: Genetics – From Genes to Proteins, Mutations

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.

Assignment details for part one:

Transcribe and translate EACH of the three following DNA gene sequences. Turn these in using the graphic organizer. The letters represent the DNA N-base sequences of the genes.

The first is the original gene. The next two are mutations of the original. Note that the changes (mutations) are shown in red.

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’

Also, answer the following questions:

• What is the significance of the first and last codons of an mRNA transcript?
• What meaning do these mRNA codons have for protein synthesis?
• Did the mutations result in a change in the final proteins? If so, describe the change.
• In general, why might a change in amino acid sequence affect protein function?

Part II: 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.

Assignment details: 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 graphic organizer.

Also answer the following questions:

Based on the Punnett square, calculate chances (percentages) for the following:

• for having a healthy child (not a carrier)
• a child that is a carrier for the cystic fibrosis trait
• a child with cystic fibrosis

Be sure to submit these percentages as part of your assignment in the Graphic Organizer.

Part III: 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.

Assignment Essay 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.

You will submit your Graphic Organizer with all answers in your Submit Assignment area.

Provide references in APA format. This includes a reference list and in-text citations for references used throughout the assignment. Note that there is a Reference page for listing sources included on the Graphic Organizer.

You will submit your Graphic Organizer with all answers.

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