Cysteine is an amino acid that contains sulfur. Fig. 2.1 displays the structure of the molecule produced when two cysteine molecules are joined together. Draw a circle around an R-group in the molecule shown in Fig. 2.1.
The ends of mucin molecules contain many cysteine residues. Mucin strands are produced when the ends of mucin molecules join together via covalent bonds between R-groups. State the name of these covalent bonds.
Mucin strands move out of the goblet cells and then take in water to make mucus. Suggest and explain how mucin strands are transported out of the goblet cells.
Cystic fibrosis is a genetic disease caused by a mutation in the human $CFTR$ gene. This results in mucus that is thicker than normal. Suggest how thicker mucus interferes with the maintenance of healthy gas exchange surfaces in the lungs.
The difference between the DNA base sequence in row 1 and the DNA base sequence in row 2 of Table 2.1 is caused by a single gene mutation. State the name of this type of gene mutation.
Rows 1 and 2 in Table 2.1 show the DNA strands used in RNA synthesis. State the term used to describe the DNA strand that is used in RNA synthesis.
Complete Table 2.1 by entering the missing bases in row 3.
The normal $CFTR$ allele is roughly 189000 base pairs long. The $CFTR$ polypeptide contains only 1480 amino acids. Explain why the number of base pairs is so much greater than the number of amino acids.
The normal CFTR allele is approximately 189000 base pairs in length. The CFTR polypeptide consists of only 1480 amino acids. Explain the reasons for this difference between the number of base pairs and the number of amino acids.