Development of a zygote
205545
controlled cell death (apoptosis) contributes to development in several ways. The two most common examples are as follows:\n\n1.  Look at your fingers and toes.  During the first stages of embryonic development of the hands, the entire hand is covered in a sheath of skin, like a webbed frog foot.  Apoptosis occurs to the "webbing", allowing you to have singled-out digits.  Sometimes, there is a genetic mutation that causes webbed toes, by mutating the gene that controls that particular type of apoptosis.\n\n2.  When your body is creating its network of blood vessels, the blood vessels start out as a solid cord of epithelium.  To make them hollow, the body uses apoptosis to get rid of the inner cells.\n\nOther examples include: deletion of the fallopian tubes in males, deletion of structures like a tadpoles tail as it becomes a mature adult, or simply controlling cell numbers, so that you do not end up with large cysts of skin or what have you.\n\nAlso, sorry about the lack of apostraphes, my computer is getting wonky suddenly.
49246
They grow, one cell at a time.
119514
Gastrulation in Human Embryo\n\nDelamination precedes gastrulation separating ICM into epiblast & hypoblast \nGastrulation occurs in epiblast (future embryo) \nGastrulation involves several types of movements and shape changes \nEnd product is three germ layers: ectoderm, endoderm and mesoderm \nThe expression of certain genes regulates the formation of the embryonic axes & the organization of the embryo \nThe Timing of Gastrulation and Subsequent Events\nGastrulation begins about 15 days of development and is followed by neurulation and the start of development of several major organ systems \n\nRole of Gastrulation\nGastrulation will covert the bilaminate epiblast into the three primary embryonic germ layers \nEctoderm: outside; this embryonic layer more or less surrounds the other germ layers \nMesoderm: middle; this germ layer lies between the ectoderm and mesoderm \nEndoderm: inside; this germ layer lies at the most interior of the embryo \nSubsequently neurulation will form epithelial and neural ectoderm from the ectoderm \n\nDuring human gastrulation, cells move over the blastodisc surface, enter the primitive streak and move internally. On the surface they move in association with other cells but once they turn the corner around the lip of the primitive streak the cells separate as individuals to migrate internally to form the mesoderm and endoderm. These are just some of the types of cell movements that occur in animal embryos. Here's a full list\n\nIngression: cells break away from the tissue and migrate as individuals \nDelamination: layers of cells separate from each others more or less as sheets of cells \nIntercalation: two cell layers interlace with each other \nEpiboly: a form of cell spreading in which cells flatten out; this allows them to cover a much larger surface area (1st detailed in frog development). \nInvagination (Evagination): a tissue layer folds in (out) \nInvolution: cells move over a lip of tissue and into the interior \nConvergent Extension: cells reorganize to form less layers allowing the cells to extend out from a point. \nNot all of these morphogenetic movements have been detailed in humans but they all have been shown to occur in other animals. Also remember, one type of cellular rearrangement does not exclude another with several different types of movement potentially occurring at the same time.
232286
Transformation\nNucleotides\nBase
332104
A is not included, viviparous organisms bear their young inside and it is born alive.
116321
"In nature, living things evolve through changes in their DNA. In an animal like a chicken, DNA from a male sperm cell and a female ovum meet and combine to form a zygote -- the first cell of a new baby chicken. This first cell divides innumerable times to form all of the cells of the complete animal. In any animal, every cell contains exactly the same DNA, and that DNA comes from the zygote. \n\nChickens evolved from non-chickens through small changes caused by the mixing of male and female DNA or by mutations to the DNA that produced the zygote. These changes and mutations only have an effect at the point where a new zygote is created. That is, two non-chickens mated and the DNA in their new zygote contained the mutation(s) that produced the first true chicken. That one zygote cell divided to produce the first true chicken. \n\nPrior to that first true chicken zygote, there were only non-chickens. The zygote cell is the only place where DNA mutations could produce a new animal, and the zygote cell is housed in the chicken's egg. So, the egg must have come first."
