meiosis stages and descriptions pdf

Meiosis stages and descriptions pdf

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7.5: Sexual Reproduction: Meiosis and gametogenesis

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What is mitosis?

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7.5: Sexual Reproduction: Meiosis and gametogenesis

Children in a family resemble their parents and each other, but the children are never exactly the same unless they are identical twins. Each of the daughters in the painting inherited a unique combination of traits from the parents. In this concept, you will learn how this happens. It all begins with sex — sexual reproduction, that is. Why do you look similar to your parents, but not identical?

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Skip navigation. Meiosis, the process by which sexually reproducing organisms generate gametes sex cells , is an essential precondition for the normal formation of the embryo. As sexually-reproducing, diploid, multicellular eukaryotes, humans rely on meiosis to serve a number of important functions, including the promotion of genetic diversity and the creation of proper conditions for reproductive success. However, the primary function of meiosis is the reduction of the ploidy number of chromosomes of the gametes from diploid 2n, or two sets of 23 chromosomes to haploid 1n or one set of 23 chromosomes. While parts of meiosis are similar to mitotic processes, the two systems of cellular division produce distinctly different outcomes. Problems during meiosis can stop embryonic development and sometimes cause spontaneous miscarriages, genetic errors, and birth defects such as Down syndrome. The process of meiosis was first described in the mids by Oscar Hertwig, who observed it while working with sea urchin eggs.

What is mitosis?

Mitosis is a process where a single cell divides into two identical daughter cells cell division. Illustration showing the five stages of mitosis. Image credit: Genome Research Limited. Cells are the basic building blocks of living things.

Skip to main content. Search form Search. Lab bench mitosis meiosis. Mitosis is the first of these studied in this lab.

Meiosis consists of two divisions, both of which follow the same stages as mitosis prophase, metaphase, anaphase, telophase. Meiosis I. Meiosis II. The second division separates sister chromatids these chromatids may not be identical due to crossing over in prophase I. The final outcome of meiosis is the production of four haploid daughter cells.

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Walker, Michelle Y. Hawley, R. Last reviewed: August The set of two successive cell divisions that serve to separate homologous chromosome pairs and thus reduce the total number of chromosomes by half. The process of meiosis Fig.

Cell division gives rise to genetically identical cells in which the total number of chromosomes is maintained. The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are prophase , prometaphase , metaphase , anaphase , and telophase. During mitosis, the chromosomes, which have already duplicated, condense and attach to spindle fibers that pull one copy of each chromosome to opposite sides of the cell. The rest of the cell may then continue to divide by cytokinesis to produce two daughter cells.

2 comments

  • Eliot P. 12.06.2021 at 04:23

    Actively dividing eukaryote cells pass through a series of stages known collectively as the cell cycle: two gap phases (G1 and G2); an S (for synthesis) phase.

    Reply
  • Juan P. J. 14.06.2021 at 02:57

    Fundamentals of organic chemistry by john e mcmurry pdf writer jazz guitar chord chart with finger position pdf

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