COMPLEX INHERITANCE. Indicator 4.7: Summarize the chromosome theory of inheritance & relate that theory to Gregor Mendel s principals of genetics.

Transcription

1 COMPLEX INHERITANCE Indicator 4.7: Summarize the chromosome theory of inheritance & relate that theory to Gregor Mendel s principals of genetics.

2 Agenda Warm-UP: page 151- what is the difference between monohybrid and dihybrid crosses? Explain picture. Notes on Complex Pattern of Inheritance Complex Patterns Activity Study Guide (24-29)

3 Chromosome Theory of Inheritance states Genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

4 Chromosome Theory of Inheritance Supported by the principles of Mendelian genetics including dominance, segregation, and independent assortment. Mendel s principles could NOT explain all parts of the chromosomes because we now have technology he did not and thus a better understanding of genetic material.

5 In the genes described by Mendel s data, one allele was always dominant and one was recessive. However Some genes do not have dominant and recessive alleles. Instead These genes show a form of intermediate inheritance. What this lesson is all about What Mendel didn t know

6 Basically means that: genes that are located on the same chromosome will be inherited together. Genes travel together during gamete formation. This is an exception to the Mendelian principle of independent assortment because linked genes do not separate independently. Gene Linkage

7 Alleles close together on homologous chromosomes are exchanged. The result is new combinations in alleles Occurs during Prophase I of meiosis I How does this relate to Mendel s principle of genetics? Explains how linked genes can be separated Crossing Over

8 Incomplete Dominance A condition in which one allele is not completely dominant over another. The phenotype expressed is somewhere between the two possible parent phenotypes Which principle of Mendel does this go beyond? Law of Dominance

9 Do not be fooled into thinking the alleles have blended to make pink. Only the phenotype is intermediate. The red & white alleles remain separate and distinct. Half the gametes of a pink snapdragon carry the allele for red, and half carry the allele for white.

10 So what happens? F1 hybrids have an appearance somewhat in between the phenotypes of the two parental varieties. Example: snapdragons (flower) red (RR) x white (rr) RR = red flower rr = white flower R r r R copyright cmassengale 10

11 r r R Rr Rr produces the F 1 generation R Rr Rr All Rr = pink (heterozygous pink) copyright cmassengale 11

12 Codominance Occurs when both alleles are expressed completely. The phenotype shows evidence of both alleles being present. Which principle of Mendel does this go beyond? Law of Dominance

13 Examples:

14 Multiple Alleles Multiple alleles can exist for a particular trait even though only two alleles are inherited. Example: Blood types: there are three alleles (A, B and O) which result in four different blood groups Mendel s principles of genetics did not explain that many traits are controlled by more than one gene.

15 Blood Types Many genes have more than two alleles for a trait. Human blood types exist as multiple alleles. Each person has only 2 of these alleles. 3 blood type alleles exist in the human population I A - Type A I B - Type B i - Type O I A & I B are codominant but are dominant over i. Type O blood is homozygous for ii.

16 Polygenic Traits Traits that are controlled by two or more genes. They show a variety of phenotypes. Example: Skin color Mendel s principles of genetics did not explain that many traits are controlled by more than one gene.

17

18 Activity!!!! Obtain 4 eggs from the front of the room for the incomplete dominance section of your activity. Complete the WS. Work on Study Guide (1-29) Closed-Toed Shoes and Notebooks Due Tomorrow! Page 160, 162, 164

19 143 Essential Questions: Why are there greater varieties of traits among organisms that sexually reproduce? 143 Mendel- Father of Genetics Complex Pattern of Inheritance enetics- study of patterns of inheritance (What Mendel couldn t explain) and variation in organisms Codominance enes- ex: hair color Both alleles for gene are dominant and expressed/seen -different forms of gene Example: white cow and brown bull have Genetics Ex: red, blonde, brown, black calf Neither allele is dominant or recessive Laws/Principles Offspring is a of the 2 alleles. of Dominance- Dominant vs. Recessive Example: Red and white flower creates pink Dominant- express allele if allele is present B-4.4- B-4.8 flower Recessive- express allele if dominant Multiple Alleles allele is absent Several alleles for trait are present creating multiple Homozygous ( ) vs. Heterozygous ( ) Example: blood type - alleles TT, Tt, tt Alleles- A, B, O Phenotype- (Tall, Short) (4) Phenotypes: A, B, AB, O of Segregation- alleles separate during Polygenic Traits 1 allele received from Mom; 1 allele from Dad Traits controlled by genes of Independent Assortment- donation of one trait Variety in traits s not affect the donation of another trait (exception- Example: height, skin color, eye color etc. ) Sex Linked Genes Genes carried by either chromosom onohybrid Cross vs. Dihybrid Cross Can be tracked through redict inheritance predicts inheritance Pedigree can also be dominant autosomal f trait of

