The components that are linked by arrow are:
Step 1: Shows chromosome number 7, with enlarged portion of CFTR gene. It is captioned 'The most common allele that causes cystic fibrosis is missing 3 DNA bases. As a result, the amino acid phenylalanine is missing from the CFTR protein'.
Step 2: Shows an abnormal CFTR is unable to transport chloride ions. It is captioned 'Normal CFTR is a chloride ion channel in cell membranes. Abnormal CFTR cannot transport ions across the cell membrane'.
Step 3: Shows human body with lungs and breathing passageways. It is captioned 'The cells in the person’s airways are unable to transport chloride ions. As a result, the airways become clogged with a thick mucus'.