What stage are chromatids are pulled apart?
In metaphase (a), the microtubules of the spindle (white) have attached and the chromosomes have lined up on the metaphase plate. During anaphase (b), the sister chromatids are pulled apart and move toward opposite poles of the cell.
What phase are homologous chromosomes pulled apart?
Anaphase I
Anaphase I: In anaphase I, the attachment of the spindle fibers is complete. The homologous chromosomes are pulled apart and move towards opposite ends of the cell.
Are chromatids pushed or pulled?
The sister chromatids are pushed and pulled by the spindle microtubules until they are all lined up along the midline of the mitotic spindle, which in most (but not all) cases is also the midline of the cell.
What is the difference between chromosome and homologous chromosome?
Chromosomes are linear arrangements of condensed deoxyribonucleic acid (DNA) and histone proteins, which form a complex called chromatin. Homologous chromosomes are made up of chromosome pairs of approximately the same length, centromere position, and staining pattern, for genes with the same corresponding loci.
When the chromatids are pulled apart and move in opposite directions What cell structure are they being pulled toward?
The sister chromatids separate from one another and are pulled towards opposite poles of the cell. The microtubules that are not attached to chromosomes push the two poles of the spindle apart, while the kinetochore microtubules pull the chromosomes towards the poles.
In which phase are chromatids pulled apart quizlet?
Fibers that extend from one pole of a cell to the other, which pull the sister chromatids apart in the anaphase stage of mitosis or the anaphase II stage of meiosis.
What structures pull chromosomes apart?
The movement of chromosomes is facilitated by a structure called the mitotic spindle, which consists of microtubules and associated proteins. Spindles extend from centrioles on each of the two sides (or poles) of the cell, attach to the chromosomes and align them, and pull the sister chromatids apart.
What happens to the nucleus during cell division?
A unique feature of the nucleus is that it disassembles and re-forms each time most cells divide. At the beginning of mitosis, the chromosomes condense, the nucleolus disappears, and the nuclear envelope breaks down, resulting in the release of most of the contents of the nucleus into the cytoplasm.
Do spindles push or pull in mitosis?
The segregation of the replicated chromosomes is brought about by a complex cytoskeletal machine with many moving parts—the mitotic spindle. It is constructed from microtubules and their associated proteins, which both pull the daughter chromosomes toward the poles of the spindle and move the poles apart.
When do the sister chromatids of a homologous chromosome separate?
After the tetrads of homologous chromosomes are separated in meiosis I, the sister chromatids from each pair are separated.
How are the homologous chromosomes pulled apart in meiosis I?
Anaphase I. In anaphase I of meiosis I the homologous chromosomes are pulled apart from each other. The homologs are cleaved by the enzyme separase to release the cohesin that held the homologous chromosome arms together. This allows the chiasmata to release and the homologs to move to opposite poles of the cell.
How are the genes associated with homologous chromosomes aligned?
As the nuclear envelope begins to break down, the proteins associated with homologous chromosomes bring the pair close to each other. The tight pairing of the homologous chromosomes is called synapsis (Figure 2). In synapsis, the genes on the chromatids of the homologous chromosomes are precisely aligned with each other.
What happens to homologous chromosomes during prophase I?
As prophase I progresses, the close association between homologous chromosomes begins to break down, and the chromosomes continue to condense, although the homologous chromosomes remain attached to each other at chiasmata. The number of chiasmata varies with the species and the length of the chromosome.