meiosis | the basic process that makes life

meiosis - the basic process that makes life 

meiosis

Have you ever questioned however 2 siblings will have an equivalent female parent and pop still look thus different? Well, nowadays we’re getting to cite a method that creates that possible----a method known as meiosis ----not to be confused with cellular division, that sounds sadly similar. cellular division makes identical body cells like your skin cells and abdomen cells. Recall from our cellular division clip that since it makes identical body cells, cellular division is very important for growth and for the repair of injury or to switch worn-out cells. however NOT meiosis.

 Meiosis could be a method that contributes to genetic variation. Meiosis additionally doesn’t create body cells. It makes sperm cell and egg cells; otherwise called gametes, the enthusiast word. you may recall that humans have forty six chromosomes. That’s what number chromosomes most body cells in your body have. however there ar some human cells that don’t have forty six chromosomes. 

Human sperm cell cells and egg cells have twenty three chromosomes. Why the quantity difference? Well, if a spermatozoan has twenty three chromosomes and an ovum has twenty three chromosomes after they move that creates forty six chromosomes. which will enable a new shaped embryo to grow to be a person's.

 Meiosis is what we tend to decision a discount division as a result of you've got a beginning cell that has46 chromosomes and your ending cells---the sperm cell and egg cells---have solely had twenty three chromosomes. Before we tend to begin moving into the stages of meiosis to form gametes, we've got to recollect what happens before meiosis will begin. Actually, this additionally happens before cellular division. It’s the stage called interphase. If you keep in mind interphase, it’s once the cell is growing, it’s replicating its desoxyribonucleic acid,it’s effecting cell processes.

 a bit like cellular division, interphase happens before meiosis goes to begin. therefore the beginning cell has forty six chromosomes, and you've got to duplicate those chromosomes in interphase before meiosis starts. That essentially suggests that you’re duplicating your desoxyribonucleic acid, since chromosomes ar made from desoxyribonucleic acid and supermolecule. prepared for the difficult part?

 Because we tend to tend to count chromosomes by the quantity of centromeres gift, once the 46 chromosomes duplicate, we tend to still say there ar forty six chromosomes as a result of the sister chromatids ar still connected and we’re investigation by centromeres. thus forty six chromosomes here, they replicate in interphase, and you continue to have forty six chromosomes during this image. however you went from forty six to ninety two chromatids. very little difficult there. 

meiosis overview 

Ok thus interphase listing done---now we are able to move in meiosis. you may keep in mind the cellular division stages PMAT; the ‘p’ was for prophase, the ‘m’ for metaphase, the ‘a’ for phase of cell division, and therefore the ‘t’ for telophase. the nice news is that in meiosis, you continue to use those terms, however as a result of meiosis is really a discount division, you’re going from forty six chromosomes to twenty three. which implies you truly divide double. thus rather than cellular division wherever you divide just once and do PMAT just once, in meiosis, you are going to divide double and so do PMAT double.

 attributable to this, in meiosis, you place numbers when the phases to point whether or not you’rein the primary division or the second division. thus let’s dive right in. thus let’s begin with the terribly opening move – prophase I. One issue i favor to recollect concerning prophase is “pro,” this really suggests that “before.”It quite helps you keep in mind that it comes before all the opposite stages begin. this is often wherever the chromosomes ar getting to condense and thicken.

 they're really getting to line up with their homologous pairs. The word homologous means the chromosomes ar about an equivalent size which they contain an equivalent forms of genes within the same locations. they're getting to match up. it's throughout this prophase one that this superb method happens known as organic process.

 i do know organic process in all probability looks like one thing terribly totally different, however this is often a extremely awful method as a result of once these chromosomes ar lined up in homologous pairs, they need the simplest way that they'll transfer their genetic info and exchange it between one another. It’s quite like these chromosomes flop over one another and that they do a touch genetic info exchange here. It makes for what we tend to call---recombinant chromosomes---which will eventually contribute to the variability that we tend to were mentioning that siblings will have even after they have an equivalent folks. additional this later.

meiosis stages

Now we tend to go into metaphase I - In metaphase I, assume if the M as standing for middle. The chromosomes area unit about to be within the middle of the cell. It’s a bit totally different, though, from cell division as a result of they’re still about to be in pairs within the middle of the cell thus it’s not one file line; they're in pairs within the middle. throughout phase of cell division I, assume A for away as a result of the chromosomes area unit about to be force away by the spindle fibres. Then, we tend to finish with telophase I, wherever you have got 2 freshly fashioned nuclei and it becomes obvious you'll finish meiosis one with 2 new cells.

 biological process follows with cacophonous the living substance. however we’re not done nevertheless. On to meiosis 2!The terribly opening move in meiosis II is prophase II. It’s not about to be nearly as eventful because it was in prophase I as a result of they're not about to have homologous pairs. They are also not about to have that incredible method known as crossing-over. That doesn’t happen once more in prophase II.

 you have got your chromosomes and therefore the spindles getting down to type like in prophase I however prophase II isn't nearly as eventful of getting that method of biological process. In metaphase II, bear in mind assume m for middle, the chromosomes area unit about to line up within the middle. This time, though, they're in a very line line. they're not in pairs like they were in metaphase I. phase of cell division II, bear in mind A for away, however this point it’s the chromatids that are becoming force away by the spindle fibres. Chromatids are becoming force away to opposite sides of the cell.

In telophase II, nuclei reform and therefore the a pair of cells area unit every about to divide thus you'll see here that four cells area unit about to be fashioned. biological process can follow to fully split the living substance. currently detain mind that meiosis in males produces spermatozoan cells and in females, it produces egg cells. as a result of freelance assortment and additionally biological process, you’re about to have selection. for instance, in a very male the four sperms cells that area unit created every time, they're all totally different from one another.

 they're additionally totally different from the beginning cell as a result of the beginning cell had forty six chromosomes and therefore the ending cells solely have twenty three. so that they aren't similar to the initial and that they aren't similar to one another. this is often about to cause a spread. A reason why 2 siblings with constant folks will look totally different from every other---they still developed from distinctive|a singular|a novel} egg and unique spermatozoon that came along.

 One last item to rely on. Scientists area unit typically wanting into the method of meiosis as a result of generally the chromosomes do not separate properly. It’s known as miosis once a cell will receive too several or too few chromosomes within the separation. This contributes to some genetic disorders, that are a few things scientists still study.