However, not all such gene abnormalities are uniformly harmful. read more, harm body structure or function and are considered disorders. read more, and Huntington disease Huntington Disease Huntington disease is a hereditary disease that begins with occasional involuntary jerking or spasms, then progresses to more pronounced involuntary movements (chorea and athetosis), mental. read more, Marfan syndrome Marfan Syndrome Marfan syndrome is a rare hereditary disorder of connective tissue, resulting in abnormalities of the eyes, bones, heart, blood vessels, lungs, and central nervous system. The skin, hair, and eyes, or sometimes just the eyes, are affected.
#DNA STANDS FOR WRONG ANSWER SKIN#
Other variations, such as albinism Albinism Albinism is a rare hereditary disorder in which little or none of the skin pigment melanin is formed. Variation in some traits, such as eye color or blood type, is considered normal. Chromosomes are structures within cells that contain DNA and many genes.
#DNA STANDS FOR WRONG ANSWER FULL#
Thus, missing an X chromosome is far less harmful than missing a nonsex chromosome (see Overview of Sex Chromosome Abnormalities Overview of Sex Chromosome Abnormalities Sex chromosome abnormalities may be caused by full or partial deletions or duplications of sex chromosomes. Turner syndrome is caused by the deletion of part. Because of X inactivation, the absence of one X chromosome usually results in relatively minor abnormalities (such as Turner syndrome Turner Syndrome Turner syndrome is a sex chromosome abnormality in which girls are born with one of their two X chromosomes partially or completely missing. Thus, one cell may express a gene from the person’s mother and another cell expresses the gene from the person’s father.
In some cells, the X from the father becomes inactive, and in other cells, the X from the mother becomes inactive. X inactivation occurs early in the life of the fetus. However, in females, most of the genes on one of the two X chromosomes are turned off through a process called X inactivation (except in the eggs in the ovaries). Normally, in the nonsex chromosomes, the genes on both of the pairs of chromosomes are capable of being fully expressed. Although the protection against malaria can help a carrier survive, sickle cell disease (in a person who has two copies of the gene) causes symptoms and complications that may shorten life span.
Malaria causes fever, chills, sweating, a general feeling of illness (malaise), and sometimes. However, when a person inherits only one copy of the sickle cell gene (called a carrier), the person develops some protection against malaria Malaria Malaria is infection of red blood cells with one of five species of the protozoa Plasmodium. For example, in the case of the sickle cell gene, when a person inherits two copies of the abnormal gene, the person will develop sickle cell disease Sickle Cell Disease Sickle cell disease is an inherited genetic abnormality of hemoglobin (the oxygen-carrying protein found in red blood cells) characterized by sickle (crescent)-shaped red blood cells and chronic. In rare cases, a mutation introduces a change that is advantageous.
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