Chapter 3 - Reproduction i Process Reproduction Heredity...

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Unformatted text preview: Reproduction i Process Reproduction, Heredity and Genetics, and Prenatal Development by which organisms create more organisms of own kind. i Male and female gametes or sex cells: i Sperm and ovum ( egg or oocyte) create oocyte) zygote. Conceiving i i Ectogenesis The process by which a fetus gestates in an environment external to the mother. Still in experimental stage of development. Many ethical and legal issues involved. Declining Male Fertility Infertility and Assisted Reproductive Technology - In-vitro fertilization (IVF) In- Gamete intrafallopian transfer (GIFT) - Zygote intrafallopian transfer (ZIFT) - Intracytoplasmic sperm injection (ICSI) - Preimplantation genetic treatment (PGT) - Sperm sorting - Embryo adoption - Frozen embryo transfer (FET) 1 Developmental Biology and Reproduction in the Twenty-First Century Cloning: A form of asexual reproduction that creates an embryo by somatic cell nuclear transfer. There are two types: - reproductive cloning - therapeutic cloning Many legal and ethical issues are involved. Ethical Dilemmas of Baby Making ARTs have significantly improved pregnancy rates. Questions: How long should embryos develop in lab? To whom do embryos belong? What type of research is being conducted? What would ectogenesis mean for parents? Birth Control Methods Contraception: prevention of a pregnancy Abstinence Abortion The Expanding Reproductive Years i Menstruation can begin at 8 or 9 years of age; average age is 12.2 to 12.8. i Advanced technology allows women to choose childbearing after menopause. 2 Heredity and Genetics i Heredity: The Human Genome Project Involves the sequencing of the genetic blueprint of all the genes on their appropriate chromosomes. Genome is divided into chromosomes. Chromosomes contain genes. Genes are made of dioxyribonucleic acid (DNA). DNA tells cells to make proteins. our biological inheritance. i Genetics: the scientific study of biological inheritance. Determination of an Embryo's Sex i 46 chromosomes (23 pairs); 22 are similar in size and shape in both men and women: autosomes. i 23rd pair: sex chromosome, determines baby's sex. 3 Phenotypes and Genotypes i Genotype: organism. i Phenotype: observable characteristics of organism. actual genetic makeup of Multifactorial Transmission Environmental factors interact with genetic factors to produce traits. i Sex-linked inherited characteristics: Genes that are linked or appear on the same chromosome are inherited together and are called sex-linked traits. i 4 Genetic Counseling and Testing i Genetic counseling: Helps parents find out risk of passing along a particular disorder or disease. i Down syndrome: Occurs in 1 out of every 800 live births. i Older women have a higher risk. i In 95% of all cases there are three copies of the 21st chromosome: trisomy 21. i Extra chromosome alters course of development and causes physical and mental characteristics. Genetic and Chromosomal Abnormalities Prenatal Development i Germinal Embryonic Period i From period: from conception to second week. i Characterized by growth of zygote and establishment of linkage between zygote and support system of mother. end of second week to eighth week i Rapid growth i Establishment of a placental relationship with mother i Early structural appearance of all chief organs i Development of recognizable human body 5 Development During Embryonic Period i i i Fetal Period i Begins Cephalocaudal Proximodistal Critical Period with the ninth week and ends with birth. i Characteristics: Organism called a fetus. i Major organ systems continue to develop and assume their specialized functions. The Timing of Birth Determined by the biochemical changes in - mother - fetus - placenta The interaction of these hormones triggers the birth process. Loss by Miscarriage i Miscarriage: Organism is naturally expelled from uterus before it is viable. i Parents may require social, family, and psychological support. 6 Maternal Medications Account for 13% of birth defects Common medications of concern: - barbiturates - antihistamines - systemic steroids - Accutane (acne drug) Maternal Infectious Diseases Rubella and other agents Chlamydia i Trichomoniasis i Human papilloma virus (HPV) i Syphilis i Genital herpes i Gonorrhea i HIV/AIDS i i Maternal Noninfectious Conditions Diabetes Maternal sensitization: the Rh factor Major drugs and chemical teratogens - smoking - alcohol - marijuana - oral contraceptives - cocaine and other hard drugs - environmental toxins - workplace toxins Maternal stress and age 7 Here's why we go to all the trouble... 8 ...
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