Chapter 1Chapter 122 – – Patterns of Heredity Patterns of Heredity and Human Geneticsand Human Genetics

ObjectivesObjectives

•Identify information presented on a karyotypeIdentify information presented on a karyotype

•Recognize the difference between male and Recognize the difference between male and female karyotypesfemale karyotypes

•Distinguish between normal and abnormal Distinguish between normal and abnormal karyotypeskaryotypes

Take out a sheet of paper and Take out a sheet of paper and write your name along with write your name along with your lab partners.your lab partners.

1. Look Figure 12.20 on page 329. Explain 1. Look Figure 12.20 on page 329. Explain what you think the picture is showing?what you think the picture is showing?

2. What do you think the numbers as well 2. What do you think the numbers as well as letters on the photograph represent?as letters on the photograph represent?

Karyotype pg. 329Karyotype pg. 329

Chromosomes come in pairs, inherited Chromosomes come in pairs, inherited from parentsfrom parents

Half from mom & half from dadHalf from mom & half from dad Humans have 23 pairs of chromosomes, Humans have 23 pairs of chromosomes,

46 total.46 total. Any more or less = abnormalityAny more or less = abnormality Sex Chromosomes – Called X and YSex Chromosomes – Called X and Y Autosomes – all non-sex chromosomesAutosomes – all non-sex chromosomes

Karyotype Fig. 12.20 pg. 329Karyotype Fig. 12.20 pg. 329 Picture of cell taken during the process of Picture of cell taken during the process of

metaphasemetaphase

3. Why metaphase?3. Why metaphase?

4. Looking at the Figure 12.20, how are the 4. Looking at the Figure 12.20, how are the chromosomes arranged?chromosomes arranged?

5. Do you think male and female karyotypes are the 5. Do you think male and female karyotypes are the same? Explain.same? Explain.

Chromosomes arranged by length, banding Chromosomes arranged by length, banding pattern, centromere locationpattern, centromere location

Comparison against a normal karyotypeComparison against a normal karyotype

PedigreePedigree PedigreePedigree = map of inheritance of genetic traits = map of inheritance of genetic traits

from generation to generationfrom generation to generation

Symbols on a PedigreeSymbols on a Pedigree Circle = FemaleCircle = Female Square = MaleSquare = Male Shaded = Affected Shaded = Affected Unshaded = UnaffectedUnshaded = Unaffected Adjoining line = Married/MatingAdjoining line = Married/Mating Connected by an adjoining line = OffspringConnected by an adjoining line = Offspring Roman Numeral = GenerationRoman Numeral = Generation

Textbook pg. 310 Fig. Textbook pg. 310 Fig. 12.212.2

6. How many generations are shown?6. How many generations are shown?

7. How many offspring did I-1 and I-2 have?7. How many offspring did I-1 and I-2 have?

8. How many boys did III-3 and III-4 have?8. How many boys did III-3 and III-4 have?

9. How many girls did II-1 and II-2 have?9. How many girls did II-1 and II-2 have?

10. What kind of trait (dominant or recessive) is being passed 10. What kind of trait (dominant or recessive) is being passed down?down?

11. What genotypes must I-1 and I-2 be in order to have a 11. What genotypes must I-1 and I-2 be in order to have a child with this trait?child with this trait?

12. What is the probability that they would have this type of 12. What is the probability that they would have this type of child? Show a Punnett squarechild? Show a Punnett square

Recessive HeredityRecessive Heredity

Caused by Caused by recessive allelesrecessive alleles Attached earlobes, Cystic fibrosis Attached earlobes, Cystic fibrosis

(defective protein leads to excessive (defective protein leads to excessive mucus production in lungs), Albinismmucus production in lungs), Albinism

Individual will only display the Individual will only display the recessive recessive phenotypephenotype if its genotype is if its genotype is homozygous homozygous recessiverecessive

Dominant HeredityDominant Heredity

Caused by Caused by dominant alleledominant allele Freckles, Widow’s peak, Hitchhickers Freckles, Widow’s peak, Hitchhickers

thumb, Huntington’s disease (brain thumb, Huntington’s disease (brain degeneration, doesn’t appear until later in degeneration, doesn’t appear until later in age), immunity to poison ivyage), immunity to poison ivy

Individual will display the Individual will display the dominant dominant phenotypephenotype if its genotype is if its genotype is heterozygousheterozygous oror homozygous dominanthomozygous dominant

When Heredity Follows When Heredity Follows Different RulesDifferent Rules

Chapter 12, Section 2 pg. 315Chapter 12, Section 2 pg. 315

Take out a sheet of paper and put your name Take out a sheet of paper and put your name along with your lab partners and answer the along with your lab partners and answer the following questions.following questions.

