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162 Cards in this Set
- Front
- Back
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What is the relationship between how far a gene is from it's centromere?
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The farther away, the larger likely hood of cross overs ie, spore pairs will be more randomized.
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what does first division segregation look like in terms of spore pair arrangement? second division
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1st division (aaaa++++)
2nd division (aa++aa++) |
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what is the molecular method of recombination?
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Holliday structure
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describe how the holliday structure is formed?
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1. the 3' ends exchange
2. ligase seals the nicks *holliday structure is a key intermediate for crossing over. |
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what types of biochemical evidence exist for the holliday structure?
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enzymes are known that can catalyze proposed steps.
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what genetic evidence lead to the holliday structure model?
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gene conversion
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what are the requirements for being able to study gene conversion in an organism?
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must be able to recover all 4 meiotic products. ie. neurospora
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when we cross and albino spore with a normal spore, why are the deviant results not able to be a mutation?
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we still see just the parental types.
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what is gene conversion?
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when one allele at low frequency changes anothe gene to itself.
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what is gene conversion associated with?
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crossing over
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what is the difference between the chiasm model and holliday model?
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holliday- each line is a single strand of DNA
- only 2 chromatids shown - this is a crossover intermediate -just a few thousand base pairs Chiasma -each line is a chromatid - crossover is complete -whole chromosome |
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how do we cause an astronomical increase in structural variants
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x ray radiate chromosomes
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What is the requirement for a chromosome to be transmitted through cell division?
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1. have a centromere
2. have normal chromosome ends ( a cell can recognize normal chromosome ends or telomeres. 3. must be linear or circular, not branched. cannot be too big or too small |
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what is a 2 break abberation and what is the result?
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1 2 [3] 4 5
becomes 1 2 4 5 or a deletion |
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what is a duplication tandem?
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1 2 [3 4 5
and 1 2 3 4 [ 5 becomes 1 2 3 4 3 4 5 |
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translocation
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1 2 3 [ 4 5
and a b [ c d e becomes a b 4 5, 1 2 3 c d e |
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How do you id a deficiency?
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cytological appearance at pachytene in a heterozygote.
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how do you id abberations in drosophila?
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look at the salivary glands in the larva
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what is special about the salivary glands?
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the chromosomes never divide from the time that they are formed in the embryo
- the gland grows b/c of increase in cell size |
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in the drosophila salivary glands, what stage are the cells permanently in?
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interphase
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about how many copies of each chromosome are there?
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2 raise to the 10, or 1024
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how are the chromosomes aligned?
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they are in perfect lateral register, called polytene chromosoms.
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What is special about the homologs in drosophila
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they are intimately synaped in interphase, creating polytene chromosomes.
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In order to see the banding pattern created by the chromomeres, what happens when you stain with geimsa?
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you see g bands (AT rich)
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what happens if you heat treat first and then stain with geimsa?
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you see the R bands, which are the reverse pattern of g bands.
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if you stain chromosomes with quinacrine, what do you see?
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flourescent q bands and dark g bands, (same as giemsa staining)
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what does 5P15 tell you about the location of the band of interest?
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chromosome 5
petit arm section 1 band 5 |
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what does a heterozygote for a deletion for 5P15 give you?
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cri du chat
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Describe FISH
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Flouresent In Situ Hybridization
1. start with 40 kb piece of DNA 2. create clone DNA using oligoprimers 3. label clone DNA with flourescent markers 4. Denature 40kb segment using high pH 5. Add flagged DNA to normal DNA and allow to hybridize. 6. observe the condensed chromosome and the flagged band. This tells you gene location |
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What did the Holliday Model explain?
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1. Gene conversion
2. the association of gene conversion with crossing over 3. the precision of crossing over. *a repair in a region of hybrid DNA creates gene conversion. |
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What are 3 important things to know about deficiencies?
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1. most have deleterious effects when heterozygous. Htzgots normally show delay and morphological defects
2. virtually always deletions are lethal when homozygous 3. animals and plants differ greatly in their abilities to transmit deficiens in their gametes. |
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what does it mean if a deficiency fails to complement?
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the mutant phenotype is expressed, ie, the deficiency knocks out part of the normal gene and causes the mutant phenotype to be expressed.
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whys is crossing over less frequent near telomeres and near centromeres?
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-there is distortion between gene distanes on the linkage map and physical map near these places.
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what was the first tendem duplication recognized?
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Bar mutation (dominant phenotype)
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we must have how many copies of each gene to function normally?
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2
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what causes colorblindness?
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unequal crossing over
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what are opsins?
