Spindle fibers
Spindle fibers
During prophase, the chromatin in the nucleus begins to condense to form chromosomes. Nuclear envelope and nucleolus dissolves. In meiosis, during early and middle prophase I of meiosis the chromosomes become distinct and rodlike. Also during early and middle prophase I of meiosis synapsis occurs. During late prophase I of meiosis the chromosomes become clearly double-stranded and the nuclear membrane begins to disappear.
Th process of independent orientation of chromosomes while in their tetrad forms. But, the more important process that also happens in prophase I is the process of crossing over where chromosomes, male and female, exchange regions of the chromosomes, one with the other.
tetrads
Prophase is the first phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. During prophase, the complex of DNA and proteins contained in the nucleus, known as chromatin, condenses.
the chromatin condenses into thick thread like structure that later becomes chromatids. [ the spindle fibers form ]
The spindle is formed during the prophase stage of mitosis or meiosis. In prophase, microtubules organize into a structure called the spindle apparatus, which helps separate the chromosomes during cell division.
A bivalent at the beginning of prophase I is composed of two homologous chromosomes that have already replicated into sister chromatids. Each homologous chromosome consists of two sister chromatids joined by a centromere. The bivalent forms as the homologous chromosomes pair up and undergo synapsis.
One pair of homologous chromosomes. One chromosome in a tetrad is paternally inherited, while the other is maternally inherited. Each chromosome consists of two chromatids.
Centromere. It is a region on a chromosome where the kinetochore forms, allowing for attachment to spindle fibers during cell division, ensuring proper segregation of chromosomes.
The phase of mitosis where the nuclear envelope and nucleus disappear is called prophase. During prophase, the chromatin condenses into discrete chromosomes, and the spindle apparatus begins to form, facilitating the movement of chromosomes during cell division.
An aster forms during the prophase stage of mitosis. Asters are composed of microtubules radiating from the centrosomes located at opposite poles of the cell. They help to organize and separate the chromosomes during cell division.