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What is the name of the genetic disorder caused by the presence of an extra chromosome 21?

A.

Turner syndrome

B.

Klinefelter syndrome

C.

Down syndrome

D.

Huntington's disease

Answer and Explanation

The Correct Answer is C

Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. It is also known as trisomy 21 because affected individuals have three copies of chromosome 21 instead of the normal two.

The extra chromosome 21 in Down syndrome occurs due to a random error in cell division, which leads to the production of an abnormal gamete (egg or sperm) with an extra copy of the chromosome. When this gamete fuses with a normal gamete during fertilization, the resulting zygote has 47 chromosomes instead of the usual 46 and develops into a fetus with Down syndrome.

Down syndrome is characterized by a range of physical and intellectual symptoms, including developmental delays, intellectual disability, distinctive facial features, heart defects, and increased risk of certain medical conditions such as leukemia and Alzheimer's disease. However, the severity and expression of these symptoms can vary widely among affected individuals.


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Related Questions

Correct Answer is C

Explanation

A frameshift mutation is a type of genetic mutation that involves the insertion or deletion of one or more nucleotides in a DNA sequence. This can cause a shift in the reading frame of the genetic code, resulting in a change in the amino acid sequence of the resulting protein. Frameshift mutations can have significant effects on the function of the protein and can lead to genetic disorders or diseases.

Correct Answer is A

Explanation

The vertebral column, also known as the spine or spinal column, is a series of bones called vertebrae that extend from the skull to the pelvis. It provides support for the body and protects the spinal cord. The five regions of the vertebral column, starting from the top and moving downwards, are:

  1. Cervical: This region is made up of seven vertebrae and is located in the neck. The first two cervical vertebrae, the atlas, and the axis are specialized to allow for head movement.
  2. Thoracic: This region is made up of twelve vertebrae and is located in the upper and middle back. The thoracic vertebrae are larger than the cervical vertebrae and articulate with the ribs.
  3. Lumbar: This region is made up of five vertebrae and is located in the lower back. The lumbar vertebrae are the largest and strongest of the vertebrae.
  4. Sacral: This region is made up of five fused vertebrae and is located in the pelvis. The sacrum forms the posterior wall of the pelvis and articulates with the hip bones.
  5. Coccygeal: This region is made up of four fused vertebrae and is located at the base of the vertebral column. The coccyx, or tailbone, provides attachment points for muscles and ligaments.

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