Meiosis begins with one parent cell, after the first division there are two daughter cells, and then those each split, resulting in a total of four daughter cells. In prophase I chromosomes become compact and homologous chromosomes pair up.
Also during prophase I, the nuclear membrane begins to break down and the spindle apparatus begins to form. In metaphase I, homologous chromosomes line up along the center of the cell in order to be pulled apart. Recall that during meiosis I, homologous chromosomes pair, cross over, and separate. Meiosis II is when the sister chromatids are separated. Chromatid disjunction occurs in anaphase II after the chromosomes line up along the equator during metaphase II. The chromosomes are then pulled apart, with one chromatid moving north, and one moving south.
The next steps are telophase, and cytokinesis, which upon completion, will result in genetically distinct haploid gametes. If you've found an issue with this question, please let us know. With the help of the community we can continue to improve our educational resources. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.
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Sister chromatids line up in the center of the cell. Correct answer: Sister chromatids are separated. Explanation : During prophase I, homologous chromosomes form tetrads along the center of the cell.
Report an Error. What is the first stage of meiosis during which a cell is considered haploid? Possible Answers: Telophase II. Correct answer: Prophase II. Explanation : A diploid cell will have two copies of each chromosome, known as a homologous pair.
Diploid cell: XX Haploid cell: X During meiosis I, the cell is diploid because the homologous chromosomes are still located within the same cell membrane. Possible Answers: The cytoplasm splits and forms two diploid daughter nuclei. The cell's chromatin condenses and forms chromosomes. You have authorized LearnCasting of your reading list in Scitable.
Do you want to LearnCast this session? This article has been posted to your Facebook page via Scitable LearnCast. Change LearnCast Settings. The diploid chromosome number varies by organism and ranges from 10 to 50 chromosomes per cell. See the following table for the diploid chromosome numbers of various organisms.
All of the somatic cells in your body are diploid cells and all of the cell types of the body are somatic except for gametes or sex cells, which are haploid. During sexual reproduction , gametes sperm and egg cells fuse during fertilization to form diploid zygotes.
A zygote, or fertilized egg, then develops into a diploid organism. Diploid cells reproduce through mitosis. In mitosis, a cell makes an identical copy of itself. Somatic cells go through mitosis and haploid gametes undergo meiosis. Mitosis is not exclusive to diploid cells. Most plant and animal tissues consist of diploid cells. In multicellular animals, organisms are typically diploid for their entire life cycles. Plant multicellular organisms have life cycles that vacillate between diploid and haploid stages.
Known as alternation of generations , this type of life cycle is exhibited in both non-vascular plants and vascular plants. In liverworts and mosses, the haploid phase is the primary phase of the life cycle.
In flowering plants and gymnosperms , the diploid phase is the primary phase and the haploid phase is totally dependent upon the diploid generation for survival. Other organisms, such as fungi and algae, spend the majority of their life cycles as haploid organisms that reproduce by spores. Each species of eukaryote has a characteristic number of chromosomes in the nuclei of its cells. Human body cells somatic cells have 46 chromosomes.
A somatic cell contains two matched sets of chromosomes, a configuration known as diploid. The letter n is used to represent a single set of chromosomes; therefore a diploid organism is designated 2 n. Human cells that contain one set of 23 chromosomes are called gametes , or sex cells; these eggs and sperm are designated n , or haploid. The matched pairs of chromosomes in a diploid organism are called homologous chromosomes.
Homologous chromosomes are the same length and have specific nucleotide segments called genes in exactly the same location, or locus. Genes, the functional units of chromosomes, determine specific characteristics by coding for specific proteins.
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