Evolution of sexual reproduction

Evolution of sexual reproduction

Aphytis mytilaspidis

Parthenogenesis

Evolution of sexual reproduction

Thelytoky

Muscidifurax uniraptor

Ploidy

Reproduction

Sexual reproduction

Thelytoky

Talk:Ploidy

Genetic purging

Selfish genetic element

Glossary of biology

Karyotype

Haploidy1

• This process helps alternating haploidy with diploidy. (differencebetween.net)

Recombination16

• Synchronized meiosis and recombination in fission yeast: observations with pat1-114 diploid cells. (ucl.ac.uk)
• Commitment to recombination and to meiosis have been timed at 2 h after meiotic induction. (ucl.ac.uk)
• We have distinguished three factors that influence intragenic recombination frequencies: temperature, azygotic versus zygotic meiosis, and the nature of the pat1 allele. (ucl.ac.uk)
• While meiosis almost certainly evolved from mitosis, it has not one but four novel steps: the pairing of homologous chromosomes, the occurrence of extensive recombination between non-sister chromatids during pairing, the suppression of sister-chromatid separation during the first meiotic division, and the absence of chromosome replication during the second meiotic division. (genetics.org)
• Meiosis assures genetic variation by regulated genetic exchange through homologous recombination (HR). HR is initiated by formation of numerous DNA double strand breaks (DSBs). (ipk-gatersleben.de)
• The fission yeast Schizosaccharomyces pombe is a useful model organism to study the mechanisms that regulate processes that occur during meiosis (e.g. recombination, chromosome behavior, and sporulation) because it synchronously enters meiosis and can be easily manipulated by a variety of genetical and cell biological techniques. (biologists.org)
• Simulation of quadrivalent meiosis results as expected in double reduction and recombination between more than two hom(oe) ologous chromosomes. (wur.nl)
• You need to be precise in your definition of recombination in the exam question if what you mean is crossing over between parental alleles in meiosis. (blogspot.co.uk)
• Recombination at meiosis occurs blindly, chancing new gene combinations in offspring, while recombinant offspring is not necessarily selected for [ 1 ]. (royalsocietypublishing.org)
• recombination deficient mutants lack crossovers and suffer meiosis I nondisjunction. (biomedcentral.com)
• Rec12 is a 345 amino acid protein required for most crossover recombination and for chiasmatic segregation of chromosomes during meiosis I. Rec12 also participates in a backup distributive (achiasmatic) system of chromosome segregation during meiosis I. In addition, catalytically-active Rec12 mediates some signal that is required for faithful equational segregation of chromosomes during meiosis II. (biomedcentral.com)
• During meiosis homologous chromosomes replicate, pair to form a "bivalent," experience a high rate of recombination, and undergo two rounds of chromosome segregation to produce haploid meiotic products. (biomedcentral.com)
• We address these issues by investigating two processes in early meiosis: 1) how chromosomes monitor their own behavior during prophase and determine if they are synapsed and 2) how chromosomes are restructured around the recombination event to prepare for chromosome segregation. (ucsc.edu)
• Results show that this evolution is better described as a network of interactions between possible sexual forms, including diploidy, thelytoky, facultative sex, assortation, bisexuality, and division of labor between the sexes, rather than a simple transition from parthenogenesis to sexual recombination. (springer.com)
• Unlike in sexuals that incorporate recombination and segregation during meiosis and the union of the sex cells with unique genetic materials, pure asexuals do not go through these processes. (biologyonline.com)
• A key adaptation involves chromosome pairing and recombination during meiosis. (plantcell.org)

Undergo8

• ORGANISMS that undergo sexual reproduction utilize a specialized cell cycle, meiosis, to generate haploid gametes. (genetics.org)
• For a diploid (2n) sporophyte to produce haploid (n) spores, the cells have to undergo meiosis. (differencebetween.net)
• During meiosis, diploid cells undergo one round of DNA replication followed by two successive chromosome segregation rounds, producing haploid gametes to maintain somatic diploidy following their fusion (Fig 1). (ipk-gatersleben.de)
• C. albicans is naturally diploid, unable to undergo meiosis, and utilizes a non-canonical genetic code. (elsevier.com)
• In brief, we crossed the cotransformed yeast cell with a non-YAC-containing strain and induced the resulting diploid to sporulate and undergo meiosis. (ox.ac.uk)
• These cells do not undergo meiosis, but just mitosis and this form of parthenogenesis is called apomictic parthenogenesis . (keepinginsects.com)
• The diploid zygotes undergo meiosis, producing haploid nuclei that will be integrated into the spores. (tripod.com)
• Process in which cells undergo meiosis to form gametes. (springer.com)

