The G1 phase, or Growth 1/Gap 1 phase, is the first of four phases of the cell cycle that takes place in eukaryotic cell division. In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis.
the cell grows and functions normally. During this time, a high amount of protein synthesisoccurs and the cell grows (to about double its original size) - more organelles are produced, the volume of cytoplasm increases and mitochondria and chloroplasts divide.
The cell grows and copies genetic material during the interpase period of the cell cycle. Then it goes ( or not ) through mitosis
Is when the two chromosomes of each bivalent (tetrad) separate and start moving toward opposite poles of the cell as a result of the action of the spindle. Notice that inanaphase I the sister chromatids remain attached at their centromeres and move together toward the poles.
The centromeres separate and the sister chromatids—now individual chromosomes—move toward the opposite poles of the cell. To replay theanaphase II The centromeres separate, and the two chromatids of each chromosome move to opposite poles on the spindle.
Chromosomes become visible, crossing-over occurs, the nucleolus disappears, the meiotic spindle forms, and the nuclear envelope disappears. To see prophase I animated, click the Play button. At the start of prophase I, the chromosomes have already duplicated.
Concept 10: Meiosis II: Prophase II. Meiosis II begins without any further replication of the chromosomes. In prophase II, the nuclear envelope breaks down and the spindle apparatus forms.
The homologous chromosome pairs reach the poles of the cell, nuclear envelopes form around them, and cytokinesis follows to produce two cells. To see telophase I animated, click the Play button. The homologous chromosome pairs complete their migration to the two poles as a result of the action of the spindle.
Concept 13: Meiosis II: Telophase II. A nuclear envelope forms around each set of chromosomes and cytokinesis occurs, producing four daughter cells, each with a haploid set of chromosomes. To see telophase II. A nuclear envelope forms around each set of chromosomes.
After prophase I, crossing-over is complete. The tetrads move to a plane — called the "metaphase plate" — halfway between the two poles of the cell. Next, the spindle fibers attach to the centromeres of each chromosome. Both kinetochores of each sister chromatid pair are turned toward the same pole
The chromosomes become arranged on themetaphase plate, much as the chromosomes do in mitosis, and are attached to the now fully formed spindle. To see metaphase IIanimated, Each of the daughter cells completes the formation of a spindle apparatus
Mitosis occurs when the nucleus of the cell divides into two identical nuclei with the same number and type of chromosomes, followed by cytokinesiswhen the cytoplasm, for both plant and animal cells, divides, thus creating two daughter cells that are genetically equal and approximately identical in size.
Cell division in eukaryotic cells includes mitosis, in which the nucleus divides, and cytokinesis, in which the cytoplasm divides and daughter cells form. Mitosis occurs in four phases, called prophase, metaphase, anaphase, and telophase