lecture 4 (Origin of eukaryotic algae: endosymbiosis)

Question 1

Using diagrams, describe general features of primary endosymbiosis

Answer 1

an organism “eats” a cyanobacteria. this is integrated into the eukaryotic host cell, becomes the chloroplast
2 membranes around the chloroplast (1 cyano, 1 host)

Question 2

Using diagrams, describe general features of secondary endosymbiosis

Answer 2

an organism “eats” a primary endosymbiont, integrating this into the cell
chloroplast has 3-4 membranes (1 cyano, 1 primary host, 1-2 secondary host membranes)
can have a nucleomorph (remnant of red/green algal endosymbiont)

Question 3

Using diagrams, describe general features of tertiary endosymbiosis

Answer 3

organism “eats” a secondary endosymbiont, integrating it into the cell.
chloroplast has more than two membranes (sometimes these can be reabsorbed)

Question 4

What groups of algae are primary endosymbionts

Answer 4

green and red algae, glaucophytes

Question 5

what groups of algae are secondary endosymbionts?

Answer 5

euglenoids, cryptomonads, haptophytes, stramenopiles, dinoflagellates, chlorarachniophytes (have nucleomorphs), apiocomplexans

Question 6

what groups of algae are tertiary endosymbionts?

Answer 6

some dinoflagelates

Question 7

what type of process must have taken place if the modern algal cell has only 2 membranes enclosing the chloroplast? if enclosed by more than 2 membranes?

Answer 7

if more than 2 membranes, definitely not a primary endosymbiont
if only 2 then primary endosymbiont or other

Question 8

what level of endosymbiosis are most algae derived from?

Answer 8

secondary endosymbiosis

Question 9

what is a nucleomorph?

Answer 9

remnant of a red/green algal endosymbiont
evidence of endosymbiosis