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Microorganisms, Infection and Immunity > Diversity and Biology of Bacteria > Flashcards

Diversity and Biology of Bacteria Flashcards

1
Q

Bacteria are

A

Single celled, without a nucleus

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2
Q

We are interested in bacteria because

A

they play a role in our body and form what we call the . microbiome (1-3% of our body weight)

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3
Q

Tuberculosis is a disease where

A

1.7 million people die from the disease each year and is one of the top 10 causes of death worldwide

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4
Q

Bacterial meningitis is

A

an infection of the brain?

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5
Q

Bacterial infections can also be…

A

foodborne (e.g. salmonella, camplyobacter)

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6
Q

The nucleoid is…

A

a double stranded circle bacterial chromosomes

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7
Q

Bacteria contain 70S ribosomes which contain…

A

30S and 50S subunits. These are major targets for antibacterial drugs

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8
Q

50S RNA is a piece of RNA which…

A

have conserved parts and some diverse parts?

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9
Q

Bacteria can also have plasmids which are…

A

Circular or linear extrachromosomal DNA’s not usually essential for cell survival. Capable of autonomous replication (able to replicate independently).

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10
Q

Plasmids are needed in bacteria for…

A

Preventing from being attacked by antibodies, and the plasmid usually encodes for proteins which aid in the invasion of host cells.

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11
Q

Shigella spp is a….

A

Human specific pathogen which can cause an acute intestinal infection. This occurs from fecal oral transmission. The bacteria can replicate in macrophages and is therefore able to evade the immune response.

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12
Q

Cell membrane of bacteria is…

A

fairly similar to mammals in structure, and have various functions such as electron transport and energy production.

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13
Q

Cell wall is a…

A

Rigid layer around the cytoplasmic membrane - this resists osmotic pressure.

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14
Q

bacteria is classified

A

according to their cell wall characteristics. Gram Strain is an example of this.

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15
Q

If you have bacteria, you can fix it onto organ cells, and stain the cells.

A

By doing so, you will find 2 different results to show gram positive or negative.

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16
Q

The difference between gram positive and gram negative bacteria is

A

gram negative have 2 layers of membranes and between the layers are lipoprotein and peptidoglycan. Gram positive is where the lipoprotein and peptidoglycan is exposed and is not between any layer.

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17
Q

A peptidoglycan is

A

a complex of sugars with side chains of amino acids.
It is designed to protect the cell wall and is rigid in shape. Peptidoglycans are recognised by the immune system. Some bacteria can change their peptidoglycan composition, our immune system may not detect the bacteria as before.

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18
Q

Teichoic acids are…

A

chains of glycerol phosphate/ ribitol phosphate. They are bound covalently to peptidoglycan

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19
Q

Gram negative bacteria have…

A

a much more complex cell wall. They also have a thinner peptidoglycan than gram positive.

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20
Q

Lipopolysaccharides are

A

essential for bacterial viability. The hydrophilic O polysaccharide repels hydrophobic molecules.

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21
Q

Porins allow…

A

The uptake of small hydrophilic molecules.

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22
Q

The S- layer is…

A

frequently found on the surface of gram positive and gram negative cells. The s layer functions are a cell wall biogenesis and the control of cell divison

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23
Q

Capsules are…

A

amphorous polysacharride slime around cells. It prevents the recognition of the bacteria by the immune system. Several genes encode the capsules.

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24
Q

The flagella

A

Provides motility and is attached via hook and basal body containing motor proteins and switch proteins (control direction of rotation)

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25
Q

Flagella is recognised by

A

the innate immune system (H- antigen) and they express antigenic and strain determinants and are a ligand for a pathogen pattern receptor to activate innate immune response

26
Q

Pili and fimbriae are

A

Protein spikes that extend from the surface. Pili are longer and more rigid than the fimbriae. Fimbriae are although more abundant.

27
Q

What is a potential function of fimbriae?

A

To allow E coli to bind to the urethra

28
Q

There are many different classes of pili varying based on

A

Structure and function. They are used to attach to surfaces, promote biofilm formation and antigens

29
Q

External Structures - pili

A

sex pillus is involved in DNA transfer in conjugation

30
Q

Why study bacterial metabolism?

A

Phenotype based identifcation - substrate utilization and growth inhibitors, and determination of metabolic activity

31
Q

Bacterial replication is essential for transmission as…

A

It identifies nutrient requirements and pathway bottlenecks (microbial pathogenesis)

32
Q

Nutritional factors include

A

Macronutrients (Carbon being main element), growth factors, and micronutrients (iron, boron e.t.c)

33
Q

Nutrient acquisition/ transport occurs via

A

Passive transport, or active transport.

