Exam 2 Review: Human Reproductive Technology in the 21st CenturyChapter 1: When Does Human Life Begin?* What is the correct order of the stages of development?- Pronuclear fusion of sperm and egg, Cleavage, Degradation of the Zona Pellucida, ImplantationI. The First Week: Fertilization and Pre-ImplantationA) The meeting of two gametes creates a unique combination of genes1. Zygote: A new individual at the one cell stage2. Match the cell to its chromosome karyotype (Sperm cell, Egg cell, and Diploid Zygote):i. Sperm: 22 autosomes, 1 X or 1 Y sex chromosomeii. Egg cell: 22 autosomes, 1 X sex chromosomeiii. Zygote: 44 autosomes, 2 X or 1 X and 1 Y sex chromosomeB) Cleavage: After fertilization, the process of early cell divisions in the development process.1. Once the blastocyst is formed, it consists of approximately 100 cells: in which 30-34 cells arecalled the inner cell mass (located in the blastocoel), while 66-70 cells surround the inner cell mass (termed the trophoblast). *Keep in mind that the ICM cells create the embryo, while the cells from the trophoblast create the placenta. C) Implantation: the process where the blastocyst clings itself to the mother’s uterus and buries itself into the uterine lining.1. After six days following the start of fertilization, blastocysts are formed.2. Once ovulation begins, the egg will be fertilized in the oviduct, then proceeds to be divide through the cleavage process. i. This results in the formation of the morula and blastocyst. 3. Once the embryo hatches from its shell (called the zona pellucida), the sperm must get through the zona pellucida.i. If the embryo impants itself before it reaches the uterus it can create a life-threatening situation for the mother termed a Tubal Pregnancy.4. Catholicism and Hinduism are the two religious beliefs that consider conception the first stage of human life.II. Post-Implantation: The First Trimester*During the first trimester, four processes occur: Morphogenesis, differentiation of trophoblast, gastrulation, and germ layer formation.1. The three germ layers include: Ectoderm (skin and nerves), Mesoderm (muscle, blood, blood vessels), and Endoderm (gut, pancreas, liver, kidneys) 2. Gastrulation: the process where differentiation of the embryo begins. It also is when germ layers and germ cells form.i. In which the ICM creates the cells of the embryo and is the collection of pluripotent cells (have the potential to become any cell of the body)A) Once Gastrulation Begins1. Identical twins are formed by the splitting of an embryo, while fraternal twins are the result of the fertilization of more than one egg.B) Organogenesis: the process where organs are formed using the instructions that resulted from gastrulationC) Fetus1. Organisms are considered embryo’s at the time of fertilization, while organisms are considered fetus’ eight weeks after fertilization.2. The fetus can be born and survive in the third trimester (27-38 weeks).D) Sex Determination1. Primary sex characteristics are the internal gonads, while the secondary sex characteristics are external.E) Consciousness1. Brainwave activity in the fetus usually begins around week 25.Chapter 2: Fertilization and Assisted ReproductionI. Louise Brown1. Brown was the first “test-tube” baby as she was conceived on July 25, 1978.II. Problems with ReproductionA) Gametogenesis: the process of undertaking meiosis to make eggs or sperm.*Know the diagrams of a sperm cell and an egg cellB) Fertilization1. The process of fertilization is: localization, penetration, prevention of polyspermy, fusion of genetic material, and initiating development.2. When the sperm penetrates the egg: i. A female reproductive tract initiates the spermii. The sperm binds to the zona pellucidaiii. An acrosomal reaction occursiv. The sperm lyses a hole in the zona pellucidav. Fusion of the sperm and egg membranes occursvi. The sperm pronucleus enters the egg cytoplasmC) In-vitro fertilization Medical Issues and Moral Dilemmas1. Multiple births, tubal pregnancy, kidney and ovary damage are all possible risks.2. Human embryonic stem cells come from an excess of unused embryos during IVF.3. The U.S. policy on federal funding for human embryonic stem cell research is as follows: i. Embryos derived from IVF clinics are either discarded, donated with no compensation, or donated with consent of parents.Chapter 3: Embryonic Stem CellsI. Adult vs. Embryonic Stem Cells1. Adult cells maintain our tissues after the tissues have formed, while ESC’s (pluripotent) are able to regenerate any tissue of the body. 2. Induced Pluripotent Stem Cells: a normal cell that was manipulated to become a pluripotent cell.3. ESC’s are created from the remaining embryos after a successful IVF.Chapter 4: Human CloningI. “Dolly”1. The first nuclear transplant experiments were performed with frog eggs and were intended to test genomic equivalence.i. The cloning of Dolly was the great advance with cloning technology.A) Reproductive vs. Therapeutic Cloning1. Therapeutic cloning: the production of genetically identical blastocyst2. Reproductive cloning: complete copy of human being (put in uterus and carried to term)3. During the process of cloning, the oocyte is taken from the mother or donor and the genetic information is removed. Then the nuclei from the person of interest is inserted into the egg.Chapter 5: Reproductive EngineeringI. Engineering the Human GermlineA) Somatic Cell Gene Therapy1. Somatic: reinserts genetically modified cells temporarily into the patient2. Reproductive gene therapy: permanently genetically engineers individuals before they are conceivedB) Reproductive Gene Therapy1. Human gene therapy: healthy gene is introduced into the patient’s body cells through a virus vector to hopefully cure the disease (isn’t 100%) C) Human-Human Chimeras1. A transgenic animal: an animal that has undergone gene therapy2. Chimera: embryos that consist of cells from two or more
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