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10 Cards in this Set
- Front
- Back
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What happens in Meiosis I?
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Prophase I:
-homologous chromosomes become paired and exchange DNA -divide into 5 stages -formation of synatonemal complex and CROSSING OVER occurs Metaphase I: -bivalent align at spindle equator -kinetochores of sister chromatids lie side by side and face the same pole of cell (different than mitosis) -chromosomes held together by chiasmata (from crossing over) Anaphase I: -homologous chromosomes separate and move to opposite spindle poles -to prevent chromatid separation, shugoshin (meiosis specific protein called guardian spirit) is produced -shugoshin protects cohesins from being degraded by separase -DOWN'S SYNDROME IS A DEFECT OF SHUGOSHIN Telophase I and Cytokinesis: -two haploid cells produced |
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What are the 5 phases of Prophase I?
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Leptotene:
-condensation of chromatin fibers -lateral elements of synaptonemal complex attach to individual chromosomes Zygotene: -central element forms (joins homologous chromosomes) -synapsis begins -telomeres of each chromosome become clustered on one side of nucleus and attach to nuclear envelope Pachytene: -synapsis complete; crossing over occurs Diplotene: -synaptonemal complex disappearing; chiasma visible -in females cells take a break from meiosis diakinesis: -bivalent ready for metaphase FORMATION OF SYNAPTONEMAL COMPLEX IS ESSENTIAL FOR RECOMBINATION AND FOR PREVENTING ANEUPLOIDY (change in number of chromosomes) |
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What happens in Meiosis II?
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resembles mitotic division
prophase II: brief Metaphase II: kinetochores of sister chromatids now face in opposite directions Anaphase II" sister chromatids separate 4 daughter cells at end (n) generates genetic diversity Nondisjuction occurs when sister chromatids in anaphase I or II dont separate (trisomy 21 - down syndrome) |
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What is Mos?
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Mos triggers metaphase II arrest of the egg cell until fertilization
c-Mos is a proto-oncogene, oocyte maturation factor involved in MAPK-signaling pathway |
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What are the two laws of genetic variability?
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The law of segregation - monohybrid
Law of independant assortment - dihybrid |
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What is incomplete dominance and codominance?
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Incomplete dominance:
F1 hybrids are intermediate between the two parents ex. Snapdragons, white flowers cross with red but produce all pink sickle cell trait Codominance: -exhibit trats of both parents -Type AB blood is an example |
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What is the Chromosomal Theory of Inheritance?
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Chromosome behavior explains the laws of segregation and independent assortment
1. Nuclei of all cells except germ contain two sets of homologous chromosomes, one from mother and one from father 2. Chromosomes are genetically continuous throughout life 3. Two sets of homologous chromosomes in a diploid cell are functionally equivalent 4. Maternal and Paternal homologues synapse during meiosis segregating into different cells 5. Maternal and Paternal pairs segregate independantly during meiosis |
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What is cDNA?
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Complementary DNA
DNA molecule copied from an mRNA template by reverse transcriptase Large DNA segments can be cloned in cosmids and yeast artificial chromosomes (YAKs) |
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What are the steps in DNA cloning?
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1. Insertion of DNA into a cloning vector
2. Introduction of recombinant vector into bacterial cells 3. Amplification of recombinant vector 4. Selection of cells containing recombinant DNA 5. Identification of clones containing DNA of interest |
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What is the difference between cDNA and gDNA?
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complementary DNA vs. genomic DNA
genomic: -Restriction Enzyme digestion --> DNA cloning --> genomic DNA clones complementary: -RNA transcription --> introns spliced out --> mRNA --> reverse transcriptase --> cDNA library (ONLY EXONS) ONLY EUKARYOTES HAVE INTRONS |
