Polygenic Inheritance 4-6 Sex-linked Traits Pedigrees Blood Typing Polygenic Inheritance Karyotypes

Sex-linked traits Traits whose genes are found on the sex chromosomes (mostly the X chromosome) Ex. Colorblindness, hemophilia, muscular dystrophy, male pattern baldness. These disorders most often predominately appear in males. Why??

Sex-linked traits continued… Female = XX Male = XY If gene is located only on the X chromosome, and a male (XY) gets the recessive allele, he has no chance of “masking” the bad gene.

Ex. Colorblindness – Normal Male x carrier (heterozygous) female XHY x XHXh Male has one chance since he only has one X. He will have whatever mother passes onto him. There is no way to mask it.

Are you colorblind? The individual with normal color vision will see a 5 revealed in the dot pattern. An individual with Red/Green (the most common) color blindness will see a 2 revealed in the dots. interesting color blindness test is below

Play.google.com izismile.com izismile.com

Pedigrees a graphic representation of genetic inheritance used to 1) organize and follow the inheritance of genetic characteristics and / or 2) determine the possible modes of inheritance

“Simple” Pedigree Autosomal Recessive

a trait controlled by more than two alleles MULTIPLE ALLELES a trait controlled by more than two alleles BLOOD TYPING Alleles: A - “dominant” B - “dominant” o - “recessive” recipient donor A A or O B B or O AB A, B, AB, or O O

ABO and Rh blood type distribution by nation (population averages) Country     O+       A+       B+       AB+        O−        A−        B−       AB−       Australia[15] 40% 31% 8% 2% 9% 7% 1% Austria[16] 30% 33% 12% 6% 3% Belgium[17] 38.1% 34% 8.5% 4.1% 1.5% 0.8% Canada[18] 39% 36% 7.6% 2.5% 1.4% 0.5% USA[33] 37.4% 35.7% 18.5% 3.4% 6.6% 6.3% 1.5% 0.6%

Red blood cell compatibility table[39][40] Recipient[1] Donor[1] O− O+ A− A+ B− B+ AB− AB+ ☻ I N G E Another Bio teacher

Phenotypes Genotypes A IA IA, IA i B IB IB, IB i AB IA IB o i i Cross a man who is heterozygous blood type B with a woman who is blood type O.

Charles Drew -experimented with blood transfusions – plasma “keeps” longer than whole blood -responsible for two of the world’s largest blood banks

Polygenic Inheritance trait that is controlled by more than one gene (having many genes). Ex. Skin color

The Human Karyotype A karyotype is a pictorial display of human chromosomes Used to determine abnormalities

Genes A gene is a sequence of DNA that codes for a protein and thus determines a trait Several hundreds of genes can be contained in one “band” of color in a karyotype.

The short arm of chromosome is the “p” arm The long arm is the “q” arm The specific place on a chromosome where a gene / trait is found is called locus (loci)