How could a type A blood and type B blood parent have type O blood children?
Multiple Alleles Definition: Genes (trait) with 3 or more alleles. Examples: Blood type
Multiple Alleles A Blood Type B Blood Type O Blood Type If these three alleles (A,B, and O ) were all possibilities to be matched up in a pair, what would be all the possible combinations?
Phenotype (Blood type) Multiple Alleles Phenotype (Blood type) Genotypes A ____________ OR ___________ B _____________ OR ___________ AB ______________ O _______________
AO= A blood type Which allele would be considered dominant? Recessive? What is the phenotype? Is this combination Heterozygous or homozygous?
BO= B Blood Type Which allele would be considered dominant? Recessive? Is this combination heterozygous or homozygous?
OO= O Blood Type Is this Homozygous Dominant or Recessive?
AB= ? Blood Type Based on what happened in the basketball game, which allele would be considered dominant? What would be the blood type? What do we call this match up (Remember Friday's lesson?)
AA= Blood type A BB= Blood type B Multiple Alleles AA= Blood type A BB= Blood type B
Blood type chart
Multiple Alleles How is this genetic scenario different from what we have seen in the past? How is this similar to what we have seen?
Practice Problem A woman with type A blood (genotype AO) is married to a type B person (genotype BO). What proportion of their children will have: _________ x ________ A blood? ______ B blood? ______ O blood _______ AB blood ______
Multiple Alleles Blood type
Blood types
Why are traffic lights always on the same orientation?
Are you color blind?
Here are the stats: About 8 -10 % of men in America are diagnosed to be color blind. About 1 out of 100 female are diagnosed to be color blind. The most common colors for blindness are red and green. http://www.colblindor.com/wp-content/images/poll-colorblind-result.gif
SO, Why are men more likely to be colorblind than women?
Sex- Linked Traits Definition: Trait whose allele is located on the X chromosome
Girl XX—Sex Chromosomes
Boy XY—Sex Chromosomes
Types of Sex C’somes X chromosome – found in women and men, much larger in size Y chromosome – found ONLY in men, much smaller
Punnett Square with Sex Chromosomes Fill in your Punnett square As always, it doesn’t matter which genotype you put on the top or the side, this could be switched and you would still get the same result. X Y XX XY X XX XY X Ratio of male to female? 50:50 or 1:1 In a population, ~ ½ of the zygotes (embryos) are male, and ½ are female k. malone ©2005
Sex Linked Genes Genes located on chromosomes X and Y are called Sex Linked genes Many sex linked genes are found on the X and very few are found on the Y (much smaller!) Colorblindness- 2 of the 3 human genes for color vision are located on the X, and males with a defective version of any 1 of these genes will have colorblindness Why? Males = XY, only one copy of X, whatever is on that X is expressed Colorblind male = XcY Normal male = XCY k. malone ©2005 Normal carrier female = XCXc Colorblind female = XcXc Normal female = XCXC
Sex Linked cont… The X chromosome (genes) codes for over 2300 traits. There are only a few genes that codes for traits on the Y chromosomes. Male: XY Female: XX Who has a higher Chance of getting the X-linked disorder? k. malone ©2005 http://www.sciencephoto.com/image/94963/large/C0030729-X_and_Y_chromosomes-SPL.jpg
X-linked genes Since males have just one X chromosome. Therefore, all X-linked alleles (good or bad) are expressed in males, even if they are a recessive trait. k. malone ©2005
XhY XHXh What is different from genotypes we have already seen? What is similar? If “H” was normal, and “h” had hemophilia, what phenotype would this boy have?
Sex-linked cross
Example of a Sex-linked Cross On which chromosomes are the genotypes attached?
Other sex-linked traits: Hemophilia A sex linked disorder found on the X-c’some that does not code for the protein necessary to clot blood
Genotype = Phenotype =