Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter 5 Lesson 1 Mendel and His Peas. Gregor Mendel Young priest that worked in the garden at a monastery in Vienna. Considered the “Father of Genetics”

Similar presentations


Presentation on theme: "Chapter 5 Lesson 1 Mendel and His Peas. Gregor Mendel Young priest that worked in the garden at a monastery in Vienna. Considered the “Father of Genetics”"— Presentation transcript:

1 Chapter 5 Lesson 1 Mendel and His Peas

2 Gregor Mendel Young priest that worked in the garden at a monastery in Vienna. Considered the “Father of Genetics” Observed traits in hundreds of pea plants.

3 Mendel’s Work - Vocabulary Traits Physical characteristics of organisims Heredity Passing of traits from parent to offspring Genetics Scientific study of heredity

4 Mendel’s Peas Why was Gregor Mendel lucky he chose peas to study? Many traits exist only in two forms Peas produce many offspring in one generation.

5 How did Mendel make his crosses? White PlantPurple Plant

6 Mendel’s Experiments True Breeding (Purebred) Plant One that always produces offspring with the same form of a trait as the parent i.e. purebred short plants will only produce short offspring.

7 Purebred purple plants will only produce purple plants X

8 White flower would mean the parents are not purebred X

9 Mendel’s Experiments Mendel crossed plants with opposite forms of a trait i.e. purple flowers crossed with white flowers Look at Figure 3 on page 152 Explain why all offspring are purple in the first generation (F 1 ) What happens in the second generation (F 2 )

10 Mendel’s Experiments Mendel studied flower color followed by six other “opposite” traits. Look at table 1 on page 154. What do you notice about the ratio of traits in the second generation (F 2 )

11 Let’s Look at another example

12 Genes and Alleles Genes Factors that control traits Alleles Different forms of a gene One allele is inherited from each parent. Alleles can be dominant or recessive

13 Dominant and Recessive Alleles Dominant allele Always seen if present Indicated by a capitol letter (T) Recessive allele Masked or hidden if dominant allele is present Indicated by a lower case letter (t)

14 Hybrid vs Purebred Hybrid Hybrid Organism has two different alleles for the trait – one dominant and one recessive. Organism has two different alleles for the trait – one dominant and one recessive. Purebred Purebred Organism has two identical alleles for a trait – two recessive OR two dominant. Organism has two identical alleles for a trait – two recessive OR two dominant.

15 Alleles are represented with capitol and lower case letters. T = Tall allele (dominant) T = Tall allele (dominant) t = Short allele (recessive) t = Short allele (recessive) Purebreds Purebreds TT – two dominant alleles – plants will be tall TT – two dominant alleles – plants will be tall tt – two recessive alleles – plants will be short tt – two recessive alleles – plants will be short Hybrid Hybrid Tt – one dominat allele and one recessive allele – plants will be tall. Tt – one dominat allele and one recessive allele – plants will be tall.

16 Phenotypes and Genotypes Phenotype Phenotype Physical appearance or visible trait Physical appearance or visible trait Example is flower color, stem height etc. Example is flower color, stem height etc. Genotype Genotype The genetic makeup or allele combination The genetic makeup or allele combination Examples are TT or Tt Examples are TT or Tt Genotypes determine phenotypes Genotypes determine phenotypes

17 Homozygous and Heterozygous Homozygous Homozygous An organism that has two identical alleles for a trait An organism that has two identical alleles for a trait TT – homozygous dominant TT – homozygous dominant tt – homozygous recessive tt – homozygous recessive Heterozygous Heterozygous An organism that has two different alleles for a trait An organism that has two different alleles for a trait Tt – heterozygous – will show the dominant trait Tt – heterozygous – will show the dominant trait

18 Probability Probability Probability The likelihood that a particular event will occur The likelihood that a particular event will occur Example: coin toss Example: coin toss

19 Punnett Squares Punnett Squares Punnett Squares chart that shows all possible combinations of alleles that can result from a genetic cross. Used to determine the probability of a particular outcome. chart that shows all possible combinations of alleles that can result from a genetic cross. Used to determine the probability of a particular outcome.

20 Using a punnett square Tt T t T t TT Tt tt (Tall) Tall Short

21 Codominance Codominance – alleles are neither dominant or recessive therefore both alleles are expressed in the offspring Codominance – alleles are neither dominant or recessive therefore both alleles are expressed in the offspring

22 Codominance The heterozygous offspring will express (show) both phenotypes

23 What is the rabbit’s phenotype for fur color? _________ What is the rabbit’s phenotype for fur color? _________ What is the rabbit’s genotype for fur color? __________ What is the rabbit’s genotype for fur color? __________ Is the rabbit heterozygous or homozygous for the fur color trait? _______________ Is the rabbit heterozygous or homozygous for the fur color trait? _______________ If black is dominant over white, what genotype would produce a white rabbit? _______ If black is dominant over white, what genotype would produce a white rabbit? _______ If fur color in rabbits was a codominant trait instead of dominant/recessive trait, what color fur would the (Bb) rabbit have? ________________ If fur color in rabbits was a codominant trait instead of dominant/recessive trait, what color fur would the (Bb) rabbit have? ________________ Consider a rabbit with black fur and the allele combination (Bb). Black (Bb) heterozygous (bb) White and black


Download ppt "Chapter 5 Lesson 1 Mendel and His Peas. Gregor Mendel Young priest that worked in the garden at a monastery in Vienna. Considered the “Father of Genetics”"

Similar presentations


Ads by Google