Unit 2 NotesKingdom Protista Protists Cells Food Chains Photosynthesis & Respiration Osmosis & Diffusion
Members of Kingdom Protista: • Most are single-celled • Multicellular protists are very simple and lack complex structures (no mouth, head, stomach….) • All protists have a nucleus (they are eukaryotes)
Protists are divided into 3 groups based on how they get their energy (food): • Plant-like protists (producers) • Animal-like protists (consumers) • Fungus-like protists (decomposers)
Think of protists as the “junk drawer” kingdom. Anything that is NOT quite an animal, NOT quite a plant, or NOT quite a fungus gets dumped into this kingdom
Most protists will be found in wet environments; like oceans, lakes and ponds. Most are microscopic, but seaweed and giant kelp can grow to be over 100 feet in length. Microscopic plant-like protists Phytoplankton Volvox Giant Kelp
Protists called phytoplankton make most of the world’s oxygen (approximately 60%) The astonishing diversity of phytoplankton is visible only under a microscope. One trait all phytoplankton share, however, is chlorophyll—the green pigment that converts energy from the sun into food – this happens inside the chloroplast
Reproduction in Protists Protists use asexual (fission) reproduction. Protists use sexual (conjugation) reproduction. Paramecium, a single-celled animal-like protist can even go back and forth between sexual and asexual reproduction from one generation to the next
Algae is a generic term that is used for all plant-like protists aa Protozoa (“first animal”) is the term used to refer to all animal-like protists Examples of protozoa: Diatoms Paramecium Amoeba • Examples of algae: Volvox Phytoplankton Giant Kelp
All plant-like protists convert the sun’s energy in to oxygen and sugar through photosynthesis, and are found at the beginning of many of earth’s food chains: Sunlight “gives” its energy to volvox (plant-like protist); then volvox “gives” its energy to the krill; then the krill “gives” its energy to the cod; then the cod “gives” its energy to the leopard seal.
Animal like protists (protozoa) are consumers and use different methods to move about to get their food: Flagella: are whip-like tails Cilia: tiny hair-like extensions Pseudopods: “false foot”, extensions of the cytoplasm Parasites: live in and steal nutrients from hosts
Fungus-like protists live as decomposers in their environments. They get their energy by consuming dead or decaying organic material.
Protists are part of the domain eukarya; all of their cells are complex: they have a nucleus and membrane-covered organelles • Animal Cell: • Plant Cell Animal cells DO NOT have: Cell wall, chloroplasts or a large vacuole. Plant cells have these three organelles. All other organelles are found in both types of cells.
Organelles Cell membrane: surrounds the cell and lets needed materials in and out of the cell Cytoplasm: gelatin-like material inside the cell, raw materials the cell needs can be found here ((gatekeeper)) Cytoplasm
Organelles Cell wall: provides strength and support for the plant cell Chloroplast: the site of photosynthesis in producers ((gatekeeper))
Organelles Mitochondria: the site of cellular respiration (releasing energy) Large vacuole: found in plant cells; stores water & minerals ((water tower)) ((power plant))
Organelles Ribosomes: where proteins are made Lysosomes: clean the cell vvvvvvv ((garbage man)) ((factory))
Organelles Nucleus: controls all activities in the cell Endoplasmic Reticulum: transportation ((roadways)) ((city hall))
Organelles These organelles allow the cell to carry out the functions necessary to live: Process information (nucleus) Provide energy (chloroplast & mitochondria) Process / transport & protein production (ER & ribosomes) Storage / recycling and getting rid of waste (vacuoles, vesicles & lysosome) Support, protection, allows material in & out (cell membrane & cell wall)
Cells need materials to enter and waste products ot leave the cell. Cells do not have mouths, noses or skin – so how do things get in and out? Extremely small materials can enter and leave through diffusion & osmosis. These materials can pass through the cell membrane.
Cell Transport Passive Transport: Active Transport: Sometimes molecules need to move from areas of low concentration to areas of higher concentration – this process requires energy and is called active transport Think going uphill on a bike • Diffusion and osmosis are passive transport – they require no energy • Movement of molecules from an area of high concentration to an area of low concentration • Think going downhill on a bike
Some molecules are too big to go through the cell membrane. In this case the a cell uses endocytosis or exocytosis to move the molecules. Endocytosis = “into the cell” Exocytosis = “out of the cell”
Evolution Protists Past… Protists Future… Some scientists believe that modern fungi evolved from ancient fungus-like protists; that modern plants evolved from ancient plant-like protists; and that modern animals evolved from ancient animal-like protists. Some scientists believe that protists evolved from ancient single-celled eubacteria and archaeabacteria
The Circle of Life Protists play a huge part in food chains & the Circle of Life. Producers make oxygen for consumers; the consumers feed off of even smaller bacteria and are a food source for larger consumers. The decomposers return important nutrients bact to the earth – thus completing the Circle of Life!
Photosynthesis & Respiration Producers take in water and carbon dioxide and in the presence of sunlight create oxygen and sugar – this happens inside the chloroplast Now that producers have created sugar (glucose) and oxygen – how is it used? • The beginning source of energy for almost every living thing on our planet is the sun • Producers are the only organisms capable of converting this energy from the sun into food (sugar/glucose) • This happens during photosynthesis
Photosynthesis and Respiration • All organisms take in this sugar and oxygen and inside the mitochondria it is converted to ATP (energy for the cell – energy NEEDED to carry out the processes of life). • Carbon dioxide and water are the garbage left over after cellular respiration • Who needs these two ingredients (think about producers and photosynthesis…)?
Photosynthesis & Respiration These two processes make up a second Circle of Life – each process uses the others “trash” as its starting ingredients. A perfect circle – nothing wasted – everything recycled and reused!!!
Cellular EnergyThere are two more ways cells release the energy stored in sugars – these are not as efficient as respiration (produces less energy) – both are used when there is no more oxygen to burn Alcoholic Fermentation Lactic Acid Fermentation Examples include yogurt and cheese Also happens sometimes when you exercise strenuously (the “burn” in your muscles) • Examples include making bread