The Chemistry of Tortoise Shells


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A Tortoise shell is a hard plate-coated shell that protects tortoises from the various predators they face.  The reason why I chose to research the chemistry of tortoise shells is because I have a Russian Tortoise as a pet and I wanted to learn more about how his shell is made naturally. My life is not necessarily affected by tortoise shells other than I have to help keep my pet’s shell intact.

Composition of ...
Calcium (Collagen 1)
Beta Keratin
Bromochloroacetic acid 

Main Chemicals, Compounds, Components
Collagen (C2H5NOC5H9NOC5H10NO2) is a protein that makes up tissue in animals tendons, ligaments, and skin. It  is also used naturally when a wound is healing because of its resistance to bacteria. Uses outside the body include supplements for osteoarthritis pain.

Beta Keratin (C2H2BrClO2) is a harder form of keratin with a stronger bond that is found in and reptiles’ claws, scales, and shells.  It is made up of beta sheets.  The beta strands that form beta sheets are composed of 2-3 backbone hydrogen bonds.

Chemistry's Role

Collagen is naturally made during translation. Two alpha chains form on the ribosome along the rough endoplasmic reticulum(RER), the polypeptide chains are released into the RER, inside the RER single peptide chains are cleaved and are made into pro-alpha chains, the amino acids lysine and proline hydroxylase in the lumen, residue of glycosylation of hydroxylysine occurs and a triple alpha helical structure is made.

Beta keratin is naturally made and is composed of beta sheets which is a secondary structure in protein. 2 or 3 backbone hydrogen bonds connect beta strands. Beta strands are polypeptide strands with 3-10 amino acids.

Background Research
When discovering the composition of tortoise shells, scientists have used many different tests.  The test I researched was Xanthoproteic testing.  With this test they found naturally occurring proteins and amino acids. Xanthoproteic testing consists of nitric acid reacting with proteins. The concentrated acid is heated and turns yellow in the presence of proteins. With this process the amino acids alanine and glycine were found.


What Keratin is

Where Keratin is found

What Keratin does

What melanin is

What melanin purpose is

Composition of collagen fibres

What collagen is

How collagen is formed


Comes before melanin in sequence

Formula for collagen

Formula for alanine

Formula for glycine

Where it is found


How the structure is made naturally

Basic information on tortoise shells

Pigment of shell information

How and what was found in the composition of the shell

Definition of unknown term

How nitric acid is used to find the composition

Formula of Beta Keratin

Bromochloroacetic acid

How scientists tested for components

About the Author
Kailey Clayton is currently a Junior at Senior High School.  Kailey has participated in cross country for three years and plans on participating again in the fall. She also enjoys listening and playing the flute in Senior High’s Symphonic Band.  After Kailey graduates she hopes to study at the University of Montana to pursue a career in Occupational Therapy.