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Characteristics Benefits Negative Effects What Are Bacteria? Bacteria are single- celled organisms. They do not contain a membrane-bound nucleus. They do not contain membrane-bound organelles. What DO They Have? Ribosomes. A single chromosome. (They have DNA!) A cell wall that protects the cells from drying out. Some bacteria may have a flagellum, or whip-like tail to help them move. How Are Bacteria Classified? Because bacteria do not have a nucleus, they are Prokaryotes. They are divided into two kingdoms: Archaebacteria Eubacteria Archaebacteria Archaebacteria live in extreme conditions such as hot springs. They generally live in oxygen-free environments. Archaebacteria Some live in The Great Salt Lake. Some live in acid waters Some live in the stomachs of cows. Eubacteria Eubacteria can live in extreme environments too. These bacteria are found just about everywhere. Some are heterotrophic. (they get their food by absorbing it) Eubacteria Some are autotrophic. (they make their own food using the energy of the sun) Some are chemosynthetic autotrophs. (they make their own food using the energy of inorganic compounds containing sulfur and nitrogen) Bacteria Have Different Shapes Bacteria generally appear as one of three shapes: rod, round or spiral. Coccus: round Bacillus: rod Spirillum: spiral Bacterial Reproduction Bacteria can reproduce by two different methods: Binary fission Conjugation Asexual/Binary Fission Binary fission is a method of asexual reproduction where : the chromosome makes a copy of itself; each copy moves to opposite ends of the cell; the cell divides, leaving each new cell with the identical DNA as the original cell. Sexual/Conjugation Conjugation is sexual reproduction. Two bacteria may exchange genetic material, or one may give part of its chromosome to another bacterium across a bridge formed between the two cells. This results in two cells with different genetic makeup. Survival of the Fittest! Bacteria have an uncanny ability to survive. They can form endospores when conditions are unfavorable for survival. An endospore is made of a tough coating, the chromosome, and a bit of cytoplasm. Endospores can survive high temperatures, dryness, freezing conditions, and harsh chemicals. Beneficial Bacteria Not all bacteria are harmful! Many bacteria live in the digestive systems of animals and humans, and aid in digestion. (Remember: extreme conditions!) Beneficial Bacteria Bacteria act as decomposers. Dead plants and animals are decomposed by bacteria and their nutrients are returned to the air and soil. Bacteria: Amoeba Sisters Beneficial Bacteria Many bacteria convert nitrogen from the air into ammonia, and then into nitrites and nitrates in the soil which can then be used by the roots of plants. Fertilizer! Other bacteria are used to make foods, such as cheese, yogurt, and vinegar. Antibiotics Antibiotics are substances which kill bacteria. Some antibiotics are produced by certain species of bacteria for the purpose of killing other bacteria. Some antibiotics are produced by certain species of fungi in order to kill bacteria that might grow near them. Antibiotics vs Bacteria •Some antibiotics work by interfering with the cell wall of the bacterium, creating holes in the cell wall. Cell contents leak and the bacteria die. •Antibiotics may not kill all of the bacteria – some may survive and reproduce, carrying the genes for ‘resistance.’ •Antibiotics are not effective against viruses, because viruses are NOT alive. Harmful Bacteria Pathogenic bacteria cause disease. The bacteria that infect the body may affect the function of normal body tissue, Or they may produce a toxin that attacks the host tissue. © Lisa Michalek Characteristics of Fungi Some members of the Kingdom Fungi, such as molds and mushrooms, are very common and grow so rapidly that they sometimes appear overnight. The first Fungi appeared on Earth about 430 million years ago. In the past, biologists grouped fungi with plants because fungi are immobile, have a cell wall and appear “rooted” in the soil. However, the unique features of fungi indicate that they should be classified as a separate kingdom. Characteristics of Fungi Fungi are Heterotrophic. The stalk and cap of the mushroom are not green like the stem and leaves of a plant. Plants appear green because they contain chlorophyll, the pigment that aids in photosynthesis. Fungi do not contain chlorophyll. Fungi obtain their energy by breaking down organic material that they absorb from their environment. Characteristics of Fungi Fungi have Filamentous Bodies. Plants are made of many cell and tissue types, but fungi are made of long, slender filaments. These filaments weave tightly together to form the fungus body and reproductive structures. Characteristics of Fungi Fungal Cells contain Chitin. The cells of all fungi have walls made of chitin. The tough polysaccharide found in the hard outer covering of insects. Plant cells have walls made of cellulose, a different polysaccharide. Characteristics of Fungi exhibit