Punnett Squares and Pedigrees Unit 5 Reproduction and

Punnett Squares and Pedigrees Unit 5 Reproduction and Heredity Lesson 5

What’s the Probability? • Humans have a 1 in 2 chance of having a boy or a girl with each pregnancy. If the first child is a girl, what is the probability that the second child will be a girl?

What’s the Probability? • Humans have a 1 in 2 chance of having a boy or a girl with each pregnancy. If the first child is a girl, what is the probability that the second child will be a girl? • 1 in 2.

What’s the Probability? • Humans have a 1 in 2 chance of having a boy or a girl with each pregnancy. If the first child is a girl, what is the probability that the second child will be a girl? • 1 in 2. • The probability of something happening is not affected by what has happened before.

Gender Determination Quick Lab • Let’s do a quick exercise that explains how gender is inherited.

Completing a Punnett Square Quick Lab • Let’s do one more quick lab that shows us how to create a Punnett square and use it to predict the probabilities of genotypes and phenotypes.

Multi-Trait Punnett Squares • Let’s make a Multi-Trait Punnett Square. We have a plant that is homozygous for green seeds (GG) and heterozygous for purple flowers (Ff) crossed with a plant heterozygous for green seeds (Gg) and homozygous for white flowers (ff).

Multi-Trait Punnett Squares • Let’s make a Multi-Trait Punnett Square. We have a plant that is homozygous for green seeds (GG) and heterozygous for purple flowers (Ff) crossed with a plant heterozygous for green seeds (Gg) and homozygous for white flowers (ff). • First, let’s write the genotypes of the two plants.

Multi-Trait Punnett Squares • Let’s make a Multi-Trait Punnett Square. We have a plant that is homozygous for green seeds (GG) and heterozygous for purple flowers (Ff) crossed with a plant heterozygous for green seeds (Gg) and homozygous for white flowers (ff). • First, let’s write the genotypes of the two plants. • GGFf and Ggff

Multi-Trait Punnett Squares • Let’s make a Multi-Trait Punnett Square. We have a plant that is homozygous for green seeds (GG) and heterozygous for purple flowers (Ff) crossed with a plant heterozygous for green seeds (Gg) and homozygous for white flowers (ff). • First, let’s write the genotypes of the two plants. • GGFf and Ggff • Next, write down the possible combinations of alleles that would be in the gametes.

Multi-Trait Punnett Squares • Let’s make a Multi-Trait Punnett Square. We have a plant that is homozygous for green seeds (GG) and heterozygous for purple flowers (Ff) crossed with a plant heterozygous for green seeds (Gg) and homozygous for white flowers (ff). • First, let’s write the genotypes of the two plants. • GGFf and Ggff • Next, write down the possible combinations of alleles that would be in the gametes. • Plant 1: GF, Gf, GF, Gf. Plant 2: Gf, gf, Gf, gf.

Multi-Trait Punnett Squares • First, let’s write the genotypes of the two plants. • GGFf and Ggff • Next, write down the possible combinations of alleles that would be in the gametes. • Plant 1: GF, Gf, GF, Gf. Plant 2: Gf, gf, Gf, gf. • Write these combinations along the top and side of a 16 -cell Punnett square and complete it. What four genotypes will you get?

Multi-Trait Punnett Squares • First, let’s write the genotypes of the two plants. • GGFf and Ggff • Next, write down the possible combinations of alleles that would be in the gametes. • Plant 1: GF, Gf, GF, Gf. Plant 2: Gf, gf, Gf, gf. • Write these combinations along the top and side of a 16 -cell Punnett square and complete it. What four genotypes will you get? • GGFf, GGff, Gg. Ff, Ggff.

Sonnem Farming • What would the genotype of a homozygous, brown-furred long-tailed Sonnem be?

Sonnem Farming • What would the genotype of a homozygous, brown-furred long-tailed Sonnem be? • BBTT

Sonnem Farming • What would the genotype of a homozygous, brown-furred long-tailed Sonnem be? • BBTT • What about a homozygous, white-furred, short-tailed Sonnem?

