LIFE D CH-2

Page 1: Overview of Heredity and Prenatal Development

Introduction to Heredity

• Heredity shapes an individual's characteristics through genetic contributions.

• The chapter will cover genetic processes during conception, prenatal development stages, effects of teratogens, parental influences on fetus, and the birth process.

Understanding Genes and Chromosomes

• Nature refers to genetic contributions in development, with genes being the basic building blocks.

• Genes: Specific nucleotide sequences that serve as instructions for protein synthesis.

• The Human Genome Project estimates approximately 20,500 human genes.

• Normal human cells consist of 46 chromosomes (23 pairs), contributed by each parent.

• Mitosis vs. Meiosis:

  • Mitosis: Process for most body cells, creates two identical cells from one.

  • Meiosis: Forms gametes (sperm and ova) with half the chromosome number (23), resulting in genetic variation.

Learning Objectives

• Define key terms: genes, mitosis, meiosis, genotype, phenotype, homozygous, heterozygous, dominant, recessive.

• Understand genetic disorders and genetic counseling.

• Explain behavioral genetics and epigenetics.

Page 2: Chromosomes and Genetics

Chromosome Pairs

• 22 autosomes (similar length) and 1 pair of sex chromosomes determine gender.

• XY results in a male, while XX results in a female.

Genotypes and Phenotypes

• Genotype: Complete set of inherited genes.

• Phenotype: Observable characteristics.

• Gene expressions:

  • Homozygous: Identical alleles received from both parents.

  • Heterozygous: Different alleles received.

• Dominance hierarchy: Dominant alleles express phenotypes, while recessive alleles require two copies.

Genetic Traits Examples

• Dominant traits: Facial dimples, curly hair.

• Recessive traits: Red hair, nearsightedness.

• Polygenic traits: Characteristics influenced by multiple genes.

Page 3: Genetic Disorders

Inheritance Patterns

• Majority of genetic disorders are dominant-linked, often less serious.

• Recessive disorders: More critical, like cystic fibrosis and sickle-cell anemia, with carriers usually unaffected.

Specific Genetic Disorders

• Tourette's Syndrome: Minor tics, manageable symptoms.

• Huntington's Disease: Fatal condition appearing in midlife.

• X-linked disorders more prevalent in males due to single X chromosome.

Twin Studies

• Monozygotic (identical) twins: Result from a single fertilized egg dividing.

• Dizygotic (fraternal) twins: Result from two separate eggs fertilized by different sperm.

Page 4: Chromosomal Abnormalities

Types of Abnormalities

• Trisomy: Occurs when extra chromosomes are present.

  • Down Syndrome (Trisomy 21): Intellectual disability with physical characteristics.

• Other trisomies include Trisomy 13 and Trisomy 18, linked to severe defects.

Sex-linked Chromosomal Disorders

• Turner syndrome (XO): Missing or incomplete X chromosome affecting females.

• Klinefelter syndrome (XXY): Extra X chromosome in males, causing various symptoms.

Table of Genetic Disorders

• Overview of recessive, dominant, and sex-linked disorders, including prevalence and effects.

Page 5: Prevalence of Chromosomal Abnormalities

Key Points on Chromosomal Abnormalities

• Maternal age is a significant risk factor for chromosomal abnormalities.

• Chromosomal abnormalities often lead to pregnancy failure or disorders like Down syndrome.

Importance of Genetic Counseling

• Supports individuals in understanding genetic conditions and risks in pregnancy.

• Advises on family history, ethnic backgrounds, and test results.

Page 6: Behavioral Genetics Overview

Definition

• Behavioral genetics studies the interactions between genetics and environment in influencing behavior.

Nature-Nurture Debate

• Genetic and environmental factors jointly shape behavior.

• Epigenetics examines how environments can change gene expression.

Correlations and Interactions

• Genotype-Environment Correlations: Children inherit both genes and the environmental conditions that shape behavior.

• Active, passive, and evocative correlations defined.

Page 7: Epigenetics and Environmental Impact

Understanding Epigenetics

• Focuses on how environmental factors influence gene expression.

• Modifications in DNA can affect long-term health and development.

Examples and Research Evidence

• Study on twins showing discrepancies in gene expression over time due to different environments.

