Protista and simple Metazoa

Announcements •There will be a quiz next lab on protsista and Annelids•Assignment for this lab include page 50,63,64,65,66,67,68.•Make sure you know your four digit number by now

Today

•Prokaryotes versus eukaryotes• Endosymbiosis •Different protists•Simple metazoa•Evolution of body cavities

Prokaryotes versus Eukaryotes• Eukaryotes possess true nucleus, membrane bound organelles and a cytoskeleton

Endosymbiosis

* Eukaryotes evolved from symbiotic association of different kinds of prokaryotes,each specialized for different function.* Eukaryotes include unicellular protists and all multicellular organisms.* Symbiosis versus parasitism

Phylogeny of protists

prokaryotes

sarcodina

Mastigophora

Ciliophora Sporozoa

Fungus like protists Plant like protists

choloroplastSpores

Cilia

Flagella

Pseudopodia

ATPRNA

DNANuclear membrane

Mitochodria

protists•Unicellular Eukaryotes having different types of membrane bound organelles like nucleus, mitochondria, contractile vacuoles and chloroplasts.1- Animal like protists (protozoa) a- Sarcodina e.g Amoeba characterize by forming pseudopodia b-Mastigophora e.g Trypanosoma characterize by having flagella

protists

C- Ciliophora e.g paramecium e.g. stentor characterize by presence cilia D-Sporozoa e.g. Plasmodium malaria characterize by forming infective spores2-Fungus like protists (slime molds) e.g Dictyostelium spp. characterize by sexual (diploid) and asexual (haploid) reproduction depending on the availability of food

protists3- plant-like protists (unicellular algae) e.g Euglena e.g golden brown algae (phytoplankton) depend on photosynthesis as energy source characterized by presence of Chloroplast

I got the picture

*We will examine pond water using the hanging drop technique*Put a drop of pond water on the slid with depression, cover with cover slip and examine under microscope* Wash the slid when you are done and bring it back to me

Metazoans* Multicellular and consume other organisms* Muticellularity permit evolution of specialized cells, tissues and organs that are able to perform narrow tasks more efficient than generalized cell. *Grouped according to level of organization (cellular, tissues and organs) and presence or absence of body cavities (coelom).*a true coelom is a cavity within the mesoderm layer and usually filled with fluid.

Phylogeny of metazoans

Tissue level

multicelularity

Organ level (mesoderm)Bilateral symmetry

Mouth and anus

EnterocoelmPoriferaCnidaria

Acoelomates Pseudocoelomates

Protostome Deuterostome

Coelomates

Multicelularity

Mouth and anuspseudocoelom

Spiral cleavage

Schizocoelom Spiral cleavage

Evolution of body cavities*During the embryonic life, there are three embryonic layers From which the different tissues and organs differentiate. These are ectoderm, endoderm and the mesoderm. Invagination of the mesoderm layer will eventually result in the formation of body cavity.* According to presence or absence of body cavity 1-Acoelomate : no cavity. 2-Pseudocoelomate: cavity between mesoderm and endoderm. 3-Schizocoelomate: true coelom formed by split in developing mesoderm. 4-Enterocoelom :true coelom formed by out-pocketing of the gut

Evolution of body cavities

Evolution of body cavities

Acoelomates

Evolution of body cavities

Pseudocoelomates

Evolution of body cavities

Schizocoelom =Protostome

Evolution of body cavities

Enterocoelom =Deutrostome

The advantages of the coelom- It allows for more extensive growth of the organs (digestive tract). - It permits the formation of an efficient circulatory system -The fluid in the coelom can transport or move materials faster than by diffusion. Animals often dump food or wastes into the coelom and depend on body movement to distribute the materials to the required areas. - The muscles of the digestive tract can become independent of the muscles of the body wall permitting more variation in movement of both sets of muscles. - The coelom provides a space for gonads to develop during breeding season or for young to grow in those animals which give birth to live young

Simple Metazoa

1- Porifera (sponge) -cellular level of organization -aquatic organisms - e.g Grantia2- Cnideria -tissue level of organization continuous layer of cells function as a tissue (epidermis and gastrodermis) i.e. one unit -radial symmetry (tentacles) -the medusa and the polyp architectures - e.g jellyfishes,corals and hydra

Simple metazoa3- Acoelomates -no body cavity -organ level of organization -bilateral symmetry -e.g.platyhelminthes(flatworms) * Planaria….Dugesia (free living) *Cestoda…..Taenia (parasitic) *Trematoda….Fasciola(parasitic)

Simple Metazoa4- Pseudocoelomates -organ level of organization -pseudocoelom -nematoda (roundworms) e.g C.elegans (free living) Ascaris lumbricoides (parasitic)

I got the picture

# start looking at the scopes and answer questions# dissect Ascaris worm -wear gloves -identify the mouth and anus under dissecting scope - start dissection from the posterior end toward the mouth -when you are done, wash your hands and discard in the orange bucket

Dissecting Ascaris female