AP BIOLOGY

Detailed explanation-1: -In most animals and fungal cells, spindle microtubules nucleate from centrosomes or spindle pole bodies.

Detailed explanation-2: -Answer and Explanation: In animal cells, the microtubules of the spindle originate in the centrioles of the cell. Centrioles are tiny organelles that are made of proteins called tubulin that form a cylindrical shape.

Detailed explanation-3: -While both animal and plant cells have microtubule organizing centers (MTOCs), animal cells also have centrioles associated with the MTOC: a complex called the centrosome.

Detailed explanation-4: -Most microtubules in animal cells first appear at centrosomes, typically associated with the nuclear envelope, and then grow outwards. In contrast, microtubule growth in plants is initiated exclusively at spatially dispersed sites.

Detailed explanation-5: -A narrow, hollow tube-like structure found in the cytoplasm (the fluid inside a cell) of plant and animal cells. Microtubules help support the shape of a cell. They also help chromosomes move during cell division and help small structures called cell organelles to move inside the cell.