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proteins linked to 11 cis retina
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why are red and green different from blue?
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they are x linked
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how similar are red and green opsin genes?
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they are 98% identical
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what makes someone red blind?
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when the chromosomes don't align perfectly at pachtene and cross over occurs, making one gamete get a partial red opsin gene.
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If somone has multiple copies of complete green opsin genes, what vision do they have?
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normal vision
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what is a multigene family? How do they arise?
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they encode related proteins. they arise through duplications and divergences. examples are globin genes and transcription factors.
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How can you get multigene families on different chromosomes?
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insertional translocation
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what is the percentage of time that ajacent one and ajacent 2 will occur?
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adj1 + adj2 = 50% of time
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what is the adjacent 1 orientation?
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Homologous centromeres go to opposite poles
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what is the adjacent 2 orientation?
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homologous centromeres to got the same pole
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which is more frequent, adjacent 1 or adjacent 2?
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adjacent 1
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why do translocation heterozygotes die 1/2 of time?
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1/2 of time you have an alternate orientation on the metaphase plate, which gives you viable zygote (no duplications or deletions) the other half, you have adjacent orientation and you get duplications and deletions when the zygote is formed.
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Why does pseudo linkage occur when dealing with translocations?
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The viable zygotes have t1 and t2, meaning that genes that at one point might have been on different chromosomes are now paired together and live to express this pseudolinkage.
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euploid
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having an integral number of haploid chromosome sets
n 2n 3n 4n 5n |
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what is anything above 2n called?
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polyploidy
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what does colchicine do?
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it binds to tubulin and and stops polymerization. this is how you make ploidy's
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why are triploids sterile?
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during gamete formation (making seeds)the chromosomes assort independantly, meaning that some gametes will get 4 chromosomes upon fertilization, some will have 2, rarely will a triploid be formed.
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autopolyploid
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chromosome sets all from the same species
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allopolyploidy
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haploid sets from different species present (2 or more species)
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under what circumstances could an allopolyploid not be sterile?
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if the chromosome sets (say 9B9A) spontaneously replicate to produce 9B 9B 9A 9A
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what is an aneuploid?
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an organisma that has a chromosome number that is not a haploid set
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what how does aneuploids occur?
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Bridges discovered these: monosomy, trisomy: and extra or deficiency of one pair of chromosomes.
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How would you tell that a fly has trisomy?
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cross a fly that is not eyeless (+ + +) to a fly that is eyeless (ey/ey).
- you will get + + ey, and when crossed to another eyeless, you will get only 1/6 of the progeny eyeless. |
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what is the most common kind of aneuploidy?
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trisomy 21
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what causes 95% of downsyndrome cases?
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non-disjunction in MI in females
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Why is it more risky to have children later in life?
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for women, the eggs are arrested at diplotene and don't finish until fertilied. however, 45 years later, the sister chromatid adhesion has failed and the chromatids are separating early
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what are 2 ways to check if a mother is carrying a child with downs?
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1. amniocentiesis- sample of amniotic fluid
2. choriotic villus sampling (snip off part of placenta) |
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why are XXX children normal?
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dosage compensator
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how is bar bodies related to sex?
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they're not, they are related to number of x chromosmes. 2 x's = 1 bar body
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what is another name for the inactive x?
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condensed heterochromatin.
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what is euchromatin?
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the opposite of heterochromatin- it condenses during division but uncoils during intephase
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what is faculative heterochromatin?
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condensed in some cells, but not in others (ie, inactive x)
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what is constitutive heterchromatin?
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always condensed DNA found near centromeres
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when does x inactivation take place?
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in the early embryo phase (60 cell stage)
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what is the specific site required for inactivation on the x chromosomes
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XIC
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what is special about the DNA of the inactive X chromosome?
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it is highly methylated
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what molecule methylates C?
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DNA methyltransferase
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What does XIST code for?
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an mRNA transcript that never leaves the nucleus, it just methylates the inactive X
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which book did Darwin carry with him on the Beagle voyage?
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Charles Lyles Principles of Geology
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What was the basic concept of Charles Lyelle's work?
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uniformitarianism
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what are the 4 principles?
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1. Uniformity of law
2. Uniformity of process 3. Gradualism 4. Non-directionalism |
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Describe uniformity of law
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A theory that explains geological features of the earth by assuming all ancient laws of physics and chemistry have not changed througout the history of the earth.
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Describe uniformity of process
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Geological processes are the same throughout time (ie, the same process of erosion has occured throughout the history of the planet)
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Describe gradualism
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Geological process occur in small changes. This increments accululate over time to produce large changes.
