lecture 5 (Euglenoids)

Question 1

if you want to find euglenoids, where would you look for them?

Answer 1

in nearshore marine, brackish sand and mudflats, wetlands, marshes, swamps

Question 2

describe the main features of euglenoid cells

Answer 2

unicellular, free-living and mobile (no truly planktonic species), single flagella emerges from flagellar pocket near the eyespot. plastids with pyrenoids around the perifery, paramylon storage granules. surrounded by lorica

Question 3

what type of pigments do euglenoids have

Answer 3

chl a, chl b, beta carotene, xanthophylls (diadinoxanthin)

Question 4

what carbon storage product to euglenoids have?

Answer 4

paramylon (granules of a polysaccharide)

Question 5

what method of feeding do euglenoids use?

Answer 5

1/3 are autotrophic or mixotrophic, 2/3 are heterotrophic

Question 6

describe the plastids and thylakoids of euglenoids

Answer 6

plastids: many per cell, shaped like plates, shallow cups or ribbons
thylakoids are in stacks of 3 or more

Question 7

what endosymbiont level are euglenoids

Answer 7

secondary endosymbionts, 3 envelope membranes (from capture of a green alga)

Question 8

describe the euglenoid light sensitive structures

Answer 8

they have a paraflagular body at the base of the flagella
also an eyespot (stigma) adjacent to the flagellar pocket, opposite of the PFB (orange-red)
allows them to swim towards/away from light

Question 9

contractile vacuole

Answer 9

discharges water from the cell via the resevoir

Question 10

describe the euglenoid light sensitive structures

Answer 10

they have a paraflagular body at the base of the flagella
also an eyespot (stigma) adjacent to the flagellar pocket, opposite of the PFB (orange-red)

Question 11

what is the function of the light sensitive system?

Answer 11

allows them to swim towards/away from light

Question 12

do euglenoids have a cell wall?

Answer 12

no

Question 13

describe the cell covering of euglenoids

Answer 13

covered in mucilage (polysaccarides/glycoproteins) which can be impregnated with minerals to form a lorica
has pellicle “small skin” which are interlocking proteinaceous strips

Question 14

what is the pellicle made of and where is it located? what is its function?

Answer 14

interlocking proteinaceous strips
runs lengthwise down the cell, below the plasma membrane
allow for peristaltic movement/metaboly (euglenoids movement in mud), keeps rigidity

Question 15

what is the name of the movement characteristic of euglenoids?

Answer 15

metaboly

Question 16

what type of motion do euglenoids have?

Answer 16

peristaltic undulations in the mud, can swim with emergent flagella

Question 17

why do euglenoids sometimes look two headed?

Answer 17

this occurs during asexual reproduction when longitudinal division is occuring (no sexual reproduction)

Question 18

characteristics of euglenoid resting cells

Answer 18

can be formed by changing/unfavourable conditions (eg. low nutrients, low N:P ratios)
loss of flagella, increase in paramylon granules, swelling/rounding of cells, deposition of polysaccharide mucilage

Question 19

classification of euglenoids is based on

Answer 19

flagella structure and number
pellicle structure
structure of feeding apparatus if heterotrophic

Question 20

euglenoids are good indicators of environments with:

Answer 20

extreme heat, extreme salinities and high decaying organic matter

Question 21

the lorica is made of what

Answer 21

mineralized mucilage