Nuclear Mitosis. Fungi Mitosis in fungi is different from mitosis in plants and in most other eukaryotes. In most eukaryotes, the nuclear envelope disintegrates in prophase and re-forms in telophase. In dividing fungi cells, the nuclear envelope remains intact from prophase to anaphase. As a result, spindle fibers form within the nucleus. The spindle fibers then drag chromosomes to opposite poles of the nucleus rather than to opposite poles of the cell. Mitosis is complete when the nuclear envelope pinches in two. Structures of Fungi All fungi except yeasts have bodies composed of slender filaments called hyphae. When hyphae grow, they branch and form a tangled mass called a mycelium. A mycelium can be made of many meters of individual hyphae. Structures of Fungi This body organization provides a high surface-areato-volume ratio, which makes a fungus well suited for absorbing nutrients from its environment. Each hypha is a long string of cells divided by partial walls. Some species do not have walls between cells. Cytoplasm flows freely throughout the hypha. Fungi Nutrition All fungi obtain nutrients by secreting digestive enzymes that break down organic matter in their environment. Fungi then absorb the decomposed molecules. Fungi Nutrition Many fungi decompose nonliving organic matter, such as leaves, branches, dead animals, and waste. Other fungi are parasites that absorb nutrients from living hosts. Fungi often grow on human foods, such as bread and fruit but also are known to attack nonfood materials such as paper, cardboard, cloth, paint, and leather. Fungi Nutrition Some fungi are useful in baking, brewing and wine-making. Others provide the flavor and aroma of certain cheeses. Many kinds of antibiotics, such as penicillin, are produced by fungi. Penicillin G Reproductive Structures Three Sexually Reproducing Phyla of Fungi Phylum Characteristics Examples Zygomycota Sexual spores are formed in Black zygosporangia; hyphae have no walls Bread Molds Ascomycota Sexual spores are formed in asci; hyphae are divided by walls Morels, Truffles, Yeasts, Cut fungi Basidiomycota Sexual spores are formed in basidia; hyphae are divided by walls Mushrooms, Puffballs, Rusts, Smuts Bread-Mold Sandwiches An Indonesian food called tempeh is made of soybeans that are boiled, skinned, and inoculated with various species of Rhizopus (bread mold). The tempeh is then fried, roasted, or diced in preparation for a meal. Today, tempeh can be found in health food and natural food stores, as well as some large supermarkets. Basidiomycetes Mushrooms are members of this phylum Other Basidiomycetes include toadstools, puffballs, jelly fungi, and shelf fungi. The basidium is the club-shaped sexual reproductive structure for which this phylum is named. Spores are produced on this structure. Basidiomycetes Asexual reproduction is rare, except in some rusts and smuts. These two important groups of plant pathogens affect many crop plants. Many mushrooms are harmless, but many are also deadly. Poisonous mushrooms cannot be discerned by a quick test such as smearing liquid from a mushroom on white paper and looking for a color change or looking for a color change in a broken stem. Only a trained mycologist should attempt to identify edible mushrooms. Mushroom Characteristics Body Structure: The multicellular body of a fungus is basically filamentous. It consists of long strings of cells called hyphae. Hyphae are woven together to form a dense mat called a mycelium. Mushroom Characteristics Nutrition: Fungi are heterotrophs. Fungi secrete enzymes that break down organic materials into simple molecules that the hyphae can absorb. Fungi store food as glycogen. Mushroom Characteristics Reproduction: Under proper conditions, underground hyphae grow upward and weave together to produce a mushroom. A mushroom has a flattened cap attached to a stem called a stalk. The underside of the cap is lined with rows of gills. Thousands of club-shaped reproductive cells called basidia form on the gills. Through fusion and meiosis, each basidium produces spores that are released and form new hyphae. Fungal Partnerships Symbiotic Relationships Fungi are involved in many kinds of symbiotic associations with algae and plants. These mutualistic relationships play important roles in ecology. Mutualism is a type of relationship in which each partner benefits. The fungus (a heterotroph) provides minerals and other nutrients that it absorbs from the environment. The algae or plant (a photosynthesizer) provides the ability to use sunlight to power the building of carbohydrates. Fungal Partnerships - Mycorrhizae A type of mutualistic relationship formed between fungi and vascular plant roots. The hyphae help transfer phosphorus and other minerals from the soil to the roots of the plant, while the plant supplies carbohydrates to the fungus. The hyphae penetrate the outer cells of the root. Fossils show that the root-like structures of the earliest plants often had mycorrhizae, which may have played an important role in the invasion of land by plants. Scientists think that