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41 Cards in this Set
- Front
- Back
Mutations can be both ______ and ______.
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spontaneous
induced |
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Name three ways in which spontaneous mutations occur
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1. Without exposure to external factors
2. Errors in DNA replication 3. Action of mobile genetic elements (transposons) |
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How do induced mutations occur?
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By agents that directly damage DNA
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Are induced mutations rare or common?
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Rare
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How rare are induced mutations?
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1 in 10 million
10 to the 7th power to 10 to 11th power |
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What is a mutagen?
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A physical or chemical agent (i.e DNA) that changes genetic material and mutates it
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What is a carcinogen?
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A substance that is an agent directly involved in causing cancer
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There is no relationship between a mutagen and a carinogen. T or F?
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False: there is a relationship: most carcinogens are ALSO mutagens
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When we test for a mutagenicity, we use this exact same test to screen for ______ ______.
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carcinogenic potential
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What is a great example of test that is used to predict mutagenic potential?
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The Ames Test
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What does a positive result from an Amest test mean?
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That the compound being tested is mutagenitic. In this case it MAY act as a carcinogen - but not always!
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What type of things might we perform an Ames test on?
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Food aditives, chemical compounds, shampoo
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What is selective pressure?
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The alter of behavior and fitness in living things. It is the driving force of evolution and natural selection
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Mutations are subject to ______ ______.
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selective pressure
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Each mutant that survives (and ultimately becomes resistant) to whatever was targeting it, will eventually becomes an ______ form of a ______
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alternate
gene |
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Why is selective pressure so important?
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Because it illustrates why antibiotics can become ineffective if ALWAYS used - even when not sick
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What happens when we continously use antibiotics and other chemicals that kill bacteria (i.e handsoap, cholorine, etc).
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The bacteria will eventually mutate, survive and then become resistant.
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Why would we NOT want to be around someone that is on antibiotics?
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We may pick up bacteria from them that has become RESISTANT due to the antibiotic.
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How many methods are there in Horizontal Gene Transfer...and what are they?
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Three
1. Conjugation 2. Transformation 3. Transduction |
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Generally speaking, what is horizontal gene transfer?
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The moving of gene material from one mature organism to another mature organism
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What is an exogenote?
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The DNA donor: the cell transferring its DNA to another cell
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What is an endogenote?
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The DNA recipient: the cell receiving the DNA from another cell
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For this test, we must always assume that horizontal gene transfer is ______.
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successful
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What is an F+ plasmid?
What is an F- plasmid? |
F+: a plasmid that carries a particular function (it is fertile)
F-: a cell that LACKS this particular function |
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The F+ cell will have the "information" in order to form a ______ pilus
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sex (see figure 14.19) on slide
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In conjugation, what is TRANSFERRED through the sex pilus?
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The plasmid: it travels FROM the F+ cell TO the F- cell.
Think of it as a man (F+) impregnating a woman (F-) |
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When conjugation plasmid transfer is complete, what do we end up with?
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Two F+ cells (they both now contain the plasmid that codes for that specific function)
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In conjugation, how does the plasmid replicate itself BEFORE it travels thru the sex pilus?
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Through the rolling circle method (look at slide 20)
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What is an Hfr cell?
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This is simply an F+ cell that has INCORPORATED its plasmid INTO is chromosome
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What happens when an Hfr cell makes contact with an F- cell?
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Because the Hfr cell's plasmid is INTEGRATED into its chromosome, the ENTIRE chromosme will now be transfered to the F- cell
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What does Hfr stand for?
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High frequency recombination
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May have to diagram the Hfr and F- mating cycle (conjugation)
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See slide 23
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What is the final outcome when an Hfr mates with an F-
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We will now have TWO Hfr cells (the F- cell will INCORPORATE the receiving DNA into its own chromosome)
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In conjugation, what is an F' (prime) cell?
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An Hfr cell in which the F factor of the chromosome loops OUT and either:
1. Leave a piece of itself behind OR 2. Takes a peice of the chromosome with it |
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An F' can now mate with an F- through conjugation. What is the result?
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Two F' cells
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What is a competent cell?
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A cell (during the growth phase) that realeases a special protein that allows it to uptake DNA during transformation
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What is happening during tranformation?
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Naked DNA is simply taken in by a competent cell (note: competence can be made artificially) See slide 27
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In simple terms, what is transduction?
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The transfer of bacterial genes through viruses
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What is important to understand when describing transduction?
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The lytic and lysogenic cycles
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What is generalized transduction?
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During the lytic cycle, any random piece of the cells genome will ACCIDENTALLY be packaged into the viruses phage-head. The virus will then inject this DNA into a new host
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What is specialized transduction?
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During the lysogenic cycle, a temperate virus will begin replicating upon entering the lytic cycle - taking specific pieces of the host's genome with it. (usually an accident)
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