207912
(m)\n\nCloning of Plant Cells and Manipulation of Plant Genes\nPlant cells exhibit a variety of characteristics that distinguish them from animal cells. These characteristics include the presence of a large central vacuole and a cell wall, and the absence of entioles, which play a role in mitosis, meiosis, and cell division. Along with these physical differences, another factor distinguishes plant cells from animal cells, which is of great significance to the scientist interested in biotechnology: Many varieties of full-grown adult plants can regenerate from single, modified plant cells called protoplasts - plant cells whose cell walls have been removed by enzymatic digestion. More specifically, when some species of plant cells are subjected to the removal of the cell wall by enzymatic treatment, they respond by synthesizing a new cell wall and eventually undergoing a series of cell divisions and developmental processes that result in the formation of a new adult plant. That adult plant can be said to have been cloned from a single cell of a parent plant. \nPlants that can be cloned with relative ease include carrots, tomatoes, potatoes, petunias, and cabbage, to name only a few. The capability to grow a whole plant from a single cell means that researchers can engage in the genetic manipulation of the cell, let the cell develop into a completely mature plant, and examine the whole spectrum of physical and growth effects of the genetic manipulation within a relatively short period of time. Such a process is far more straightforward than the parallel process in animal cells, which cannot be cloned into full-grown adults. Therefore, the results of any genetic manipulation are usually easier to examine in plants than in animals.
352772
Those are gametes.  Once they fuse (egg+sperm) they are called a zygote... The name you need though is gametes.
97049
It is slightly more complicated. Prenatally a baby has what are called ovatesties. These will either become ovaries or testicles. On the Y chromosome is a gene (SRY) sex determining region of Y chromosome. It can get put on an X if a mutation occurs. Anyway sometime during development the SRY gene get turned on. This produces testosterone will cause the rest of he sexual organs to develop. \nThe X chromosome contains many genes that can produce different affect in different cells. Only one is need (the other is a Barr body) and the other has many functions in the cell. If you look at a calico cat for instance this will show you the best example. A calico being female has too X chromosomes. In some cells the maternal X is active and in others the paternal X. This shows up in the coat pattern.
545283
After Meiosis four gametes are produces which fertilize and a new organism is formed.\nThis is the most basic answer
220230
Here you go! Hope this helps.\n\nhttp://web.uvic.ca/~rburke/burkelab/neuraldevelopment.htm
22813
when the sperm fertilizes the egg
598817
life begins at conception. At the rate changes happend from the instant of conception is amazing. there is a beating heart only 8 days after conception.
435434
A fertilized egg will develop and grow and one day enter the world where it will be given a name. \n\nAnyone can argue that it is not human until it breathes but, even they must admit by aborting the fetus it is prevented from being born. \n\nA fetus has a heartbeat. Abortion stops that heartbeat. Think about it.
16655
In nature, living things evolve through changes in their DNA. In an animal like a chicken, DNA from a male sperm cell and a female ovum meet and combine to form a zygote -- the first cell of a new baby chicken. This first cell divides innumerable times to form all of the cells of the complete animal. In any animal, every cell contains exactly the same DNA, and that DNA comes from the zygote. \n\nChickens evolved from non-chickens through small changes caused by the mixing of male and female DNA or by mutations to the DNA that produced the zygote. These changes and mutations only have an effect at the point where a new zygote is created. That is, two non-chickens mated and the DNA in their new zygote contained the mutation(s) that produced the first true chicken. That one zygote cell divided to produce the first true chicken. \n\nPrior to that first true chicken zygote, there were only non-chickens. The zygote cell is the only place where DNA mutations could produce a new animal, and the zygote cell is housed in the chicken's egg. So, the egg must have come first.
109139
Great stuff going on right now having to do with developmental genes (like Hox genes).  You may know this as "Evo Devo" or evolutionary developmental biology.\n\nCheck out the book "Endless Forms Most Beautiful," by Sean Carroll.  He also gives ideas for research and new fields, lots of peer-reviewed papers.\n\nI just read it this Fall, it was great.
431855
Life begins when the sperm fertilizes the egg - whether it happens the old-fashioned way or in a lab somewhere.