when plants invaded the land the soil of that time completely lacked organic matter. Plants with mycorrhizae can grow successfully in infertile soil. Fungal Partnerships - Mycorrhizae In many plants, the mycorrhizae do not physically penetrate the plant root but instead wrap around it. These kinds of mycorrhizae are important because they aid the growth of many commercially significant trees, such as pines, oaks, beeches, and willows. Some produce economically important edible mushrooms, and some of the ascomycete species produce an edible fruiting body called a truffle. Fungal Partnerships - Lichens A lichen is a symbiosis between a fungus and a photosynthetic partner such as a green algae, a cyanobacterium, or both. The photosynthetic partner provides carbohydrates. It is protected from the environment by the fungal partner, which helps it absorb mineral nutrients. In most lichens, the fungus is an ascomycete. Fungal Partnerships - Lichens When you look at a lichen, you are seeing the fungus. The photosynthetic partner is hidden between the layers of hyphae. Sunlight penetrates the layers of hyphae and enables the partner to carry out photosynthesis. Fungal Partnerships - Lichens The tough construction of the fungus combined with the photosynthetic abilities of the algae, or cyanobacterium, has enabled lichens to colonize harsh habitats. Lichens have been found in arid desert regions and in the Arctic; they grow on bare soil, on tree trunks, and on sun-baked rocks. Fungal Partnerships - Lichens During succession, lichens are often the first colonists. They break down rocks and prepare the environment for other organisms. Lichens are a key component of primary succession because they are able to grow on rock and help break the rock down into soil. Lichens containing cyanobacteria carry out nitrogen fixation and introduce useful forms of nitrogen into the soil. Fungal Partnerships - Lichens Lichens are able to survive drought and freezing by becoming dormant. When moisture and warmth return, lichens resume normal activities. In harsh environments, lichens may grow slowly. Some lichens that grow in the mountains appear to be thousands of years old and cover an area no larger than a fist. These lichens are among the oldest living organisms on Earth. Fungal Partnerships - Lichens Although lichens are known to survive extremes of temperatures, they are susceptible to chemical changes in their environment and can become a living indicator of the amount of pollution in the environment in which they live. Lichens have no roots, so the nutrients they take up must come from the air. Rain, fog, and dew wet the surface of a lichen. When they are wet, lichens absorb nutrients and any pollutants that are in the air. Indicator Species Xanthoria parietina Xanthoria polycarpa 1 cm 1 cm Physcia tenella 1 cm Usnea cornuta Hypogymnia physodes Nitrogen-loving Sulphur-tolerant Indicator of clean air 1 cm 1 cm What Do You Know About Viruses? You probably know that they cause diseases. And you probably know that they are so small, you can’t see them unless you use a high Did you know that resolution microscope! viruses are NOT alive? Viruses Viruses are hundreds of times smaller than bacteria. Scientists must use an electron microscope to see viruses. Viruses There are many different kinds and types of viruses. What Do All Viruses Have In Common? They do not move on their own, nor use energy. They do not eat or release wastes. They do not carry on metabolism. They are made of only a protein coat and either DNA or RNA. Can Viruses Do ANYthing? Viruses have one function in common with living things: - they can reproduce! - but, only inside a living cell. So, How Can They Hurt Us? Since they have genetic material, they have the capability of infecting living things. Each type of virus can specifically infect only certain kinds of cells. A plant can be infected with a virus that will not affect you. You can be infected with a virus that will not affect your dog. Viral Specificity – The Secret Weapon! The protein coat of a The ‘knobs’ on the outside of the virus are protein markers, which chemically recognize only host cells. virus is specific to its host cell. The virus will only attach to a cell which it chemically recognizes. Viral Specificity A virus cannot attach to a cell membrane for which it does not have a specific molecular attraction. Viruses Viruses cannot move. They are at the mercy of the elements. If you are infected with a virus, and you sneeze, you may be transmitting the virus to others through the moisture particles you expel! Tricky Viruses… And, depending on the type of virus, the viral particles may survive ‘intact’ for hours on a surface before degrading. If you touch that surface with your hands, and then touch your eyes, nose, or mouth, you may become infected! IF the virus has specificity to your cells! What Does the Virus Do Once It Invades Your Body? First, a virus must attach to a host cell and inject its genetic material, or be enveloped by the host cell. From here, the virus will take one of two