Chromosome Numbers in Mitosis and Meiosis

The video explains chromosome numbers in mitosis and meiosis. It describes how a chromosome with two sister chromatids is considered one unit until they separate. In mitosis, human body cells start with 46 chromosomes, duplicate them, and end with two identical cells, each with 46 chromosomes. In meiosis, cells also start with 46 chromosomes, but after division, four cells are produced, each with 23 chromosomes, representing a reduction in chromosome number.

What defines a single chromosome when sister chromatids are involved?

• A single chromatid

• Two chromatids separated

• Two chromatids attached together

• Four chromatids attached

During mitosis, how many chromosomes do human body cells typically have before and after the process?

• 46 before, 23 after

• 23 before, 46 after

• 23 before, 23 after

• 46 before, 46 after

What happens to sister chromatids during mitosis?

• They duplicate again

• They are pulled apart

• They remain attached

• They disappear

How many chromosomes does a human cell have at the start of meiosis?

• 92

• 23

• 46

• None

What is the chromosome count in each cell after meiosis and cytokinesis?

• None

• 23

• 92

• 46