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Sex Linked Inheritance: (why females are superior to males) (just kidding) (no, but seriously) (ok, I am kidding) (or am I?)
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Warm Up What % probability will a child be born a male? Female? How could we set up a punnett square to show this?
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Cornell Notes Read pages 170-171 In the margin of your paper, define the bold terms. In the large portion of your paper, discuss 3 main points. On the bottom, summarize in 3 sentences what you read.
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The difference between males and females. Females have 2 X chromosomes. They always give one X to their offspring. The X chromosome has more information than the Y. That’s why females are superior to males. Males have 1 X chromosome and 1 Y chromosome. They can give either to offspring.
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Human Genome Autosomes (1 – 22) Sex Chromosomes (X and Y)
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XY
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Human Y-chromosome SRy locus Males have sperm cells which may have an X chromosome or a Y chromosome. Male gametes (sperm) determine the gender of the offspring when the egg is fertilized.
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Punnett Square to determine gender. A male gamete XY chromosomes fertilizes the egg (XX). What is the chance that the offspring will be female?
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Punnett Square to determine gender. A male gamete XY chromosomes fertilizes the egg. XY XXXX
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Punnett Square to determine gender. A male gamete XY chromosomes fertilizes the egg. XY XXXX XX XY XXXY
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X chromosomes have genes that Y chromosomes don’t. X Chromosomes can be carriers of certain recessive traits. In females, the other X probably does not have the trait and can over rule the recessive diseased trait. Baldness Color Blindness Duchenne Muscular Dystrophy Adrenoleukodystrophy Fragile X Syndrome
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Punnett Square to determine gender. A carrier female for colorblindness, marries a normal man. Will their children be color blind? B= normal b= color blind Y’s don’t have the trait. X B Y XBXbXBXb
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Punnett Square to determine gender. A carrier female for colorblindness, marries a normal man. Will their children be color blind? B= normal b= color blind Y’s don’t have the trait. X B Y XBXbXBXb XBXBXBXB XBYXBY XBXbXBXb XbYXbY
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Punnett Square to determine gender. Normal Female Normal Male Carrier Female (isn’t colorblind) Colorblind Male X B Y XBXbXBXb XBXBXBXB XBYXBY XBXbXBXb XbYXbY
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Inheritance patterns: Sex-linked recessive conditions The disease is never passed from father to son. Males are much more likely to be affected than females. All affected males in a family are related through their mothers. Trait or disease is typically passed from an affected grandfather, through his carrier daughters, to half of his grandsons.
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PRACTICE On your pink sheet of paper… practice the following…
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