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Genetics and Inheritance of Traits or Genetic Disorders

Part I: Genetics - From Genes to Proteins, Mutations

Background: DNA represents the architectural blueprint for all living systems, encoding specific instructions in the sequence of its four nitrogen-containing base pairs that are necessary for building the organism. During the process of transcription, the information in the DNA codons of a gene is transcribed into RNA.

A change in the DNA sequence, for example as a result of a "mistake" during DNA replication, is defined as a mutation. Mutations may result in a change in the "blueprint," which may then change the resulting protein product.


Transcribe and translate EACH of the three following DNA gene sequences and answer the related questions on the worksheet.

Note: The first is the original gene. The next two are mutations of the original.

Original Gene sequence 3'-T A C C C T T T A G T A G C C A C T-5

Mutated gene sequence 1 3'-T A C G C T T T A G T A G C C A T T-5'

Mutated gene sequence 2 3'-T A A C C T T T A C T A G G C A C T-5'

Part 2:
Inheritance of Traits or Genetic Disorders

Background: Cystic fibrosis is an inherited disease that affects the respiratory, digestive, or reproductive systems of the body, with symptoms ranging from mild to severe. Bob and Sally are recently married. Upon deciding to plan a family, both Sally and Bob find out that they are both heterozygous for cystic fibrosis, but neither of them has symptoms of the disorder.

Complete a Punnett Square for cystic fibrosis for this couple using the following alleles: C = normal allele; and c = allele for cystic fibrosis.

Complete the Punnett Square in the ATTACHED WORKSHEET.

Part 3: Cell division, sexual reproduction and genetic variability

Background: Eukaryotic cells can divide by mitosis or meiosis. In humans, mitosis produces new cells for growth and repair; meiosis produces sex cells (gametes) called sperm and eggs. Although mutations are the ultimate source of genetic variability, both meiosis and sexual reproduction also can contribute to new genetic combinations in offspring.

Question: How do both meiosis and sexual reproduction (fertilization) produce offspring that differ genetically from the parents? Be sure to talk about the two specific steps in meiosis that increase variability as well as the process of fertilization.

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Solution Summary

Genetics and inheritance of traits or genetic disorders are examined.