Biology Chapter 12 Powerpoint

Biology chapter 12 powerpoint

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Unformatted text preview: Chapter 12 Chromosomal Inhe Drosophila Chromosomes 2 3 Chromosomal Inherit Outline X-Linked Alleles Human X-Linked Disorders Gene Linkage Crossing-Over Chromosome Map Changes in Chromosome Number Changes in Chromosome Structure Human Syndromes 4 Chromosomal Inherit Chromosomal Inheritance Humans are diploid (2 chromosomes of each type) Humans have 23 different kinds of chromosomes Arranged in 23 pairs of homologous chromosomes Total of 46 chromosomes (23 pairs) per cell One of the chromosome pairs determines the sex of One an individual (The sex chromosomes) an The other 22 pairs of chromosomes are autosomes Autosomal chromosomes are numbered from Autosomal smallest (#1) to largest (#22) smallest The sex chromosomes are numbered as the 23rd pair 5 Chromosomal Inherit Sex Determination in Humans Sex is determined in humans by allocation of Sex chromosomes at fertilization chromosomes Both sperm and egg carry one of each of the 22 Both autosomes autosomes The egg always carries the X chromosome as The number 23 number The sperm may carry either and X or Y If the sperm donates an X in fertilization, the zygote If will be female will If the sperm donates a Y in fertilization, the zygote If will be male will Therefore, the sex of all humans is determined by the Therefore, sperm donated by their father sperm 6 Chromosomal Inherit X-Linked Alleles Genes carried on autosomes are said to be Genes autosomally linked autosomally Genes carried on the female sex chromosome Genes (X) are said to be X-linked (or sex-linked) (X) X-linked genes have a different pattern of X-linked inheritance than autosomal genes have inheritance The Y chromosome is blank for these genes Recessive alleles on X chromosome: ­ Follow familiar dominant/recessive rules in Follow females (XX) females ­ Are always expressed in males (XY), whether Are dominant or recessive dominant ­ Males said to be monozygous for X-linked Males genes genes 7 Chromosomal Inherit Eye Color in Fruit Flies Fruit flies (Drosophila melanogaster) are common are subjects for genetics research subjects They normally (wild-type) have red eyes A mutant rec...
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This note was uploaded on 01/22/2012 for the course BIOLOGY SC Bio Sci 93 taught by Professor Dr.dianeo'dowdanddr.rahulwarrior during the Summer '10 term at UC Irvine.

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