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Human Genetics.

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Presentation on theme: "Human Genetics."— Presentation transcript:

1 Human Genetics

2 Multiple Alleles There are more than two possible genes that can be inherited for a trait. Examples Flower color Blood type

3 Sex-linked Traits Trait for which the gene is located on one of the sex chromosomes. XHXH ~ female, normal XHXh ~ female, normal carrier XhXh ~ female, hemophiliac XHY ~ male, normal XhY ~ male, hemophiliac

4 Pedigrees A family tree that shows how a particular trait is passed from parents to offspring. Be able to read and interpret

5 Pedigree of a Sex-linked Trait
Colorblindness is sex-linked. Blue box is colorblind White box is normal vision with two normal genes. Half blue/half white is a carrier with normal vision, but one abnormal gene.


7 Karyotypes Process in which cells undergoing mitosis are crushed, and their chromosomes paired up. This can reveal abnormalities as seen below. Female – 2 X chromosomes

8 Nondisjunction The failure of chromosomes to separate during anaphase I or II of meiosis. Can result in too many chromosomes (Down Syndrome) or not enough (Turner Syndrome)

9 Autosomal Dominant Diseases
If the abnormal gene is present, the person has the disease Huntington’s Disease

10 Huntington’s Disease Chromosome 4 HH or Hh Nerve cells degenerate
Symptoms include: mood swings, irritability, loss of memory, and uncontrolled movements People of western European descent

11 Autosomal Recessive disease
Must have 2 abnormal forms of the gene for the disease to be present Cystic Fibrosis Tay Sachs PKU (Phenylketonuria) Sickle Cell Anemia

12 Cystic Fibrosis Chromosome 7 cc
Causes think, sticky mucus to build up in the lungs, digestive tract, and other areas of the body Mainly Caucasians

13 Tay Sachs Chromosome 15 tt
Causes a buildup of a chemical on the nerve cells Babies lose or fail to gain motor and mental skills Paralysis usually occurs Death at an early age Jews of eastern European descent and French-Canadians

14 PKU Chromosome 12 pp Born without the ability to break down phenylalanine Smaller than normal head, epilepsy, and mental retardation may occur when undiagnosed Caucasians and east Asians

15 Sickle Cell Anemia Chromosome 11 ss
Red blood cells form an abnormal crescent shape Pain; spleen, lung, and heart damage, and anemia People of African descent

16 Sex-linked Diseases Gene for the disease is carried on the sex-chromosome Colorblindness Hemophilia

17 Colorblindness Carried on the X chromosome XbXb or XbY
Cannot distinguish between colors Affects all races and ethnic groups

18 Hemophilia Carried on the X chromosome XhXh or XhY
Blood does not clot well because missing the gene that codes for a blood clotting protein Affects all races and ethnic groups

19 Chromosomal Aneuploidy Diseases
A disease caused by an abnormal number of chromosomes Down Syndrome Turner’s syndrome Kleinfelter’s syndrome XYY Male

20 Down’s Syndrome Autosomal anueploidy Trisomy (three chromosomes at 21)
Mental retardation, upward slant to the eyes, decreased muscle tone, and a variation of other symptoms

21 Turner’s Syndrome Sex chromosome anueploidy Monosomy
Alters development in females; shorter than average, infertile, extra skin on the neck, skeletal abnormalities, heart defects, and kidney problems

22 Kleinfelter’s Syndrome
Sex chromosome anueploidy Trisomy (XXY) Armpit and facial hair, enlarged breasts, tall stature, and abnormal body proportions Increased possibility of learning disorders

23 XYY Male Sex chromosome anueploidy Trisomy (XYY)
Increased risk of learning disabilities, delayed speech and language skills

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