General

Question 1

when did microorganisms first evolve

Answer 1

3.5 billion years ago

Question 2

around how many species of microorganisms are always present in the air

Answer 2

725

Question 3

when did cyano bacteria and O2 producing photosynthesising organisms appear

Answer 3

2.5-3 billion years ago

Question 4

when did the modern eukaryotic cells appear

Answer 4

1.4 billion years ago

Question 5

when did humans appear on earth

Answer 5

400 thousand years ago

Question 6

what two sequences is the tree of life based on

Answer 6

16S and 18S rRNA sequences

Question 7

what three groups are protozoans (protista) traditionally classified into

Answer 7

Amoebae (have pseudopodia)
Flagellates (have flagella)
Ciliates (have cilia)

Question 8

what is the biological species concept suggested by Mayr in 1963

Answer 8

is fundamental ecological and genetic unit. groups of interbreeding natural populations that are reproductively isolated

Question 9

what is the current definition of a bacterial/archael species

Answer 9

a category that circumscribes a genomically coherent group of individual isolates/strains sharing a high degree of similarity in many independent features, comparatively tested under highly standardised conditions

Question 10

what is an open reading frame

Answer 10

a portion of a DNA molecule that when translated into amino acids contains no stop codons

Question 11

what is polyphasic taxonomy

Answer 11

take information from different areas including: phenotypic data, genotypic data and phylogenetic data

Question 12

what is quorum sensing

Answer 12

Quorum sensing is the regulation of gene expression in response to fluctuations in cell-population density.
QS bacteria produce autoinducers. Create a beneficial phenotype (survives well in high density for example)

Question 13

what are common sites of primary biofilm infection

Answer 13

mouth (through bleeding gums), catheter entries (such as the subvenous catheter), and implanted medical devices (such as an artificial hip joint).

Question 14

what are common sites of secondary biofilm infection

Answer 14

brain, kidneys, intervertebral spaces, bones around implanted medical device.

Question 15

what is dysbiosis

Answer 15

an imbalances between healthy microflora and disease microflora - can lead to ill health

Question 16

what is the difference between commensalism and symbiosis

Answer 16

Commensalism is a symbiotic relationship in which one species benefits while the other species is not affected.
Symbiosis both benefit

Question 17

what are enterotypes

Answer 17

a classification of living organisms based on the bacteriological composition of their gut microbiota

Question 18

what are the three enterotypes

Answer 18

• Type 1: high levels of Bacteroides
• Type 2: few Bacteroides but Prevotella common
• Type 3: high levels of Ruminococcus

Question 19

what are the mechanical anatomical barriers to infection (4)

Answer 19

epithelial surfaces (physical impermeable barrier, desquamation)
movement of cilia (or peristalisis)
flushing action of tears and saliva
trapping effect of mucus

Question 20

what are the chemical anatomical barriers to infection (6)

Answer 20

• Fatty acids in sweat inhibit the growth of bacteria.
• Lysozyme and phospholipase found in tears, saliva and nasal secretions can breakdown the cell wall of bacteria and destabilize bacterial membranes.
• The low pH of sweat and gastric secretions prevents growth of bacteria.
• Defensins found in the lung and gastrointestinal tract have antimicrobial activity.
• Surfactants in the lung act as opsonins (substances that promote phagocytosis of particles by phagocytic cells).
• Low pH of the stomach (1-2pH) can break down bacterial cell walls

Question 21

what are the biological anatomical barriers to infection

Answer 21

The normal flora of the skin and in the gastrointestinal tract can prevent the colonization of pathogenic bacteria by secreting toxic substances or by competing with pathogenic bacteria for nutrients or attachment to cell surfaces.

Question 22

what is sarcoidosis

Answer 22

a disease characterized by the growth of tiny collections of inflammatory cells (granulomas) in any part of your body — most commonly the lungs and lymph nodes. But it can also affect the eyes, skin, heart and other organs