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Microtubules are hollow structures composed of a protein, tubulin, which has two forms: alpha-tubulin and beta-tubulin - VCE - SSCE Biology - Question 2 - 2013 - Paper 1
Question 2
Microtubules are hollow structures composed of a protein, tubulin, which has two forms: alpha-tubulin and beta-tubulin. A tubulin dimer is formed when one alpha-tubu... show full transcript
Worked Solution & Example Answer:Microtubules are hollow structures composed of a protein, tubulin, which has two forms: alpha-tubulin and beta-tubulin - VCE - SSCE Biology - Question 2 - 2013 - Paper 1
Step 1
Describe the structure of microtubules.
Answer
Microtubules are cylindrical structures composed of tubulin proteins. Each microtubule is made up of multiple protofilaments, which are linear chains of tubulin dimers. In the case of microtubules, 13 protofilaments align alongside each other to form a complete microtubule. The combination of alpha-tubulin and beta-tubulin in dimers contributes to the structural integrity and functionality of the microtubule.
Step 2
Explain the composition of tubulin.
Answer
Tubulin is a globular protein that exists mainly in two forms: alpha-tubulin and beta-tubulin. These two forms of tubulin combine to form a dimer, which is the basic building block of microtubules. The α and β subunits associate in a head-to-tail fashion, leading to the formation of protofilaments.
Step 3
What is the significance of protofilaments in microtubules?
Answer
Protofilaments are crucial for the stability and dynamics of microtubules. They are formed by the polymerization of tubulin dimers and provide structural support, allowing microtubules to maintain their shape. The arrangement of the 13 protofilaments side by side is essential for the overall functionality of microtubules, which are involved in various cellular processes including transport and cell division.