7 Sex-Limited, Influenced Traits and Sex Linked Some traits are carried on the sex chromosomes =X and YMost Traits are on XY is smaller, so few genes located.
8 Sex-Limited TraitsGenes inherited by both male and female but expressed only in one sex due to SEX HORMONESEX: Beards, breasts, antlers, milk production, feathers on bird
9 Sex-Influenced Traits Autosomal genes influenced by sex.Genes DOMINATE in one sex and RECESSIVE in otherMales and females with the same genotype will have different phenoypesEX: Index vs Ring fingerShort index finger: Dom. in MalesRec. in Females(FYI: Shorter man’s index finger,the higher amt of prenatal testosterone(corresponds to physically aggressive behavior)
10 Sex-Influenced Traits Examples Continued:Hairlip and GoutDominant in malesRecessive in femalesSpina Bifida:Dom. in femalesRec. in Males
11 Sex-Influenced Traits Other Examples:Baldness:Dom. In MalesRec. in FemalesB=baldness, B’=normal hairBB=bald (male/female)B’B’=normal hair (male/female)BB’= bald (male) normal (female
13 Sex Linkage Controlled by GENES on SEX CHROMOSOMES. X chromosome is larger than y more genes carried on the XX-Linked Genes: genes found on X chromosomeAppear mostly in malesOnly one copy of X; nothing to counteract “bad gene”Females would need two copies to express trait
14 Traits on X Chromosome Red-Green Color Blindness (XR Xr Y°) Hemophilia (inability of blood to clot)XH-normal XHY° XhY°-hemoMuscular Dystrophy (I muscles)
16 4) Sex-linked traits A recessive gene on the X chromosome Examples: color-blindness & hemophiliaGenotypes: Phenotypes:XNY normal maleXnY colorblindXNXN normal femaleXNXn carrier femaleXnXn colorblind
18 XN Y XN Xn XNXN XNY XN Xn XnY Cross of carrier female & normal male Phenotypes???
19 Hemophilia X-linked recessive Most Common in males “Bleeder’s Disease” Missing clotting factorBleeding spontaneously and in joints
20 Xh Y XH Xh XHY XHXh Xh Xh XhY Hemophilia Hemophila is sex-linked recessive trait.Normal clotting is dominant.Hemophiliac Male X Carrier (Heter.) FemaleLET: XH normalXh hemoYO no traitXhYXHXHYXHXhXhXh XhXhY
35 Turner’s syndrome XX XX O Only 1 sex chromosome is present. *Associated with underdeveloped ovaries, short stature, webbed neck, and broad chest.*Individuals are sterile, and lack secondary sexual characteristics.*Mental retardation typically not evident .XXXXO