What do chromatids contain

What Happens during Prometaphase? Each microtubule is highly dynamic, growing outward from the centrosome and collapsing backward as it tries to locate a chromosome. Eventually, the microtubules find their targets and connect to each chromosome at its kinetochore , a complex of proteins positioned at the centromere.

The actual number of microtubules that attach to a kinetochore varies between species, but at least one microtubule from each pole attaches to the kinetochore of each chromosome.

A tug-of-war then ensues as the chromosomes move back and forth toward the two poles. What Happens during Metaphase and Anaphase? Figure 2: Types of microtubules involved in mitosis. During mitosis, several types of microtubules are active. What Happens during Telophase? During telophase , the chromosomes arrive at the cell poles, the mitotic spindle disassembles, and the vesicles that contain fragments of the original nuclear membrane assemble around the two sets of chromosomes.

Phosphatases then dephosphorylate the lamins at each end of the cell. This dephosphorylation results in the formation of a new nuclear membrane around each group of chromosomes.

When Do Cells Actually Divide? Figure 3: Mitosis: Overview of major phases. The major stages of mitosis are prophase top row , metaphase and anaphase middle row , and telophase bottom row. Mitosis is the process of nuclear division, which occurs just prior to cell division , or cytokinesis. During this multistep process, cell chromosomes condense and the spindle assembles. The duplicated chromosomes then attach to the spindle, align at the cell equator, and move apart as the spindle microtubules retreat toward opposite poles of the cell.

Each set of chromosomes is then surrounded by a nuclear membrane, and the parent cell splits into two complete daughter cells. Cell Biology for Seminars, Unit 5. Topic rooms within Cell Biology Close. No topic rooms are there. Or Browse Visually. Student Voices. The numbers of chromosomes is the DNA content are the same as in the female, however their are only 9 arms the C value is effectively the same. At this stage, the number of chromosomes equals the number of chromatids, and these are the same between males and females.

When this cell undergoes mitotic division, metaphase chromosomes are maximally compact and have duplicated their DNA 4C , however the two DNA strands chromatids remain attached to a single centromere. Chromosomes are made of a single piece of DNA that is highly organized.

The replicated chromosomes have an X shape and are called sister chromatids. The sister chromatids are pairs of identical copies of DNA joined at a point called the centromere. Then, a structure called the mitotic spindle begins to form. The two chromatids of a duplicated chromosome are held together at a region of DNA called the centromere see figure below.

Centromeres are the attachment points for microtubules , which are responsible for the guiding the movement of chromosomes during mitosis and meiosis. Most eukaryotic cells contain two sets of chromosomes, with one set originating from the father and the other from the mother. For example, every human cell has 23 pairs of chromosomes: one chromosome from each pair is inherited from the father via the sperm , and the other is inherited from the mother via the egg.