Genetics and heredity

4,341 views

Published on

Published in: Education, Lifestyle, Technology
0 Comments
4 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
4,341
On SlideShare
0
From Embeds
0
Number of Embeds
2,269
Actions
Shares
0
Downloads
121
Comments
0
Likes
4
Embeds 0
No embeds

No notes for slide
  • After this slide you should do the Genetics Overview and Genetics Problems #1.
  • In humans, the term sex-linked traits usually refers to X-linked traits. The human X-chromosome is much larger than the Y. Thus, there are more X-linked than Y-linked traits. Most X-linked genes have no homologous loci on the Y chromosome. Most genes on the Y chromosome not only have no X counterparts, but they encode traits found only in males (e.g. testis- determining factor). Examples of sex-linked traits in humans are color blindness and hemophilia. Fathers pass X-linked alleles to only and all of their daughters. Males receive their X chromosome only from their mothers. Fathers cannot, therefore, pass sex-linked traits to their sons. Mothers can pass sex-linked alleles to both sons and daughters. Females receive two X-chromosomes, one from each parent. Mothers pass on one X-chromosome (either the maternal or paternal homologue) to every daughter and son.
  • The link to the website at the bottom gives a complete history and breakdown of royal hemophilia
  • Colorblindness is a sex-linked trait. You can ask questions about each individual, you could also ask genotypes/phenotypes. (See below for sample questions) Questions you can ask: Individual 2 is most likely a: carrier female If individual 8 is not color blind, what is the probability that this individual is a carrier?: 0 Let us say individual 12 marries a normal, non-carrier female.  What is the probability that one of his sons will be color-blind? : 0 (males don’t donate X to sons)
  • Genetics and heredity

