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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.

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Presentation on theme: "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."— Presentation transcript:

1 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.

2 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)?

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

4 A female carrier of an X- linked recessive allele for a disorder hooks up with a normal male, their sons have a _____ chance of inheriting the disorder. _____ of their daughters will have it, but _____ of them are likely to be carriers XAXA XaXa XAXA Y XAXAXAXA XaXAXaXA XAYXAYXaYXaY

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

6 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? XrYXrY XX

7 Standard Key:

8 Reading a Pedigree: Are there carriers? IF YES – its recessive IF NO – its dominant

9 Reading a Pedigree: If its recessive, are there any male carrier? IF YES – its autosomal IF NO – its X-linked

10 Reading a Pedigree: If its dominant, analyze an affected son.

11 What type of disorder? What type of disorder is shown in the pedigree below? How do you know? Use your notes from Friday! 5-23 Are there any carriers? Analyze an affected son (can a son get it from dad?)

12 5-20 What type of disorder?

13 Hemophilia (X-linked recessive) Pedigree from Queen Victoria What type of disorder?

14 Announcement: Questish quizish type deal will be Friday 5-27

15 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 doesnt matter if trait is dominant or recessiveMales – b/c they only have one X (XY) so it doesnt matter if trait is dominant or recessive –Examples: Colorblindness – carried on X-chromosomeColorblindness – carried on X-chromosome Hemophilia – impaired blood clottingHemophilia – impaired blood clotting

16 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

17 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

18 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

19 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?

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

21 How do you identify a dominant genetic disorder on a pedigree (use notes page 5 if needed)? 5-24

22 Announcement: Questish quizish type deal will be Friday 5-27

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

24 edicine/landsteiner/http://nobelprize.org/educational_games/m edicine/landsteiner/ Blood typing activity google – first link

25 Universal donor

26 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

27 Codominance

28 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

29 Incomplete Dominance

30 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) (doesnt matter if trait is dominant or recessive)Males – b/c they only have one X (XY) (doesnt matter if trait is dominant or recessive) –Examples: ColorblindnessColorblindness HemophiliaHemophilia

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

32 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

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

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

35

36 Single-Allele Traits – traits caused by one dominant alleleSingle-Allele Traits – traits caused by one dominant allele Huntingtons Disease –Huntingtons 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

37 Standard Key: = normal male = carrier male (one bad allele + one good allele) = affected male (has disease / disorder) = normal female or = carrier female (one bad allele + one good allele) = affected female (has disease / disorder)


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