Developmental and Educational Psychology - lecture notes (2018-2019)
There is only 15% chance on a woman’s most fertile days to get pregnant. Upon ejaculation, 500 million sperms cells try to get to the egg, 6 hours later, only 1% reaches the egg. Gametes are the sex cells, which each have 23 chromosomes. When these fuse together, it becomes a zygote with 46 chromosomes. Zygote (0-2 weeks)In the first weeks, cell division, aka mitosis, starts. Processes that occur are;Cell migration means that cells move within the embryo to eventually for cells and arms etc. Cell differentiation means that cells reach their destination and become specific cells. Apoptosis; cells die. ( excess cells fall away).2 weeks after conception, the zygote has moved to the uterus, this is a vulnerable stage that 50% of the zygotes do not survive. This is due to genetic defects. This implantation means that the zygote implants itself in the uterus well. Cells become a hollow sphere called the inner cell mass. Some parts of these become the embryo, embryonic sack or placenta. hGC is secreted, which can be tested for pregnancy.TwinsIdentical twins happen when the inner cell mass splits into two embryo’s. Genetically identicalFraternal twins happen when 2 eggs...
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