How does a mutation in DNA cause sickle cell disease?
Sickle cell disease is caused by a mutation in the hemoglobin-Beta gene found on chromosome 11. Hemoglobin transports oxygen from the lungs to other parts of the body. Red blood cells with normal hemoglobin (hemoglobin-A) are smooth and round and glide through blood vessels.
What does the mutation in the sickle cell trait do?
If mutations that produce hemoglobin S and beta thalassemia occur together, individuals have hemoglobin S-beta thalassemia (HbSBetaThal) disease. Abnormal versions of beta-globin can distort red blood cells into a sickle shape. The sickle-shaped red blood cells die prematurely, which can lead to anemia.
What effect does pleiotropy have on gene expression?
Quite simply, pleiotropy reflects the fact that most proteins have multiple roles in distinct cell types; thus, any genetic change that alters gene expression or function can potentially have wide-ranging effects in a variety of tissues.
What is pleiotropy give example?
When one single gene starts affecting multiple traits of living organisms, this phenomenon is known as pleiotropy. A mutation in a gene can result in pleiotropy. One example of pleiotropy is Marfan syndrome, a human genetic disorder affecting the connective tissues.
What does epistasis influence?
More important, epistasis makes the marginal (that is, additive) effects of alleles depend on the current genetic background. Thus, even though the immediate response of allele frequencies to selection is due to the additive component of genetic variance, these additive effects may change over time.
How do you know if a gene is pleiotropic?
Pleiotropy (from Greek πλείων pleion, “more”, and τρόπος tropos, “way”) occurs when one gene influences two or more seemingly unrelated phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene.
What is epistasis example?
Epistasis is a circumstance where the expression of one gene is affected by the expression of one or more independently inherited genes. For example, if the expression of gene #2 depends on the expression of gene #1, but gene #1 becomes inactive, then the expression of gene #2 will not occur.