Principles Of Inheritance And Variation

The probability of color blindness in their offspring can be determined using a genetic understanding of X-linked traits, such as color blindness. Since color blindness is a recessive trait found on the X chromosome, we will analyze the genetic makeup of the parents:

All male and female children will inherit at least one X^c chromosome from the mother. Thus, all offspring will be color blind. Hence, the probability is 100%.

- -Thalassemia is caused by mutations/deletions in genes located on chromosome 16.
- -Thalassemia is caused by mutations in the -globin gene located on chromosome 11.
Therefore, both 16 and 11 are involved in respective forms of thalassemia.

Step 1: Non-disjunction refers to the failure of homologous chromosomes to separate during meiosis.
Step 2: When this occurs in the 21st chromosome pair, it results in an extra copy (trisomy 21).
Step 3: This leads to a total of 47 chromosomes in the zygote instead of the normal 46.
Step 4: The child exhibits symptoms of Down’s Syndrome: mental retardation, flattened facial profile, and short stature.
Step 5: Other syndromes result from different chromosomal abnormalities (e.g., XXY for Klinefelter’s, XO for Turner’s).