- Nuclear equivalence
According to the principle of nuclear equivalence , the nuclei of essentially all differentiated adult cells of an individual are genetically though not necessarily metabolically identical to one another and to the nucleus of the zygote from which they descended. This means that virtually all somatic cells in an adult have the same genes. However, different cells express different subsets of these genes. The evidence for nuclear equivalence comes from cases in which differentiated cells or their nuclei have been found to retain the potential of directing the development of the entire organism. Such cells or nuclei are said to exhibit totipotency . ref cite book last Solomon, Berg, Martin first Eldra, Linda, Diana W. title BIOLOGY, 9th edition year 2011 publisher Brooks Cole isbn 978 1 111 77437 0 pages 370 ref References reflist Uncategorized date April 2012 ... more details
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- Pluriblast
The pluriblast is a Pluripotency pluripotent population of Cell biology cells in the early mammal ian conceptus that is distinct from the trophoblast , and gives rise to the germ layer s of the embryo proper , as well as extraembryonic endoderm and extraembryonic mesoderm . Both the pluriblast and trophoblast arise from the Totipotency totipotent cells of the early conceptus. By definition, the pluriblast does not give rise to trophoblast cells during normal development, although it may retain this potential under experimental conditions. In most eutheria n mammals the pluriblast is termed the inner cell mass , as it forms a mass of cells within the fluid filled blastocyst , bounded by the trophoblast. However in metatherian marsupial mammals, and indeed in a small number of eutherian mammals, the pluriblast forms part of the blastocyst wall and no structure exists that can be described as an inner cell mass. Inner cell mass is thus a morphological term peculiar to the majority of eutherian mammals, whereas pluriblast is a functional term more widely applicable to conserved aspects of mammalian development. References Johnson MH and Selwood L 1996 . Nomenclature of early development in mammals. Reproduction, Fertility and Development. 8 759 764. Category Developmental biology ... more details
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- Archaeocyte
Archaeocytes from Greek language Greek wikt archaios archaios beginning and wikt kytos kytos hollow vessel or amoebocytes are Amoeba amoeboid cells found in Sea sponge sponges . They are Totipotency totipotent and have varied functions depending on the species . Location Archaeocytes are located in the mesohyl , an acellular gelatinous matrix, along with other specialized sponge cells including collencyte s and structural elements called spicule s. They move about within the mesohyl with amoeba like movements performing a number of important functions. Functions Cellular differentiation is an essential function of the archaeocyte. All specialized cells within the sponge have its origins with the archaeocyte. This is especially important in Biological reproduction reproduction as the sex cells of the sponge in sexual reproduction are formed from these amoeboid cells. Similarly in asexual reproduction amoebocytes result in the formation of gemmule s which are cyst like spheres containing more amoebocytes as well as other sponge cells including the phylum specific choanocyte . These cells move within the walls of a sponge and form spicules. References cite book author Tschinkel, Hayward, Mahoney and Felgenhauer year 2000 title An introduction to Animal Diversity edition 5th publisher Pearson Custome Publishing location Boston id ISBN 0 536 61552 7 cite book author C. Hickman Jr., L. Roberts, S. Keen, A. Larson and D. Eisenhour year 2007 title Animal Diversity edition 4th publisher McGraw Hill location New York id ISBN 978 0 07 252844 2 Cell biology stub Category Poriferans Category Cell biology Category Animal cells fr Archaeocytes pl Archeocyt sr ... more details
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- Cell potency
including RNA regulation may play a role in maintaining totipotency at different stages of development ... more details
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- Reprogramming
selfref This article discusses the epigenetic phenomenon for the writing of computer code, see computer programming Reprogramming refers to erasure and remodeling of epigenetic marks, such as DNA methylation , during mammalian development ref Reik . After fertilization some cells of the newly formed embryo migrate to the germinal ridge and will eventually become the germ cells sperm and oocytes . Due to the phenomenon of Genomic Imprinting genomic imprinting , maternal and paternal genomes are differentially marked and must be properly reprogrammed every time they pass through the germline. Therefore, during the process of gametogenesis the primordial germ cells must have their original biparental DNA methylation patterns erased and re established based on the sex of the transmitting parent. After fertilization the paternal and maternal genomes are once again demethylated and remethylated except for differentially methylated regions associated with imprinted genes . This reprogramming is likely required for totipotency of the newly formed embryo and erasure of acquired epigenetic changes. In vitro manipulation of pre implantation embryos has been shown to disrupt methylation patterns at imprinted loci ref Mann and plays a crucial role in cloned animals ref Wrenzycki . Somatic cell nuclear transfer An oocyte can reprogram an adult nucleus into an embryonic state after somatic cell nuclear transfer , so that a new organism can be developed from such cell ref Hochedlinger see also cloning Reprogramming is distinct from development of a somatic epitype ref Lahiri , as somatic epitypes can potentially be altered after an organism has left the developmental stage of life. ref Mathers biology stub References note Reik cite journal author Reik W, Dean W, Walter J title Epigenetic reprogramming in mammalian development journal Science volume 293 issue 5532 pages 1089 93 year 2001 month August pmid 11498579 doi 10.1126 science.1063443 url http www.sciencemag.org cgi pmidlooku ... more details
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- History of plant breeding
crops like sorghum and alfalfa. Molecular genetics and bio revolution Totipotency shown by plants ... more details
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- Plant tissue culture
plants, The method in which totipotency of cells is realized in the form of de novo organogenesis, either ... more details
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- Gene gun
, specialized, tissue cells of an entire plant. This capability of total re generation is called totipotency ... more details
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- Human embryogenesis
to form all of the different cell types in the developing embryo. This cell potency totipotency ... more details
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- Induced pluripotent stem cell
