Answer:
They are thick, strong and made up of thousands of tubulin which are spiral in shape.
Explanation:
In eukaryotic cells, they have microtubules which are fibres serving as tracks for cell to cell transport and regulate the shape of a cell.
Microtubules are different from other cytoskeletal filaments because they possesses a cylindrical shape with the tube having a larger diameter of 20-25 nm as compared to microfilament that have a diameter of 3-6 nm.
Microtubules are made of subunits of proteins called tubulin named alpha and beta that is not present in other cytoskeletal filaments.
nebular hypothesis
The most widely accepted theory of planetary formation, known as the nebular hypothesis, maintains that 4.6 billion years ago, the Solar System formed from the gravitational collapse of a giant molecular cloud which was light years across. Several stars, including the Sun, formed within the collapsing cloud.
Answer:
<em>When focusing on a slide, ALWAYS start with either the 4X or 10X objective. Once you have the object in focus, then switch to the next higher power objective. Re-focus on the image and then switch to the next highest power.</em>