Protist Notes Continued PDF

Protist Notes Continued II. Algae (plant-like) o Perform photosynthesis o Contain chlorophyll and produce oxygen as a byproduct o Many are unicellular, but some are multicellular o Some are colonial (they live as a group with each cell having specific functions. Two groups of al...

Protist Notes Continued II. Algae (plant-like) o Perform photosynthesis o Contain chlorophyll and produce oxygen as a byproduct o Many are unicellular, but some are multicellular o Some are colonial (they live as a group with each cell having specific functions. Two groups of algae: Unicellular and Multicellular 1. Unicellular Algae They are classified by the type of outer cover and movement. Dinoflagellates – These are unicellular algae with two flagella used to spin the cell through water. They are covered with cellulose plates and the majority live in saltwater habitats. These are responsible for “red tides”. Diatoms – These are algae that lack both cilia and flagella and have glasslike cell walls containing silica. They come in a variety of shapes and patterns. Since they have rigid cell walls, they have pores that allow gases and other materials to pass through. They are the most abundant organisms in the ocean. Many are used as abrasives in polishing agents, detergents, and toothpastes. 2. Multicellular Algae Were once classified as plants because of chloroplasts and photosynthesis, but they are classified as protists because they have different reproductive structures from plants. They are not necessarily microscopic. Green Algae – Also called Chlorophyta. Most live in freshwater, but some live in the ocean. Either grow as filaments, linked end to end, or as flat leaf-like cells. Example: Chlamydomonas (ponds and moist soil) It has flagella that can be retracted when it becomes dormant. Volvox (common colonial green algae) Live in ball-shaped colony. Some green algae live in symbiotic relationships with fungus = lichen Red Algae – Also called Rhodophyta. They grow in warm, saltwater habitats. Not all of them are red, some can be orange, green, brown, and black. Can carry out photosynthesis at great depths because of the different pigments other than chlorophyll. Very important for coral reefs. Brown Algae – Also called Phaeophyta. Grow in cool, saltwater habitats. Example: Kelp These have root-like structures that keep them anchored. These also have specialized air bladders to help them float.  Algae are also a large component of plankton, but they are the part of plankton referred to as phytoplankton because they carry out photosynthesis. III. Fungus-like protists Divided into 3 groups: Plasmodial Slime Molds; Cellular Slime Molds; Water Molds. Decomposers recycle organic material into the environment. They extract their nutrients from dead organic materials. 1. Plasmodial Slime Molds (slimy or wet in appearance) Many different colors. They assume different forms during their life cycle. Plasmodium – The feeding stage; during this phase the mold forms a mass of cytoplasm similar to amoeba. It feeds on bacteria and other small organisms. Spores – When conditions are not good for feeding, the mold stops feeding and forms a body that produces spores. When conditions improve, the spores are released and develop into plasmodium again. 2. Cellular Slime Molds (slimy or wet in appearance) Alternates between stages similar to plasmodial slime mold, but forms pseudoplasmodium “false plasmodium” when food is scarce. 3. Water Molds (includes white rusts and downy mildews) They are decomposers or parasites. They typically grow in freshwater on decaying plants and animals. They are not true fungus because: - Their cell walls contain cellulose instead of chitin. - Their spores have flagella whereas true fungi produce spores without flagella. Water Mold caused the Irish Potato Famine