Question

cftr mutations
more than 1,000 mutations in the cftr gene have been identified in people with cystic fibrosis. most of these mutations change single protein building blocks (amino acids) in the cftr protein or delete a small amount of dna from the cftr gene. the most common mutation, called delta f508, is a deletion of three nucleotides causing the loss of one amino acid at position 508 in the cftr protein. the resulting abnormal channel breaks down shortly after it is made, so it never reaches the cell membrane to transport chloride ions.
below is an abbreviated dna sequence from the wild-type cftr gene. wild-type refers to the most common form of the gene, in this case, it is the normal sequence for a fully functioning cftr protein

1. use the base code to transcribe each letter into rna to form an mrna strand. write the mrna below the dna. use the codon chart to translate the mrna into the amino acid sequence. write the amino acid sequence below the mrna.

	tag	tag	aaa	cct	caa	agg	ata
amino acids

in order for a gene to be expressed, such as the gene that codes for the chloride channels, the cell must follow specific steps. the codon chart below can be used to simulate one step in the process used by the cell when producing the chloride channels.
5.using the figures above, construct an explanation that summarizes how the dna sequence is expressed by cells to produce normal chloride channels in the cell membrane.

Explanation:

For Question 4:

Step1: Transcribe DNA to mRNA

In transcription, DNA thymine (T) pairs with RNA adenine (A), DNA adenine (A) pairs with RNA uracil (U), DNA cytosine (C) pairs with RNA guanine (G), and DNA guanine (G) pairs with RNA cytosine (C).

• DNA TAG → mRNA AUC
• DNA TAG → mRNA AUC
• DNA AAA → mRNA UUU
• DNA CCT → mRNA GGA
• DNA CAA → mRNA GUU
• DNA AGG → mRNA UCC
• DNA ATA → mRNA UAU

Step2: Translate mRNA to amino acids

Use the circular codon chart to match each mRNA codon to its corresponding amino acid:

• AUC → Isoleucine (Ile)
• AUC → Isoleucine (Ile)
• UUU → Phenylalanine (Phe)
• GGA → Glycine (Gly)
• GUU → Valine (Val)
• UCC → Serine (Ser)
• UAU → Tyrosine (Tyr)

First, the wild-type CFTR DNA sequence in the cell undergoes transcription: the DNA double helix unwinds, and complementary mRNA is synthesized using base-pairing rules (A→U, T→A, C→G, G→C). This mRNA carries the genetic code for the CFTR protein out of the nucleus. Next, translation occurs: ribosomes read the mRNA codons (3-base sequences) and use a codon chart to match each codon to a specific amino acid, which are linked together to form the CFTR protein polypeptide chain. Once fully synthesized, the functional CFTR protein is transported to the cell membrane, where it folds into a chloride channel that facilitates chloride ion transport across the membrane.

Answer:

	TAG	TAG	AAA	CCT	CAA	AGG	ATA
Amino Acids	Ile	Ile	Phe	Gly	Val	Ser	Tyr

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For Question 5: