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83 Cards in this Set
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centimorgan |
centimorgan (cM) or map unit (m.u.) is the unit for genetic linkage. It is defined as the distance between chromosome positions for which the average number of chromosomal cross overs in a single generation is 0.01 or 1% |
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genotype |
genetic constitution of an organism, consists of two alleles per trait
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phenotype |
the observable set of traits or set of traits caused by the genotype and environment |
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Self-Fertilization, "selfing" |
Plants can be manually self fertilized, which ensures no introduction of new alleles into the gene pool |
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Cross-fertilization, "cross" |
simply mating between male and female gametes from different sources |
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true-breeding/pure-breeding |
Homozygous for all alleles, an organism that when self crossed will produce offspring identical to the parent |
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monohybrid cross |
Mendel's cross of a two true-breeding plants that differ on a single trait |
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Reciprocal crosses |
It is a modified cross where the parents with switched traits are crossed. If same offspring as original cross, then trait is not sex-dependent |
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Mendel's First Law |
Principle of Segregation - allele pairs segregate during gamete formation. Half the gametes carry one allele, half the gametes carry theo ther |
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locus/gene locus |
Specific location of a gene on a chromosome |
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Test cross |
A cross of an individual expressing a dominant phenotype with a individual that is homozygous recessive. The offspring will tell if the individual is heterozygous or homozygous dominant |
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wild-type allele |
functional allele that predominates, highest frequency in the population in the wild. Generally dominant |
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Loss-of-function mutations |
mutations of a gene, usually recessively, that causes reduced or nonfunction of the gene, reducing biological functionality |
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null mutation |
a mutation that results in no protein or a protein with no function in comparison to normal function |
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Mendel's Second Law |
Principle of independent assortment: pairs of alleles on different chromosomes segregate independently in the formation of gametes |
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Dihybrid Cross |
Dihybrids are heterozygous for two pairs of alleles at different foci. The cross is a cross between two of these. 9:3:3:1 normally |
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Trihybrid Cross |
Crossing individuals that are heterozygous for three pairs of alleles at different foci. Normal: 27:9:9:9:3:3:3:1 |
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null hypothesis |
predicted results and observed data are said to be the same. This is tested via chi-square |
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chi-square |
Comparing expected and actual data, it's the sum of all (expected-actual)^2/expected. This is translated to p test by looking at degrees of freedom (variables-1). Benchmark for validity is 5%, 0.05 |
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Pedigree Rules |
Offspring are organized left to right in order of increasing date of birth. Fraternal twins are two sides of a triangle, identical are a triangle |
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Homologous chromosomes |
Chromosomes that contain the same genes. They pair during meiosis, each member is called a homolog |
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Sex Chromosomes |
Most animals and plants are differentiated in sex by the combination of sex chromosomes. Sexes are generally one morphologically similar pair and one that isn't |
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Centromere |
Constriction along chromosome length that also connects sister chromatids after division. Its presence is crucial, they will not line up in metaphase without it. |
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Metacentric |
Chromosome centromere is located in the center |
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Submetacentric |
Chromosome centromere is located past the midpoint of the chromosome |
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Acrocentric |
Chromosome centromere is very close to the end of the chromosome, leaving one long arm and almost a bulb |
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Telocentric |
centromere is at the very end of a chromosome, only one arm exists |
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karyotype |
complete set of all metaphase chromosomes, often visualized since this is the stage that they are the most condensed |
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Somatic cell cycle phases |
Interphase (longest), and Mitosis (quite short). Chromosome replication occurs during interphase
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Sister chromatids |
After interphase, all chromosomes are replicated. Copies of the exact same chromosome are sister chromatids, held together by the two attached, replicated centromeres. After separating they're known as daughter chromosomes |
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Prophase |
Chromatids condense and form the double sister chromatid state, nucleolus shrinks or disappears. Mitotic spindle develops outside the nucleus, with centrioles in animals. These centrioles pairs are duplicated and each becomes the focus of an array of microtubules called the ASTER. |
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Prometaphase |
Developing spindle enters nuclear area. Kinetochore binds to centromeres |
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Kinetochore |
Specialized protein complex that binds to centromeres during mitosis/meiosis. Kinetochore microtubules from the spindle bind to the kinetochores and manipulate chromosome positioning |
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Metaphase |
Kinetochore microtubules align all the chromosomes and centromeres along the metaphase plate, 90 degrees to the spindle axis |
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Anaphase |
The joined centromeres of the two sister chromatids separate and daughter chromosomes move to opposite poles of the cells |
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Telophase |
Daughter chromosomes group at opposite sides of the cell and begin to decondense and uncoil. Nuclear envelope reforms, spindles disappear |
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Cytokinesis |
Division of cytoplasm, splits parent cell into two daughter cells. In plants a new cell plate is formed between the nuclei. |
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Prophase I stages |
leptotene, zygotene, pachytene, diplotene, diakinesis in that order |
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Leptotene |
"thin threads" - Extended chromosomes begins condensation and are visible as threads |
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Zygotene |
"paired threads" - Condensation continues, homologous chromosomes find each other and align alongside each other. They synapse and zip-up, aligning the homologs perfectly, base pair per base pair |
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Synapsis |
Formation of the synaptonemal complex along homologous chromosomes in zygotene which zips them up
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Pachytene |
"thick threads" - Once synapsis is completed, crossing over occurs. Condensed AF |
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Bivalent/tetrad |
The synapsed set of two homologous chromosomes in pachytene |
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Recombinant chromosome |
Any chromosome resulting from crossing over that differs from the starting chromosome |
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diplotene |
"two threads" - The centromeres are pulled apart and the bivalent begins to break down. The result of crossing over appears here as chiasmas exist at the locations |
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Chiasma |
Locations where crossing over occurs, seen in diplotene. Locations where the homologous chromosomes are very closely associated. This prevents the homologous chromosome pairs from separating prior to anaphase |
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Sex chromosomes |
can be heterogametic or homogametic though those aren't associated with being male or female. Those two terms refer to how what kinds of gametes an organism can make
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hemizygous |
a gene is present only once in the individual, with no corresponding homologous gene. Usually sex-linked |
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Crisscross inheritance |
Male to female offspring or otherwise. Generally evidence of sex linked inheritance |
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Nondisjunction |
Chromosomes do not segregate appropriately during meiosis, leading to an incorrect number of chromosomes |
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Turner Syndrome |
Nondisjunction leading to XO females. More or less normal other than shorter than average and less feminine |
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Klinefelter Syndrome |
Nondisjunction leading to XXY males. Underdeveloped testes, tall, subnormal intelligence |
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XYY Syndrome |
No real issues. They're male obviously. |
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Epistasis |
One gene being dependent on other genes. For instance, a null allele albinism trumping any hair color gene. Or a specific dominant phenotype above another |
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Pleiotropy |
production of superficially unrelated phenotypes by a single allele |
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Lethal allele |
Almost always recessive alleles that are lethal when homozygous. This results in different ratio of offspring than normal |
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Penetrance |
% of carriers of an allele that are affected by it |
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Expressivity |
Degree to which a recessive phentoype is shown, the magnitude of loss of function |
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5-bromo-uracil |
A base analog to uracil or thymine or something I dunno. It gets incorporated into DN during mitosis which allows us to track its stain. |
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Harlequin chromosomes |
Sister chromatids that stain differently, usually due to incorporation of a base analog during mitosis |
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ZW Sex determination |
The convention where males have two identical ZZ sex chromosomes whereas females have ZW. The functionality is opposite that of XY as far as inheritance goes |
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XXX |
This is usually lethal but in humans results in perfectly normal females for the most part |
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consanguineous mating |
INCEST IS BAD MMMMKAAAY |
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cis |
alleles are together on the same chromosome, in coupling |
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trans |
alleles are on different homologs, in repulsion |
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linkage |
association of genes together on the same chromosome |
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recombination |
process of generating nonparental gametic types |
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recombination frequency |
nonparental gametes/total gametes*100, maxes out at 50% |
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cohesin |
protein complex responsible for binding sister chromatids or homologous chromosomes in mitosis/meiosis |
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separase |
enzyme responsible for dissolving cohesin in anaphase, resulting in separation of homologous chromosomes/sister chromatids and breaking apart chiasmata |
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Interference |
The inhibition of a crossover occurring near another crossover site. Is 1 - coefficient of coincidence. Intereference is complete within 10 map units |
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Auxotroph |
A genotypic mutation resulting in an organism requiring additional nutritional supplementation compared to the wild type |
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NPD |
Non-parental ditype - 4 strand double cross over, doubly recombinant, cross over occurs after replication |
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parental ditype |
tetrad containing two parental genotypes, no crossover |
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tetratype (TT) |
4 different genotypes, two parental two recombinant from a singular crossover, cross over occurs after replication |
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patroclinous |
like father in phenotype |
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matroclinous |
like mother in phenotype |
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polar body |
discarded product of meiosis |
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Branch migration |
changes region of hybrid DNA |
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Excision repair |
eliminates base pair mismatches
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Chromatid interference |
the idea that in meiosis, a cross over two chromatids might affect which two chromatids cross over exist. This however, is not true and this is why recomb frequency maxes out at 50% |
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phototroph |
wild type in respect to nutritional requirement, DOES NOT MEAN its a wild type |
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ade-2 |
encodes an enzyme that synthesizes adenine, mutant spores create red colonies |