to totipotency or pluripotency an overview of methods. Various methods exist to revert adult somatic cells to pluripotency or totipotency. In the case of totipotency, reprogramming is mediated ... during mitosis, such that nuclear envelope break down occurs, to support reprogramming to totipotency .... No cocktail has been identified to completely reprogram adult cells to totipotency or pluripotency ... more details
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- Callus (cell biology)
is known as totipotency . Regeneration of a whole plant from a single cell allows researchers ... more details
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- Sperm
pp semi indef small yes Other uses File Complete diagram of a human spermatozoa en.svg thumb right 350px Diagram of a human sperm cell The term sperm is derived from the Greek word sperma meaning seed and refers to the male reproductive Cell biology cells . In the types of sexual reproduction known as anisogamy and oogamy , there is a marked difference in the size of the gamete s with the smaller one being termed the male or sperm cell. A uniflagellar sperm cell that is Motility motile is referred to as a spermatozoon , whereas a non motile sperm cell is referred to as a spermatium . Sperm cells cannot divide and have a limited life span, but after fusion with Ovum egg cells during fertilization, a new organism begins developing, starting as a Totipotency totipotent zygote . citation needed date January 2011 Sperm develops in the testicles . Etymology The term sperm probably comes from sperma which in Greek is seed or Latin something sown . Production The spermatozoa of animal s are produced through spermatogenesis inside the male gonad s testicle s via meiosis meiotic division. They are carried out of the male body in a fluid known as semen . Human sperm cells can survive within the female reproductive tract for more than 5 days post coitus. ref Gould JE, Overstreet JW and Hanson FW 1984 Assessment of human sperm function after recovery from the female reproductive tract. Biol Reprod 31,888 894. ref Sperm cells in algal and many plant gametophyte s are produced in male Gametangium gametangia Antheridium antheridia via mitosis mitotic division. In flowering plant s, sperm nuclei are produced inside pollen . citation needed date January 2011 Anatomy File Sperm egg.jpg thumb right 200px Sperm fertilizing a female s egg The sperm cell consists of a head, a midpiece and a tail. The head contains the Cell nucleus nucleus with densely coiled chromatin fibres, surrounded anteriorly by an acrosome , which contains enzymes used for penetrating the female egg. The midp ... more details
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- Inner cell mass
of the mouse embryo lose totipotency after the fifth cleavage division Expression of Cdx2 and Oct4 ... more details
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- Plant evolution
Plant evolution is the subset of evolution ary phenomena that concern plants . Evolutionary phenomena are characteristics of Population biology populations that are described by average s, median s, Frequency distribution distributions , and other Statistics statistical methods. This distinguishes plant evolution from Plant morphology Plant development plant development , a branch of developmental biology which concerns the changes that individuals go through in their lives. The study of plant evolution attempts to explain how the present Biodiversity diversity of plants arose over Geologic time scale geologic time . It includes the study of Mutation genetic change and the consequent Natural selection variation that often results in speciation , one of the most important types of Evolutionary radiation radiation into Taxonomy taxonomic groups called clade s. A description of radiation is called a Phylogenetics phylogeny and is often represented by type of diagram called a phylogenetic tree . Evolutionary trends Differences between plant and animal physiology and reproduction cause minor differences in how they evolve. One major difference is the totipotency totipotent nature of plant cells, allowing them to reproduce asexually much more easily than most animals. They are also capable of polyploidy where more than two chromosome sets are inherited from the parents. This allows relatively fast bursts of evolution to occur, for example by the effect of gene duplication Gene duplication as an evolutionary event gene duplication . The long periods of dormancy that seed plants can employ also makes them less vulnerable to extinction, as they can sit out the tough periods and wait until more clement times to leap back to life. The effect of these differences is most profoundly seen during extinction events. These events, which wiped out between 6 and 62 of terrestrial animal families, had negligible effect on plant families. ref name McElwain2007 cite journal author McElwa ... more details
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- Myelomalacia
because they are Totipotency Totipotent . Adult stem cells are generally limited to differentiating ... more details
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- Transgenerational epigenetics
, MA and P Hajkova 2010 Epigenetic reprogramming of mouse germ cells toward totipotency. Cold Spring ... may allow for restoration of totipotency in stem cells or cells more generally, thus generalizing regenerative ... more details
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- Dolly (sheep)
somatic cell are still capable of reverting back to an embryonic Totipotency totipotent state, creating ... more details
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- Joan E. Strassmann
title Caste totipotency and conflict in a large colony social insect year 2002 last1 Strassmann ... more details
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- Living systems
of variables . By asserting that societies ranging from Totipotent Totipotency totipotential communities ... more details
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- Stem cell
. In the strictest sense, this requires stem cells to be either totipotency totipotent or pluripotency ... ref Totipotency Totipotent a.k.a. omnipotent stem cells can differentiate into embryonic and extraembryonic ... of the fertilized egg are also totipotent. ref cite journal title Totipotency, pluripotency and nuclear ... more details
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- Index of genetic engineering articles
Thymine Thymine dimer Ti plasmid Topoisomer Topoisomerase Totipotency Totipotent Toxicogenomics Trait ... more details
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- Tissue engineering
multipotent and the latter mostly pluripotency pluripotent some cells are totipotency totipotent ... more details
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- Index of genetics articles
Totipotency Totipotent Toxicogenomics Trait biological Trans isomer Trans Trans conformation ... more details
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- Epigenetics
the ability to differentiate into several cell types totipotency and multipotency . In mammal s, some ... more details
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- Gene
to species from which Totipotency totipotent embryonic stem cells can be established, and therefore ... more details
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