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Biology 1001A Part1 - midterm.pdf

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Biology 1001A
Tom Haffie

HIV October-06-12 9:15 PM Pre Lecture 1. The general mechanismsby which vaccines protect against diseases. - They create a catch of "weapons"for your body's immune system to use when needed - When a person gets a viral infection, it may take days or weeks for your body to fight back at full strength - When said person is pre-immunized there are forces in the body pre-trained to recognize and fight off certain viruses 2. Why developing a vaccine against HIV is relativelychallenging, compared to other diseases. - They are always changing - Mutates furiously - Decoysto evade immune system - Attacks the cells trying to fight it - Hides itself in your genome 3. Why people are encouraged to get a flu vaccince each year (as opposed to one time only) - They virus changes all the time and therefor one certain antibody cannot be used - A best guess is taken at what the most prevalent strain of virus will be and the vaccine is issued Lecture Epidemic- A widespread occurrence of an infectious disease in a communityat a particular time Pandemic- When the infectious disease hits goes global The fatalities and number of people living with HIV and AIDS is beginning to no longer increase, in the case of AIDS, descend The Tree of Life -After 30 years there is still no cure for HIV -Viruses do not a have a place on the tree of life because they are not living organisms -they cannot reproduce without a host -they are obligate parasites: they cannot live without a host -they have no metabolicprocesses -they have no cells -Anti-viral therapy has severe side effects -cannot kill the virus without damaging host cells -Viruses such as HIV store their informationon RNA, not DNA -must go through reverse transcription which has a high rate of error which cause mutations -Reverse transcription RNA DNA -Retro viruses use reverse transcription -HIV focuses on immune cells in the human body HIV Lifecycle -HIV fuses to host cell and injects informationinto host cell -RNA is reversed transcribed into DNA -reverse transcriptase -Splices DNA into host DNA -Splices DNA into host DNA -Transcription, translation, new viruses assemble and bud off or lyse out -The immune system collapses and host will succumb to a secondary virus AZT mimics Thymidine and inhibits reverse transcriptase -AZT attempts to stop reversetranscription -AZT mimics thymidine and inhibits reverse transcription -AZT will attach to a DNA chain and will cause a stop -AZT resistance began and is now completelyresistant to the drug -the virus has changed and AZT is now recognized and avoided -in addition to a high mutation rate there is also a high reproduction rate Humans have evolvedtoo -some people have not contracted the disease despite repeated exposure -they have a deletion of a set of amino acids of a protein -1 copy = slightly protected -2 copies = completelyprotected -the strange geographical distribution could be due to: -possible selection pressure by HIV -forward in N. Europe due to historical epidemics (plague, small pox) -chance and history? Origins October-06-12 9:15 PM Pre Lecture 1. characteristics shared by all life. All life: 1. Displays order 2. Harnesses and utilizes energy 3. Reproduces 4. Responds to stimuli 5. Exhibits homeostasis 6. Grows and develops 7. Evolves 2. in what way properties of life are "emergent". - The properties of life are considered "emergent" because they emerge from many simpler interactions that, in themselves,do not have the properties found at higher morecomplex levels. - Ex. The ability to harness and utilize energy is not a property of moleculesor proteins or biological membranesin isolation; rather the ability emerges from the interactions of all three of these as parts of a metabolic process. 3. characteristics of the "habitable zone" of a solar system. - A position where heat from the sun allows for surface temperaturesto be within a range that allows water to exist in a liquid state. 4. conditions of a primitive Earth. Atmosphere-probably contained an abundance of water vapour from the evaporationof water at the surface, as well as large quantities of Hydrogen (H2), Carbon dioxide (CO2), ammonia (NH3), and methane (CH4). Almost a completeabsence of oxygen (O2). No ozone layer (O3)- allowed UV light to reach the lower atmosphereand drive the formation of biologically important molecules. 5. types of moleculesthat were, and were not, synthesized by the Millar-Urey experiment. Moleculesthat were synthesized: - Urea - Amino acids - Lactic, formic and acetic acids Moleculesnot synthesized with the addition of Hydrogen Cyanide (HCN) and Formaldehyde (CH2O) - Building blocks of complexbiological molecules Amino acids Nucleic acids Sugars Phospholipids 6. importance of liposomesin evolution of first cells. - Early protobionts(a group of abiotically produced organic moleculesthat are surrounded by a membrane or membranelikestructure) were similar to liposomes(a lipid vesicle in which the lipid moleculesform a bilayer very similar to a cell membrane). - Clay catalyzed the polymerizationof nucleic acids and accelerated the formation of lipid vesicles. - Clay became encapsulated in these vesicles, which would provide catalyticallyactive surfaces within membrane vesicles upon which key reactions could take place. within membrane vesicles upon which key reactions could take place. 7. characteristics of mimivirus that suggest it should be considered to be alive. - The fact that it can get sick makes it more alive 8. characteristics of virophage. - A virophage infects a mamavirus(slightly larger than a minivirus) and uses its machinery to replicate - Produces fewer and often more deformedmamavirus particles which makes the virus less effective Lecture According to the OparinHaldane hypothesis, what was the compositionof the primordial atmosphere? A: molecular hydrogen (H2), water, ammonia,and methane What was the main conclusion of the now famous Miller-Urey experiment? A: Simple "building block" moleculescan be created under abiotic conditions. Some scientists argue that viruses are not living. Which of the following statementsis true and supports the argument that viruses are, therefore,not alive? A: Viruses do not contain ribosomes,therefore they are not alive. Life DevelopedEarly -Life on earth developed quite early, shown through geological evidence, shown through stromatolites(3.5 bya) -Earth is 4.6 billion years old -Cyanobacteria are very sophisticated so they were therefor they are most likely not the first form of life LUCA (Last Universal CommonAncestor) -Using the tree of life to show what is living, we can determine that viruses are not living -Humans are derived from the last universal commonancestor (the main stem of the tree of life) -Characteristics of the living things on the tree of life -Genetic system based on DNA -everything has ATP -they all share proteins (central dogma) -cells are made up of lipids -commonsystem of protein assembly -glucose and glycolysis What Came Before LUCA The last universal commonanswer -does not mean that everything came from the exact same form of life -there was most likely many forms of early life -it was the last commonancestor that survived that created the tree of life Prokaryotesdo not exist on the tree of life -they are not a single group of organisms -bacteria and archaea do not share anything in commonand they cannot be grouped into prokaryotes -the pro would assume that they came before, which they did not -also suggests that evolution movesfrom simplecomplexwhich is not always true simple to complex ....misconception Reductive evolution They stream lined themselves
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