week 6 - protists --> ameoboza

Question 1

amboebozoa superphyla

Answer 1

• Use PSEUDOPODIAL movement
  o Via big (lope like) protrusions
   Fake feet, large extensions
• Diverse group
  o Important (to us) for two reasons
   As pathogens
• E.g. Entamoeba
   As cell biology models
• Lots of similarities between these cells and those in our bodies
• E.g. Dictyostelium

Question 2

amboebozoa
types

Answer 2

• Gymnamoebas
• Entamoebas
• Slime moulds

Question 3

amboebozoa
Gymnamoebas

Answer 3

• Aquatic and soil habitats
  o Where most amoeba are
• Use pseudopodia to move by amoeboid movement and phagocytose food
  o Also use membrane to ingest food
• Feed on bacteria other protists and organic particles
• Often be found in ponds
• Size varies 15-750 microns

e.g. Chaos carolinensis
can have up to 1000 nuclei in one cell (3mm)

Question 4

amboebozoa
Entamoebas

Answer 4

• Patasites
• Common in oral and intestinal tract of animals
• Example:
  o Entamoeba histolytica
   Simple life cycle
   Basically switching between trophozoites
• Which are feeding and eating lots of bacteria
   When bacteria runs out they will form cysts
• Able to survive longer out in the environments
• Transmission

Question 5

amboebozoa
slime moulds

Answer 5

• Feed on decaying plant matter/bacteria.fungi
  o Important in ecosystems (maintaining nutrient cycles)
• Soil dwelling
• Previously grouped with fungi
  o Fuiting bodies and spores
• Two forms:
  o Cellular
  o Plasmodial
   Grow in different ways but have the same survival mechanism
• Coordinated reproduction

Question 6

amboebozoa
slime moulds
e.g. Plasmodial: Physarum polycephalum

Answer 6

For much of the year live as single cells
In autumn come together
* Yellow goo
* All over forest looking for bacterial film
Eats anything in its path
* Decaying matter
Provides an essential service in cleaning up woodlands
Grows much more rapidly as it finds fungal prey (its food)
When all food is gone
* Coordinated effort in mass reporduction
* Some cells form stems others form spores
* Cells are scattered

Question 7

amboebozoa
slime moulds
e.g. Cellular: Dictypstelium discoideum

Answer 7

• When in starvation can form an ariel hyphy with a spore on top
  When lots of food independent

When one cell secretes a pulse of hormone cAMP
Aggregation starts
Cells response b =y moving near the hormone and emitting own hormone
This response becomes wide spread
* Synchronised creating waved of accelerated movement
o Passing through the migrating cells
Move towards aggregation centre
The aggregations of cells round up and then each turns into a slug
* A pseudo plasmodium
These slugs are active
* Searching the terrain for a suitable place to settle and leaving a trail of slime as they go
* Slugs can fuse together
Slugs flatten onto the surface and then grow a thin stalk with a fruiting body on the tip
* Throughout these manoeuvres the amoeba remain sperate individuals
The pseudo plasmodium differentiate into three main types of cells with different functions
* Base
* Stalk
* Spores in fruiting body
They coordinate and sacrifice (cellular altruism)
The mature spores are later released