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Biology Exam Review Weeks 5-9.docx

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Fiona Bawl

The Classification of Living Things Viruses  • Latin for “poison” • Do not display the essential characteristics of living things • Not classified in any of the 6 kingdoms of living things • 10nm to 275nm • Each virus is a molecule of nucleic acid (DNA or RNA) surrounded by a protein coast (capsid) • Protein coat protects the nucleic acid and determines what type of cell a virus can infect (helps the virus attach itself to specific receptor on the host cell – “lock and key”) • RNA viruses have a special enzyme called reverse transcriptase • Viruses are not living and are unable to reproduce on their own • They use living cells as their host and reproduce within the living cell • Antibiotics are of no use – vaccines can prevent some viral infections • “The ultimate parasite” • They manipulate/force the living cell into producing new viruses by incorporating their viral genes into the host cell’s DNA • Once inserted, the viral DNA is called a provirus and it is replicated along with the host’s DNA • RNA viruses are usually more lethal than DNA viruses because they remain ‘hidden’ for a long time (latency period) before the body’s immune system is triggered • During this time, many viruses are being produced in the host cells, using the host’s raw materials and machinery • RNA viruses comprise 70% of all viruses and have a much higher mutation rate as a result of replication errors Taxonomy – practice of classifying organisms, founded 300 years ago by Swedish botanists Carolus Linnaus Binomial Nomenclature – using a two-word Latin name for each species (Genus species) Taxon – (plural) group of species Taxa – only a single type of organism *Taxon species include members that resemble each other so closely that they can interbreed and produce fertile offspring. Evidence from Biochemistry • Technology has allowed scientists to look at organisms at a fundamental level – the molecules from which they are made of • Comparing protein molecules (determined by your genes) can indicate genetic similarities and differences • Guinea pigs are not longer considered rodents and have their own taxon because of these advances in technology • Humans, chimpanzees, gorillas and orang-utans are now classified in the same family Hominidae Kingdom Archaea • Archaea are found in the following extreme environments: o hot springs; boiling sea-floor vents; alkaline or acidic waters; saline environments, ie the Dead Sea; volcanoes; hot coals; below Earth’s surface • As different from bacteria as they are from plants and animals. The cell membranes of some archaea contain unusual lipids (fats), so they remain stable at very high temperatures. Others have different fatty substances that remain liquid and functional at cold temperatures. • There are 3 main groups of archaea, based on their metabolism. o Methanogens are methane-producing archaea that live in oxygen-free environments such as swamps. o Halophiles are salt-loving archaea that live in extremely saline environments such as salt pools. o Thermoacidophiles are heat- and acid-loving archaea that live in extremely hot and acidic environments such as hot sulphur springs. • All archaea thrive in conditions similar to those presumed to have existed in Earth’s early atmosphere. Bacteria Classifying Bacteria • done through comparisons of shape, cell wall structure, food sources and energy, and RNA analysis • bacteria are not genetically different in the way that humans, plants and animals are species differentiate due to instant mutations Shapes • cocci: round • bacilli: rod shaped • spirili: spiral shaped • bacteria also grow in distinct patterns or shapes • prefix: diplo- is cells arranged in pairs • staphylo- cells arranged in clusters • strepto- chains Cell wall structures differ depending on arrangements of amino acids and sugar molecules gram- positive bacteria: thick protein layer, stain purple gram- negative bacteria: thin protein layer, stain pink The Black Death: Bubonic Plague • Occurred in China in early 1330s • Transmitted to people by fleas • Caused painful swelling of lymph glands • Caused spots on the skin that turned black • In 1347, Italian merchant ships returned from a trip to the Black Sea, many onboard already dying • After 5 years 25 million people were dead – one third of Europe’s population • The bubonic form of the disease was only one manifestation of the horrible pandemic • The cause of the plague was not discovered until the late 19 century • Bacteria called Yersinia pestis External Body Features that Fight Bacteria • Tears with enzymes destroy bacteria • Pharynx – muscle-lined respiratory passages trap bacteria • Trachea (wind pipe) – cilia sweep bacteria upward (smokers don’t have this, causing cancers) • Sweat on skin kills bacteria • Stomach acid destroys bacteria (except clostridium dificil) • More than 100 trillion bacteria inhabit your body. That’s as many cells as you have. Over 500 different bacterial species live in your mouth. Most bacteria (12 trillion) live in your armpits. A bacterial species can create ulcers in your stomach. 3 pounds of E.coli live in your colon. • Sterile areas (no bacteria!) are your liver, gall bladder, brain, blood, lower lungs, and thymus. Kingdom Protista • Most are single-celled • All eukaryotes like plants, animals and fungi • Classified together because they don’t fit into any of the other kingdoms • Classified into 3 major groups based on their type of nutrition: 1) Protozoa – animal-like heterotrophs that ingest or absorb their food, some are parasites (ie, cause of malaria) 2) Algae – plant-like autotrop
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