Question Video: Determining the Group of Proteins That Keratin Is Most Likely to Belong To | Nagwa Question Video: Determining the Group of Proteins That Keratin Is Most Likely to Belong To | Nagwa

Question Video: Determining the Group of Proteins That Keratin Is Most Likely to Belong To Biology • First Year of Secondary School

Keratin is a long protein found in hair and nails, with many repeats of the sulfur-containing amino acid cysteine. Using the table, determine the group of proteins that keratin is most likely to belong to.

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Video Transcript

Keratin is a long protein found in hair and nails, with many repeats of the sulfur-containing amino acid cysteine. Using the table provided, determine the group of proteins that keratin is most likely to belong to.

Proteins can be classified into globular and fibrous, according to their structure, or simple and conjugated, according to their composition.

Now, we need to use the clues given in the question to classify keratin. The first clue we are given in the question is that keratin is a long protein and also that it’s found in hair and nails, which are strong, stable, and insoluble structures. This suggests that keratin is classified as a fibrous protein. Let’s see if we can confirm this.

Next, the question tells us that keratin contains many repeats of the amino acid cysteine. This also fits with the definition of a fibrous protein, which is a protein that has a repetitive primary structure. Each cysteine contains a thiol or SH group. Thiol groups can form disulfide bridges with other thiol groups. This plays an important role in the secondary and tertiary structure of the protein, providing additional stability and insolubility.

We can now answer our question. Keratin is most likely to belong to the group of fibrous proteins.

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