Fertilization8

• Fusion of gametes at fertilization reconstitutes diploidy. (nih.gov)
• 1998) in which haploid eggs /gametes are produced by meiosis but diploidy restored without fertilization (but sometimes with insemination). (marlin.ac.uk)
• Precise partitioning of the genome in meiosis is essential so that diploidy is reestablished upon fertilization, which is critical for embryonic development ( H assold and H unt 2001 ). (genetics.org)
• Sex in eukaryotes is a composite process, consisting of meiosis and fertilization (or, more generally, 'mixis', the process of fusion of cells and nuclei), which can be coupled to reproduction [ 3 ]. (royalsocietypublishing.org)
• This definition can be relaxed to also include autogamy (self-fertilization), which must be seen as a derived trait, retaining meiosis. (royalsocietypublishing.org)
• Production of offspring by meiosis, gamete formation, and fertilization. (cram.com)
• During this specialized cell division, diploid cells give rise to haploid gametes, such as sperm and eggs, so that diploidy is restored by fertilization. (ucsc.edu)
• each pronucleus normally carries a haploid set of chromosomes, so that the merging of the pronuclei in fertilization reestablishes diploidy. (thefreedictionary.com)

Polyploidy1

• Polyploidy permits cells to reach higher rates of transcription per nucleus but precludes a return to diploidy. (springer.com)

Homologous chromosomes pair2

• recombinational DNA repair (promoted during meiosis because homologous chromosomes pair at that time) and complementation (also known as heterosis , hybrid vigor or masking of mutations). (wikipedia.org)
• Early in meiosis, homologous chromosomes pair, synapse and recombine with their unique partner. (ucsc.edu)

Aneuploidy3

• This finding suggests that in rats the peripheral blood micronucleus assay is a less sensitive indicator for the genotoxic potential of CARB than the epididymal sperm aneuploidy/diploidy assay. (biomedsearch.com)
• The XY variant prevailed in gonosomal aneuploidy and diploidy and was associated with abnormal chromosomal segregation in meiotic anaphase I. The contribution of human sperm chromosomal imbalance to early embryonic lethality and to some forms of chromosomal abnormalities in the off-spring is discussed. (deepdyve.com)
• Tetraploidy can constitute a metastable intermediate between normal diploidy and oncogenic aneuploidy. (embopress.org)

Diploid cells1

• Diploid cells divide into haploid cells in a process called meiosis . (wikipedia.org)

Alleles5

• If meiosis occurs, the offspring will get only a fraction of the mother's alleles since crossing over of DNA takes place during meiosis, creating variation. (wikipedia.org)
• We characterized female-sterile alleles of the condensin complex component dcap-g and used them to define roles for condensin in Drosophila female meiosis. (genetics.org)
• Diploidy is a problem because obtaining a phenotype for a recessive mutation requires engineering the mutation in both alleles of a gene. (sciencemag.org)
• Does it refer to the new mixtures of alleles in germline cells produced during meiosis? (blogspot.co.uk)
• Having two copies of every gene, only one of which is expressed , allows deleterious alleles to be masked, an advantage believed to have led to the evolutionary development of diploidy (Otto and Goldstein). (bionity.com)

Female meiosis4

• In most animal species, chromosome segregation during female meiosis occurs on spindles assembled in the absence of the major microtubule-organizing center, the centrosome. (nih.gov)
• In contrast, information about female meiosis in scorpions is scarce due to the difficulty of finding meiotic cells. (springer.com)
• We discuss the possible origin of these bivalents in the framework of chiasmatic or achiasmatic female meiosis. (springer.com)
• These results contribute to increase the scarce evidence of female meiosis in scorpions and raise new questions about its mechanism. (springer.com)

Segregation8

• Acentrosomal spindle assembly and chromosome segregation during oocyte meiosis. (nih.gov)
• The existence of both pathways may provide a fail-safe mechanism to ensure high fidelity of chromosome segregation during meiosis. (deepdyve.com)
• In meu14 Δ cells, the segregation and modification of the SPBs (spindle pole bodies) and microtubule elongation during meiosis II were aberrant. (biologists.org)
• Rescue of a single yeast artificial chromosome from a cotransformation event utilizing segregation at meiosis. (ox.ac.uk)
• We present a simple method to rescue the required YAC that utilizes the segregation of chromosomes at meiosis. (ox.ac.uk)
• The rec12-117 and rec12-D15 mutants manifest segregation errors during both meiosis I and meiosis II. (biomedcentral.com)
• Remarkably, the rec12-Y98F (active site) mutant exhibited essentially normal meiosis I segregation patterns, but still exhibited meiosis II segregation errors. (biomedcentral.com)
• All of these events are required for the proper segregation of chromosomes during meiosis. (ucsc.edu)

