GREGOR MENDEL 1822-1884 The monk who worked with?

MENDEL’S GOAL EXPLAIN the PATTERN of HEREDITY from PARENT to OFFSPRING

WHY PEA PLANTS? EASY to GROW REPRODUCE offspring in a SHORT TIME Get offspring results quickly Only 7 traits (genes) Each TRAIT HAS 2 FORMS (physical) Avoid any confusion in results MALE & FEMALE parts on flowers allow for SELF-FERTILIZATION OR MENDEL could control breeding with CROSS FERTILIZING

HOW MENDEL CROSS FERTILIZED

FLOWERS & THEIR PARTS Female flower parts Male flower parts

MENDEL’S FIRST TRAIT EXPERIMENT- Flower Color Two purebred parents are crossed One parent has PP it has purple flowers The other has pp white flowers The offspring are all purple. Because they have one dominant gene P. White recessive offspring Purple Dominant

Mendel’s Discovery HW assignment Breeding Pea Color http://nj.pbslearningmedia.org/asset/hew06_int_dominantgene/

MENDEL’S OBSERVATIONS OF OF 1ST PURE-BRED CROSS The PARENT’s generation uses the code P. They are PUREBRED plants. They had 2 genes that were both represented by the same letters, either PP for purple flowers or pp for white flower color. The OFFSPRING generation uses the code F-1 offspring are Heterozygous, Pp. They have 2 genes, one dominant and one recessive.

MENDEL’S OBSERVATIONS OF 1ST PURE-BRED CROSS ALL OFFSPRING had DOMINANT, purple flowers None had the white flowers, or Recessive trait.

MENDEL’S 2ND EXPERIMENT SELF-FERTILIZATION CROSS He bred the F-1GENERATION Remember the F-1 were HYBRIDS, Pp They had two genes, one dominant and one recessive. Mendel did not realize this. He saw purple flowers. So he expected to see? All purple offspring

F-2 RESULTS Some PURPLE & also some White flowered plants appear HOW WAS THIS POSSIBLE?! THE RECESSIVE TRAIT was always there in the genes of the flowers. To get a white flower two recessive genes had to come together in an offspring to show up. pp The phenotype ratio of offspring he had by flower color was 3:1 Three purple to one white. The genotype ratio he got was 1 PP, 2Pp, 1 pp it is written at 1:2:1

Mendel’s 2nd experiment Crosses purebreds Mendel’s 1st exp. Mendel’s 2nd experiment Crosses hybrids

Law of Dominance & Recessive Traits Some traits are dominant over others Some traits may not be expressed unless inherited on both genes

Principle of Segregation For any trait, the pair of alleles from each parent separate and only one allele passes from each parent on to an offspring. Which allele is inherited is a due to chance.

PRINCIPLE OF INDEPENDENT ASSORTMENT different pairs of alleles are passed to offspring independently of each other (during meiosis and fertilization) Some offspring may not resemble their parents.

ABILITY TO PREDICT FUTURE EVENT PROBABILITY http://nortonbooks.com/college/biology/animations/ch10a05.htm ABILITY TO PREDICT FUTURE EVENT PREDICT THE FREQUENCY OF OFFSPRING TRAITS EXAMPLE A COIN TOSS WHAT are the CHANCES of GETTING HEADS with 1 COIN? ½, one side is heads, the other is tails WHAT are the CHANCES of getting HEADS with 2 COINS? ½ x ½ =? ¼!

2 trait cross-dihybrid Cross a homozygous X recessive Gamete combos from each parent are only RY or ry F-1 generation All are heterozygous genotypes

Cross of the F-1 offspring hybrids

DI-HYBRID CROSSES Use your Worksheet Di-hybrid Crosses If you need help, go to this tutorial