A Family History That Shows How a Trait Is Inherited

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People have understood for centuries that certain traits are inherited (transmitted from PowerPoint Presentation

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People have understood for centuries that sure traits are inherited (transmitted from

People have understood for centuries that sure traits are inherited (transmitted from

People accept understood for centuries that certain traits are inherited (transmitted from generation to generation) but did not understand how it happened. Mendel's experiments answered many of these questions, because his experiments were then advisedly planned, executed, and quantified.

Uploaded on Aug 08, 2014

• sex activity chromosomes
• xx xy ten
• recessive organism
• adventure factors
• merely smoothen
• gametes s s

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People accept understood for centuries that certain traits are inherited (transmitted from

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1. People have understood for centuries that sure traits are inherited (transmitted from generation to generation) but did not sympathize how it happened. Mendel'south experiments answered many of these questions, because his experiments were so carefully planned, executed, and quantified.

2. Mendelworked with peas A. produced many offspring B. worked with plants that "bred truthful", due east.grand., plants with purple flowers e'er produced plants with purple flowers C. He could control the breeding procedure As well, he could self-fertilize the plants ("self-cross") D. He counted the offspring and analyzed the results Due east. He bred plants and then that they differed in only ane characteristic, or but two… F. For each trait in that location were but two possible outcomes

3. Case: Monohybrid cross (plants are identical except for one characteristic, or trait) Mendel examined seed shape. Plants had either smooth or wrinkled seeds. He crossed plants having smooth seeds with plants having wrinkled seeds. Result: all of the plants had smooth seeds. Next, he planted the seeds from this cantankerous and self-fertilized them. What happened?

4. He nerveless over 7000 seeds and counted them. 5474 were smoothen 1850 were wrinkled ¾ were smoothen, and ¼ were wrinkled In Mendel'southward terminology: P1 (parents) Smooth Ten wrinkled F1 (first generation) all smooth F2 (second generation) 5474 polish 1850 wrinkled

5. Mendel examined seven traits and always got the same results. Interpretation: The F1 always showed only one of the ii parental traits, and always the same trait. It didn't matter which institute donated the pollen The trait that "disappeared" in the F1 generation reappeared in about 25% of the F2's So traits did not blend, just remained unchanged from 1 generation to another

6. Mendel's conclusions: Traits (what we now call genes) are not always expressed. Genes that are always expressed are chosen dominant genes Genes that are not expressed if a dominant gene is present are called recessive genes

7. The P1 plants and F1 plants have the same appearance (smooth seeds) but accept different genes: The P1 plants produce only smooth seeds, but the F1 plants produce smooth and wrinkled seeds These plants take the aforementioned PHENOTYPE (outward advent) But have different GENOTYPES (genetic makeup) Each parent contributes the aforementioned amount of genetic information

8. Symbols for dominant and recessive traits Upper example letter-dominant version of the gene Lower case letter- recessive version Smooth seeds are dominant, then Due south stands for polish seeds Wrinkled seeds are recessive, so due south stands for wrinkled seeds

9. A plant that ever produces smooth seeds has two Due south alleles. The smooth seed allele is dominant to the wrinkled seed allele SS=homozygous dominant homozygous: both alleles are the same ascendant: both alleles are dominant A plant that always produces wrinkled seeds has two southward alleles: homozygous recessive. The F1 plants are Ss: heterozygous (i allele from each parent)

10. Mendel's Law of Segregation Each parent has two genes for a trait (allele: variant version of a gene) Each gamete receives 1 of the 2 genes Parent SS ss Gametes S Southward s s Offspring Ss

11. Crosses involving two traits: Principle of independent assortment Mendel worked with seeds on this Yellow (Y) is dominant to green (y) Polish (South) is dominant to wrinkled (s) P1 cantankerous: Smooth xanthous (SSYY) with wrinkled dark-green, (ssyy) F1s are all smooth and yellow (SsYy) He crossed these with each other:

12. X = all SSYY ssyy SsYy SY Sy sY sy SSYY SSYy SsYY SsYy SY Sy sY sy SSYy SSyy SsYy Ssyy SsYY SsYy ssYY ssYy SsYy Ssyy ssYy ssyy

13. Out of xvi possible combinations; 9 accept at to the lowest degree one re-create of BOTH dominant alleles (S and Y) 3 have at least i copy of S and are homozygous recessive for yy 3 have at to the lowest degree i copy of Y and are ss 1 has recessive for ss and yy And so the s and y alleles were distributed randomly into gametes during meiosis (independent assortment)

14. We at present know (and Mendel did not) that this happens because genes are on chromo- somes. Genes Chromosomes Occur in pairs (alleles) occur in pairs (homologues) Members of a gene pair Homologues dissever split up during meiosis during meiosis Members of one gene pair Members of 1 pair assort independently of of chromosomes other gene pairs assort independently during meiosis of others during meiosis

15. These laws apply to many examples of genetic inheritance. Variations have also been observed.

16. Multiple alleles • More than two alleles in the population • (although whatsoever organism has two) • Both alleles may be expressed: codominant • Example : ABO claret groups • Three alleles, IA, IB and I • Type O is recessive (ii) • Type A person could exist IAIA or Iai • What is genotype for type B? type AB? Type O?