Prophase1

• Meiosis consists of an extended prophase I (leptotene, zygotene, pachytene, diplotene and diakinesis) during which meiotic chromosome axis, synaptonemal complex (SC) and crossover (CO)-formation take place. (ipk-gatersleben.de)

Gamete3

• Presence of only half of the parental number of chromosomes in a spore or gamete, as brought about by meiosis. (cram.com)
• Meiosis in the parents' gonads produce gamete cells which only contain 23 chromosomes each. (wikipedia.org)
• begingroup$ @chris I think that this question means the OP doesn't know of diploidy and assumes that a more or less random half of the chromosomes present in a normal cell end up in a gamete. (stackexchange.com)

Oocyte5

• In mammals, oocyte meiosis is error prone and underlies most birth aneuploidies. (nih.gov)
• Here, we review recent work on acentrosomal spindle formation and chromosome alignment/separation during oocyte meiosis in different animal models. (nih.gov)
• Haineman RZ, Hughes RD (1970) Reproduction, reproductive organs and meiosis in the bisexual non-parthenogenetic mite Caloglyphus mycophagus , with reference to oocyte degeneration in virgins. (springer.com)
• We used the QA26 allele of passenger component incenp to investigate the role of the passenger complex in oocyte meiosis. (genetics.org)
• After two PGD treatment cycles and two natural pregnancies, information was available on 12 meioses, none of which produced an oocyte with a single intact chromosome 22. (biomedcentral.com)

Doubling of the chromosomes1

• Diploidy might be restored by the doubling of the chromosomes without cell division before meiosis begins or after meiosis is completed. (wikipedia.org)

Frequencies1

• Although the absolute frequencies of diploidy were low, ranging from 0.03% in the control group to 0.22% in the highest dose group, the observed dose-response relationship was highly significant. (biomedsearch.com)

Undergoes meiosis1

• At the advent of favorable growing season, the zygospore nucleus undergoes meiosis to form meiospores which germinate to give rise to a new haploid plant. (botanystudies.com)

Stage of meiosis2

• After the first stage of meiosis, the pronucleus fuses with its sister polar nucleus, thus restoring the correct number of chromosomes. (wikipedia.org)
• First stage of meiosis II. (cram.com)

Sperm and eggs1

• Mules, hinnies, and other normally sterile interspecific hybrids cannot produce viable gametes because the extra chromosome cannot make a homologous pair at meiosis , meiosis is disrupted, and viable sperm and eggs are not formed. (newworldencyclopedia.org)

Eggs3

• In this case the female produces normal haploid eggs through meiosis, but in one of various way diploidy is restored. (keepinginsects.com)
• Worker-laid Cape honey bee eggs yielding females, instead of actually being fertilised, have their diploidy restored during a modified meiosis II. (beeaware.org.au)
• Meiosis is the process that halves the genetic content and produce haploid eggs and sperm. (stackexchange.com)

Genetics1

• Genetic control of chromosome synapsis at meiosis in Rye Secale cereale L.: the sy19 gene controlling heterologous synapsis," Russian Journal of Genetics , vol. 37, no. 1, pp. 71-79, 2001. (hindawi.com)

Parthenogenesis3

• Many other cases of obligate parthenogenesis (or gynogenesis) are found among polyploids and hybrids where the chromosomes cannot pair for meiosis. (wikipedia.org)
• Parthenogenesis involving meiosis is more complicated. (wikipedia.org)
• In other cases, collectively called automictic parthenogenesis, the ploidy is restored to diploidy by various means. (wikipedia.org)

Pronucleus1

• Concurrent with sperm fusion, meiosis is reinitiated from metaphase I arrest, polar bodies form, and the female pronucleus develops. (thefreedictionary.com)

Ploidy2

• Gametes are formed by the process of meiosis in which, after a single round of replication, two successive cell divisions reduce the ploidy of the genome. (nih.gov)
• You can also try reading en.wikipedia.org/wiki/Ploidy , but I admit the language will be hard for somebody who is not a native speaker of English and does not know much biology. (stackexchange.com)

