CMB1003/L11 Eukaryotic Microorganisms

Question 1

What rRNA is found in eukaryotes, prokaryotes and mitochondria?

Answer 1

E - 18S
P - 16S
M - 12S

Question 2

Describe hydrogenosomes. (4)

Answer 2

Produce hydrogen
Produce ATP through substrate level phosphorylation
Some have genome with mitochondrial signature
Nuclear genomes encode reduced fractions of mitochondrial proteins set

Question 3

Describe mitosomes. (4)

Answer 3

Reduced in size
No evidence for any capacity to produce ATP
No genome
Nuclear genomes encode reduced mitosomal/mitochondrial proteins set

Question 4

Give 2 structures that are interpreted to be homologues to mitochondria.

Answer 4

Hydrogenosomes
Mitosomes

Question 5

What is the disease caused and mode of transmission of Cryptosporidium species?

Answer 5

Acute watery diarrhoea
Water-borne outbreaks

Question 6

What is the disease caused and mode of transmission of Plasmodium species?

Answer 6

Malaria, acute febrile disease
Mosquitoes

Question 7

What is the disease caused and mode of transmission of Toxoplasma gondii?

Answer 7

Birth defects or encephalitis
Ingestion of undercooked meat

Question 8

What is the disease caused and mode of transmission of Trichomonas vaginalis?

Answer 8

Inflammation of urogenital tract
STD

Question 9

How does an apicomplexan parasite enter a cell?

Answer 9

Apical organ orchestrating moving junction-mediated entry

Question 10

How does a kinetoplastid parasite enter a cell? (2)

Answer 10

Lysosome-mediated entry
Phagocytosis

Question 11

How do microsporidia enter cells? (2)

Answer 11

Polar tube-mediated entry
In combination with endocytosis and/or phagocytosis

Question 12

What are the 2 most common microsporidia species identified in humans?

Answer 12

Enterocytozoon bienusi
Encephalitozoon intestinalis

Question 13

Describe the life cycle of microsporidia. (5)

Answer 13

Strict obigate intracellular parasite
Depend on one or more host
Mostly animal hosts; some protists
Host switching
Largely zoonotic origins

Question 14

Describe stramenopiles. (2)

Answer 14

Many free-living species
Some are symbionts/parasites

Question 15

Describe alveolates. (3)

Answer 15

Dinoflagelletes
Ciliates
Apicomplexa

Question 16

Describe the process that led to discovery of the apicoplast in Plasmodium. (3)

Answer 16

Molecular data - discover of unexpected small genome
Genome organisation and phylogeny linked it to plastids
Ultrastructural studies identify new organelle

Question 17

Give an example of Apicomplexa infecting humans.

Answer 17

Plasmodium falciparum - human-anopheles mosquito life cycle with mitochondria and apicoplast
Toxoplasma gondii - cat-prey life cycle, zoonotic parasite with mitochondrion and apicoplast
Cryptosporidium parvum, C. hominis - only 1 host required - often zoonotic, with mitosomes and no apicoplast

Question 18

What is the definitive host and intermediate hosts of Toxoplasma gondii?

Answer 18

D - felines
I - birds & mammals

Question 19

Name 3 excavata.

Answer 19

Parabasalia
Diplomonada
Euglenozoa

Question 20

Describe parabasalia. (3)

Answer 20

Mainly obligate symbionts
Include parasitic forms
Found in invertebrates, birds and mammals
Anaerobes
Have hydrogenosomes

Question 21

Describe diplomonada. (3)

Answer 21

Many host-dependent
Include parasitic forms
Anaerobes
Have hydrogenosomes or mitosomes

Question 22

Describe euglenozoa. (3)

Answer 22

Free-living and parasitic forms
Kinetoplastids, parasites
Some have secondary plastids
Some have complex mitochondrial genomes - kinetoplasts

Question 23

Describe Trichomonas vaginalis. (3)

Answer 23

Most common STD
Common in resource-limited conditions
Strongly associated with HIV, HPV and Mycoplasma
Linked with prenatal and post-natal complications
Positively correlated with cervical, possibly aggressive prostate cancers