Gregor Mendel 1866 o Characteristic of sexual reproduction in plants that was important to the success of Mendel s experiment Many true breeding varieties were available The plants are easy to grow and grow quickly Many off spring are produced Pea plants can self fertilize or be cross pollinated control mating Traits are distinct o In Mendel s experiments the allele masked in the F1 hybrid but that re appeared unchanged in the F2 was termed recessive o In Mendel crosses yellow seed YY is dominant to green seed yy If the F1 hybrid Yy demonstrating the dominant phenotype yellow was allowed to self pollinate what would be the expected ratio of the progeny 3 yellow 1 green because Yy x Yy YY Yy Yy yy Independent Assortment of Alleles o Independent Assortment o Genes During gamete formation the separating pairing of the alleles of one allelic pair is independent of the separating pairing of the alleles of another allelic pair Are genetic characteristics controlled by factors that come in pairs Alternate forms of genes are alleles Genotype the genetic makeup you have TT Tt tt Phenotype the physical characteristic that gene shows o Homozygous vs Heterozygous Tall Short o Crosses Homozygous alleles are identical true breeding Heterozygous alleles are different one dominant one recessive Test Cross cross whatever you re testing dominant hetero homo with homozygous recessive DD Dd vs dd Purpose determine the genotype homo or hetero of an individual with the dominant phenotype Dihybrid Cross cross two true breeding plants that differed in two traits GGWW vs ggww Purpose determine if any relationship existed between different allelic pairs Monohybrid Cross cross between two pure breeding plants that differ in a single trait DD vs dd Backcross cross F1 offspring back with parent Dominance o Co dominance Both phenotypes are expressed simultaneously R red r white Rr random UNLESS SAID Heterozygous color is orange Rr is orange o Incomplete Dominance R red r white Rr Pink BLENDED Blood Types Multiple Alleles o Alleles ABO more than 2 alleles aka multiple alleles A B Dominant O Recessive only homozygous o Genotypes Phenotype AA AO A A O BB BO B B O AB AB Co dominant OO O Recessive only homozygous o Blood transfer AB universal recipient O universal donor Antibodies o A Anti B Antibodies Can t receive B Can receive O o B Anti A Antibodies Can t receive A Can receive O o AB Neither A B Antibodies Can receive ANY o O Both Anti A B antibodies Can ONLY receive O o EXAMPLE Which of the following blood types could be the father AB B The child has blood type B the mother has blood type A Mode of Inheritance o 3 questions to ask Does this appear in every generation Are males and females affected equally Yes Dominant No Recessive Yes Autosomal No Sex linked Is the parent of origin male or female or both Either Autosomal Mom Sex linked X linked 50 boys show Dad Sex linked Y linked 100 boys show o Both pass to sons o Polygenic inheritance Mode of inheritance in which the additive effect of two or more genes determines a single phenotypic character Traits such as height eye color and skin color o Sex Linked vs Sex Influenced Linkage genes are located on the same chromosome and tend to be inherited together Sex Linked genes located on the sex chromosomes X linked genes located on X chromosome passed from mother boys show disease girls can be carriers Y linked genes located on Y chromosome passed ONLY from father to son Sex Influenced traits genes NOT linked to the sex chromosome Vary in expression depending upon the sex of the individual Autosomal genes are responsible for phenotype but hormone levels determine expression o Example male pattern baldness Mitosis vs Meiosis o Mitosis Cells divide once Result in 2 Diploid Cells 46 chromosomes each Growth and development PHASES Interphase G1 S G2 o Stages preceding mitosis in cell cycle G1 proteins lipids and carbohydrates are synthesized in preparation for division and cell grows in size S replication of DNA also proteins synthesized Each cloned chromoson is composed of 2 arms chromatids and connect at the centromere G2 cell continues to grow M phase Mitosis pg 24 SEE PICTURE o Prophase o Metaphase Chromosomes condense and form the tightly coiled structures in the dividing cell nuclear envelope begins to break down Microtubules enter nuclear region and form a spindle apparatus They attach to sister chromatids and line up at the equator of the spindle Most tightly condensed form Attachments between the two sister chromatids of each chromosome break they split and go to opposite poles of the cell o Anaphase o Telophase Chromosome decondenses cell splits Two diploid daughter cells are formed each containing 46 chromosomes Clones of parent cell o Meiosis 1 and 2 Cells divide twice Result in 4 Haploid Cells 23 chromosomes each PHASES Sex cells egg and sperm Increases genetic variation Meiosis 1 reduction division o Interphase 1 SAME as mitosis o Prophase 1 Homologous chromosomes pair to form a tetrad Genetic material is exchanged between chromatids crossing over Recombination of maternal and paternal genes increases diversity of gametes Tetrads line up on equator and attach to o Metaphase 1 spindle o Anaphase 1 Homologous chromosomes separate Maternal and paternal chromosomes randomly sort to each daughter cell o Telophase 1 Cell divides 2 haploid daughter cells with a single set of chromsomes Each cell has 22 autosomes and 1 sex chromosome Also identical copies even with less chromosomes Meiosis 2 o Prophase 2 o Anaphase 2 Chromosomes attach to spindle apparatus Sister chromatids separate at centromere and move to opposite poles of cell like anaphase in mitosis o Telophase 2 Cells divide again 4 haploid daughter cells with 23 chromosomes each Gametogenesis is always associated with meiosis mammals humans Males sperm meiosis begins in testis with puberty and continues declining rate for rest of their lives o 4 equal haploid sperm cells results from meiosis Females egg meiosis begins in ovaries during fetal development but the cells become arrested during meiosis 1 doesn t make eggs forever like male w sperm o Puberty leads to some continuation of follicle development but haploid egg doesn t progress unless fertilized o 3 polar bodies and 1 viable egg result from meiosis Defects o Each person has 46 chromosomes 23 from mom 23 from dad 22 autosomes and 1 sex chromosome X from mom X or Y from dad XX girl or XY boy Sets of chromosomes 1N Haploid 2N Diploid normal 3N
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