1. BE101 Introduction to Biological Systems
Dr. Michael Parkinson

2. Lecture Structure Lectures in QG15 & QG13 each week.
A round up of points and coverage of examination type questions on Monday 5:00 in QG15
These overheads are available to view as powerpoint presentations at: webpages.dcu.ie/~parkinsm/teaching.htm
Any standard Biology text will do for reading around e.g. Mader Biology (all at 570 in the library).

3. Schedule of topics Evolution of eukaryotes and protists Fungi
Plant Evolution
Plant reproduction
Plant Structure
Plant growth and development
Photosynthesis

4. The origins of eukaryotic diversity
Dr Michael Parkinson
School of Biotechnology
The origins of eukaryotic diversity can be traced back approximately 1.8billion years.

5. What I’m going to cover in this lecture
The origin of Eukaryotes
The classification of Protists
3 of the more primitive groups of Protists
Archezoa
Euglenozoa
Alveolates

6. 3 things that you should watch for in this lecture
The way that eukaryotes have evolved from primitive ancestors
The way that the organisms are classified and the factors that affect their classification
The ways that protists can affect public health

7. Evolution of eukaryotes by serial endosymbiosis
Nuclear membrane and endoplasmic reticulum formed from invagination of plasma membrane akin to phagocytosis
Inclusion of organelles from phagocytosis of aerobic bacterium / cyanobacterium
The origin of microtubule structures (flagellae, cilia, cytoskeleton) is unknown

8. 1. Nucleus formation
Phagocytosis is a very common phenomenon in Protists.
Invagination of the plasma-membrane is expected to give
rise to:
a double membrane covering around the nucleus,
a system of membranes within the cell continuous with the nucleus
and the plasma membrane.

9. 2. Origin of organelles c.f. Forams Phagocytosis of cyano- bacterium
Photoautotrophic
eukaryote
Phagocytosis
of an aerobic
bacterium
This scheme fits in very well with what we know about the symbiotic relationships of protists. For example, many members of the Archezoa actively phagocytise aerobic bacteria.
Many Foraminifera phagocytise algae, and form long lived symbiotic relationships with them.
c.f. Archezoa
Heterotrophic
eukaryote

10. Features of ‘Protists’
All eukaryotes
Mostly unicellular
‘Primitive’ and thought to have diverged early from a ‘universal ancestor’
Very diverse

11. Types of ‘Protist’ Archezoa e.g Giardia Euglenozoa Alveolata
Rhodophyta
Plantae
Dinoflagellates
Euglenoids
Red
Algae
Green
Algae
Ciliates
Don’t try and take this down. This is just to give you a taste of the different forms of Protists. They are mostly unicellular, and before the electron microscope was invented, it was a nightmare to classify them based on structure. They vary from flagellated (euglenozoa and kinetoplastids) to ciliated (ciliates) to non-motile (apicomplexans), and from single cells (all those mentioned) to quite complex multicellular forms, some very closely related to green plants (brown, red and green algae).
Apicomplexans
(sporozoans)
Kinetoplastids
Stramenopila = Diatoms+Golden Algae+Brown algae+Water moulds

12. Evolutionary relations
For many years, all organisms that did not conveniently fit into other groups were placed into the ‘Protists’.
Classification is in a very active and dynamic state.
Recently, molecular phylogeny based on similarity in DNA + electron microscopy has led to reclassification to give MONOPHYLETIC groups - organisms are grouped if they have a common ancestor.

13. This is a map of the Eukaryotes based on similarities in the sequence of rRNA. It is too complicated to take down, so just listen and make sense out of it as we go along.
The longer the lines are, the more ancient. The Metazoa (animals) and Fungi form fairly tight and distinct groups showing their relatively recent evolution.
We see immediately that amonst the rest of the Eukaryotes, the most ancient groups (longest lines) are the Microsporidia, Trichomonads and Diplomonads. These are collectively lumped into the Archezoa, as you’ll see in the next slide. The Euglenophytes and the Amoebae-flagellates are the next most ancient group. These are both normally flagellated. The alveolates form a more recent grouping with ciliates (cilia), dinoflagellates (2 flagellae) and non-motile, parasitic organisms, the sporozoans. If you look at these under the electron microscope, you see small vesicles under the cell surface, Alveolii, hence the name Alveolates.
Again a very diverse group is the Stramenopiles. This includes the golden brown algae (single celled), the brown algae (can grow up to 100 feet long), and oomycetes (fungus-like). They all have flagellae at some stage in the life cycle with flimmer (cross hairs).
The red algae evolved relatively recently and are closely related to the green algae and plants. The king of the protists (speaking as a botanist) is the green algae and plantae.
It is obvious that an amoeboid form of living has evolved independently at least 5 times giving at least 5 different amoeboid groups.

