Gen Bio Unit 2 Human Reproductive Technology in 21st Century Study Guide Ch 1 Objectives 1 Stages of Human Embryonic Development a Fertilization and Pre Implantation Development i Fertilization of female gamete egg by the male gamete sperm forming zygote single celled embryo ii Each gamete contains 23 chromosomes cells contain 46 creates a specific genotype iii DNA is packed into the nucleus 1 Nucleus of gametes only contain half the DNA of other cells so it is called a pronucleus iv Sperm and Egg fusion of their haploid nuclei one of each chromosome then creates a diploid zygote b Cleavage Pre implantation stages i Following fertilization the zygote divides through cell division and creates a blastocyst stage 1 This process of early cell division is called the cleavage ii When finished the blastocyst consists of about 100 cells 34 30 cells called the Inner Mass Cells ICM that are bunched up inside the sphere like blastocyst and the 66 70 cells that surround the blastocyst called the trophoblast 1 ICM cells will form the embryo trophoblast cells will form the placenta a ICM Embryonic Tissue Trophoblast Extra Embryonic Tissue iii These cell divisions occur while the embryo is moving through the oviduct until it reaches the uterus where it undergoes implantation in the uterine wall 1 Human cleavage can be achieved in a Petri Dish in vitro i Process by which blastocyst attaches to the mother uterus and buries itself into the uterine lining In this process the extra embryonic tissues chlorion will develop from the trophoblast and create the placenta iii First thing that must happen for the embryo to implant is it must ii hatch from then zona pellucida 1 After attachment ICM cells proliferate in cell division and the ICM expands to create the amniotic cavity where the embryo will develop a Placenta is how the baby exchanges oxygen gets food and waste with mother c Implantation Takes place 5 6 days after fertilization 2 Post Implantation Fetal Development The First Trimester 60 days or 8 weeks a Period from implantation to birth is called gestation i Not much information done on post implantation b Gastrulation and Germ Layer Formation days 15 23 i Gastrulation is important because 1 It represents then beginning of specialized cell types 2 Many embryos do not survive beyond this stage 3 Twinning is no longer possible ii Differentiation Process by which the single fertilized zygote produces all different cell types 1 Creates the different cell types of the body germ layers makes cell types to exchange water and food with mother make the cell types that ensure the next generation germ cells iii Units of information in the DNA is called genes making use of a gene is called gene expression not using a gene is called gene repression or silencing iv Germ Layers 3 types 1 Ectoderm Skin and nerves 2 Mesoderm Muscle blood blood vessels 3 Endoderm Gut pancreas liver kidneys v Germ Cells The cells that will make the gametes sperms and egg vi Fraternal Twins Born at the same time but are no more related genetically than two siblings born years apart Identical Twins Born at then same time and are genetically identical Derived from the same original union of a sperm and egg vii c Organogenesis gastrulation i The process of forming organs from the basic plan led by 1 Begins with neurulation or formation of the brain and spinal cord followed by the limbs heart eats and eyes d The Fetus Divided into 23 stages i Remaining 28 30 weeks referred to as fetus ii Can be born and survive in the third trimester 27 38 weeks e Sex Determinism i Autosomal chromosones 22 pair of chromosomes ii Sex chromosones 1 pair of 1 X egg 1 pair of X and Y sperm iii Mitosis all normal cell division in the body Meiosis when germ cells divide in a way to produce the sex gametes 1 Male germ cells continue to divide by mitosis and can enter meiosis to produce gametes throughout nearly the entire lifetime 2 Formation of external genitalia the secondary characteristics occur weeks 10 14 f Consciousness Brainwaves occur in week 25 seventh month g Birth Development of the lungs are last lead to the first breath 3 VIEWS ON HUMAN LIFE a In the USA it is not illegal to perform research in the death of a human embryo b Catholicism Time of conception zygote has complete rights as an adult c English common law When fetus can be felt moving 1 hunna 20 days d e Traditional Jews Crowning appearance of head during birth Islam Soul is acquired at 120 days Ch 2 Objectives 1 Types of Assisted Reproductive Technology ART a In vitro fertilization i Artificial hormones are administered to the woman to stimulate production of hormones that induce ovulation ii The woman s eggs are collected by aspiration using either ultrasound guided aspiration or laparoscopy iii Sperm is collected and placed in a solution so the best swimmers swim to the top for collection Donor may be needed if the guy sucks GDI then 50 100 000 are placed in a Petri dish for 12 18 hours 50 80 of eggs undergo fertilization and begin cleavage iv 3 days after egg retrieval and fertilization the best looking embryos are transferred to the uterus v Many embryos are either frozen or discarded or used for medical research when process is over and there are leftovers 2 Prenatal Diagnosis a How we can determine the genetic constitution of a child before the birth i Can be done by either sampling the placenta or the amniotic fluid 3 People can become sterile by having mistakes or defects in any on of these steps a Localization b Penetration c Preventation of Polyspermy d Fusion of Genetic Material e Initiating Development 4 Benefits Dangers and Ethical Dilemmas of ART a Benefits Can have a child as before couldn t b Dangers Still not enough research on long term effects When IVF clinics inject more than embryo to increase the chance of success which could lead to multiple births twins triplets etc Sperm mix ups c Ethical Dilemmas Question of when life begins murder question playing God tough decisions of having handicap kids what to do with the extra embryos Ch 3 Objectives 1 Embryonic stem cells ESCs Have unlimited potential to produce any cell type in the body Figure 3 1 a Definition of a stem cell is a cell that can both self renew divide and make more stem cells and produce the cells of a particular tissue b Can give rise to fewer and fewer cell types as they commit to being more and more specialized cell types i College student and major analogy ii Pluripotent cells These cells have
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