The Origin of Eukaryotes

1. Internal membranes evolved from inward folds of the plasma membrane.

2. Endosymbiosis – chloroplasts and mitochondria evolved from prokaryotes that lived within a larger host prokaryotes.

Protists

Eukaryotes that are not animals, plants or fungi.

Grouping Protists byType of Nutrition

Animal-like: heterotrophs (protozoans) – ingest food

Fungus-like: heterotrophs – feed on decaying organic matter.

Plant-like: autotrophs (algae) make their own food by photosynthesis

Protozoans

Characterized by how they move

Can be free living or parasites: Parasites live in a close relationship

with a host, and causes it harm.

Protozoans with Flagella Called Zooflagellates Most reproduce asexually Some are free living, some are

parasites

Protozoans with Pseudopodia

Pseudopodia – temporary extensions of the cytoplasm also used to surround and engulf prey

Examples: Amoeba Forams – has porous shell from which

pseudopodia extend through

Protozoans with Cilia (cilialites)

Example: Paramecium Arrangement of cilia are adapted to

different functions. Many cilia joined together work to aid

movement Cilia rings around the mouth aid in the

uptake of food. Can produce sexually or asexually. Have two types of nuclei.

Protozoans Lacking Motility

Paracites that don’t have a means of moving – Apicomplexans

The apical complex is a structure on the tip of the cell that helps for penetrating host cells.

Describe two "animal-like" characteristics of protozoans.

No cell wall Frequently are free living Eat organisims

Describe two functions of cilia in protozoans.

Mobility Filter water for food particles

Fungus-like protists

Slime MoldsPlasmodialCellular

Water MoldsMildews

Plasmodial Slime Molds Unicellular Plasmodium – single mass of

cytoplasm undivided by membranes & containing many nuclei

Extend pseudopodia to engulf bacteria & organic matter.

Cytoplasmic streaming to distribute nutrients and oxygen throughout the organism.

Plasmodial Slime Molds When food and water are scarce, sporangia

develop.

Tips of sporangia produced spores that can be dispersed by wind.

In favorable conditions the spores release haploid cells that

unite forming zygotes.

Cellular Slime Molds

Have both unicellular and multicellular stages in the life cycle.

Plant-like Protists

Photosynthetic

Euglenoids

Single-celled

Posses one or two flagella

Lack a cell wall

Dinoflagellates

Unicellular

Cell wall made of cellulose

2 flagella which produce a spinning movement

Component of plankton- microscopic organisms near the surface of bodies of water.

Dinoflagellates

Impacts: Red tides Bioluminescence

Diatoms

Unicellular

Cell wall made of silica.

When they die, they sink to the bottom of the ocean forming diatomaceous earth.

Seaweeds

Multicellular Classified by the pigment they

contain Brown Algae – accessory pigments &

chlorophyll Red Algae – red pigment &

chlorophyll Green Algae – chlorophyll

Test Questions

RNA was believed to be the first nucleic acid because it can copy itself in small pieces without the aid of enzymes.

Cells vs. Viruses Cells

Alive Reproduced

independently Cell membrane

surrounds nucleic acid

Viruses Inert Need host to

reproduce Protein coat with

nucleic acid inside

Bacteria vs. Virus

Bacteria – Reproduce independently Can be treated with an antibiotic

Virus Need host to reproduce Can be prevented using a vaccine

Transformation – Bacteria pick up pieces of DNA from the environment

Conjugation – two cells join and transfer genetic info between them

Transduction – Viruses infect bacteria carrying genes from one cell to the next

Reproduction of a Virus