Euglenophyta

Question 1

Endosymbiosis of euglenids

Answer 1

Secondary endosymbiosis

-green algae eaten
-2 inner membranes from Cyanobacteria of green algae in primary endosymbiosis
-1 membrane from protist good vacuole

Question 2

Euglena habitat

Answer 2

-abundant and may form water blooms in ponds, tanks, puddles, and livestock water
-occur in freshwater, marine and brackish water as well as moist soils and mud

Question 3

Euglenoids are associated with ______

Answer 3

Dissolved organics-used as environmental indicators
-utilize simple organic compounds produced by decay microorganisms: short-chain fatty acids, vitamin B1 and B12

Question 4

Feeding habits of euglenoids

Answer 4

Phagotrophic (can swallow), general or specialized predators (diatoms)

Others are osmotrophic (uptake dissolved organic compounds by osmosis

Some parasitic like Trypanosoma sp. (sleeping sickness in Africa)

Question 5

Only ______ of euglenophyta possess green-pigmented chloroplasts: other have __

Answer 5

1/3

Colourless plastids or lack plastids

Question 6

Why is the classification of euglenozoa controversial

Answer 6

Some are parasitic (kinetoplastida)
Some are photosynthetic (euglenoidea)

Asexual reproduction cannot be distinguished according to reproductive compatibility

Question 7

Typical features of autotrophic Euglena sp.

Answer 7

-flagellar pocket (reservoir)
-flagellar canal
-two flagella
-contractile vacuole (freshwater species)
-Paramylon granules (carbohydrate reserve)
-plastids
-Pyrenoids (proteins and enzymes for synthesis of carbohydrates)
-nucleus
-eye spot (stigma)

Question 8

At the anterior of euglena is a thin channel (______) that leads to a flagellar pocket (_____)

_____ flagella arise in the pocket within the cell, but only _____ emerges

Answer 8

Flagellar canal

Reservoir

2

1

Question 9

Contractile vacuole purpose

Answer 9

Expel excess water in hypotonic environments

Question 10

The eyespot is located where in Euglena?

Answer 10

In cytoplasm, adjacent to flagellar pocket

Question 11

Many Euglenoids are facultative heterotrophs, what does this mean?

Answer 11

Ingest organic matter as carbon and energy source, as well as performing photosynthesis

Question 12

_______ lost in at least one group of Euglenophyta after the acquisition of plastids

Answer 12

Phagotrophy

Question 13

Autotrophic species of Euglenoids have what food organelles

Answer 13

Tubular cytostome or vestigial digestive system

Question 14

Fossil record of Euglenophyta

Answer 14

-ancient group of eukaryotic algae
-oldest fossils (460 mya)
-lack of calcified structures to resist decay means fossils are rare

Question 15

Eugelnophyta resemble the green algae in having ________

Answer 15

Chlorophylls a and b and B-carotene as photosynthetic pigments

Question 16

Chloroplasts in Euglena

Answer 16

Cells have a number of small chloroplasts

Each chloroplast is surrounded by an envelope consisting of 3 membranes

Outer sin for plastic membrane with endoplasmic reticulum of his endosymbiont origin

Question 17

How is a triple membrane of Euglenophyta adaptive in marine environments?

Answer 17

Increases supply of CO2 which creates more photosynthesis

Caused low CO2 levels in atmosphere 285mya

Question 18

Euglenophyta and dinophyta have evolution of _______ membrane endoplasmic reticulum

Answer 18

1

Question 19

Carbohydrate reserve in paramylon

Answer 19

-paramylon is a beta 1,3 glucan that can be hydrolysis to d-glucose and is found only in Euglenophyta

Question 20

Pyrenoid

Answer 20

Localized concentrations of ribulose 1-5 biphosphate carboxylase-oxygenate (RubisCO)
-associated with synthesis of sugars
-may be capped with plates of paramylon

Question 21

Paramylon appearance

Answer 21

-not green
-not in chloroplast unless cap of Pyrenoid

Question 22

How many flagella can Euglenophyta have

Answer 22

2-7

Question 23

Eulgenophyta motility

Answer 23

-2 flagella in the pocket at the cell anterior
-emergent flagella carry rows of long fibrillar hairs (mastigonemes) on flagella surface=tinsel flagella
-mastigonemes flex to increase surface area of the lower stroke and fold during the recovery stroke
-a second rudimentary flagellum may also be present in the reservoir
-extension of both flagella from the reservoir are considered by some to be a primitive condition

Question 24

Flagella internal structure

Answer 24

-diameter of the flagellum is increased by the presence of a lattice-like structure known as the parafalgellar rod (in Euglena, extends the length of flagella)
-provides attachment for hair-like processes, may participate actively in flagellar movement (ATPase) or control flagellar frequency

-emergent flagella carry rows of long flagellar hairs on surface
-increase flagellar hydrodynamic resistance and thrust

-flagellum with 9+2 microtubules and paraflafellar rod

Question 25

Outer covering of euglena

Answer 25

No cell well!!!

Plasma membrane is covering!

Just under the outer membrane is a pellicle
-consists of a number of helically wound strips of protein, each strip with a thick edge and a thinner flange
-alternating pattern of ridges and grooves

Question 26

Euglenoids movement (metaboly)

Answer 26

-peristaltic wave of contraction and expansion passes over the entire body from the anterior to the posterior end and the animal moves forward

-the body becomes shorter and wider first at anterior end, then in the middle and later at the posterior end

-Euglenoids movements made by the contractions of cytoplasm or by the contractions of protein filaments in the cytoplasm below the pellicle

-cells also flex side-to-side with flexible pellicle

Question 27

Euglenophyta light sensing

Answer 27

-positive movement of Euglenoids towards light of moderate intensity from regions of darkness (positive phototaxis) and a movement away from light of very high intensity (negative phototaxis)

-movements are associated with the stigma (eyespot): located next to flagellar pocket (carotenoid pigments) + paraflagellar body: flavin-based light detector at the base of the flagella (sensitive to blue light)

Question 28

Euglenophyta reproduction

Answer 28

-reproduce asexually by binary fission
-Euglenoids reproduce very rapidly, absorbing their flagellum and dividing haploid cells through mitosis

-reproduction in the Euglenoids occurs by longitudinal division of the cells. During mitosis which precedes division, the nuclear envelope remains intact and the nucleolus persists

Question 29

Euglenophyta cysts

Answer 29

-formed by many species of Euglenoids to survive unfavourable conditions
-cells round up then secrete a thick mucilaginous layer, and loose their flagella

-in certain genera, cell division within the slime layer leads to the formation of a palmelloid colony, which may form extensive sheets of cells covering many square feet of mud surface