Sonnem Farming • What would the genotype of a homozygous, brown-furred long-tailed Sonnem be? • BBTT • What about a homozygous, white-furred, short-tailed Sonnem? • bbtt

Sonnem Farming • What would the genotype of a homozygous, brown-furred long-tailed Sonnem be? • BBTT • What about a homozygous, white-furred, short-tailed Sonnem? • bbtt • Let’s do a Punnett square that shows the possible outcomes for this cross. It will be a multi-trait or dihybrid cross.

Punnett Square- Dihybrid Cross • Make a four by four Punnett square. Across the top, have the following: BT, BT, BT. Across the side, have the following: bt, bt, bt.

Punnett Square- Dihybrid Cross • Make a four by four Punnett square. Across the top, have the following: BT, BT, BT. Across the side, have the following: bt, bt, bt. • What will all the offspring be?

Punnett Square- Dihybrid Cross • Make a four by four Punnett square. Across the top, have the following: BT, BT, BT. Across the side, have the following: bt, bt, bt. • What will all the offspring be? • Bb. Tt

Punnett Square- Dihybrid Cross • Make a four by four Punnett square. Across the top, have the following: BT, BT, BT. Across the side, have the following: bt, bt, bt. • What will all the offspring be? • Bb. Tt • If we were to repeat for Straight/Curly ears (SS or ss) and Long/short legs (LL or ll), would we get the same type of results?

Punnett Square- Dihybrid Cross • Make a four by four Punnett square. Across the top, have the following: BT, BT, BT. Across the side, have the following: bt, bt, bt. • What will all the offspring be? • Bb. Tt • If we were to repeat for Straight/Curly ears (SS or ss) and Long/short legs (LL or ll), would we get the same type of results? • Yes, they would all be Ss. Ll.

Interpreting Pedigree Charts Quick Lab • Let’s do one last quick lab that shows us how to use pedigrees to predict patterns of inheritance of a recessive trait.

Introduction • Welcome to the lesson, "Punnett Squares and Pedigrees. " In this lesson, you will learn how patterns of heredity can be predicted by Punnett squares and pedigrees. • EQ: How are patterns of inheritance studied? • The vocabulary words in this lesson are Punnett square, ratio, probability, and pedigree.

Vocabulary • Punnett square: A graphic used to predict the results of a genetic cross • Ratio: A comparison of two numbers using division • Probability: The likelihood that a possible future event will occur in any given instance of the event • Pedigree: A diagram that shows the occurrence of a genetic trait in several generations of a family

Punnett Squares • Look at the Punnett square on page 340 showing the pea flowers. How is the symbol for each allele the same?

Punnett Squares • Look at the Punnett square on page 340 showing the pea flowers. How is the symbol for each allele the same? • Each allele is symbolized by the same letter, F.

Punnett Squares • Look at the Punnett square on page 340 showing the pea flowers. How is the symbol for each allele the same? • Each allele is symbolized by the same letter, F. • How can you tell which allele is dominant and which allele is recessive?

Punnett Squares • Look at the Punnett square on page 340 showing the pea flowers. How is the symbol for each allele the same? • Each allele is symbolized by the same letter, F. • How can you tell which allele is dominant and which allele is recessive? • A capital F is used for the dominant allele, and a lowercase f is used for the recessive allele.

Punnett Squares • Look at the Punnett square on page 340 showing the pea flowers. How is the symbol for each allele the same? • Each allele is symbolized by the same letter, F. • How can you tell which allele is dominant and which allele is recessive? • A capital F is used for the dominant allele, and a lowercase f is used for the recessive allele. • In this Punnett square, which trait is dominant?

