Mendel’s Results and Conclusions DOMINANT means a trait that covers up or dominates another trait RECESSIVE means a trait that does not appear but his hidden by the dominant trait LAW OF SEGREGATION states that a pairs of traits is segregated (separated) during the formation of gametes LAW OF INDEPENDENT ASSORTMENT states that factors separate independently of one another during gamete formation (ie the flower color and seed color are completely separate…one may be dominant and the other recessive)
Mendel to Molecular Genetics Mendel’s findings led to modern day MOLECULAR GENETICS On a chromosome there are GENES which occur in pairs. Mendel’s factors are now called ALLELES, which are each of the genes in a pair. Letters represent alleles, capitalized for dominant traits, lowercase for recessive traits.
Genotype An organism’s genetic makeup is its GENOTYPE. GENOTYPE = 2 alleles that are inherited from the parents White-Flowering Pea Plant’s genotype is pp Purple-Flowering Pea Plant’s genotype is PP or Pp
Phenotype An organism’s appearance is its PHENOTYPE The phenotype for a PP or Pp plant is PURPLE FLOWERS. The phenotype for a pp plant is WHITE FLOWERS
Alleles HOMOZYGOUS happens when both alleles of a pair are alike, pp or PP HETEROZYGOUS happens when the alleles of a pair are different, Pp. PROBABILITY is the likelihood that a specific event will occur. Probability- Number of times of an event is expected to happen/ Number of times an event could happen Mendel’s yellow seed color appeared 6022 times, the recessive green appeared 2001 times. Probability of the dominant trait– 6022/8023=.75 or 75%
Probability What is the probability of drawing an Ace?? Calculating Probability Quick Lab
Monohybrid Crosses A cross in which only one characteristic is tracked is called a MONOHYBRID CROSS Biologists use a PUNNETT SQUARE to predict the traits of the offspring.
Incomplete Dominance Sometimes an organism will have a phenotype in between that of the parents, this is called INCOMPLETE DOMINANCE.
Are you a Tongue Roller? Scenario: Both Parents are tongue rollers, 3 kids are tongue rollers, 1 kid is not. What are the genotypes of the parents? Of the kids?
Dihybrid Crosses A DIHYBRID CROSS is a cross in which 2 characteristics are tracked. For example to track and predict the traits of both seed texture and seed color.
Dihybrid Cross Scenario: A female Labrador retriever has a litter of puppies. 9 are black with black noses. 3 are black with pink noses, 3 are white with black noses, and one is white with a pink nose. Write down the genotype for each puppy! What might the genotypes for the mom and dad be??