If a woman is a carrier of an X-linked recessive allele for a disorder and her mate does not, their sons have a ______ chance of inheriting the disorder. ______ of their daughters will have it, but ______ of them are likely to be carriers. 5-12

5-13 If a man has an X-linked recessive disorder and his mate does not carry the allele for it, _____ of their girls will be carriers. _____ of their boys will inherit the harmful allele.

Why are there more X sex linked traits?Why are there more X sex linked traits? Linked genes are usually …Linked genes are usually … Mutations in an organisms gametes = ?Mutations in an organisms gametes = ? Mutations that cause death = ? Example from class = ?Mutations that cause death = ? Example from class = ? What type of mutation causes Down syndrome (2 correct answers)?What type of mutation causes Down syndrome (2 correct answers)?

Read 12.2 and answer #s 1-8 on the bottom of page 248 – DUE tomorrow (Friday 5-13) 5-12

Pedigree – diagram that shows how a trait is inherited over several generations Squares = ? Circles = ?

Study the simple pedigree. The man is red (pink) because…?Study the simple pedigree. The man is red (pink) because…? The daughters are blue because …?The daughters are blue because …? Is it possible to get a son that has Hemophilia or is a carrier? Explain!Is it possible to get a son that has Hemophilia or is a carrier? Explain! If one of the sons hooks up with a female carrier, what will happen?If one of the sons hooks up with a female carrier, what will happen?

Hemophilia (X-linked recessive) Pedigree from Queen Victoria Why only male hemophiliacs in this generation? _______________________ __________________________________ __________________________________ How did she become a carrier? 1. __________________________ ________________ 2._____________________________________ ___________ 3.__________________________________________

X-Linked Traits Traits carried on the X chromosomeTraits carried on the X chromosome –Who will show more X-linked disorders, males or females? Why? Males – b/c they only have one X (XY) so it doesn’t matter if trait is dominant or recessiveMales – b/c they only have one X (XY) so it doesn’t matter if trait is dominant or recessive –Examples: Colorblindness – carried on X-chromosomeColorblindness – carried on X-chromosome Hemophilia – impaired blood clottingHemophilia – impaired blood clotting

Carriers – people who carry an allele for a disorder, but do not have the disorder (Heterozygous)Carriers – people who carry an allele for a disorder, but do not have the disorder (Heterozygous) Genetic disorders – any disease / disorder that has a genetic basisGenetic disorders – any disease / disorder that has a genetic basis Polygenic – characteristics that are influenced by several genesPolygenic – characteristics that are influenced by several genes –Examples: Skin color – six genesSkin color – six genes Other examples – eye color, height, hair colorOther examples – eye color, height, hair color

Complex characters - characteristics that are influenced strongly by both environment and genesComplex characters - characteristics that are influenced strongly by both environment and genes Sun = darker skinSun = darker skin Height = several genes but also nutrition and diseaseHeight = several genes but also nutrition and disease

An example of a human trait that is polygenic and a complex character = _____ because

Who will show more X-linked disorders, males or females? Why?Who will show more X-linked disorders, males or females? Why? Linked genes are usually …Linked genes are usually … Germ-cell mutations = ?Germ-cell mutations = ? Chromosomal mutations cause changes to chromosome ___ or ___. Example from class = ?Chromosomal mutations cause changes to chromosome ___ or ___. Example from class = ? What is a pedigree?What is a pedigree?

Multiple Alleles – genes that have three or more alleles (usually 2)Multiple Alleles – genes that have three or more alleles (usually 2) –Example: Blood Type –What are the blood types? ABOABO –Three alleles – I A, I B, i Blood Types – A, B, AB, OBlood Types – A, B, AB, O

Antigens – proteins, carbs etc on outside of red blood cells Antibodies – immuno proteins that destroy unrecognized antigens

medicine/landsteiner/ medicine/landsteiner/ “Blood typing activity” google – first link

How do you identify a dominant genetic disorder on a pedigree? 5-17

Quizish Questish type deal on Friday Also bring your binder  last binder check likely. 5-17

Codominance – when both alleles are expressed in the phenotype (I A, I B – neither is dominant over the other – both carbs are produced on cell surface)Codominance – when both alleles are expressed in the phenotype (I A, I B – neither is dominant over the other – both carbs are produced on cell surface) In codominance, you see both traitsIn codominance, you see both traits Red cow x white cow = roan cow

Codominance

Incomplete dominance – mix between two parents (blend)Incomplete dominance – mix between two parents (blend) In incomplete dominance, you see a mix or blend of both traitsIn incomplete dominance, you see a mix or blend of both traits Example:Example: –straight hair mom X curly hair dad = wavy haired child –Red flower x white flower = pink flower

Incomplete Dominance

X-Linked Traits (review) Traits carried on the X chromosomeTraits carried on the X chromosome –Who will show more X-linked disorders, males or females? Why? Males – b/c they only have one X (XY) (doesn’t matter if trait is dominant or recessive)Males – b/c they only have one X (XY) (doesn’t matter if trait is dominant or recessive) –Examples: ColorblindnessColorblindness HemophiliaHemophilia

X-linked Dominant If mother affected  equal chance of sons / daughters affected If father affected  All daughters will have, sons ok No carriers possible

X-Linked Recessive If mother carrier  50% chance son will be affected, no daughters will have (females can be carriers) If father affected  Sons will be ok, All daughters are carriers

Autosomal Dominant Affected individual  50 / 50 chance of producing affected children No carriers possible

Autosomal Recessive Occurs if both parents are carriers (only 25% of the time) Carriers possible

Single-Allele Traits – traits caused by one dominant alleleSingle-Allele Traits – traits caused by one dominant allele Huntington’s Disease –Huntington’s Disease – –caused by one dominant allele. Onset is so parents have children before they realize they have it –Forgetfulness, irritability, muscle spasms and mental illness, then death –Genetic testing now beginning to be used to determine if either parent has disease