Kingdom Protista

Objectives:1. Explain how eukaryotic cells evolved from

prokaryotes.2. Describe some distinguishing characteristics of

kingdom Protista3. Describe the ‘two stage’ lifecycle of some Protists

Quiz

• Answer the following questions...

1)What does phylogeny mean?

2)What kingdoms are in Domain Eukaryote?

3)How do bacteria reproduce?

4) Why are viruses not part of the six kingdom classification system?

Protista

• This kingdom contains organisms that display animal-like, plant-like and fungi-like characteristics.

Origin of Eukaryotes

• Protists were the first eukaryotes– Cell structure: membrane bound nucleus and

organelles…– Perhaps these membranes developed from

the folding of the cell membrane.– Beneficial because it increased surface area

for exchange of gases and nutrients– Eventually the folding may have cleaved and

formed membranes within the cell.

http://learn.genetics.utah.edu/content/begin/cells/organelles/

Aerobic prokaryotes benefit from food supply.Eukaryotes benefit from energy.

Photosynthetic prokaryotes benefit from carbon dioxide inside of eukaryotes and eukaryotes benefit from extra food produced by prokaryotes.

EVERYONE WINS

Origin of the mitochondria and chloroplasts

Double membrane mitochondria and chloroplasts contain DNA (chromosomes) of their own…resembling DNA of prokaryotes.

While outer membrane structure is typical of eukaryotic cells, the inner member structure is similar to that of prokaryotes.

Also…mitochondria and chloroplasts reproduce, during mitosis, by binary fission just like prokaryotes … mmmm what do you think?

Endosymbiosis…

• A symbiotic relationship where a single-celled organism actually lives within the cells of another organism…

• What if mitochondria and chloroplasts actually evolved from single-celled organisms that lived within the ancestral prokaryotic cells???

Three Groups of Protists

• 1. Plant-Like: contain chlorophyll and may produce food through photosynthesis, … but not always (some have flagella and no cell wall)

• 2. Animal-Like (Protozoa): heterotrophs and are very likely to be parasitic

• 3. Fungi-Like (slime moulds): some produce spores

Life-Cycles

• Single celled protists reproduce …– Sexually: Conjugation – cells line up and exchange

genetic information– Asexually: Binary fission – cell divides into two

identical daughter cells (like mitosis)

• Multi-celled protists…not so simple

• May involve formation of sex cells (haploid)– Sperm fuses with egg resulting in a diploid zygote

• Some alternate between a diploid and haploid stage and produce haploid spores.– Spores divide and grow into a haploid organism

(gametophyte) that produces haploid sex cells– Sperm fuses with egg resulting in a diploid zygote that

grows into a multicellular sporophyte.

Gametophyte: Haploid organism that produces haploid sex cells in an alternation of generations life cycle

Sporophyte: Diploid organism that produces haploid spores in an alternation of generations life cycle

There are three types of protists

1) Plantlike Protists

- contain chlorophyll, autotrophic

ex. Euglena

ex. green, brown, and red algae

- normally aquatic, can be found in both freshwater and marine environments floating on cell surface

- also known as phytoplankton: tiny floating organisms that manufacture their own food, the first link in an aquatic food web

• algae are responsible for 67% of the global supply of oxygen through photosynthesis!

• they are also the main source of crude oil

2) Fungi-like Protists

- also known as slime moulds: can clump together to form a slug-like mass that can travel to a “better place”

-prefer cool, shady moist places

- heterotrophic saprophytes: feed on dead and decaying matter

3) Animal- like Protozoa

- considered to be the “first animals”

- motile: often will have flagella to help with movement

- heterotrophic: can be pathogenic or not

ex. Plasmodium

- a pathogenic protozoan that causes malaria

Four Phyla of Animal-Like Protists

• There are many different phyla of plant and animal-like protists...

• Phyla (all with some distinguishing characteristics)– Scarodina (ie: amoeba)– Mastigophora – Ciliophora (contain cilia)– Sporozoa

State 1 or 2 distinguishing characteristics of each phyla.

Your Task…• Read through pages 349-356• Discuss with your partner how plant-like, animal-

like and fungi-like are similar/different. Discuss some distinguishing characteristics of each group (How could you tell them apart? What about their movement and feeding habits?)

• Movement, Feeding, Reproduction, Unique characteristics

• Answer questions 1, 3, 4, 5 – 8 and 10

Plenary1. What are mitochondria and chloroplasts

thought to have evolved from?2. What selective pressures do you think

favoured this evolution?3. Name the three distinct groups that make up

the Protists4. Name 3 characteristics which are

characteristic of organisms from other kingdoms that some Protists display

5. Why are some Protists considered to be ‘animal-like’, ‘plantlike’, or ‘fungilike’?

6. What is a gametophyte and a sporophyte?7. What is interesting about the life-cycle of

some Protists?

SarcodinaForaminifera: This group of protozoa have shells that can group up to several inches in diameter.

Amebas change the shape of their bodiesextensions of the body called pseudopodia, or false feet.