Page 8: Prenatal Development Stages

Overview

• Prenatal development consists of three stages: germinal, embryonic, and fetal.

• Each phase entails critical changes in the developing organism's structure.

Germinal Period

• Lasts approximately 14 days; begins at conception and ends with implantation.

• The zygote starts cell division (mitosis) and forms a blastocyst.

Embryonic Period

• Begins at implantation; crucial development of major organs and structures occurs.

• Sensitive to teratogens and other harmful exposures.

Page 9: Fetal Period Development

Fetal Growth

• Lasts from 9 weeks to birth; further growth and development of body parts occur.

• By 24 weeks, significant brain development occurs, preparing the fetus for survival outside womb.

Sensory Development

• Development of hearing, vision, and reflexes begins during this stage.

Page 10: Teratogens

Definition and Impact

• Teratogens: Environmental agents that can cause abnormalities during prenatal development.

• Factors influencing teratogenic impact:

  • Timing, amount, number of exposures, genetic makeup, and sex of the fetus.

Common Teratogens

• Alcohol, tobacco, prescription drugs, illicit drugs, and environmental pollutants noted.

Page 11: Specific Teratogenic Effects

Alcohol

• Leading cause of preventable intellectual disabilities when consumed during pregnancy.

• Fetal Alcohol Spectrum Disorders (FASD) lead to recognizable physical and cognitive issues.

Tobacco

• Associated with numerous pregnancy complications, including low birth weight.

Illicit Drugs

• Use linked to preterm birth, small head size, and lasting developmental issues.

Page 12: Maternal Factors Affecting Development

Age and Health Risks

• Older mothers at risk for complications including high blood pressure and genetic disorders.

• Teenage mothers face increased risks due to lack of care and negative behaviors.

Gestational Diabetes

• Defined and explained as a risk factor for mother and child during pregnancy.

Page 13: High Blood Pressure and Rh Disease

Types of Hypertension

• Chronic and gestational hypertension explained with associated risks.

Rh Disease

• Definition and explanation of how it affects pregnancies.

Page 14: Weight Gain and Stress During Pregnancy

Recommended Weight Gain

• Guidelines based on pre-pregnancy weight outlined and discussed.

Stress and Its Effects

• High stress levels linked to pregnancy complications and adverse outcomes.

Page 15: Assessing Prenatal Health

Assessments Recommended

• Routine tests in prenatal care including ultrasounds and blood tests.

Advanced Diagnostic Procedures

• Explanation of amniocentesis and chorionic villus sampling as needed tests.

Page 16: Infertility and Reproductive Technologies

Infertility Statistics

• Overview of infertility causes and treatments.

In Vitro Fertilization (IVF)

• Explanations of IVF and alternative methods, and their success rates.

Page 17: Complications of Pregnancy

Minor vs Major Complications

• Description of common minor complications during pregnancy.

• Major complications including ectopic pregnancy and preeclampsia highlighted.

Page 18: Pregnancy Complications and Maternal Mortality

Key Statistics

• Maternal mortality rates discussed alongside contributing factors.

Spontaneous Abortion

• Explanation of causes and statistics surrounding miscarriages.

Page 19: Birth Preparation and Experiences

Preparing for Childbirth

• Focus on education and emotional readiness as critical factors for expectant parents.

Labor Stages

• Stages of vaginal delivery comprehensively detailed.

Page 20: Cesarean Birth

Cesarean Sections

• Outline of the procedure and reasons for performance provided.

Induced Birth

• Situations warranting induced deliveries explained.

Page 21: Newborn Assessment and Issues

Apgar Assessment

• Description of the assessment process immediately after birth.

Neonatal Behavioral Assessment Scale (NBAS)

• Assessment details for newborns, especially those with low Apgar scores.

Page 22: Anoxia, Low Birth Weight, and Preterm Birth

Definition of Conditions

• Key definitions and issues faced by low birth weight and preterm babies described.

Effects of Anoxia

• Consequences of temporary lack of oxygen on infants noted.

Page 23: Maternal Concerns Postpartum

Emotional Changes

• Overview of the 'baby blues' vs postpartum depression.

Impact of COVID-19

• Discussion of how the pandemic has affected maternal and neonatal health, with vaccine data included.