Cellular division questions (practice) | Khan Academy
In most sexually reproducing organisms, somatic cells are diploid, containing two copies of each chromosome, while the sex cells are haploid, having one copy. a), Mitosis produces cells that have a haploid number of chromosomes. b), Meiosis produces cells that have a diploid number of chromosomes. c), Meiosis. Start studying Quiz Notes - Mitosis vs Meiosis. Somatic (body cells) are (diploid /haploid) (2N/1N)?. diploid 2N Mitosis: Cell type of parent cell (diploid/haploid )?. diploid Mitosis: Genetic relationship of daughter cells to one another?.
The 46 chromosomes of a human cell are organized into 23 pairs, and the two members of each pair are said to be homologues of one another with the slight exception of the X and Y chromosomes; see below. Human sperm and eggs, which have only one homologous chromosome from each pair, are said to be haploid 1n.
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When a sperm and egg fuse, their genetic material combines to form one complete, diploid set of chromosomes. So, for each homologous pair of chromosomes in your genome, one of the homologues comes from your mom and the other from your dad.
Image of the karyotype of a human male, with chromosomes from the mother and father false-colored purple and green, respectively. Image modified from " Karyotype ," by the National Institutes of Health public domain.
The two chromosomes in a homologous pair are very similar to one another and have the same size and shape. Most importantly, they carry the same type of genetic information: However, they don't necessarily have the same versions of genes.
That's because you may have inherited two different gene versions from your mom and your dad. It's possible for a person to have two identical copies of this gene, one on each homologous chromosome—for example, you may have a double dose of the gene version for type A. On the other hand, you may have two different gene versions on your two homologous chromosomes, such as one for type A and one for type B giving AB blood. The sex chromosomes, X and Y, determine a person's biological sex: XX specifies female and XY specifies male.
These chromosomes are not true homologues and are an exception to the rule of the same genes in the same places. Aside from small regions of similarity needed during meiosis, or sex cell production, the X and Y chromosomes are different and carry different genes.
The 44 non-sex chromosomes in humans are called autosomes. Chromosomes and cell division Image of a cell undergoing DNA replication all the chromosomes in the nucleus are copied and chromosome condensation all the chromosomes become compact.
In the first image, there are four decondensed, stringy chromosomes in the nucleus of the cell. After DNA replication, each chromosome now consists of two physically attached sister chromatids.
After chromosome condensation, the chromosomes condense to form compact structures still made up of two chromatids.
As a cell prepares to divide, it must make a copy of each of its chromosomes. The two copies of a chromosome are called sister chromatids. The sister chromatids are identical to one another and are attached to each other by proteins called cohesins. The attachment between sister chromatids is tightest at the centromere, a region of DNA that is important for their separation during later stages of cell division.
As long as the sister chromatids are connected at the centromere, they are still considered to be one chromosome. Parthenogenesis can operate on either a haploid or a diploid cell. In haploid parthenogenesis, a rare form of parthenogenesis that occurs in a few species of bees, nematodes, and plants, offspring develop from haploid eggs to produce haploid adults.
On the other hand, the process of diploid parthenogenesis, a more common and varied form of the phenomenon, may proceed along two pathways.
Automixis automictic parthenogenesis is a postmeiotic process in which a haploid cell may either duplicate its chromosomes or join with another haploid cell. In both cases, diploid zygotes develop and grow into diploid adults. Such organisms are not true clones of the mother, however, because the meiotic process separates and recombines the genetic material.
A second form of diploid parthenogenesis, apomixis apomicitic parthenogenesisforgoes complete meiosis altogether. Instead, two genetically identical diploid egg cells are produced from a parent cell through mitosis the process of cell duplicationand one or more of these daughter cells, which are both diploid and clones that is, genetically identical of the original parent cell, develop into a diploid offspring.
Diploid vs. Haploid: Similarities and Differences
Diploid parthenogenesis occurs in insects such as aphids as well as in some rotifers and flowering plants see animal reproductive system and plant reproductive system. Autopolyploidy means that more than two haploid chromosome sets of the same species are present; this can occur as a result of incomplete segregation in meiosis, or if two sperm cells fertilize the same egg cell.
Allopolyploidy results when the parent cells are not of the same species, resulting in a daughter cell containing a complete diploid chromosome set from each parent cell. An example of this is a mule, which is a cross between a horse and a donkey.
- Chromosome number
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Such organisms are usually sterile. The result of these events is aneuploidy or a cell that does not contain a diploid chromosome number. This is the basis of many genetic diseases, such as Down syndrome resulting from trisomyor Edwards syndrome also resulting from trisomy. The full chromosome set of a woman with Down syndrome. Trisomy occurs on the 21st chromosome. Wikimedia Commons Other abnormalities in chromosome sets include a change in the arrangement of the chromosomal set.
A deletion of part of a chromosome, in humans, can lead to diseases such as cri du chat syndrome; a repetition of part of a chromosome resulting from unequal crossing over of genetic material during meiosis.
Inversions of gene sequences, translocations of chromosome segments, can result in familial Down syndrome in humans; and fragile sites in chromosomes, such as Martin-Bell syndrome in humans, a common cause of mental retardation.
What is the Difference Between Haploid and Diploid? What Does it Mean? A haploid chromosome set occurs in eukaryotes when a sex cell or gamete is produced. This cell contains half of the genetic material, or chromosomes, of its parent cell.
A diploid chromosome set occurs in most eukaryotes in somatic cells — that is, non-sex cells. These cells contain the entire set of genetic material, or chromosomes, of the organism, or double the haploid chromosome set. Thus, the entire gene set of an organism is located in every cell of that organism.
The depiction of the diploid chromosome set of an organism is known as a karyotype. The karyotype is organized by the order of the size of the chromosomes and the location of the centromere. Karyotype of a human male, showing a diploid chromosome number of Wikimedia Commons Wrapping Up Haploid vs.
Diploid Diploid and haploid cells and organisms occur in nature. The differences between haploid and diploid chromosome sets are in the number of chromosomes present, and in the types of cells in which they occur. Haploid cells contain half the chromosome count of diploid cells, and are mostly germ cells, whereas diploid cells are somatic cells.
Some organisms have a haploid and a diploid life cycle, such as algae. Diploid cells reproduce via mitosis creating daughter cells identical to the parent cells and each other.