Early Beliefs & Mendel

Transcription

1 Early Beliefs & Mendel

2 reor Mendel n Austrian Monk from mid 19th century n Considered to be the Father of enetics n Did experiments with arden peas to explain the mechanism of heredity and inheritance in plants. n He studied 7 characteristics: seed colour, seed shape, pod shape, pod colour, flower colour, flower position, & stem lenth.

3 Mendel s Experiments n The breedin of two oranisms with different traits is called a n Mendel would cross two parent plants ( eneration) eneration). n If two plants from the F1 eneration are to cross they would produce plants.

4 n Each ene has a locus on a chromosome. Most enes will exist in two forms (dominant and recessive) each called an n If the two alleles on a ene are the same the individual is n If the two alleles on the ene are different the individual is n The set of alleles than individual has is a enotype n but the outward appearance on an individual will be its

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6 n dominant ~ expression of the enetic trait in offsprin. n upper case letters used to stand for trait n recessive ~ dominant alleles, which determine the enetic trait. n lower case letter used to stand for trait n Mendel found that 75% of offsprin expressed the dominant trait, while 25% expressed the recessive trait.

7 characteristics dominant recessive dominant recessive trait trait trait trait seed shape round wrinkled flower position seed colour yellow reen pod shape inflated constricted side of stem end of stem pod colour reen yellow stem lenth flower colour purple white tall short

8 Mendel s Conclusions n Law of Sereation~ n 1. Oranisms inherit two copies of enes, one from each parent. n 2. Oranisms donate only one copy of each ene to their ametes because enes separate durin amete formation.

9 Punnet Squares n Proper Format for a Punnet Square: (4I marks) n 1. Let Statement ~ i.e. let T be dominant trait for & t be recessive trait for n 2. State the type of cross: between TT x tt P1 Cross n 3. Complete Punnet Square

10 Keep an Eye on it! n 1. enotype vs. Phenotypes: n what the offsprin will have in their alleles vs. what they will look like. n 2. Probability vs. Ratios: n What the offsprin percentaes would be (%) vs. the total ratio (1:2:1)

11 Side Note Look at what the question is askin you A. probability (%) or ratio (_ : _) B. enotype (Bb) or Phenotype (blonde) 2. If the question is not specific with probability or ratio... then you ALWAYS do probability! 3. If the question is not specific with enotype or phenotype... then you ive

12 Lets Practice reen pod colour () is dominant to yellow pod colour () in pea plants. Predict the phenotypes and enotypes of the offsprin produced when a plant homozyous for reen pods is crossed with a plant homozyous for yellow pods.

13 Solution Let be dominant for reen pod colour Let be recessive for yellow pod colour

14 Lets Practice reen pod colour () is dominant to yellow pod colour () in pea plants. Predict the phenotypes and enotypes of the offsprin produced when a plant homozyous for reen pods is crossed with a plant homozyous for yellow pods.

15 Solution Let be dominant for reen pod colour Let be recessive for yellow pod colour P1 Cross x

16 Solution Let be dominant for reen pod colour Let be recessive for yellow pod colour F1 Cross x

17 Solution Let be dominant for reen pod colour Let be recessive for yellow pod colour F1 Cross x

18 Solution Let be dominant for reen pod colour Let be recessive for yellow pod colour F1 Cross x

19 Solution Let be dominant for reen pod colour Let be recessive for yellow pod colour F1 Cross x

20 Lets Practice reen pod colour () is dominant to yellow pod colour () in pea plants. Predict the phenotypes and enotypes of the offsprin produced when a plant homozyous for reen pods is crossed with a plant homozyous for yellow pods. Notice... Question didn t say probability or ratio...so you do probability!

21 Solution Let be dominant for reen pod colour Let be recessive for yellow pod colour P1 Cross x reen Pod reen Pod reen Pod reen Pod Therefore, There is a 100% probability of the enotype and 100% probability for reen pod colour phenotype.