Prentice Hall - Science Explorer - Cells and Heredity
Chapter 3- The Science of Heredity
Section 2- Probability and Heredity
Questions - Comments - Key Words - Connections
Probability Connection: Mathematics Probability unit!! Two Up game. |
Main Ideas; Visuals + Predictions
Principles of Probability
Probability: A number that describes how likely it is that an event will occur. Mathematics of probability Ex: a coin has a probability of 1 in 2, 1/2, or 50%, because it has only two side either heads or tales. Independence of Events Ex: if you toss a coin more than once the toss doesn't effect the next outcome of the toss. So, if you tossed the coin 5 times and got all heads the next toss would not be heads because it has a 50% chance so, it has and equal chance of it being tales or heads. Probability and Genetics Punnett Square: A chart that shows all the possible combinations of alleles that can result from a genetic cross. |
Connection: In my old school we learnt about genetics/ cells in Biology and i learnt how to use a punnett square, heterozygous, homozygous, phenotype and genotype too.
Phenotype Homozygous Heterozygous Codominance Question: The chicken punnett square shows as if there is a mixture of black and white feathers but then that goes against the fact of Mendel's heredity influence, because it said he changed scientist views of heredity because they thought the traits of individual organisms were simply a blend of their parents' characteristics. But actually Mendel's experiments demonstrated that the parents’ traits do not simply blend in the offspring. * So, according to the idea, does the chicken punnett square show codominance?? * so do the parents' traits blend or do not blend in the offspring?? |
Using a Punnett Square * In a genetic cross, the allele that each parent will pass on to its offspring is based on probability.
* In the Punnett Square figure above, the probability that an offspring will be rr is 1 in 4, or 25%. Then, the probability that an offspring will be Rr is 2 in 4, or 50% and the probability of an offspring to be RR is 1 in 4, 25%. * This image shows a punnett square of a cross between a white and black Guinea pig. All of them are black so, there is 0 in 4, 0% white guinea pigs. However, the white allele may appear in later offsprings.
Phenotypes and Genotypes Phenotype: An organism’s physical appearance, or visible traits. Genotype: An organism’s genetic makeup, or allele combinations. Homozygous: Having two identical alleles for a trait.
Ex: TT or tt Heterozygous: Having two different alleles for a trait. Ex: Tt Codominance Codominance: A condition in which neither of two alleles of a gene is dominant or recessive. |