VIRUSES What is a virus? n A non-cellular particle made up of genetic material that can invade living cells. n Viruses can grow and reproduce but only with the help of a host.
STRUCTURE OF A VIRUS n Capsid n DNA or RNA n tail n tail fibers Bacteriaphage
Virus Diversity n Viruses are specific to the cells they attack. Ex. HIV only attacks white blood cells, herpes only attacks cells of the lips or genitals, bacteriaphages only attack bacteria n Ways of attacking cells; injecting DNA into cell (bacteriaphages) or completely entering the cell
LIFE CYCLE OF A VIRUS 1. Attachment n Virus attaches to a specific host cell 2. Entry n virus injects cell with its own DNA 3. Replication n host cell destroyed new viral DNA and proteins made. 4. Assembly n new virus particles assemble 5. Lysis and Release n new virus particles released.
ARE VIRUSES LIVING? n Biologists do not consider viruses living; they do not belong to ANY kingdom. n Viruses can not live independently. n However, in a host, viruses can grow, reproduce, regulate gene expression and even evolve. n Should they be considered living?
n #1 http://www.youtube.com/watch?v=D2Uuc 76DvlI n # 2 http://www.youtube.com/watch?v=800F BiTjaLY http://www.youtube.com/watch?v=800F BiTjaLY
Reproduction Sexual reproduction n conjugation n A bridge forms between 2 bacteria. DNA is transferred from one to the other bacteria Asexual Reproduction n Binary fission n No genetic recombination
Domain Archaea Kingdom Archeabacteria n Ancient Bacteria n Prokaryotic (no organized nucleus) n Have separate evolutionary history and biochemistry from other bacteria. n Found in harsh environments
Domain Bacteria Kingdom Eubacteria n Ubiquitous (commonly occurring) and diverse n Occur in every habitat and environment on earth, even acidic and radioactive ones. n Most are harmless or even beneficial but some are pathogenic (disease causing) n Ex. Bubonic Plague, cholera, syphillus, anthrax, and leprosy all caused by bacteria.
Identifying Bacteria 2 Types: 1. Gram – n Bacteria with a thin wall of peptidoglycan n Do not stain with Gram’s Stain n Ex. N. gonorrhoea, salmonella, E. Coli 2. Gram + n Thick wall of peptidoglycan n Staphyloccus, streptococcus
IMPORTANCE n Fix nitrogen - break down nitrogen to make it usable n Recycle nutrients - break down nutrients of dead organisms returning the nutrients to the environment. n Food and medicines - food formed from fermentation (yogurt, cheese, butter) n Disease
Disease Transmission n Word Scramble – In groups of 2 complete the word scramble cutouts.
Word Scramble Game Unscramble the letters to spell a word using the hint and definition on the right. Letters: e, g, m, r Word: This word is a noun. This may not be seen, but it can make you sick! (Definition: a microorganism that causes diseases.) Unscramble the letters to spell a word using the hint and definition on the right. Letters: a, g, i, m, n, o, r, s Word: This word is a noun that ends with the suffix “-ism.” This refers to an individual form of life. (Definition: a living being, a form of life considered as an entity.) Unscramble the letters to spell a word using the hint and definition on the right. Letters: c, e, f, i, i, n, o, s, t, u Word: This word is an adjective. This can be used to describe a germ that spreads from person to person. (Definition: that which corrupts or contaminates; spreading rapidly to others.) Unscramble the letters to spell a word using the hint and definition on the right. Letters: c, e, f, i, n, t Word: This word is a verb. Germs do this to people and cause diseases. (Definition: affect, contaminate, taint.)
Unscramble the letters to spell a word using the hint and definition on the right. Letters: a, i, m, n, r, s, t, t Word: This word is a verb containing the prefix “-trans.” This describes the action when a germ is moved from one person to another. (Definition: send, spread, pass on.) Unscramble the letters to spell a word using the hint and definition on the right. Letters: a, i, i, m, n, n, o, r, s, s, s, t Word: This word is a noun. This happens not only to germs but also to radio waves. (Definition: an act or process of spreading.) Unscramble the letters to spell a word using the hint and definition on the right. Letters: a, d, e, e, i, s, s Word: This word is a noun. Some of this can be prevented by eating healthily and exercising daily. (Definition: illness.) Unscramble the letters to spell a word using the hint and definition on the right. Letters: m, m, o, p, s, t, y Word: This word is a noun. A common cold shows this as a cough, sore throat, sneezing, headache, slight fever, runny nose, etc. (Definition: a sign or indication of something)
Keep the words that you just unscrambled in mind as we discuss the following questions. n 1. What are some infectious diseases you already know about and what are their symptoms? n 2. What makes these diseases contagious? n 3. To help stop or minimize the transmission of infectious diseases, what information do you think would be important to know and what are some precautions that one could take?
n You will be simulating the transmission of diseases from one person to another. Each person will be given a cup with a liquid in it. n You will exchange liquid with 3 partners by combining then splitting the contents of the 2 cups. Be sure to record who you exchange with!
n When the class is finished we will add phenolphthalein (C 20 H 14 O 4 ) which is an indicator of bases. n Phenolphthalein stays clear in water but will turn pink in the presence of a solution above 7 ph. n 3 of the cups had a common base, sodium hydroxide NaOH. n Let’s check your cup! n Now, in groups of 3 complete the summary sheet.