    1. 1. Genetics and Heredity
    2. 2. Probability
    3. 3. Probability <ul><li>The likelihood that a specific event will occur </li></ul><ul><li>Probability = # of 1 times event occurs number of possible outcomes </li></ul><ul><li>Example: What is the probability that a tossed coin will be heads? </li></ul><ul><li>½ or 50% </li></ul>
    4. 4. Probability <ul><li>The First Law of Probability : the results of the first trial of a chance event do not affect the results of later trials of the same event. </li></ul><ul><li>In other words, no matter how many times a flipped coin lands on tails, every flip still has a ½ chance of tails. </li></ul>
    5. 5. Probability <ul><li>Second Law of Probability: The probability of two or more independent events occurring together is the product of their separate probabilities. </li></ul><ul><li>What is the probability that a couple will have four boys? </li></ul><ul><li>50% (1/2 probability each time) </li></ul><ul><li>½ x ½ x ½ x ½ = 1/16 </li></ul>
    6. 6. Inherited Traits
    7. 7. Are these inherited traits? Your eye color Your height Your hair color and texture
    8. 8. Are these inherited traits? Your personality Your musical, athletic, and artistic abilities
    9. 9. Think about this…. <ul><li>“ My parents have brown eyes, why are mine blue?” </li></ul><ul><li>“ My brother is tall. Why am I short?” </li></ul><ul><li>“ Why does my sister have blonde hair while mine is brown?” </li></ul>
    10. 10. Gregor Mendel <ul><li>These are questions that Gregor Mendel tried to answer.. </li></ul><ul><li>Born in 1822 in Austria </li></ul><ul><li>1843 – Studied Theology </li></ul><ul><li>1846-Studied Science at the University of Vienna </li></ul>Father of Genetics
    11. 11. Mendel’s studies led to: <ul><li>Dominant (H) </li></ul><ul><li>Homozygous (HH or hh) </li></ul><ul><li>Genotype (HH, Hh or hh) </li></ul><ul><li>Purebred (HH or hh) </li></ul><ul><li>Recessive (h) </li></ul><ul><li>Heterozygous (Hh) </li></ul><ul><li>Phenotype (blonde, brown, red) </li></ul><ul><li>Hybrid (Hh) </li></ul>Concepts in Inheritance
    12. 12. Theory of Heredity <ul><li>Inherited allele for purple P </li></ul>Inherited allele for purple P HOMOZYGOUS purple flower PP
    13. 13. Theory of Heredity <ul><li>Inherited allele for purple flower (P) </li></ul>Inherited allele for pink flower ( p ) HETEROZYGOUS purple flower (P p )
    14. 14. Theory of Heredity <ul><li>Inherited for pink flower ( p ) </li></ul>Inherited for pink flower ( p ) HOMOZYGOUS pink flower ( pp )
    15. 15. PREDICTING HEREDITY
    16. 16. PUNNETT SQUARES <ul><li>A Punnett square is a tool used to help predict the probability of offspring of a couple. </li></ul><ul><li>1. Decide the genes that could be passed on to the offspring in the gametes from each parent. </li></ul><ul><li>2. Cross the different gene/gamete possibilities for each possible offspring combination. </li></ul>
    17. 17. Monohybrid Cross <ul><li>Monohybrid Cross: a cross that shows the possible offspring for one trait </li></ul><ul><li>Aa x Aa </li></ul><ul><li>A: White fur </li></ul><ul><li>a: Brown fur </li></ul>Parent Aa has what gentotype? Parent Aa can produce a gamete with either an “A” or with an “a”
    18. 18. Monohybrid Cross <ul><li>Monohybrid Cross: a cross that shows the possible offspring for one trait </li></ul><ul><li>Aa x Aa </li></ul><ul><li>A: White fur </li></ul><ul><li>a: Brown fur </li></ul><ul><li>Aa produces gamete “A” or “a” </li></ul>A a A a <ul><li>Separate the two genes (as though they were separating into different gametes) and place one outside the first row on the left and the other under it outside the second row. </li></ul><ul><li>Separate the other parent genes and place at the top, one above each column. </li></ul>
    19. 19. Monohybrid Cross <ul><li>Monohybrid Cross: a cross that shows the possible offspring for one trait </li></ul><ul><li>Aa x Aa </li></ul><ul><li>A: White fur </li></ul><ul><li>a: Brown fur </li></ul><ul><li>Cross over the genes to fill in the boxes of the square. </li></ul>A a A a AA Aa Aa aa
    20. 20. Genotypic Ratios <ul><li>Genotypic Ratios compare the possible genotypes (gene combinations in the offspring. </li></ul><ul><li>Genotypic ratio: </li></ul><ul><li>Number of offspring with homozygous dominant genes AA </li></ul><ul><li>Number of offspring with heterozygous/hybrid genes Aa </li></ul><ul><li>Number of offspring with homozygous recessive genes aa </li></ul><ul><li>Aa x Aa </li></ul><ul><li>A: White fur </li></ul><ul><li>a: Brown fur </li></ul><ul><li>Sometimes abbreviated as: </li></ul><ul><li>GR = #hom dom (AA) : #hyb (Aa) : hom rec (aa) </li></ul>GR = 1 : 2 : 1 A a A a AA Aa Aa aa
