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A yeast meiocyte that is undergoing meiosis must pass through a number of checkpoints in order to complete the cell cycle. [3] If a meiocyte divides and this division results in a mutant cell, the mutant cell will undergo apoptosis and, therefore, will not complete the cycle. [3]
[6] [7] [8] There are almost invariably only two gamete types, all analyses showing that intermediate gamete sizes are eliminated due to selection. [9] [10] Since intermediate sized gametes do not have the same advantages as small or large ones, [11] they do worse than small ones in mobility and numbers, and worse than large ones in supply. [12]
Gametes are produced within the gonads through a process known as gametogenesis. This occurs when certain types of germ cells undergo meiosis to split the normal diploid number of chromosomes (n=46) into haploid cells containing only 23 chromosomes. [10] Anatomy of the testis
Two single-celled haploid gametes, each containing n unpaired chromosomes, fuse to form a single-celled diploid zygote, which now contains n pairs of chromosomes, i.e. 2n chromosomes in total. [ 17 ] The single-celled diploid zygote germinates, dividing by the normal process ( mitosis ), which maintains the number of chromosomes at 2 n .
The abbreviation is not always a short form of the word used in the clue. For example: "Knight" for N (the symbol used in chess notation) Taking this one stage further, the clue word can hint at the word or words to be abbreviated rather than giving the word itself. For example: "About" for C or CA (for "circa"), or RE.
Automixis [1] is the fusion of (typically haploid) nuclei or gametes derived from the same individual. [2] The term covers several reproductive mechanisms, some of which are parthenogenetic. [3] Diploidy might be restored by the doubling of the chromosomes without cell division before meiosis begins or after meiosis is completed.
Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes.Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitosis.
Anisogamy is the form of sexual reproduction that involves the union or fusion of two gametes which differ in size and/or form. [12] The smaller gamete is considered to be male (a sperm cell), whereas the larger gamete is regarded as female (typically an egg cell, if non-motile).