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Describe Non-directionalism
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dynamic steady state.
(radioactive decay hadn't been discovered yet) |
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What was Alvarez's theory?
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Theory of impact crises which went agains uniformitarianism: said that a massive distruction happened some 65 million years ago that could be traced back to an asteroid.
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which of the uniformitarianism postulates as proposed by lyell can be tested for?
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gradualism and non-directionalism
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what wasw the religion of Thomas Henry Huxley?
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agnostic- believe that theology is unknowable.
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why was huxley against creationism?
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it invoked supernatural elements that were not scientifically reasonable.
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what must a theory have according to huxley?
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falsification potential
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what is another word for active doubt, in terms of critically analyzing darwin's hyopthesis?
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hypothetico deductivism
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parsimony
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the simplest hypothesis is the working hypothesis
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The first two statements of lyelle's uniformitariansism are essentially statements of what?
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parsimony
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darwin's theory is a theory of what?
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population. Population evolve, not individuals.
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What is the first of the 5 theories that Maryr partioned Darwin's ideas into?
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Evolution as such- evolutinon is neither constant nor perpetually cycling, but directionally changing.
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What is Mayr's second theory of darwin?
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Common Descent- All plants and animals have common descendants from which one form into which life was breathed.
*this theory was scientifically although not socially accepted. |
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what is a lineage?
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a series of ancestor-descendents (population through time
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what are the 4 possible events that a lineage can do?
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1. persist w/o change
2. persist w/ change 3. branch-bifurcate -branch of lineages 4. go extinct |
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what is divergence of character
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separate lineages that accumulate differences from the common ancestor and from each other.
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Who proposed phylogeny?
what is phylogeny? |
Earnest Haekel
- the structure of evolutionary history is a branching tree of lineages |
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ontongeny recapitualtes phylogeny
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(aka, biogenic law) proposed by Haekel, says that developmental stages repeat adult stages of ancestral forms.
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Describe what the notochord is and what it tells us about ontongeny recapitulating phylogeny
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1. notochord is a key developmental structure that develops in the interveterbral disks as a precursor for the nervous system. no lineages have lost notochord.
2. The ONLY organism that has a notochord as an adult is the amphioxius. perhaps at some point we evolved from amphioxius, or something that had a notochord as an adult. |
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Terminal addition
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characteristics acquired through the adult stages of an organism and passed onto progeny
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condensation
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as new features are added, others are condensed back into earlier phases.
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name the three exceptions to haekels phylogeny vs ontolgy postulate
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1. caenogenesis
2. heterochrony 3. heterotrophy |
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caenogenesis
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evolution of new characteristics not restricted to preadult stages (ie, a catpiller has structures not present in butterflies)q
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heterochrony
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evolutionary change in developmental rates and timing. morphological evolution is a change in timing of evolutionary events.
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heterotrophy
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evolutionary change in location of structures.
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what is the most important concept in all of evolutionary biology?
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homology
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HOMOLOGY
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richard owen
the same organ in different organisms under a variety of form and function. ie, we assume that as we are comparing gene sequences, we have a common ancestor and that gene will preform a similar function to our own gene, or that the organ of a mouse functions very similarily to human livers. |
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groups within groups tells us what?
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indicates a sharing of homologies.
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monophyletic group
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a group of 2 or more species that include the most recent common ancestor and all decendants from this common ancestor. ex: chrodates
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why are dinosaurs not a monophyletic group?
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The most recent common ancestor of dinosaurs is also the most recent common ancestor of crocadiles and birds. These are still around today, so the MRCA did leave descendants.
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what is a clade?
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a monophyletic group
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How do you diagnose clades?
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the sharing of homologies
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synaphamorphy
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shared derived character
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what is the outgroup?
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A close relative of the ingroup
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what is the requirement for the ancestral state in the ingroup?
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it mustbe shared by the outgroup as well
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alignment
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site homology
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sites that are only in the ingroup
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are hypothesized to have evolved and make them more closely related than they are with the outgroup
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parallelism
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lineages diverge from common ancestor but not from each other. similar mutational or developmental processes occur in two lineages independantly.
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morphological parallelism
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requires two separate origins of the derived morphological state. ie salamanders similarily developed gills and ways of breathing.
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reversal
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evolutionary return to an ancestral characgter formerly changed or lost
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convergance
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?
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homoplasy
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referrs to character similarity that does not reflect common ancestry
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why is the position of the root of life hard to pinpoint?
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we have no outgroup for the tree of life
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why do we study ribosomal DNA?
