Graded notes

Review Meiosis 2 mitosises, chromosomes replicated in interphase 1, homologous pairs, crossing over, 4 haploid daughter cells

Review Meiosis Pair of homologous chromosomes vs. homologous chromosomes….s phase…..

Gregor Mendel: Austrian Monk who studied pea plants

Pea plants (1 st Mendel did this: ) True-breeding: if self-pollinate, produce offspring identical to themselves Cross pollinate: male sex cells in pollen from one plant fertilize egg cells of flower in another plant (Then he tested flowers together w/2 different characteristics; purple/white) Traits: specific characteristics (seed color, height, texture)

Monohybrid Cross Mono = one trait (flower color) Hybrid = Offspring of two different breeding varieties Mendel reasoned that F1 plants carried two factors for the flower color trait (Purple and White). “Factors” called genes

Mendel’s crosses: P: Parental generation F1: Offspring or 1st generation Hybrids: Offspring of crosses between parents with different traits Testing of other traits…one trait disappears in F1, Reappears in F2

Conclusions of Mendel’s crosses: Genes: Chemical factors that determine traits passes on from one generation to another Alleles: Different forms of genes for trait Ex. Plant height has two forms  produces tall plants & short ones

Alleles on Homologous chromosomes

Principle of Dominance: states that some alleles are dominant and other are recessive Dominant: Trait will always show up; Shown with capital letters Recessive: Trait does not show up; Shown with lower case letters

Homozygous: (TT) organism has 2 identical alleles for particular trait Heterozygous: (Tt) organism has 2 different alleles for particular trait Phenotype: physical characteristics you see (yellow, round) Genotype: genetic makeup (Tt); what we write

What are alleles? Since one allele is inherited from each parent, two letters are needed to represent the alleles of a gene Different forms of gene Where do alleles come from? One from each parent GENOTYPE? Don’t Copy -two letters that represent the alleles of a gene EX. RR, Rr, rr

Phenotype? the outward appearance of an organism (what it looks like) If a farmer has a red flower (RR) give genotype and phenotype - the genotype is RR - the phenotype is red Don’t copy

1. A brown dog (bb) the genotype ________ the phenotype _______ 2. A long haired cat (Hh) the genotype _______ the phenotype _______

(Review) Mendel learned that the alleles of each individual separate and end up in gametes because of MEIOSIS!! MEIOSIS!! Replication of chromosomes

Ex. A female pure brown dog (bb) b b bb Dominant or Recessive?

PRACTICE on paper A hybrid male yellow canary (Yy) Y y Y y Dominant?

A pure female white flower (rr) r r Practice! rr Dominant? Recessive?

If a male red flower (Rr) and a female pure white (rr) flower from above got their gametes together (fertilization) What kind of combinations could be formed? X Practice on own paper before showing next slide! Write out male=Rr, female=rr. Which is dominant, recessive? What are we crossing? (Write Genotypes)

Male red flower (Rr)Female white flower (rr) Rr Sperm 1 Sperm 2 rr Egg 1Egg 2 Answers? Write out alleles for each gamete of cross. R r r r

= = = = GenotypePhenotype Show possible offspring of crossing different alleles. R r r R r r r r

A punnet square is a chart that helps us predict the probability that an offspring with a particular genotype and phenotype will be produced Punnett Squares show the chances that one male’s sperm & one female’s eggs can make certain offspring

Create a punnett square using male red (Rr) and female white (rr) flowers. To Make a punnet square there are a few simple steps to follow: 1) Draw a box and divide it into four parts

2) Label the left hand side of the box with the genotype of male parent (R=Red, r=White) R r

3) Label the top of the box with the genotype of the female parent R r rr

4) In the middle boxes place 2 alleles. One letter comes from the left side and one from the top R r rr Rr r Rr r You have predicted what kind of offspring these 2 parents could have!!! R= Red r= White Red______% White______%

You now know the possible genotypes for the offspring of these two parents. The genotypes of the offspring are: R r rr Rr r 2: Rr, 2: rr Red=50% White=50% 2: Red, 2: White The phenotypes of the offspring are:

1. A cross between a female with straight hair (SS) and a male with curly hair (ss). Draw out punnett square: genotypes_____________ phenotypes______________ Straight______% Curly_______%

2. A cross between a black dog (Bb) and a brown dog (bb). Draw out Punnett Square. genotypes_____________ phenotypes_______________ Black_______% Brown________% Ratio_____:______

3. A cross between a yellow corn (Yy) and another yellow corn (Yy) (y = white corn). Draw out Punnett Square. genotypes_________________ phenotypes_________________ Yellow corn_______% White corn________% Ratio_____:______