20 Codominance Both alleles for gene are dominant and expressed/seen Example: white cow and brown bull have white and brown calf Incomplete Dominance Neither allele is dominant or recessive Offspring is a blend/mix of the 2 alleles. Example: Red and white flower creates pink flower Multiple Alleles Several alleles for trait are present creating multiple genotypes Example: blood type Alleles- A, B, O (4) Phenotypes: A, B, AB, O Polygenic Traits Traits controlled by 2 or more genes Variety in traits Example: height, skin color, eye color etc. Sex Linked Genes Genes carried by either X or Y chromosome Can be tracked through pedigree Pedigree can also be dominant autosomal Complex Pattern of Inheritance (What Mendel couldn t explain)

21 Quiz Monday on Mendel s Laws (segregation, dominance, independent assortment) and complex patterns of inheritance (codominance, incomplete, multiple alleles, and polygenic) Agenda: Warm UP: Quarter Sheet (Use to study for quiz) Blood Typing Lab Study Guide Finish Work Sheets Notebooks Due Today! Page 160, 162, 164

22 Pre-Lab Questions 1. What does it mean to have a blood type? 2. What are the three alleles for blood type? 3. What are the possible blood types? A, B, AB, and O type Blood 4. Which two alleles are dominant? A and B 5. Which allele is recessive? O 6. Type A blood can be expresses as I A I A or. I A i 7. Type B blood can be expresses as or. 8. Type AB blood can be expresses as. ii 9. Type O blood is expressed as. I B I B I A I B Presence of antigens (protein) that determine blood transfusions and compatibility I A, I B, i I B i

23 10 I B i I A I A I B I A i i I B i ii Offspring Phenotype probability: A, B, AB, O blood types

24 Mom: type B BB or BO Child: type O OO Dad?: type AB B B B O A AB AB B BB BB Child would be either type AB or type B. A AB AO B BB BO Child would be either type AB, type A, or type B. A woman with type B blood has a child who is type O. She suspects a man with type AB blood is the father. Is she correct? Why or why not?

25 No way that the child could have the recessive allele if the father has both dominant alleles Congratulations, you are NOT the father!

26 Directions of Lab.. Blood Typing Lab Directions REVAMP Yellow Water = A Type Blood Blue Water = B Type Blood Green Water = AB Type Blood Clear Water = O Type Blood

27 Directions of Lab.. Procedure: Clean your well plate to make sure it will not contaminate your results. Notice that the well plate has numbers and letters. A row will represent A blood type individuals B row will represent B blood type individuals C row will represent AB blood type individuals D row will represent O blood type individuals Place one pipette full of the corresponding blood type in the first 4 wells. A row will have Yellow water in numbers 1-4.

28 Add test blood to see test compatibility. If it changes color, it is not! DO NOT MIX PIPETTES BETWEEN COLORS!!! 5 drops of A blood type (yellow) to #1. 5 drops of B blood type (blue) to #2. 5 drops of AB blood type (green) to #3. 5 drops of O blood type (clear) to #4.

29 Add test blood to see test compatibility. If it changes color, it is not! DO NOT MIX PIPETTES BETWEEN COLORS!!! 5 drops of A blood type (yellow) to #1. 5 drops of B blood type (blue) to #2. 5 drops of AB blood type (green) to #3. 5 drops of O blood type (clear) to #4. Any change in color from the original blood type (type A) represents agglutination, or tendency of blood to form clots with an incompatible blood type (i.e. if the color changes, those blood types CANNOT MIX) Record your observations (color) in the Compatible Blood Types Data Table first column, even if there was no change.

30 Repeat steps 3-6 with the following: B row will have B Type (blue water) in numbers 1-4.Test. Record. C row will have AB Type (green water) in numbers 1-4. Test. Record. D row will have O Type (clear water) in numbers 1-4. Test. Record. Clean your wells. Complete compatible (+) or incompatible (-) table and answer post-lab questions.

31 After Lab. Notebooks Graded Page 160 Page 162 (2 sheets) Page 164 Page 166 (Lab Today) Quiz on Monday

32 Partners Station 1: Jerrica, Conner Station 2: Ashlyn, Blake Station 2: Skyler, Andrew Station 3: Hayley, MJ Station 4: Tori, Michael K. Station 4: Lauren, Damorris Station 6: Destiny, Jordan Station 7: Mello, Emily Station 7: Brandon, Tyler Station 8: Jared, Alexis Station 8: Noah, Airyauna Station 5: Cole, Hannah Station 5: Shane, Dania

33 Partners Station 1: Maycie, Brittany Station 2: McKenzie, Ethan Station 3: Chris, Chris Station 4: Michael, Rachel Station 4: Kameron, Alex Station 7: Brianna, Sim Station 7: Station 8: Station 8:Bradley, Michaela Station 5: Blake, Harris Station 5: Station 6: Mia, Samantha

34 Agenda Warm-UP- Look at notebook for grades Quiz Monday on Mendel s Laws (segregation, dominance, independent assortment) and complex patterns of inheritance (codominance, incomplete, multiple alleles, and polygenic) Notes on Sex-Linked Traits and Pedigree Pick a Risk and Pedigree WS Work on Study Guide Monday- Dragon or Potato Head Genetics

