Sickle cell anemia is an autosomal condition expressed when a person has a homozygous mutant genotype (use HSHS or H^SH^S) for synthesizing hemoglobin protein with altered shape. A person with a normal gene for synthesizing normal hemoglobin will have a genotype of HNHN (or type as H^NH^N). A person with a heterozygous genotype (use HNHS or H^NH^S) will experience fatigue, weakness, and an increased risk of cardiovascular diseases (sickle cell trait). A male with sickle cell trait and a normal female have children. A) What are the genotypes of the parents involved in the cross? B) What are all the possible gametes for each parent? (This information will help you to draw a Punnett Square on a scratch paper to determine the answer for the next question). C) What are the expected phenotypic frequencies of the offspring that result from this cross?
Added by Joanna F.
Step 1
Step 1: Determine the genotypes of the parents involved in the cross. Show more…
Show all steps
Your feedback will help us improve your experience
Suman K and 97 other Biology educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Sickle cell anemia is a disease that is caused by a mutation in the gene that produces hemoglobin. Hemoglobin carries oxygen in red blood cells. The HbA allele produces normal hemoglobin and the HbS allele produces hemoglobin that sticks together and causes red blood cells to sickle. Heterozygous individuals (HbAHbS) produce both normal and "sickle" hemoglobin so the HbA and HbS alleles are codominant. Heterozygotes do not develop sickle cell anemia and are described as having the sickle cell trait. Individuals that are homozygous for the sickle allele (HbSHbS) only produce "sickle" hemoglobin and develop sickle cell disease.A man who is homozygous for the normal allele married a woman with the sickle cell trait. What is the expected probability of this couple having a boy with the sickle cell trait? Record your answer as a value between 0 and 1 rounded to two decimal places.Answer
Madhur L.
Sickle-cell anemia arises from a mutation in the gene for the beta chain of human hemoglobin. The change from a GAG to a GTG in the mutant eliminates a cleavage site for the restriction enzyme MstII, which recognizes the target sequence CCTGAGG. These findings form the basis of a diagnostic test for the sickle-cell allele of the gene. Describe, using numbered steps, a PCR-based assay. In addition, Draw a picture of the results you would expect from: 1) a person who is homozygous for the mutant gene, 2) a person who is homozygous for the normal gene, and 3) a person who is heterozygous.
Sickle-cell anemia is a genetic disease. In the U.S., it is especially prevalent among blacks: one person in four hundred suffers from it. The disease is controlled by one gene-pair, with variants $A$ and $a,$ where $a$ causes the disease but is recessive: $$\begin{array}{l}{A / A, A / a, a / A-\text { healthy person }} \\ {a / a-\text { sickle-cell anemia. }}\end{array}$$ (a) Suppose one parent has the gene-pair $A / A$ . Can the child have sickle- cell anemia? How? (b) Suppose neither parent has sickle-cell anemia. Can the child have it? (c) Suppose both parents have sickle-cell anemia. Can the child avoid having it? How?
Recommended Textbooks
Biology for AP Courses
Objective Biology for NEET
Introduction to General, Organic and Biochemistry
Transcript
Watch the video solution with this free unlock.
EMAIL
PASSWORD