courses, depending on the type of virus. Two Types of Viral Replication Viruses may undergo one of two methods of replication inside the cell: Lytic cycle Lysogenic cycle Viral Replication – Lytic Cycle In the lytic cycle, viruses attach to the host, take over the cell’s machinery, and new viral particles are made right away. The host cell’s nucleus, ribosomes, and other organelles are forced into creating and assembling these new viral particles. Lytic Cycle The cell fills up with the newly-formed viruses and cannot function. The cell bursts, releasing the newlyformed viruses. This may only take 30 minutes! Lytic Cycle The newly-formed viruses can attach to new host cells and repeat the process. Only the host’s immune system can attack the viruses and get the infection under control! Colds, flu, and measles viruses go through a lytic cycle. Bacterial Diseases Strep throat, tuberculosis, anthrax, Lyme disease, tooth cavities, cholera and tetanus are examples of diseases caused by bacteria. Bacterial Diseases Cholera is caused by drinking unclean water that contains the cholera bacteria. Tetanus can be contracted when the tetanus bacteria, found in the soil, get into your body through a puncture wound. Lyme disease can be contracted after being bitten by the blacklegged tick. Viral Replication – Lysogenic Cycle In the lysogenic cycle, viruses attach to the host, but mix their genetic material with the host’s, and do not cause new viral particles to be made right away. Lysogenic Cycle Later, something may trigger new viruses to be made and then the lytic cycle begins. Lysogenic cycles may be months to years long! Lysogenic Cycle HIV/AIDS, shingles, cold sores, and warts are examples of diseases caused by viruses that go through the lysogenic cycle. HIV/AIDS The HIV/AIDS virus attacks the immune system. It may lie dormant for years before it enters the lytic cycle. The HIV virus may be spread by sharing needles, or exchange of body fluids such as blood. Defense Against Disease Wash hands thoroughly with soap and water, often. Cover your mouth with a tissue or your sleeve when coughing or sneezing. Get vaccinated against common viral diseases. Defense Against Disease Stay away from others who may have a viral infection. Do not share food dishes and drinking glasses with others who are sick. Stay home when sick – do not pass around your illness. Bacteria and Viruses. 1. Bacteria contain a membrane-bound nucleus. 2. Many bacteria are helpful in digestion. 3. Bacteria are used in the manufacture of yogurt, cheeses, and vinegar. 4. Prokaryotic cells have _____ mitochondria organelles a nucleus a cell wall chloroplasts Answer: D – Prokaryotic cells have a cell wall. They do not have any membranebound organelles. 5. Antibiotics kill all bacteria every time. 6. Many diseases caused by bacteria actually make you sick because of the toxins they produce. 7. Which of the following spreads disease-causing bacteria? Access to new hosts Low temperatures Mutation by heat energy Availability Exposure to sunlight Answer: A – Access to new hosts spreads disease. Low temperatures keep bacteria from growing rapidly, and exposure to sunlight usually kills bacteria. 8. Viruses contain a nucleus and a cell wall. 9. What characteristic do viruses share with all living organisms? movement respiration reproduction metabolism growth Answer C – Reproduction. Viruses can replicate only inside a living cell. Viruses do not carry on respiration, movement, metabolism, or growth. 10. HIV, the virus that causes AIDs, can hide inside a cell for years, then become active and start killing cells. 11. Polio, measles, mumps, and the flu are all caused by viruses. 12. Streptococcus, anthrax, and cholera are caused by viruses. 13. Many viral diseases can be prevented by vaccines. 14. Some bacteria can take nitrogen from the air and convert it into fertilizer for plants. 15. Bacteria act as decomposers. 16. Viruses have external protein markers which allow them to recognize a specific host cell and infect it. 17. Once a virus enters a cell, it can cause the host cell to immediately make new viruses. This is called an invasion the lysogenic cycle a mutation the lytic cycle AIDS Answer: D – The lytic cycle is the immediate take- over of the cell by the virus. The lysogenic cycle is when the virus is incorporated into the host’s DNA and does not immediately kill the host cell. 18. The human immunodeficiency virus attacks a person’s respiratory system first. 19. Some bacteria have flagella. These structures are used for making protein digestion replication attaching to surfaces locomotion Answer: E – Flagella are used for locomotion. 20. Antibiotics are used to kill viruses. 21. Pathogenic bacteria are disease-causing bacteria. 22. Which of the following is a way that HIV can be transmitted? Shaking hands Hugging a person Sharing needles Infected toilet seats Sharing food Answer: C – Sharing needles is a way to transmit HIV. 23. Cholera is a bacterial disease transmitted by contaminated water. 24. Tooth cavities are caused by acids released by bacteria in the mouth.