How is mitosis similar to meiosis

If you learn best through examples, you'll also love our break-down of commensalism. What are the most important science classes to take in high school? Check out our guide to learn all the high school classes you should be taking. She has taught English and biology in several countries. Our new student and parent forum, at ExpertHub. See how other students and parents are navigating high school, college, and the college admissions process. Ask questions; get answers. How to Get a Perfect , by a Perfect Scorer.

Score on SAT Math. Score on SAT Reading. Score on SAT Writing. What ACT target score should you be aiming for? How to Get a Perfect 4. How to Write an Amazing College Essay. Cells are the basic building blocks of living things. The human body is composed of trillions of cells, all with their own specialised function.

A stem cell is a cell with the unique ability to develop into specialised cell types in the body. In the future they may be used to replace cells and tissues that have been damaged or lost due to disease. If you have any other comments or suggestions, please let us know at comment yourgenome.

Can you spare minutes to tell us what you think of this website? Open survey. In: Facts In the Cell. A large structure called the meiotic spindle also forms from long proteins called microtubules on each side, or pole, of the cell.

Between prophase I and metaphase I, the pairs of homologous chromosome form tetrads. Within the tetrad, any pair of chromatid arms can overlap and fuse in a process called crossing-over or recombination. Recombination is a process that breaks, recombines and rejoins sections of DNA to produce new combinations of genes.

In metaphase I, the homologous pairs of chromosomes align on either side of the equatorial plate. Then, in anaphase I, the spindle fibers contract and pull the homologous pairs, each with two chromatids, away from each other and toward each pole of the cell. During telophase I, the chromosomes are enclosed in nuclei. The cell now undergoes a process called cytokinesis that divides the cytoplasm of the original cell into two daughter cells. Each daughter cell is haploid and has only one set of chromosomes, or half the total number of chromosomes of the original cell.

Meiosis II is a mitotic division of each of the haploid cells produced in meiosis I. Meiosis has various timescales in different organisms, which can be affected by several factors including temperature and environment of the organism, and the amount of nuclear DNA. The process lasts 6 hours in yeast but can last more than 40 years in human females, due to a developmental hold at prophase I, until ovulation. What is an example of a disease caused by an error in this process?

Uncontrolled mitosis occurs in cancer, where either genes that stop cell division tumour suppressors are switched off, or genes that encourage cell division oncogenes are overactive. Errors in meiosis can lead to the wrong number of chromosomes ending up in germ cells, this is called aneuploidy.

This can trigger miscarriage, but is occasionally tolerated. Another example is Klinefelter syndrome , where XY males have an additional X chromosome. Mitosis is the Greek word for thread , after the thread-like chromosomes that can be seen under the microscope in dye-stained cells during cell division. This refers to the outcome of meiosis, where the genetic information in each new cell is halved. Oskar Hertwig described the fusion of egg and sperm in the transparent sea urchin egg in In mitosis, prophase, metaphase, anaphase and telophase occur once.

Meiotic prophase I is much longer that mitotic prophase. This is where chromosomes exchange sections of DNA. This is important for generating genetic diversity but is also crucial mechanically to hold homologous chromosomes together. Mitotic prophase is much shorter that meiotic prophase I. There is no crossing over in mitosis.

In meiotic metaphase I pairs of homologous chromosomes line up along the metaphase plate. The way in which the homologous pairs are oriented randomly with respect to the cell poles is referred to as the law of independent assortment and ensures a random and independent distribution of chromosomes to the daughter cells of meiosis I and ultimately to the haploid gametes at the end of meiosis II.

In anaphase of meiosis I cohesin at the centromeres of the chromosomes is not cleaved and it therefore continues to hold sister chromatids together as the homologous chromosomes are segregated to opposite cell poles. In anaphase of mitosis and meiosis II , cohesin protein holding the centromeres of the sister chromatids together is cleaved , allowing the sister chromatids to segregate to opposite poles of the cell , at which point they are called chromosomes.

In meiosis, cytokinesis must occur twice : once after telophase I and again, after telophase II. In mitosis, cytokinesis does not always occur , some cells divide and are multinucleate , like muscle cells.

Are uncondensed but are still organised. The entire genome is replicated to create two identical semi-conserved copies of each chromosome. Align along the metaphase plate, the midpoint between the two centrosomes. Sister chromatids are joined at the centromere by proteins that form a structure called a kinetochore.

Cohesin is cleaved at the centromere of chromosomes, resulting in sister chromatids being pulled to opposite poles of the cell. Chromosomes have returned to their interphase structure. This is a topic of much research, but it seems as though each chromosome occupies its own territory within the nucleus.