Question

Which phase do the chromosomes duplicate?

Which phase does the cell spend most of its lifetime and approximately how long?

What is the mitotic spindle?

What is a centriole and what is its function?

Centrioles are located inside what?
Where does the mitotic spindle grow out of?

Duplicate chromosomes and duplicated centrosomes would mark the end of what?

Answer 1

The cell cycle is divided into four phases M (mitosis) phase, G1 (the period between mitosis and inititation of DNA replication) phase, S (the period of nuclear DNA replication) phase and G2 (the period between the completion of DNA replication and mitosis) phase. So the chromosomes duplicate in the S or synthesis phase.

The human cells spend most of its time in the S phase and for approximately 10 hours.

The mitotic spindle is the macromolecular machine that segregates chromosomes to two daughter cells during mitosis. The major structural elements of thespindle are microtubule polymers, whose intrinsic polarity and dynamic properties are critical for bipolarspindle organization and function.

Centrioles are made of protein strands called microtubules. Centrioles are made of nine triplets of microtubules arranged in a cylinder. They help in cell division. During mitosis, specifically in the prophase, these centrioles migrate to the poles from which microtublues radiate and help in DNA replication.

Centrioles are paired organelles. They are typically located together near the nucleus in the centrosome, a granular mass that serves as an organizing center for microtubules.

Cellular microtubules disassemble and reassemble into the mitotic apparatus consisting of a football-shaped
bundle of microtubules (the spindle) with a star-shaped cluster of microtubules radiating from each end, or spindle pole.

The duplicate chromosomes and duplicated centrosomes mark the end of S phase.