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all organisms have it
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endosymbotic theory
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mitochondria and chloroplasts ressemble bacteria cells, and were at some point enveloped into eukaryotes like plants this allowed the evolution of photosynthesis.
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giardia
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lost it's mitochondria in the process of becomming parasitic, but evidence suggests that it's ancestral state had mitochondria.
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Multiplication of species
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geographic splitting of a population followed by evolutionary divergance of the separate parts
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allopatric speciation
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aka multiplication of species
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what is a species according to mayr?
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a reproductive community of populations that occupies a specific niche in nature. the members of the same species should be able to interbreed AND produce offspring.
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what is a niche?
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A set of resources acutally or potentially used by a population
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what is a prezygotic barrier?
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prevents zygote formation
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name the prezygotic barriers
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temporal
ecological behavioral mechanical gametic |
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what is a temporal prezygotic barrier?
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if two species develop different seasons for mating, they will not mate.
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what is an ecological prezygotic barrier?
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some frog species become associated with ponds, others with streams, and the two won't mate.
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what is a behavioral prezygotic barrier
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members of the same species must be able to recognize mating rituals. if mating rituals differ, mating will not occur
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mechanical
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genetalia are not compatible
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chemical
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must be appropriate reactions between sperm and egg. if the chemisty of fertilization is wrong = no zygote
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what are the 3 post zygotic barriers?
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hybrid inviability
hybrid sterility hybrid breakdown |
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what is hybrid breakdown
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hybrid is fertile but when the hybrid tries to produce gamets, the desirable characteristics will be scrambled and lost.
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Why is it a problem that the biological species concept considers groups of species a single unit of evolution?
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by evaluating species that might have had millions of years to evolve separately by solely their ability to interbreed shortchanges the phenotypic, niche and other aspects of their evolutionary progress. evolution is more than just the ability to interbreed
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what is the phylogetic species concept?
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the alternate theory to the biological species concept.
- it is a lineage of ancestor desendant populations diagnosably different from other such lineages |
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in terms of reproduction, what does the phylogentic species concept say?
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it applies to asexual as well as sexual organisms
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what are two sources of allopatry?
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1. vicariance
2. founder effect |
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what is vicariance?
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subdivide formerly continuous habitat. organisms that could have once reproduced were no longer able to (ismus of panama)
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what is the founder effect?
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if mocking birds migrate to an island, the island population could develop differently than the mainland population.
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what is gradualism?
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change occurs in small increments, never in jumps
latin: naturan non facit saltum (nature never jumps) |
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what are non-gradualism variations called? what is an example?
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sports, or monsters. example was the ancon sheep which had very short legs.
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How did Darwin and Huxley differ in their opinion of how to treat sports?
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Darwin thought that sports were rareities and would have never survived in nature/would have never passed on genes. Huxley though we shouldn't disregard them.
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what are darwins first three observations in his explanatory model of evolution?
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obs1- organisms have great fertility
obs 2- population do not increase exponentially, but remain constant obs3- natural resources are limited |
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obs1 + obs2 + obs3 =
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inference 1
among organisms of the same population, there is a struggle for survival. # of organisms that survive and reproduce is much less than those that are birthed. |
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obs 4 and 5
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obs 4- variations exist in a population and allow for selection of traits
obs 5- variation is heritable |
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inf1 + obs4 + obs 5
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inference 2
varying organisms show differential survival and reproduction depending on advantageous traits. |
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inference 3
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natural selection produces new adaptations and species.
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is natural selection a random process?
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no, but there is a random step.
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what is the random component of natural selection?
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mutation -->origins of variation.
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what is the non-random component of natural selection
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organisms with favorable traits have higher rates of survival and reproduction.
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what is a teleological process?
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one that has a preexisting goal or endpoint. Natural selection has no preexisting goal or endpoint.
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describe dennets algorhymthic nature of natural selection
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1. substrate neutrality- the nature of the algorhythm is that it works regardless of what you plug into it. ie, conditions of population, variation, heridity and differential survival.
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describe underlying mindlesness
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no teleology
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describe the guarenteed results
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and evolutionary change or lack of change
1. if mean value of a trait is desired, outliers get weeded out and the mean is selected for. 2. stabalizing vs. directional selection |
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what is stabalizing vs. directional selection
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stabalizing- if mean is selected for
directional selection- if extreme value is selected for. |
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adaptation
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a trait that evolved by natural selection for a particular role
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exaption
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a trait hijacked by natural selection. ie, feathers were originally for insulation, and through natural selection, they became necessary for flight.
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