Punnett Squares • Look at the Punnett square on page 340 showing the pea flowers. How is the symbol for each allele the same? • Each allele is symbolized by the same letter, F. • How can you tell which allele is dominant and which allele is recessive? • A capital F is used for the dominant allele, and a lowercase f is used for the recessive allele. • In this Punnett square, which trait is dominant? • Purple flowers, F

Punnett Squares • Look at the Punnett square on page 340 showing the pea flowers. How is the symbol for each allele the same? • Each allele is symbolized by the same letter, F. • How can you tell which allele is dominant and which allele is recessive? • A capital F is used for the dominant allele, and a lowercase f is used for the recessive allele. • In this Punnett square, which trait is dominant? • Purple flowers, F. White flowers, f, is recessive. • What does each box show?

Punnett Squares • How can you tell which allele is dominant and which allele is recessive? • A capital F is used for the dominant allele, and a lowercase f is used for the recessive allele. • In this Punnett square, which trait is dominant? • Purple flowers, F. White flowers, f, is recessive. • What does each box show? • The alleles of one possible cross

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have?

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have? • Both parents have one dominant and one recessive allele.

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have? • Both parents have one dominant and one recessive allele.

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have? • Both parents have one dominant and one recessive allele. • What does the dominant allele produce?

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have? • Both parents have one dominant and one recessive allele. • What does the dominant allele produce? • Round peas

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have? • Both parents have one dominant and one recessive allele. • What does the dominant allele produce? • Round peas • What does the recessive allele produce?

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have? • Both parents have one dominant and one recessive allele. • What does the dominant allele produce? • Round peas • What does the recessive allele produce? • Wrinkled peas

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have? • Both parents have one dominant and one recessive allele. • What does the dominant allele produce? • Round peas • What does the recessive allele produce? • Wrinkled peas • What two genotypes (pairs of alleles) will produce a phenotype (physical appearance) of a round pea?

Punnett Squares • Look at page 341. This Punnett square is showing round and wrinkled peas. What kinds of alleles do both parents have? • Both parents have one dominant and one recessive allele. • What does the dominant allele produce? • Round peas • What does the recessive allele produce? • Wrinkled peas • What two genotypes (pairs of alleles) will produce a phenotype (physical appearance) of a round pea? • RR and Rr

Punnett Squares • What does the dominant allele produce? • Round peas • What does the recessive allele produce? • Wrinkled peas • What two genotypes (pairs of alleles) will produce a phenotype (physical appearance) of a round pea? • RR and Rr • What genotype will produce a phenotype of a wrinkled pea?

Punnett Squares • What does the dominant allele produce? • Round peas • What does the recessive allele produce? • Wrinkled peas • What two genotypes (pairs of alleles) will produce a phenotype (physical appearance) of a round pea? • RR and Rr • What genotype will produce a phenotype of a wrinkled pea? • rr

Ratios and Percentages • Ratios and percentages can show the same information but in different ways. For example, if you toss a coin in the air, and there is a 50% chance that the coin will land heads-up, this means that out of 100 times the coin is tossed, it landed heads-up 50 of those times. A ratio expresses this idea too, but it is not necessarily based on 100. A 50% chance that a coin tossed will land heads-up can be expressed as a ratio of 1: 2. The ratio indicates that, on average, the coin will land heads-up one of every two times it is tossed.

Ratios and Percentages • Ratios and percentages can show the same information but in different ways. For example, if you toss a coin in the air, and there is a 50% chance that the coin will land heads-up, this means that out of 100 times the coin is tossed, it landed heads-up 50 of those times. A ratio expresses this idea too, but it is not necessarily based on 100. A 50% chance that a coin tossed will land heads-up can be expressed as a ratio of 1: 2. The ratio indicates that, on average, the coin will land heads-up one of every two times it is tossed. • If there is a 50% chance of having a boy baby, what is the ratio?