35 Sex-linked Traits Involves genes on either the X or Y chromosome. In organisms that undergo sexual reproduction, the pair of chromosomes that determines the sex of the organism is called the sex chromosomes. 3. Females = XX Males = XY

36 During Meiosis I, when chromosome pairs separate, each gamete (egg) from the female parent receives an X chromosome. The gametes (sperm) from the male parent can either receive an X or a Y chromosome. Show the Punnett square for offspring being male or female during fertilization: X X X Y XX XX XY XY In humans, the Y chromosome carries very few genes while the X chromosome contains many genes that affect many traits. Sex-linked Traits

37 Traits that are expressed in only one sex. Sex-linked genes are carried by both male and females. Genes are activated by hormones of one sex but not by the hormones of the other sex. Ex: Beard growth - males & milk production - females Sex chromosomes are X and Y XX genotype for females XY genotype for males Many sex-linked traits carried on X chromosome Sex-linked Traits (more information) copyright cmassengale 37

38 Sex-linked Traits Example: Eye color in fruit flies Sex Chromosomes fruit fly eye color XX chromosome - female Xy chromosome - male copyright cmassengale 38

39 Female offspring will inherit the gene (X from male & female parent) and the law of dominance will apply. Male offspring will inherit the gene on the X chromosome but not on the Y chromosome. Since males only have one X chromosome, they express the allele whether it is dominant or recessive. In other words: there is no second allele to mask the effects of the other allele. If a gene is linked on the X Chromosome

40 Sex-linked Trait Hemophilia is one example; give another example with a Punnett square: Eye color in fruit flies Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) X R Y x X r X r Remember: the Y chromosome in males does not carry traits. RR = red eyed Rr = red eyed rr = white eyed X r X r XY = male XX = female X R Y copyright cmassengale 40

41 Sex-linked Trait Solution: X r X r X R Y X R X r X r Y X R X r X r Y 50% red eyed female 50% white eyed male copyright cmassengale 41

42 X-linked recessive Cannot distinguish between different colors Most common type is red/green colorblindness Heterozygous females have mosaic retinas in which they have patches of color vision Heterozygous female is considered a carrier

43 A chart made to show: inheritance patterns (trait, disease, disorder) within a family through multiple generations. Through the use of a pedigree chart and key: the genotype and phenotype of the family members and genetic characteristics of the trait can be tracked. Pedigrees

44

45 Pedigrees: Symbols 3. Draw how each is represented: Male: square Female: circle Affected: colored in

46 Pedigree: family record that shows how a trait is inherited over several generations Shows both recessive and dominant traits First Step in genetic counseling Symbols: Male: Female: Carrier: Marriage Line: Offspring: Fraternal Twins: Identical Twins:

47 Pedigree Key

48

49 Family with dominant autosomal genetic trait: *Three things we can infer based on the pedigree: 1. It is on an autosome and not sex chromosome because both males and females have the trait. 2. It is not sex linked due to number one. 3. The gene is dominant because each of the people who have the trait has only one parent who has the trait. Pedigrees: Example #1

50 Family with recessive sex-linked genetic trait: This is common in X- linked, recessive traits because females who receive the gene for the trait on the X chromosome from their fathers also receive an X chromosome from their mothers which hides the expression of the trait. Pedigree: Example #2

51 The trait skips a generation. In generation II, all of the offspring receive an X chromosome from their mother. Because the males only receive the X chromosome from their mother, they do not receive the gene carrying the trait. Because the females receive an X chromosome from their mother and father, they are heterozygous and do not express the recessive trait, but they are carriers. Pedigree: Example #2

52 In generation III, the offspring of all of the females from generation II have a 50/50 chance of passing a trait-carrying gene to their children. If the males receive the trait-carrying gene, they will express the trait. If the females receive the trait-carrying gene, they will again be carriers Pedigree: Example #2

53 Pedigree Example #1 Must be an autosomal dominant trait Autosomal b/c if affects both males and females almost equally Dominant b/c it occurs in every generation

54 Pedigree Example #2 Must be a sex-linked recessive trait Sex-linked b/c it occurs in more males than females Recessive b/c it skips a generation

55 Pedigree Example #3 Must be a autosomal recessive trait Autosomal b/c it affects both males and females equally Recessive because it skips many generations

56 Activity!!!! Pedigree Activity (Pick a Risk and WS) Genotypes of all affected individuals (dark shapes) 2, 7, 8, 11,16, 18, 20, 22, 23, 27, 30 (Look at OFFSPRING/Parents!!!) Study for quiz Work on Study Guide (30-33) Quiz MONDAY!

57 Pick A Risk Activity- page 169 Grab the following colored pencils: RED ORANGE YELLOW GREEN BLUE/Purple Low Risk- 5 or more red Medium Risk- 4 red High Risk- 3 or fewer red After? WS

58 Activity!!!! Pedigree Activity (Pick a Risk and WS) Genotypes of all affected individuals (dark shapes) 2, 7, 8, 11,16, 18, 20, 22, 23, 27, 30 (Look at OFFSPRING/Parents!!!) Study for quiz Work on Study Guide (30-33) Quiz MONDAY!