17. Blood types are inherited in Mendelian fashion. You can utilise the format AO for a type A heterozygote, AA for a blazon A homozygote, etc. If two type A parents have a blazon O child, what must their genotypes exist? AO and AO Can a blazon O man begetter a blazon B child? If so, what is the genotype of the child? Yes; type BO Tin can a type AB man and a blazon B woman have a type A kid? Yeah, if the woman's genotype is BO

18. Other furnishings on phenotype Incomplete authority Multiple alleles (continuous variation) Pleiotropic effects cystic fibrosis, sickle cell anemia Environmental effects temperature sensitivity "risk factors" Penetrance; expressivity

19. Sex linkage-Morgan'due south experiment White-eyed male wing was crossed with a red-eyed female fly All of the F1 (offspring had cherry eyes). F1 flies were crossed with each other. A iii:1 red:white ratio was observed- but all of the white-eyed flies were male. The F1 females were exam-crossed with the white-eyed males What is a testcross?

20. What is a testcross? Is an organism with the dominant phenotype homozygous dominant or heterozygous? How can you lot find out? What kind of mating experiment will tell you? Cross the organism with a homozygous recessive organism: A- X aa What will be the issue if the test organism is AA? All of the offspring will have the dominant phenotype. What volition exist the result if the test organism is Aa? Half of the offspring will have the dominant phenotype And half volition have the recessive phenotype.

21. Dorsum to the testcross of F1 females with white-eyed males What happened? Phenotypic ratio was 1:1:1:1 crimson-eyed females white-eyed females ruby-eyed males white-eyed males As expected Why did recessive trait "disappear" in F1 females? The eye-colour trait is on the X chromosome.

22. Except for the sex chromosomes, the other (autosomal) chromosomes are homologous pairs. Genetic Data on those chromosomes is inherited as pairs of alleles (homozygous or heterozygous). Sex chromosomes: in flies and humans, females have two X chromosomes and males have one Ten and i Y. Implications: when 2 gametes fuse, if both contain X chromosomes, the offspring is female. If one gamete contains X and the other Y, the offspring is male. (independent assortment of chromosomes)

23. Y X Twenty XY X XX XY 10 A female offspring must inherit which chromosome from her male parent? A male offspring must inherit which chromosome from his father? So if a recessive allele is on the X chromosome, a female needs two copies to accept the recessive phenotype, simply a male needs merely ane.

24. The P fly cantankerous: let West=red optics and w=white eyes (male) white-eyed (female) red-eyed Xw Y XWXw XW XWY XWXw XWY XW All of the F1 flies accept ruddy eyes. The females are heterozygous ("carriers"). The males have inherited the crimson-eye gene from their mothers.

25. The F1 cross: Males: XWY Females: XWXw XW Y XWXW XWY XW XWXw XwY Xw All of the females take red optics. Half of the males take red eyes and half have white eyes.

26. Testcross of the F1 females (XWXw) XWXw X XwY Xw Y XWXw XWY XW XwXw XwY Xw Red-eyed female person:white-eyed female person:blood-red-eyed male: White-eyed male ane:1:i:1

27. In flies, white heart color is sexual practice-linked recessive Recessive, because red eyes are dominant to white Sex-linked, because the gene is on the X chromosome

28. How can y'all tell if a characteristic is inherited in a X (sex)-linked recessive manner? Males with the affected Ten chromosome, and Homozygous females, are affected. Phenotype is seen much more often in males. Affected males inherit the allele from their mothers and pass it on to their daughters. Daughters of affected males are usually heterozygous and thus unaffected. Sons of heterozygous mothers have a 50% run a risk of inheriting the gene.

29. Some X-linked recessive traits in humans • Colour blindness (red or green) • Hemophilia • Duchenne muscular dystrophy • SCID (severe combined immune deficiency syndrome

30. X-linked dominant traits • Afflicted males produce all affected daughters and no afflicted sons • A heterozygous affected female person volition transmit the gene to half of her children (male or female) • Well-nigh twice every bit many females as males are affected • Few of these traits are known in humans

31. Genes on Y chromosome are passed only from father to son Mitochondrial Dna is passed from mother to all offspring. Only daughters can pass on the same Deoxyribonucleic acid to their offspring. In humans, patterns of inheritance are studied with full-blooded assay

32. Full-blooded analysis Used in human genetic analysis humans don't produce plenty offspring for counting analysis Pedigree chart: a diagram that shows the membership and bequeathed relationships in a family Pedigree analysis: utilize of family history to determine how a trait is inherited; used in the study of man heredity

33. Constructing a full-blooded = male person = female person = mating = parents and children. Parents are the upper group, children the lower. From left to right, children are shown in nativity order (so the son is the youngest kid). or = unaffected past the trait in question or = affected past the trait in question

34. A pedigree of three generations I. grandparents II: parents III: most recent generation you Your mother Your father

35. Inheritance of an autosomal dominant trait Each afflicted kid has at least i affected parent. Two affected parents can have an unaffected child.

36. Inheritance of an autosomal recessive trait Two unaffected parents can accept an afflicted child.

37. Inheritance of sex-linked recessive traits Trait is seen much more than frequently in males. Unaffected females may be "carriers" who laissez passer the afflicted Ten chromosome to their sons. Affected males pass the afflicted chromosome to daughters just non sons.

38. Inheritance of X-linked dominant traits An affected father passes the trait to all of his daughters and none of his sons. An affected woman has a 50% hazard of passing the trait to both sons and daughters.

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