Biology
Performance Task #3
Directions to the Student:
You are a physician in the year 2020. A couple expecting a child comes into your office in order to
undergo routine prenatal testing which include genetic tests. After conducting preliminary tests, there
appears to be genetic information that concerns the future health of the fetus. One area of concern
was
the fourth chromosome. Below are essential segments of three different genes on chromosome #4
(the
spaces represent sections of the chromosome that do not affect these particular traits).
Fetal chromosome #4:
...ACCGGCAACGTT.... CCTGAGGATTCA...TCTAGGGAGACC...
(site 1) (site 2) (site 3)
Site 1 is the portion of a gene which has the potential to cause Huntington's disease. Likewise, site 2
is a
portion of the gene which has the potential to cause Marfan’s Syndrome. Site 3 is the portion a gene
which has the potential to cause sickle-cell anemia. The hospital lab is out of service, so you will
need to
analyze the data yourself.
To aid you in this process we have included an amino acid dictionary. Be sure to show all of your
work
so you can reference it when explaining the issues to the parents. Below are the amino acid
sequences
that correlate to Huntington's, Marfan’s Syndrome, and sickle-cell anemia.
A. Huntington's: tryptophan, proline, alanine, serine.
B. Marfan Syndrome: glycine, leucine, leucine, serine.
C. Sickle-cell anemia: arginine, serine, leucine, tryptophan
You search through the hospital's electronic library and find the following descriptions:
A. Huntington's Disease -- The incorrect form of a protein which alters normal brain cell activity;
adults lose balance and coordination. The quality of life decreases with age. The onset does not
usually occur until after age 30, however this disease is fatal.
B. Marfan Syndrome – The elastic tissues in one’s body-- including skin, lungs, and blood vessels-are supposed and nourished by a strong resilient framework of connective tissue. Marfan
syndrome is caused by a defect in the gene that enables the body to produce fibrillin, a protein
that helps give connective tissue its electivity and strength.
C. Sickle-cell anemia-- Mutations in the beta-globin gene cause blood cells to become distorted and
take on a sickle shape (A normal blood cell is round, kind of shaped like a donut without the
hole cut completely through). When the cells have this distorted shape, they can't travel through
the blood vessels easily and get clogged in the narrow passages.
Task One:
Determining Possible Genetic Diseases
Step 1: Figure out the amino acid sequence for each DNA site.
Rewrite the sections of DNA in the space provided:
________________________________________________________________________
Transcribe the section of DNA into mRNA in the space provided:
________________________________________________________________________
Translate the mRNA into an amino acid sequence in the space provided:
________________________________________________________________________
Step 2: Circle either have or not have for each genetic disorder.
Based on the DNA from site #1, the child will have / not have Huntington’s Disease.
Based on the DNA from site #2, the child will have / not have Marfan’s Syndrome.
Based on the DNA from site #3, the child will have / not have Sickle-Cell Anemia.
Step 3: Writing a paragraph (at least 5 sentences).
Based on what you have written for Step 2, write a paragraph that explains what genetic disease(s)
are
coded for in the child’s DNA. Write paragraph in the space provided.
Genetic Diseases Occur In This Family?
TASK 2
Step 1: Understanding Meiosis
1. Define Inheritance (IN YOUR OWN WORDS):_____________________________________
_________________________________________________________________________________
_________________________________________________________________________________
2. Define Meiosis (IN YOUR OWN WORDS):________________________________________
_________________________________________________________________________________
3. What type of cell is produced by meiosis? __________________________________________
_________________________________________________________________________________
4. Why is meiosis important when we study genetics? ___________________________________
_________________________________________________________________________________
5. What is independent assortment and how does it affect offspring ________________________
_________________________________________________________________________________
6. What is crossing over and how does it affect offspring? _______________________________
_________________________________________________________________________________
7. What is a recessive allele? _______________________________________________________
_________________________________________________________________________________
8. How can recessive alleles be passed on even though they are not “seen?” __________________
_________________________________________________________________________________
Step 2: Writing a paragraph
Take your answers for questions # 1,2,4,5,6,8 (in that order) and form a paragraph that explains the
concept of inheritance.
Step 3: Understanding Mutations
9. Define mutation (IN YOUR OWN WORDS): ______________________________________
_________________________________________________________________________________
10. What is the difference between a frame shift mutation and a point mutation? _______________
_________________________________________________________________________________
11. . What is the difference between a gametic and a somatic mutation? _____________________
12. . How can mutations affect the functioning of a cell? ________________________________
_________________________________________________________________________________
13. . Give at least two reasons that explain why mutations, even if they occur, may NOT affect the
functioning of a cell. __________________________________________________________
_________________________________________________________________________________
Step 4: Writing the paragraph. Rewrite the answers to questions # 1, 4 & 5 in the form of a
paragraph.
Draw a Punnett Square that demonstrates how the parents passed on the “disorder causing”
alleles to their child. NOTE THIS MUST BE DONE FOR EACH OF THE DISEASES THAT
THE CHILD HAS!
Explain each of the Punnett Squares in Words. Be sure to use correct terminology such as:
homozygous, heterozygous, dominant allele, recessive allele.
______________________________________________________________________________