Some genes are said to be “linked”. Explain this term and the implications it has as to the inheritance of certain traits. Provide 2 (human) examples of linked genes?
In genetics, the term "linked genes" refers to genes that are located close to each other on the same chromosome. During the process of chromosome segregation, chromosomes usually assort independently, meaning that each pair of chromosomes segregates randomly into different gametes. However, when genes are linked, they do not segregate independently and are generally inherited together.
The implications of linked genes in inheritance are that they are less likely to assort independently during gamete formation. This means that if two genes are located close to each other on the same chromosome, it is more probable that they will be inherited together and not undergo recombination.
Here are two examples of linked genes in humans:
1. Hemophilia and color blindness: Hemophilia is a genetic disorder that impairs the body's ability to form blood clots. Color blindness is a condition that causes an individual to have difficulty distinguishing between certain colors. Both hemophilia and color blindness are linked to the X chromosome. Since these genes are closely located on the X chromosome, they are often inherited together, making these conditions more prevalent in males.
2. Male pattern baldness and hair color: Male pattern baldness is a condition characterized by hair loss in certain areas of the scalp in males. Hair color refers to the natural color of an individual's hair. Both male pattern baldness and hair color are influenced by genes that are located on the same chromosome. These linked genes can be inherited together, potentially resulting in a pattern where individuals with specific hair colors are more likely to experience male pattern baldness.
To determine if genes are linked, geneticists perform experiments such as crossing over experiments and genetic linkage analysis. These techniques help identify the patterns of inheritance and the linkage between specific genes on a chromosome.