X-linked recessive inheritance

High school (ages 12+)
Human Body

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/x-linked-recessive-inheritance

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the number of x-linked genes?Approximately 499 sequenced X-linked genes are known
2. What is the mechanism of expression in females?Requires homozygous mutation on both X chromosomes, or skewed X-inactivation
3. What does X-linked recessive inheritance mean?It means a change in a gene on the X chromosome can cause a trait that shows up in boys and in girls only if both of their X chromosomes have the change.
4. Why do boys get X-linked recessive disorders more often than girls?Boys have only one X chromosome, so if that one has the change, they show the trait. Girls have two X chromosomes, so they usually have one normal copy that hides the change.

Hemizygous: Possessing only one allele for a gene, as males do for X-linked genes.
X-chromosome Inactivation (Lyonization): The random silencing of one X chromosome in female somatic cells, creating mosaicism.
Variable Expressivity: The occurrence of a phenotype with differing intensity or characteristics among individuals with the same genotype.