    21. 21. Phenotypic Ratios <ul><li>Phenotypic Ratios compare the possible phenotypes (appearance of the offspring); how many show the dominant trait or recessive trait. </li></ul><ul><li>Phenotypic ratio: </li></ul><ul><li>Number of offspring showing the dominant trait (AA & Aa) </li></ul><ul><li>Number of offspring showing the recessive trait (aa) </li></ul><ul><li>Aa x Aa </li></ul><ul><li>A: White fur </li></ul><ul><li>a: Brown fur </li></ul><ul><li>Sometimes abbreviated as: </li></ul><ul><li>PR = #show dom (AA & Aa) : #show rec (aa) </li></ul>PR = 3 : 1 A a A a AA Aa Aa aa
    22. 22. Practice! Cross a HOMOZYGOUS dominant female with a HETEROZYGOUS male using the same trait. AA AA Aa Aa What is the genotypic ratio? What is the phenotypic ratio? 2:2 or 50% 4 white fur A A A a
    23. 23. Dihybrid Cross <ul><li>Dihybrid Cross: shows the possible offspring for two traits </li></ul><ul><li>This shows a cross between parents hybrid for two traits: BbRr x BbRr </li></ul>Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth BbRr x BbRr BR bR br bR Br BR br Br BBRR BbRR BbRr BBRr BBrr BbRr Bbrr BbRR BbRr bbRR bbRr BbRr Bbrr bbRr bbrr BBRr
    24. 24. Dihybrid Crosses <ul><li>How many of the offspring would have a black, rough coat? (#dom/dom) </li></ul><ul><li>How many would have a black, smooth coat? (#dom/rec) </li></ul><ul><li>How many would have a white, rough coat? (#rec/dom) </li></ul><ul><li>How many would have a white, smooth coat? (#rec/rec) </li></ul>16 Phenotypic Ratio: # dom/dom : # dom/rec : # rec/dom : # rec/rec Phenotypic Ratio: 9:3:3:1 BR bR br bR Br BR br Br BBRR BbRR BbRr BBRr BBrr BbRr Bbrr BbRR BbRr bbRR bbRr BbRr Bbrr bbRr bbrr BBRr
    25. 25. Dihybrid Crosses <ul><li>If mouse #1 were crossed with mouse #16, what would their offspring look like? </li></ul><ul><li>#1 x #16 </li></ul><ul><li>BBRR x bbrr </li></ul>16 1 <ul><li>#6 x #10 </li></ul><ul><li>BBrr x BbRr </li></ul><ul><li>#14 x #16 </li></ul><ul><li>Bbrr x bbrr </li></ul>Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth BR bR br bR Br BR br Br BBRR BbRR BbRr BBRr BBrr BbRr Bbrr BbRR BbRr bbRR bbRr BbRr Bbrr bbRr bbrr BBRr
    26. 26. More Complex Patterns of Heredity <ul><li>Codominance </li></ul><ul><li>Multiple Alleles </li></ul><ul><li>Sex-Linked Traits </li></ul>
    27. 27. Codominance <ul><li>Codominance: two dominant alleles are expressed at the same time </li></ul>C R C R C W C W C R C W
    28. 28. Codominance <ul><li>Sickle-Cell Anemia is another codominant trait. </li></ul>N A =Normal RBC N S =Sickle Cell RBC National Institute of Health, http://www.cc.nih.gov/ccc/ccnews/nov99/ Photo attributed to Drs. Noguchi, Rodgers, and Schechter of NIDDK. N A N A N S N A N S N A N S N A N A N A N A N A
    29. 29. Multiple Alleles <ul><li>Multiple Alleles: traits with more than 2 alleles </li></ul><ul><li>Blood type has 3 alleles: A, B, O </li></ul><ul><li>A and B are codominant over O </li></ul><ul><li>O is recessive </li></ul>Phenotype Genotype Can Receive From Can Donate To A I A I A , I A i A, O A, AB B I B I B , I B i B, O B, AB AB I A I B A, B, AB,O AB O ii O A, B, AB, O
    30. 30. What are Sex-Linked Traits? <ul><li>Traits that are located on one of the sex chromosomes (XY or XX) </li></ul>Hemophilia: Failure of blood to clot Muscular Dystrophy: wasting away of muscles Alix and Nicholas II
    31. 31. Can I inherit a sex-linked disease? Fathers (XY) can only pass disorders to daughters (XX) Mothers (XX) can pass disorders to both sons (XY) and daughters (XX) Most disorders are carried on the X chromosome, so males are more likely to inherit them.
    32. 32. How can I tell if I have a genetic disorder? <ul><li>Karyotypes are a “map” of all 46 (23 pair) of chromosomes. </li></ul>
    33. 33. What’s wrong with this Karyotype? Is this a male or a female?
    34. 34. What’s wrong with this Karyotype? Turner’s Syndrome
    35. 35. What’s wrong with this Karyotype? Klinefelter’s Syndrome
    36. 36. What’s wrong with this Karyotype? Down Syndrome
    37. 37. Pedigree Analysis <ul><li>A pedigree shows inheritance of genetic traits over several generations </li></ul>male female Female Carrier Marriage Offspring
    38. 38. Royal Hemophilia Pedigree http://www.sciencecases.org/hemo/hemo.asp
    39. 39. Pedigree for Colorblindness

    ×