Pedigrees are one of the more challenging concepts to wrap your head around in genetics. The basics of pedigrees, what the symbols and charts represent are easy, however interpreting and creating the pedigrees from a description can be quite the task. Today in class students tried their hand at pedigrees not just with pen and paper but with Swedish fish and gummi bears. The fish were "female" and the bears were "boys" and by reading about the family history, students were able to assemble pedigrees using their candy to represent the family members, with their color(s) representing their genotype.
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Today continued our exploration of pedigree charts. Depending on the type of trait, either Autosomal recessive or Autosomal Dominant, the Heterozygous individuals may be completely shaded in or only half shaded in. If the heterozygotes are completely shaded in, we can infer that the trait being traced in Autosomal Dominant, because the presence of a single dominant allele causes the trait to be expressed. However for Autosomal recessive disorders, the Heterozygotes are carriers of the recessive allele although they do not express the trait. We use half shaded symbols to show that the individual carries the affected allele despite not expressing the trait themselves.
Students had the opportunity to finish their fruit fly digital lab in class today. Early finishers began working through an online Bacterial DNA identification lab in which they got to simulate lab techniques used in modern scientific investigations. Click the image to the left to go to the lab and use the file below to guide your investigation of DNA using simulated techniques like bacteria isolation, PCR, and DNA sequencing.
Fruit flies are a classic model organism for studying genetics. Fruit flies. Drosophila melanogaster share up to 60% of their DNA with humans which means by studying fruit flies we can also study a lot about human genetics. In class students completed a fruit fly digital lab in which they cross-bred flies and looked at the resulting genotypes and phenotypes of the offspring. The trait we focused on was wing shape. Normal wings are straight but a mutant wing shape of "curly" is possible when a single dominant allele for curly shape is present. Students also spent time researching the importance of fruit flies in the study of human diseases as well as why they are such a great model organism. You can download the worksheet for this lab below.
Students reviewed their quiz results today and we also addressed some misconceptions that kept popping up on many of our quizzes. The biggest misconception was about the relationship between DNA, Genes, and Alleles. Click on the picture of DNA to the left to learn more about how all three of these things are related. Also, we watched the CrashCourse Biology video on Heredity to try and tie together everything we've been learning the last few weeks. You can check out that video below to learn more about heredity as well as the genetics of earwax! In class we took our first summative assessment for the year. Genetics Quiz 1 covered the structure and function of DNA, genes, and alleles, as well as Punnet Squares and Non-Mendelian genetics. Tomorrow we will finally fold our origami genes and assemble a DNA chain across our ceiling.
DOUBLE BONUS GOLD TAPE QUESTION!! Everyone who completes this gold tape task and turns in their work to Mr. Powell by the end of school Friday September 15 will get two pieces of gold tape. The Denver Broncos are not only a football team, but also a rare breed of horse. They exhibit Mendelian inheritance for many of their traits including coat color, height, and ear size. In Denver Broncos, Blue coat (B) is dominant to orange coat, Tall height (T) is dominant to short height, and Big ears (E) are dominant to small ears. Complete a TRIHYBRID cross for the two parent horses: BbTtEe x BbTtee 1) What are the percent chances (or ratios) for each phenotype and genotype in the offspring? 2) Draw a picture (with color) of the least common bronco possible from this cross.
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AuthorMr. Powell is a High School Science Teacher in Western Colorado. Archives
May 2024
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