Ratios and Percentages • Ratios and percentages can show the same information but in different ways. For example, if you toss a coin in the air, and there is a 50% chance that the coin will land heads-up, this means that out of 100 times the coin is tossed, it landed heads-up 50 of those times. A ratio expresses this idea too, but it is not necessarily based on 100. A 50% chance that a coin tossed will land heads-up can be expressed as a ratio of 1: 2. The ratio indicates that, on average, the coin will land heads-up one of every two times it is tossed. • If there is a 50% chance of having a boy baby, what is the ratio? • 1: 2

Ratios and Percentages • If there is a 50% chance of having a boy baby, what is the ratio? • 1: 2 • If the first child is a girl, what is the probability of the next child being a boy?

Ratios and Percentages • If there is a 50% chance of having a boy baby, what is the ratio? • 1: 2 • If the first child is a girl, what is the probability of the next child being a boy? • 50%

Pedigrees • Look at the pedigree chart on page 344. What do the man and woman have in common in the first generation?

Pedigrees • Look at the pedigree chart on page 344. What do the man and woman have in common in the first generation? • The are both carriers of a trait.

Pedigrees • Look at the pedigree chart on page 344. What do the man and woman have in common in the first generation? • The are both carriers of a trait. • How do you know?

Pedigrees • Look at the pedigree chart on page 344. What do the man and woman have in common in the first generation? • The are both carriers of a trait. • How do you know? • Both are shown as half-shaded, which means they carry the trait.

Pedigrees • Look at the pedigree chart on page 344. What do the man and woman have in common in the first generation? • The are both carriers of a trait. • How do you know? • Both are shown as half-shaded, which means they carry the trait. • In the second generation, who expresses the trait and who carries the trait?

Pedigrees • Look at the pedigree chart on page 344. What do the man and woman have in common in the first generation? • The are both carriers of a trait. • How do you know? • Both are shown as half-shaded, which means they carry the trait. • In the second generation, who expresses the trait and who carries the trait? • The daughter, 4, expresses (has) the trait. Two sons, 2 and 5, carry the trait.

Pedigrees • Look at the pedigree chart on page 344. What do the man and woman have in common in the first generation? • The are both carriers of a trait. • How do you know? • Both are shown as half-shaded, which means they carry the trait. • In the second generation, who expresses the trait and who carries the trait? • The daughter, 4, expresses (has) the trait. Two sons, 2 and 5, carry the trait. • What happens to the trait in the third generation?

Pedigrees • How do you know? • Both are shown as half-shaded, which means they carry the trait. • In the second generation, who expresses the trait and who carries the trait? • The daughter, 4, expresses (has) the trait. Two sons, 2 and 5, carry the trait. • What happens to the trait in the third generation? • One daughter, 3, carries the trait. The other daughter and son are not carriers. No one in this generation has the trait.

Pedigrees • How do you know? • Both are shown as half-shaded, which means they carry the trait. • In the second generation, who expresses the trait and who carries the trait? • The daughter, 4, expresses (has) the trait. Two sons, 2 and 5, carry the trait. • What happens to the trait in the third generation? • One daughter, 3, carries the trait. The other daughter and son are not carriers. No one in this generation has the trait. • What happens to the trait in the fourth generation?

Pedigrees • In the second generation, who expresses the trait and who carries the trait? • The daughter, 4, expresses (has) the trait. Two sons, 2 and 5, carry the trait. • What happens to the trait in the third generation? • One daughter, 3, carries the trait. The other daughter and son are not carriers. No one in this generation has the trait. • What happens to the trait in the fourth generation? • One daughter, 3, is a carrier and one daughter and a son, 1 and 2, have the trait.

Summary • A Punnett square is a diagram that can be used to predict how a trait will pass from two parents to their offspring. • A pedigree is a diagram that shows how a trait is passed down through generations in a family. • Sex chromosomes, and X chromosomes in particular, carry alleles that determine other traits. • Sometimes these traits are associated with disorders.

Description Wheel • For homework tonight, make a description wheel about Punnett Squares and a description wheel about pedigrees. In each, clarify the functions of the Punnett square and pedigree.