Objectives Section 12.2Objectives Section 12.2

Distinguish between alleles for Distinguish between alleles for incomplete dominance and codominanceincomplete dominance and codominance

Explain the patterns of multiple allele and Explain the patterns of multiple allele and polygenic inheritancepolygenic inheritance

Analyze the pattern of sex-linked Analyze the pattern of sex-linked inheritanceinheritance

Summarize how internal and external Summarize how internal and external environments affect gene expressionenvironments affect gene expression

Figure 12.7 pg. 316Figure 12.7 pg. 316 1. Look at the figure and give 2 differences between 1. Look at the figure and give 2 differences between

this Punnett square and Mendelian Punnett squares.this Punnett square and Mendelian Punnett squares. 2. What is the genotype for the red flowered 2. What is the genotype for the red flowered

snapdragon? White flowered? Pink?snapdragon? White flowered? Pink? Red = RRRed = RR White = R’R’White = R’R’ Pink = RR’Pink = RR’ 3. What phenotype is the result of crossing the red 3. What phenotype is the result of crossing the red

and white snapdragons?and white snapdragons? All PinkAll Pink 4. How is this different than Mendelian genetics? (Tall 4. How is this different than Mendelian genetics? (Tall

x Short = )?x Short = )? A third phenotype possibility exists (Pink), not just red A third phenotype possibility exists (Pink), not just red

or whiteor white

Incomplete DominanceIncomplete Dominance Incomplete DominanceIncomplete Dominance = phenotype of a = phenotype of a

heterozygoteheterozygote is in between the dominant & is in between the dominant & recessive phenotypes, recessive phenotypes, appearance of a third appearance of a third phenotype.phenotype.

No Longer Upper and Lowercase letters No Longer Upper and Lowercase letters AA or or aa

Flowers known as Snapdragons come in 3 colors Flowers known as Snapdragons come in 3 colors but have 2 alleles, R and R’. The ‘ is called but have 2 alleles, R and R’. The ‘ is called prime.prime.

R’R’ = R’R’ = WhiteWhite R’R or RR’ = R’R or RR’ = PinkPink RR = RR = RedRed

Sample Problems - Show the Punnett SquaresSample Problems - Show the Punnett Squares

Cross the following snapdragons and give the genotype Cross the following snapdragons and give the genotype and phenotype ratios.and phenotype ratios.

5. Red Flower x White Flower5. Red Flower x White Flower

Phenotypic Ratio = Phenotypic Ratio = 0Red0Red : 4: 4Pink Pink : 0: 0WhiteWhite

Genotypic Ratio = Genotypic Ratio = 0 RR 0 RR : 4: 4R’R R’R : 0: 0 R’R’R’R’

6. Pink Flower x Pink Flower 6. Pink Flower x Pink Flower

Phenotypic RatioPhenotypic Ratio = = 1Red 1Red : : 2Pink 2Pink : : 1White1White

Genotypic Ratio = Genotypic Ratio = 1RR1RR : : 2R’R 2R’R : : 1R’R’1R’R’

7. White Flower x White Flower7. White Flower x White Flower

Phenotypic Ratio = Phenotypic Ratio = 0 Red 0 Red : : 0 Pink 0 Pink : : 4 White4 White

Genotypic Ratio = Genotypic Ratio = 0 RR 0 RR : : 0 R’R 0 R’R : : 4 R’R’4 R’R’

Text pg. 316 Figure 12.7Text pg. 316 Figure 12.7

RedRed x White = all x White = all pinkpink PinkPink x x PinkPink = 1 = 1RedRed: 2: 2PinkPink: 1White: 1White

