Sex linked traits *Hemophilia *Muscular dystrophy *Red/green colorblindness *Rickets
Discovery of Sex Linkage Thomas Hunt Morgan First to associate a specific gene on a specific chromosome (early 1900’s) Mated flies
Sex linked genes Genes located on sex chromosomes Most are usually genes on X chromosomes Have unique patterns of inheritance –Mothers pass sex-linked alleles to daughters and sons –Fathers pass sex-linked alleles to daughters, NOT sons
Muscular Dystrophy Absence of a key protein called dystrophin Symptoms: weakening of muscles 1 out of 3500 males in US Rarely live past 20’s
Hemophilia Sex linked recessive Absence of proteins required for blood clotting Sons born to women with a family history of hemophilia Queen Victoria of England –Introduced to royal family thru a mutation in one of sex cells: carrier of allele –The royal families of Prusia, Russia, Spain had Hemophilia genes that spread thru their families
In Codominance, phenotypes of both alleles are exhibited in the heterozygote Example: Pink/white flower, Roan horse both colors are being expressed.
How can I make lots of money? If I was a horse breeder and I wanted to sell Roan horses what horse color do I want for my breeding stock? RR (red), rr (white), Rr (Roan)? Draw Punnent Square.
Incomplete Dominance Offspring has a phenotype that is intermediate between the traits of its two parents. Ex. Red flowering Snapdragon is crossed with a white flowering Snapdragon the offspring is pink flowers. Neither the red or the white Allele is dominant. There is just less pigment.
Fig. 14-10-1 Red P Generation Gametes White CRCRCRCR CWCWCWCW CRCR CWCW
Fig. 14-10-2 Red P Generation Gametes White CRCRCRCR CWCWCWCW CRCR CWCW F 1 Generation Pink CRCWCRCW CRCR CWCW Gametes 1/21/2 1/21/2 In incomplete dominance, the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties
Fig. 14-10-3 Red P Generation Gametes White CRCRCRCR CWCWCWCW CRCR CWCW F 1 Generation Pink CRCWCRCW CRCR CWCW Gametes 1/21/2 1/21/2 F 2 Generation Sperm Eggs CRCR CRCR CWCW CWCW CRCRCRCR CRCWCRCW CRCWCRCW CWCWCWCW 1/21/2 1/21/2 1/21/2 1/21/2
Fig. 14-11 IAIA IBIB i A B none (a) The three alleles for the ABO blood groups and their associated carbohydrates Allele Carbohydrate Genotype Red blood cell appearance Phenotype (blood group) I A I A or I A i A B I B I B or I B i IAIBIAIB AB iiO (b) Blood group genotypes and phenotypes
Antigens – Located in Plasma. “Bad Guy” Antibodies – located on surface of red blood cells. “Anti-A antibodies” Blood Group AntigensAntibodiesCan give blood to… Can receive blood from… ABA, BNONEABAB, A, B, O Universal Receiver AABA, ABA, O BBAB, ABB, O ONONEA & BA,B,AB,O Universal Donor O
What Blood Types will be… An Universal Donor? O. Does not contain any A or B antigens (bad guys) at all. An Universal Recipient? AB. Can receive blood from all other blood groups.
Rh Factor Rh is a protein that is attached to a red blood cell. Rh- is the absence of the Rh factor on the red blood cell. (Just like the O blood cell.) You can give Rh- blood to a patient with Rh+ blood but not vice versa. Mother has 1 st child…the child is Rh+ (from the father)…baby’s and mother’s blood mix at time of delivery. Once exposed to Rh+ mother makes Rh antibodies. Mother is pregnant with 2 nd child (Rh+, same dad) The mother has Rh antibodies so her body attacks the babies blood cells and she miscarries.
Rh factor Treatment: Rh Immune Globulin- It destroys baby cells in mom’s blood and suppresses mom’s Rh antibody production.