Chromosomes is reduced2

• In all cases reproduction consists of a basic pattern: the conversion by a parent organism of raw materials from the environment into offspring-or into cells that develop into offspring (see meiosis meiosis , process of nuclear division in a living cell by which the number of chromosomes is reduced to half the original number. (thefreedictionary.com)
• In the first stage of sexual reproduction, "meiosis", the number of chromosomes is reduced from a diploid number (2n) to a haploid number (n). (wikipedia.org)

Sister chromatids1

• In meiosis I (MI) homologous chromosomes segregate from their partners in a reductional division, and during meiosis II (MII) sister chromatids segregate from one-another in an equational division similar to mitosis. (biomedcentral.com)

Cell11

• Nuclear dispositions of subtelomeric and pericentromeric chromosomal domains during meiosis in asynaptic mutants of rye ( Secale cereale L.)," Journal of Cell Science , vol. 114, no. 10, pp. 1875-1882, 2001. (hindawi.com)
• During this amitotic division, the internal repair mechanism of a cell restores the damaged parts of DNA to normalcy and when the damage is irreparable kills the cell thus preventing abnormalities from being carried to the next generations, thus giving adaptive advantage in favour of meiosis(1). (differencebetween.net)
• Transcription of meu14 + is induced abruptly after the cell enters meiosis. (biologists.org)
• We are interested in the mechanisms that ensure that chromosomes segregate correctly during cell division, particularly in meiosis. (ucsc.edu)
• Between fertilisation and meiosis there can be a large number of cell divisions without change of the number of chromosomes. (wikipedia.org)
• Thanks to the used selection cassette, these cells can be easily corrected to diploidy, which provides closely matched control cell lines. (embopress.org)
• 31)If at the end of meiosis, the four daughter cells have four chromosomes, how many chromosomes were in mother cell? (thegeneralknowledge.in)
• Aneuploidies During meiosis one of the chromosome pairs does not separate so two copies go to one cell and the other inherits nothing. (studystack.com)
• Results from RNA interference experiments indicate that at least one of these kinases is required for cell-cycle progression during meiosis and mitosis. (biologists.org)
• The cell division which produces sperm or ova in the testis or ovary is known as meiosis. (geneticalliance.org.au)
• Mating and meiosis - the specialized cell division that reduces the number of chromosomes in a cell - are related, but in most yeasts they are regulated separately. (shamskm.com)

Nucleus1

• The diploid nucleus proceeds directly to meiosis and the production of a four-spored ascus. (microbiologyresearch.org)

Mutation2

• The mutation pat1-114 has been used to synchronize meiosis in the fission yeast Schizosaccharomyces pombe. (ucl.ac.uk)
• 1. Diploidy - protects against effects of mutation. (brainscape.com)

Investigate1

• It allows to generate data for tetraploid and diploid populations, and to investigate different models of tetraploid meiosis. (wur.nl)

Molecular2

• Finally, we review the evidence that much of the molecular machinery required for the initial forms of homolog pairing probably existed in proto-eukaryote unicellular forms prior to the evolution of meiosis and therefore could have been readily "recruited" for the new role. (genetics.org)
• We combine genetic and biochemical approaches with high-resolution microscopy and cytological techniques to gain a more informed view of how molecular events during meiosis govern and are governed by higher-order chromosome behavior. (ucsc.edu)

Salivary glands1

• Sexual reproduction takes place in the salivary glands (SG) of the tsetse vector and involves meiosis and production of haploid gametes. (biomedcentral.com)

Nuclear division1

• Taken together, we conclude that meu14 + is crucial in meiosis in that it participates in both the nuclear division during meiosis II and the accurate formation of the forespore membrane. (biologists.org)

Produces1

• Mitosis instead of Meiosis (MIME) produces diploid gametes that is identical with the maternal genetic composition and is a key step in the artificial creation of apomixes. (bvsalud.org)

Achiasmatic2

• All cytogenetically studied scorpions present male achiasmatic meiosis and lack heteromorphic sex chromosomes. (springer.com)
• Debus B (1978) "Nodules" in the achiasmatic meiosis of Bithynia (Mollusca, Prosobranchia). (springer.com)

Absence2

• The lack of meiosis coupled with the absence of plasmids makes genetic engineering cumbersome, especially for essential functions and gene families. (sciencemag.org)
• Makrantoni v, friedman kl, because the absence of the fidelity of the levels in meiosis 68. (stgeorgeleader.com)

Generate1

• Defects in meiosis can generate gametes, and therefore embryos, with the incorrect number of chromsomes. (ucsc.edu)