34
Q

Passive transport occurs via

A

simple diffusion e.g. small hydrophobic molecules

Facilitated diffusion e.g. hydrophobic molecules req….

35
Q

Proton symports are

A

Driven by electrochemical transmembrane proton gradient
Co- transport in same direction, hence, symport
Example of such is Lactose permease in E.coli

36
Q

ABC transport is..

A

ATP binding cassette. It is a form of active transport. Hydrolysis of ATP drives transport. Specific binding proteins involved

37
Q

Group Translocation is…

A

substrate modified, generally phosphorylated, during transport, e.g. phosphotransferase system.
The energy is provided by the PEP passed along chain of enzymes

38
Q

Glucose transport systems

A

Bacteria can encode for different systems depending on the needs of the bacteria and the area in question

39
Q

Catabolism is where

A

Amino acids, monosaccharides and glycerol+ fatty acids are broken down into simpler products to form energy

40
Q

E.coli has….

A

transcription factors which enact to cause certain genes to transcribe.

41
Q

Listeria spp

A

are gram positive rods, and come from natural human habits such as soil, dust e.t.c.

42
Q

Listeria is engaged in cell- cell spread

A

This is to avoid extracellular defences. This is why cystosolic replication occurs.

43
Q

Energy generation happens due to…

A

the production of ATP and NADH

44
Q

Respiration occurs via..

A

the proton gradient which is used to power ATP synthase to subsequently produce ATP

45
Q

Aerobic Respiration is where

A

oxygen is involved

46
Q

Anaerobic respiration is where

A

Nitrate is reduced to nitrite via nitrate reductase (in the context of bacteria)

47
Q

Mycobacterium tuberculosis is where

A

the bacteria enters the phagosome but manipulates the phagosome so that a lysosome is not formed and it is not degraded.

Host cell lipids are an essential carbon source during infection. It can switch from a carb based metabolism to a fat based metabolism

These bacteria can also survive under energetically unfavourable condition and poorly oxygenated conditions

48
Q

Bacterial Growth is…

A

the increase in the number of cells, not the size of a single bacterium. This occurs by binary fission.

49
Q

Binary fission occurs via…

A
  1. elongation of cell wall, membrane, and cell volume

2. Chromosome duplication

50
Q

Fts proteins

A

interact to form a divisome, a cell division apparatus

51
Q

A divisome….

A

forms the septal ring and defines the cell division plane

52
Q

There are different types of Fts proteins, such as,,,

A

ftsl - for peptidoglycan biosynthesis

ftsk - responsible for chromosome separation

53
Q

min proteins are

A

cytoskeletal proteins that are coiled in poles. They form a bipolar gradient that help to localise the ring

54
Q

The bacterial cell cycle is highly regulated….

A

with steps occuring such that:

  1. G1
  2. S-phase
  3. G2
55
Q

Bacterial cell cycle can be controlled via…

A

Nutritional control - whereby starvation can lead to replication and growth and fast growth leads to division.

56
Q

Effect of the stress…

A

results in regulated proteolysis by Lon. If there is no stress, DNAa is able to conduct replication, however, when there is a heat shock for example, the DNAa and any unfolded protein is broken down to avoid any reeplication

57
Q

Endospores can be formed….

A

when the bacteria is triggered due to adverse conditions, and the mother cell secretes a protein coat (calcium dipicolinate) to protect then lyses…….

58
Q

Spore forming bacteria include….

A

botulism, tetanus, anthrax

59
Q

A generation time for bacteria is..

A

the time required to complete fission cycle from parent cell to 2 daughter cells.

60
Q

Requirements for growth include

A

Temperature (death above the maximum temperatures comes from enzyme inactivation), pH (5-8 being the optimum usually), oxygen

61
Q

Listeria monocytogenes is a…

A

food borne pathogen, facultative anaerobe, can grow in temps between 0 and 45 degrees, it can tolerate high salt concentrations

62
Q

helicobacter pylori…

A

colonises the human stomach (1.5-3.5), causes acute gastritis and several ureases, it has flagellum which gives its ability to move around to areas which are not as acidic, and release bicarbonate and ammonia which are of higher pH to mask itself,

Microorganisms, Infection and Immunity (8 decks)

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