Genetics ReviewGenetics Review

Mendelian Genetics – Simple Dominant Mendelian Genetics – Simple Dominant & Recessive Traits (Tall TT or Tt or short & Recessive Traits (Tall TT or Tt or short tt)tt)

Incomplete Dominance – 3 phenotypes Incomplete Dominance – 3 phenotypes (FF = red, FF’ = pink, F’F’ = white)(FF = red, FF’ = pink, F’F’ = white)

Pedigree – Map to show how traits are Pedigree – Map to show how traits are passed from parent to offspring (not passed from parent to offspring (not shaded – doesn’t have trait, half shaded shaded – doesn’t have trait, half shaded – carrier, shaded – has trait– carrier, shaded – has trait

Erminette ChickensErminette Chickens This is an example of codominance.This is an example of codominance. Looking at the feathers of the chicken below can Looking at the feathers of the chicken below can

you explain the meaning of codominance?you explain the meaning of codominance? How is the phenotype different than in incomplete How is the phenotype different than in incomplete

dominance (hint: flower colors)? dominance (hint: flower colors)?

Codominance pg. 323Codominance pg. 323

BothBoth alleles for a gene are expressed in a alleles for a gene are expressed in a heterozygous individualheterozygous individual

You have 2 different letters for alleles – B & W•Black Feathers FBFB = Black Feathers•White Feathers FW FW = White•When the 2 alleles are combined a chicken with both black and white feathers is created.•Erminette chickens FBFW = Black & White•Neither allele is dominant or recessiveNeither allele is dominant or recessive

Codominance Practice ProblemsCodominance Practice Problems

Cross a chicken that is homozygous for Cross a chicken that is homozygous for the black alleles with a chicken that is the black alleles with a chicken that is homozygous for the white alleles.homozygous for the white alleles.

1.What color feathers did the offspring have?1.What color feathers did the offspring have?

Cross 2 chickens from the F1 generation to Cross 2 chickens from the F1 generation to make the F2 generation?make the F2 generation?

2.What color feathers did the offspring have?2.What color feathers did the offspring have?

Blood TypesBlood Types

BLOOD TYPE.ppt

Sex Determination & Sex-Sex Determination & Sex-linked Inheritancelinked Inheritance

Combination of Combination of sex chromosomes (X and sex chromosomes (X and Y)Y) determine an individual’s gender determine an individual’s gender

Males XYMales XY, , X chromosome comes from X chromosome comes from mom & Y chromosome comes from dadmom & Y chromosome comes from dad

Females XXFemales XX, , both mom & dad give an X both mom & dad give an X chromosomechromosome

Sex-linked TraitsSex-linked Traits = traits controlled by = traits controlled by genes on sex chromosomesgenes on sex chromosomes

Red-Green colorblindness Red-Green colorblindness Hemophilia (blood doesn’t clot properly)Hemophilia (blood doesn’t clot properly) Male Pattern BaldnessMale Pattern Baldness Duchenne Muscular Distrophy (muscular Duchenne Muscular Distrophy (muscular

degeneration leading to eventual degeneration leading to eventual paralysis)paralysis)

Most of sex-linked traits are found on Most of sex-linked traits are found on genes on the genes on the X chromosomeX chromosome (X-linked (X-linked trait)trait) because it is larger than the because it is larger than the Y Y chromosomechromosome

X-linked traits display more in males X-linked traits display more in males because they only have 1 X because they only have 1 X chromosome, whereas females get 2 X chromosome, whereas females get 2 X chromosomes so they can be carriers of chromosomes so they can be carriers of the trait but not display the phenotypethe trait but not display the phenotype

Color Blindness - Recessive TraitColor Blindness - Recessive Trait B = Normal b = color blind B = Normal b = color blind

MalesMales

XXBBY = NormalY = Normal XXbbY = Color BlindY = Color Blind FemalesFemales

XXBBXXBB = Normal = Normal

XXBBXXbb = Carrier (Normal) = Carrier (Normal)

XXbbXXbb = Color Blind = Color Blind

Can males be carriers for color blindness? Can males be carriers for color blindness? Why or why not?Why or why not?

Polygenic InheritancePolygenic Inheritance Characteristics that are influenced by Characteristics that are influenced by

several genesseveral genes