A video on hemophilia

Determine the mode of inheritance Dominant or Recessive – do this first Autosomal or sex linked If there are 2 traits: Linked or unlinked

Sex Linked inheritance Males – XY Females – XX Y chromosome carries genes for sex determination X chromosome carries many other genes besides sex determination (such as colorblindness)

X – Linked recessive The gene is recessive and on the x chromosome in males higher than in females Ex. Color blindness is recessive. If a male is color blind and marries a woman who is not color blind and does not carry the color blind allele, what percent of their offspring will be color blind? If their daughter marries a man who is not color blind, what percent of their offspring will be color blind? What percent will be carriers?

2 genes are either linked or unlinked They are linked if they are very close on the chromosome They will be passed onto offspring more frequently together since crossing over is less likely to occur between them. How would we know two genes are linked by looking at offspring? It is not in a ratio of 9:3:3:1

Cross of the following questions in your packet: 2, 4a, 8, 9, Also, do not complete the pedigree analysis portion

Practice problem If you want practice, type in tahoma as the course ID and ap biology2 as the student account – I will tell you if you are right or wrong If you are ready to begin, type in tahoma as the course ID and ap biology as the student account Remember, for each population, you need to give me which trait(s) are dominant and which are recessive, if it is sex-linked, and if two traits are linked or unlinked (if the population gives you two traits)

statistics If the P value is greater than.05 then it must match the ratio you entered (or close enough) For stats students – a P value of less than.05 means it is statistically significantly different than your expected values – in this case our expected values are the phenotypic ratios. Therefore if it is less than.05, the population must not match the expected phenotypic ratio and the mode of inheritance must be different then you predicted.