In the octaploid wheat, the haploid(n) and basic number(x) of chromosomes are
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Ploidy (/ˈplɔɪdi/) is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes.
Somatic cells, tissues and individuals can be described according to the number of sets present (the ploidy level): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploin] or septaploid[ (7 sets), etc. The generic term polyploid is used to describe cells with three or more chromosome sets.] Half of all known plant genera contain polyploid species, and about two thirds of all grasses are polyploid.[6] In mammals and birds, ploidy changes are typically fatal. There is, however, evidence of polyploidy in organisms now considered to be diploid, suggesting that polyploidy has contributed to evolutionary diversification in plants and animals through successive rounds of polyploidization and rediploidization.[
Humans are diploid organisms, carrying two complete sets of chromosomes: one set of 23 chromosomes from their father and one set of 23 chromosomes from their mother. The two sets combined provide a full complement of 46 chromosomes. This total number of chromosomes is called the chromosome number.
The number of chromosomes found in a single complete set of chromosomes is called the monoploid number (x). In most animals, the haploid number (n) is unique to gametes(sperm or egg cells), and refers to the total number of chromosomes found in a gamete, which under normal conditions is half the total number of chromosomes in a somatic cell.
The haploid number for humans (half of 46) is 23; and the monoploid number equals 46 divided by the ploidy level of 2, which is also 23. When a human germ cell undergoes meiosis, the two sets of 23 chromosomes are split in half to form gametes. After fusion of a male and a female gamete (fertilization) both containing 1 set of 23 chromosomes, the resulting zygote has 46 chromosomes: 2 sets of 23 chromosomes (22 autosomes, and 1 allosome).
The common potato (Solanum tuberosum) is an example of a tetraploid organism, carrying four sets of chromosomes. The potato plant inherits two sets of 12 chromosomes from the pollen parent, and two sets of 12 chromosomes from the ovule parent. The four sets combined provide a full complement of 48 chromosomes. The haploid number (half of 48) is 24. The monoploid number equals the chromosome number divided by the ploidy level: 48 chromosomes in total divided by a ploidy level of 4 equals a monoploid number of 12.
The commercial common potato crop is propagated vegetatively (asexual reproduction through mitosis),] in which case new individuals are produced from a single parent, without the involvement of gametes and fertilization, and all the offspring are genetically equal to each other and to the parent.
Examples of species with x=11PloidyNumber of chromosomesSpeciesDiploid2n = 2x = 22EucalyptusTriploid2n = 3x = 33BananaTetraploid2n = 4x = 44Coffea arabicaHexaploid2n = 6x = 66Sequoia sempervirensOctoploid2n = 8x = 88Opuntia ficus-indica
Because the chromosome number is generally reduced only by the specialized process of meiosis, the somatic cells of the body inherit and maintain the chromosome number of the zygote. However, in many situations somatic cells double their copy number by means of endoreduplication as an aspect of cellular differentiation. For example, the hearts of two-year-old children contain 85% diploid and 15% tetraploid nuclei, but by 12 years of age the proportions become approximately equal, and adults examined contained 27% diploid, 71% tetraploid and 2% octaploid nuclei.
When a germ cell with an uneven number of chromosomes undergoes meiosis, the chromosomes can't be evenly divided between two cells resulting in aneuploidgametes. Triploid organisms for instance are usually sterile. Because of this, triploidy is a common way of making seedless fruit such as bananas and watermelons. If the fertilization of human gametes results in three sets of chromosomes the condition is called triploid syndrome.
Somatic cells, tissues and individuals can be described according to the number of sets present (the ploidy level): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploin] or septaploid[ (7 sets), etc. The generic term polyploid is used to describe cells with three or more chromosome sets.] Half of all known plant genera contain polyploid species, and about two thirds of all grasses are polyploid.[6] In mammals and birds, ploidy changes are typically fatal. There is, however, evidence of polyploidy in organisms now considered to be diploid, suggesting that polyploidy has contributed to evolutionary diversification in plants and animals through successive rounds of polyploidization and rediploidization.[
Humans are diploid organisms, carrying two complete sets of chromosomes: one set of 23 chromosomes from their father and one set of 23 chromosomes from their mother. The two sets combined provide a full complement of 46 chromosomes. This total number of chromosomes is called the chromosome number.
The number of chromosomes found in a single complete set of chromosomes is called the monoploid number (x). In most animals, the haploid number (n) is unique to gametes(sperm or egg cells), and refers to the total number of chromosomes found in a gamete, which under normal conditions is half the total number of chromosomes in a somatic cell.
The haploid number for humans (half of 46) is 23; and the monoploid number equals 46 divided by the ploidy level of 2, which is also 23. When a human germ cell undergoes meiosis, the two sets of 23 chromosomes are split in half to form gametes. After fusion of a male and a female gamete (fertilization) both containing 1 set of 23 chromosomes, the resulting zygote has 46 chromosomes: 2 sets of 23 chromosomes (22 autosomes, and 1 allosome).
The common potato (Solanum tuberosum) is an example of a tetraploid organism, carrying four sets of chromosomes. The potato plant inherits two sets of 12 chromosomes from the pollen parent, and two sets of 12 chromosomes from the ovule parent. The four sets combined provide a full complement of 48 chromosomes. The haploid number (half of 48) is 24. The monoploid number equals the chromosome number divided by the ploidy level: 48 chromosomes in total divided by a ploidy level of 4 equals a monoploid number of 12.
The commercial common potato crop is propagated vegetatively (asexual reproduction through mitosis),] in which case new individuals are produced from a single parent, without the involvement of gametes and fertilization, and all the offspring are genetically equal to each other and to the parent.
Examples of species with x=11PloidyNumber of chromosomesSpeciesDiploid2n = 2x = 22EucalyptusTriploid2n = 3x = 33BananaTetraploid2n = 4x = 44Coffea arabicaHexaploid2n = 6x = 66Sequoia sempervirensOctoploid2n = 8x = 88Opuntia ficus-indica
Because the chromosome number is generally reduced only by the specialized process of meiosis, the somatic cells of the body inherit and maintain the chromosome number of the zygote. However, in many situations somatic cells double their copy number by means of endoreduplication as an aspect of cellular differentiation. For example, the hearts of two-year-old children contain 85% diploid and 15% tetraploid nuclei, but by 12 years of age the proportions become approximately equal, and adults examined contained 27% diploid, 71% tetraploid and 2% octaploid nuclei.
When a germ cell with an uneven number of chromosomes undergoes meiosis, the chromosomes can't be evenly divided between two cells resulting in aneuploidgametes. Triploid organisms for instance are usually sterile. Because of this, triploidy is a common way of making seedless fruit such as bananas and watermelons. If the fertilization of human gametes results in three sets of chromosomes the condition is called triploid syndrome.
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In the octoploid wheat, the haploid (
) and basic number (
) of chromosomes are 
and 
respectively.
Explanation:
- Ploidy of an organism is the sets of the same chromosomes contained in its genome.
- Thus, the ploidy may vary while the number of chromosomes of a set (the basic chromosome number) stays the same for a species, generally.
- Whereas, a haploid set of chromosomes is just the half number of chromosomes originally contained in the genome. This can vary from organism to organism.
- Therefore, the haploid chromosome number of octoploid wheat is
whereas, the basic chromosome number
.
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