Karyotype:The visual description of the complete set ofchromosomes in one cell of an organismF123ISVTEKaryotype of ahuman male67891011129n1680888305131415161718srL192021224-11Fig 4.4
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 4-11 Karyotype Karyotype: The visual description of the complete set of : The visual description of the complete set of chromosomes in one cell of an organism. chromosomes in one cell of an organism. Karyotype of a human male Fig 4.4
Karyotypes can be produced by cutting micrographimages of stained chromosomes and arranging them inmatchedpairs ofdecreasing size.酒436-7689101112An16B8888565131415161718a37..19202122Autosomes-chromosomesin matching pairsSex chromosomes-unmatchedchromosomes4-12Fig4.4
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 4-12 Autosomes – chromosomes in matching pairs Sex chromosomes - unmatched chromosomes Karyotypes Karyotypes can be produced by cutting micrograph can be produced by cutting micrograph images of stained chromosomes and arranging them in images of stained chromosomes and arranging them in matched pairs of decreasing size. matched pairs of decreasing size. Fig 4.4
Chromosomes carry information fordeterminingtraitIn many species,one pair of chromosome determinesan individual's sex.Walter Sutton studied chromosome dynamics duringspermatogenesis in great lubber grasshopper.WalterS.Sutton(1877-1916)4-13
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 4-13 Chromosomes carry information for Chromosomes carry information for determining trait determining trait Walter S. Sutton (1877-1916) In many species, one pair of chromosome determines In many species, one pair of chromosome determines an individual an individual’s sex. Walter Sutton studied chromosome dynamics during spermatogenesis in great lubber grasshopper
Prior to meiosis, precursor cells inthetestes contain24 chromosomes:11matched pairs (autosomes)and2unmatchedchromosomesXandY(sexchromosomes)QSperms contain 11 chromosomes andaX or Y in equal numbersAfterfertilizationDiploidcellsCells withXX werefemales2n=24Cells with XY weremalesConclusion:X and Y chromosomesdetermine sex.Haploidcells(gametes)n=124-14
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 4-14 Prior to meiosis, precursor cells in Prior to meiosis, precursor cells in the testes contain 24 chromosomes: the testes contain 24 chromosomes: 11 matched pairs ( 11 matched pairs (autosomes autosomes) and 2 ) and 2 unmatched chromosomes X and Y unmatched chromosomes X and Y (sex chromosomes sex chromosomes). Sperms contain 11 chromosomes and Sperms contain 11 chromosomes and X or Y in equal numbers. X or Y in equal numbers. After fertilization After fertilization Cells with XX were females. Cells with XX were females. Cells with XY were males. Cells with XY were males. Conclusion: Conclusion: X and Y chromosomes X and Y chromosomes determine sex. determine sex. 12 24
Sex chromosomesProvide basis for sexdeterminationOne sexhas matchingpair.The other sex has one ofeach type of chromosome.PhotobyA.SYRED/SHuman X and Y chromosome4-15Fig.4.6a
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 4-15 Sex chromosomes Sex chromosomes Provide basis for sex Provide basis for sex determination determination One sex has matching One sex has matching pair. The other sex has one of The other sex has one of each type of chromosome. each type of chromosome. Human X and Y chromosome Fig. 4.6 a