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Chapter 3. Reproduction, Heredity and Genetics, and Prenatal Development. Reproduction. Process by which organisms create more organisms of own kind. Male and female gametes or sex cells: Sperm and ovum create zygote. Male Reproductive System. Testes: produce sperm
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Chapter 3 Reproduction, Heredity and Genetics, and Prenatal Development
Reproduction • Process by which organisms create more organisms of own kind. • Male and female gametes or sex cells: • Sperm and ovum create zygote
Male Reproductive System • Testes: produce sperm • Penis: Man’s external organ
The Female Reproductive System • Ovaries produce ova. • Ovum released approximately every 28 days. • Moves through fallopian tubes where it may be fertilized by sperm. • Uterus prepares itself for conception. • Unfertilized ovum shed; expelled through cervix and vagina.
How and When Fertilization Occurs • Menstrual Cycle • Ovulation • Fertilization • Multiple Conception
Conceiving or Avoiding Conception • Infertility and Assisted Reproductive Technology • In Vitro Fertilization • Ethical Dilemmas of Baby Making • Birth Control Methods a. Contraception b. Abortion
Infertility and Assisted Reproductive Technology • In vitro fertilization (IVF) • Gamete intrafallopian transfer (GIFT) • Zygote intrafallopian transfer (ZIFT) • Intracytoplasmic sperm injection (ICSI) • Preimplantation genetic treatment (PGT) • Ovarian and sperm cryopreservation • Sperm sorting (sperm separation) • Embryo adoption
Ethical Dilemmas of Baby Making • ARTs have significantly improved pregnancy rates • Questions: • How long should embryos develop in lab? • Who do embryos belong to? • What type of research is being conducted?
Birth Control Methods • Abstinence • Contraception • Abortion
The Expanding Reproductive Years • Menstruation can begin at 8 or 9 years of age; average 11 to 12 • Advanced technology allows women to choose childbearing after menopause.
Heredity and Genetics • Heredity: our biological inheritance • Genetics: the scientific study of biological inheritance
The Human Genome Project • 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 DNA
What are Chromosomes and Genes? • Chromosomes • Genes • DNA • Human genome • Mitosis • Meiosis
Determination of an Embryo’s Sex • 46 chromosomes (23 pairs) 22 are similar in size and shape in both men and women: autosomes • 23rd pair: sex chromosome, determines baby’s sex.
Principles of Genetics • Gregor Johann Mendel • Dominant and Recessive Characteristics a. Allele (dominant or recessive) b. Homozygous characteristic c. Heterozygous characteristics d. Polygenic inheritance
Phenotypes and Genotypes • Genotype: Actual genetic makeup of organism • Phenotype: Observable characteristics of organism
Multifactorial Transmission • Environmental factors interact with genetic factors to produce traits. • Sex-Linked Inherited Characteristics: Genes that are linked or appear on the same chromosome are inherited together: Sex-linked traits.
Genetic Counseling and Testing • Genetic Counseling: Helps parents find out risk of passing along a particular disorder or disease.
Genetic and Chromosomal Abnormalities • Downs’ Syndrome: Occurs in 1 out of every 800 live births. • In 95% of all cases there are three copies of the 21st chromosome: trisomy 21 • Extra chromosome alters course of development and causes physical characteristics.
Box: Human Diversity • Prenatal diagnosis: Amniocentesis Ultrasonography Fetoscopy Chorionic villus biopsy Maternal blood sampling
Prenatal Development • Germinal Period: From conception to second week. • Characterized by growth of zygote and establishment of linkage between zygote and support system of mother.
Embryonic Period • From end of second week to eighth week. • Rapid growth • Establishment of a placental relationship with mother • Early structural appearance of all chief organs • Development of recognizable human body.
Development during embryonic period • Cephalocaudal • Proximodistal • Critical Period
Fetal Period • Begins with the ninth week and ends with birth • Characteristics: Organism called a fetus • Major organ systems continue to develop and assume their specialized functions.
Loss by Miscarriage • Miscarriage: organism is naturally expelled from uterus before it is viable.
Prenatal Environmental Influences • Teratogens: Drugs and other chemical agents that can cause birth defects: • Smoking • Marijuana • Hard Drugs • Alcohol • Oral Contraceptives • Toxins in environment and workplace
Maternal Infectious and Noninfectious Diseases: • Rubella and Other Agents • Syphilis • Genital Herpes • HIV/AIDS • Diabetes • Maternal Sensitization: The Rh Factor • Maternal Stress • Maternal Age • Maternal Nutrition and Prenatal Care