions of the plasma membrane;

A

Serves as a selectively permeable barrier:
Controls movements of molecules across the cells

31
Q

What are the infoldings of the plasma membrane called. Why are they present?

A

mesosomes

Site for DNA replication and cellular respiration

32
Q

Functions of the cell wall;

A

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
Q

What is the composition of the cell wall?

A

Structural difference between these two groups Gram+ = purple
Gram- = red

34
Q

Why is the cell wall so important?

A
  • Only a few bacteria do not posses cell walls (e.g. mycoplasma)
  • Target of many antibiotics (anti-bacterial drugs)
35
Q

What is peptidoglycan/ murein?

A

Essential components of the bacterial cell wall

36
Q

Composition of Peptidolycan?

A

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
Q

Name a bacteria that does not incl. peptidoglycan?

A

Archea

38
Q

The Peptidoglycan formation ; STEP by STEP

A

1) ubunit: NAG + NAM

2) Repition of the subunit form individual strands/chains

3) Peptidoglycan strands (transpeptidation reaction)

39
Q

How are peptidoglycan strands formed and what enzyme takes part?

A

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
Q

Cell wall of Gram +ive bacteria

A

thick structure (several layers) of peptidoglycan, separated from the plasma membrane by a thin periplasmic space

41
Q

Cell wall gram +ive =
TEICHOIC ACIDS - what is it made up of?

A

alcohol and a phosphate group (-ive charge)

42
Q

What is TEICHOIC ACIDS functions?

A

Bind to and regulate movement of cations into cell
Regulate cell growth and prevent cell lysis
Linked also to the cell membrane

43
Q

Cell wall of Gram -ive bacteria

A

Cell wall is thinner, more complex and more susceptible to mechanical breakage

44
Q

Composition of cell wall gram -ive

A

a thin peptidoglycan layer

periplasmic space, containing degradative

enzymes and lipoproteins

outer membrane (the most external)

45
Q

Composition of the Outer membrane in Gram- bacteria:

A

Phospholipid bilayer
Lipopolysaccharides (LPS): acting as antigen and endotoxin
Porins: membrane pores that allow the passage of molecules
Lipoproteins

46
Q

What are the funcitons of Outer membrane in Gram- bacteria:

A
  1. Evade phagocytosis and immune system
  2. Permeability barrier to antibiotics (penicillin), digestive enzymes, etc
47
Q

What is the process of gram staining?

A

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
Q

Gram staining - principles
+ive

A

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
Q

Gram staining - principles
-ive

A

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
Q

External to cell wall

A

Glycocalix

51
Q

External to cell wall

A

Glycocalix

Some bacteria have an additional viscous layer/coat (called glycocalyx), composed of a network of polysaccharides, lying outside the cell wall

52
Q

Components external to cell wall - Glycocalix

A

Capsule: thick, well organised and firmly attached
Slime layer: thin, unorganised and loosely associated

53
Q

Functions of components external to cell wall e.g. Glycocalix

A
  • Confer pathogenicity (only capsule)
  • Prevent phagocytosis by host phagocytes
  • Avoid desiccation by preventing water loss
  • Aid in attachment to solid surfaces
54
Q

Cytoplasm

A

Location (inside the plasma membrane) of most biochemical activities

55
Q

Nucleoid

A

central region containing circular DNA (up to 3500 genes)

56
Q

Plasmids

A

small, nonessential, circular DNA (5-100 genes; e.g., antibiotic resistance, production of toxins, digest antibiotics)
They replicate independently

57
Q

Ribosomes

A

acterial ribosomes are termed 70S ribosomes (50S + 30S), which distinguish them from the 80S of eukaryotic cells

Selective antibiotic target

58
Q

Inclusion bodies

A

granules as reserve deposits of nutrients in the form of high molecular weight polymers. E.g. glycogen, polymeric phosphates, etc.

59
Q

Name the 5 different classes of antibiotics:

A

Cell wall

Plasma membrane

Ribosomes
(30S subunits, 50 subunits)

Metabolic Pathways

DNA synthesis + RNA synthesis

60
Q

Describe the structure of Flagella:

A

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
Q

The composition of Flagella:

A

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
Q

Flagella and bacteria movements

A

Flagella rotate to = “run” or “tumble”
Direction of flagella determines the movements
(tails help movement)

63
Q

Other bacterial appendages
1) Fimbriae (1-500 per bacteria)

2) Sex Pili

A

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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