14. Summary of evolutionary relations
Animals
Fungi
Plants
Distance apart
Green algae
Red algae
Stramenopila
Alveolates
If we were to look at the evolutionary relations of the protists, a picture would emerge pretty much like this.
Archezoa are the most ancient (remember the long lines on the chart of 16s RNA evolutionary tree).
Euglenozoa
Archezoa
time

15. Ways of classifying ‘Protists’
Plantae
Archezoa
Protista
Chromista
Plantae
Plantae
Archezoa
Euglenozoa
Alveolata
Stramenopila
Rhodophyta
Diplomonads
Trichomonads
Microsporidians
Depending on which textbook you use, you will see the classification of the protists in one of these guises.
The one I shall be using is the 3rd one down. I’ll be covering each of these groups in turn.
Euglenoids
Heterotrophic Flagellates (Kineto-plastids)
Dino-flagellates
Api-complexans
(sporozoans)
Ciliates
Amoeboids
Diatoms
Golden Algae
Brown algae
Water Moulds
Red algae
Green algae and plants

16. ARCHEZOA (from Greek Arkhaios meaning ancient)
Considered to be the most primitive of all eukaryotes
No mitochondria (some engulf bacteria)
Mostly parasitic (e.g. Giardia)
3 Sub-groups
Diplomonads (includes Giardia)
Trichomonads (e.g. Trichomonas)
Microsporidians

17. Giardia An important parasite Transmitted by both water and animals
Probably the most important source of holiday diarrhea

18. Trichomonas
An STD

19. EUGLENOZOA Flagellates 2 sub-groups
euglenoids Photosynthetic but may be heterotrophic or mixotrophic
Kinetoplastids Symbiotic or parasitic e.g. Trypanosoma, Leishmania

20. Trypanosoma
Causes sleeping sickness in cattle and man in Africa transmitted by the Tsetse Fly
In Americas, Chagas disease

21. Chagas disease / Sleeping Sickness

22. Life cycle involves biting/sucking insects

23. Leishmania
The life cycles of members of the genus involve a vertebrate host (e.g., the human) and a vector (a sand fly) that transmits the parasite between vertebrate hosts

24. Cutaneous Leishmaniasis

25. ALVEOLATA
All have small membrane bound cavities (Alveoli) beneath the cell surface.
3 subgroups
Ciliates
Apicomplexans
Dinoflagellates

26. Ciliates All have cilia for locomotion and feeding
Reproduce by binary fission

27. Trichodina sp.
This genus contains many species, perhaps as many as 200, most of which are found as commensals or facultative or obligate parasites on aquatic invertebrates, fish,
and amphibians.

28. Apicomplexans (Sporozoa)
All parasites of animals
All have a complex at the apex of the cell for penetrating host tissues (Apicomplex)
‘Relict’ plastids possibly related to dinoflagellates with 4 bounding membranes
Plasmodium falciparum
Pneumocystis carinii (Pneumonia)
Toxoplasma gondii (toxoplasmosis)
Cryptosporidium parvum (cryptosporidosis)

29. Apicoplast (plastid of Apicomplexan)
4 membranes
Genome of circular plasmid
Smallest genome of any plastid (35kb)
Codes for a number of genes
Provides a means of attacking the parasite

30. Malaria - Plasmodium/mosquito

31. Malaria - infection with an Apicomplexan, Plasmodium

32. Dinoflagellates Abundant components of the phytoplankton
Blooms cause red tides in coastal waters
Can be an important symbiont in coral reefs