LIFE D CH-2

Page 1: Heredity and Prenatal Development

Introduction to Heredity and Prenatal Development

• Exploration of how heredity shapes individuals.

• Genetic processes during conception will be outlined, alongside genetic and chromosomal disorders.

• Examination of prenatal development, maternal and paternal impacts on the fetus, and birthing processes.

Understanding Heredity

• Nature: The genetic contribution to development.

  • Genes: Sequences of nucleotides that serve as instructions for protein synthesis.

  • Estimates suggest around 20,500 human genes from the Human Genome Project (NIH, 2015).

  • Chromosomes: Normal human cells have 46 chromosomes (23 pairs).

Cell Division Processes

• Mitosis: Process for creating body cells, involving precise duplication and division of chromosomes.

• Meiosis: Formation of gametes (sperm and ova) resulting in cells with half the genetic material (23 chromosomes).

Key Learning Objectives

• Define essential genetic concepts: genes, genotype, phenotype, differentiation in allele forms (homozygous, heterozygous).

• Address genetic and chromosomal disorders.

• Understand polygenic traits and incomplete dominance.

• Explore genetic counseling and behavioral genetics, including genotype-environment interactions and epigenetics.

Page 2: Genetic Inheritance

Chromosome Structure

• Autosomes: 22 pairs of similarly-sized chromosomes.

• Sex chromosomes: XX for female and XY for male, determining gender.

Genotypes and Phenotypes

• Genotype: Genetic makeup.

• Phenotype: Expressed characteristics.

• Homozygous vs. Heterozygous: Homozygous individuals have identical alleles while heterozygous individuals have different ones.

• Dominant and Recessive Traits: Dominant traits manifest even with one allele (e.g., dimples), while recessive traits appear only in homozygous conditions (e.g., red hair).

• Polygenic traits: involve multiple genes contributing to a single phenotype, resulting in a range of variations, such as height and skin color.

• Incomplete Dominance: is a genetic situation in which neither allele is completely dominant over the other, leading to a phenotype that is a blend of both traits, such as in the case of pink flowers resulting from red and white parent flowers.

Genetic Disorders

• Sickle Cell Disease: Involves a recessive allele impacting red blood cell shape, requires two copies for manifesting symptoms.

• Genetic disorders typically linked to dominant traits include

  • Huntington's Disease (affects the nervous system, appears midlife).

  • Recessive disorders: Include cystic fibrosis (lung and digestive issues), and phenylketonuria (untreated leads to intellectual deficits).

Page 3: Types of Genetic Disorders

Dominant and Recessive Genetic Disorders

• Recessive Disorders: Conditions exist if a child inherits defective gene copies from both parents (e.g., Tay Sachs).

• Dominant Disorders: At least one defective gene from either parent results in manifestation (e.g., Huntington’s Disease).

• Sex-Linked Disorders: Typically found on X chromosomes, affecting males more often due to their single X chromosome.

Page 4: Chromosomal Abnormalities

Definition and Causes

• Chromosomal Abnormalities: When a child inherits too many or too few chromosomes (common cause includes maternal age).

• Trisomy 21 (Down syndrome): Characterized by three copies of the 21st chromosome causing intellectual disability and distinctive physical features.

• Turner Syndrome: An XO condition affects females' cognitive function, sexual development, and height.

• Klinefelter Syndrome: XXY condition in males resulting in reduced testosterone levels and potential fertility issues.

Page 5: Genetic Counseling

• Purpose: A service to assist individuals in identifying, testing, and understanding potential genetic conditions.

• Reasons for seeking genetic counseling include family health history, membership in at-risk ethnic groups, and personal medical concerns.

Page 6: Behavioral Genetics

Overview

• Focuses on the interplay between genetic predispositions and environmental factors affecting behavior.

• Genotype-Environment Correlations:

  • Passive correlation: Inherited genetics and environment provided by family.

  • Evocative correlation: Reactions from the social environment based on inherited traits.

  • Active correlation: Seeking environments that match genetic inclinations (niche picking).

Page 7: Epigenetics

Epigenetic Modifications

• Studies how environmental influences affect gene expression, potentially inherited through cell divisions.

• Example: Varying gene expression of monozygotic twins over time due to differing life experiences.

Page 8: The Human Genome Project

• Launched in 1990 with goals to sequence the 3 billion base pairs of human DNA.

• Achievements: Identification of genes linked to over 1800 diseases, creation of a comprehensive genetic variation database (HapMap).

Page 9: Prenatal Development Overview

Stages of Prenatal Development

• Divided into three periods: germinal, embryonic, and fetal. Each stage is critical for different developmental milestones.

Page 10: The Germinal Period

Description

• Lasts about 14 days post-conception. Involves fertilization, formation of a zygote, and initial cell division.

• Blastocyst Formation: The zygote develops into a blastocyst, setting the stage for implantation into the uterus.

Page 11: The Embryonic Period

Key Developments

• Follows implantation, with structures forming and functions organized in a growing embryo.

• Recognizable anatomical features begin to appear, including primitive heart and limbs.

Page 12: The Fetal Period

Progression

• From week 9 to birth. Key developments include the formation of body parts and organ systems.

• Age of viability: The fetal stage where survival outside the womb is possible, usually around 24 weeks.

Page 13: Prenatal Brain Development

• Begins around the 3rd gestational week with neurons forming and migrating to their designated brain regions.

• Neurogenesis: The majority of neuron production occurs before mid-gestation.

Page 14: Teratogens

Factors Impacting Development

• Environmental factors that can disrupt healthy development, emphasizing critical timing and genetic susceptibility.

• Alcohol and tobacco exposure pose significant risks leading to developmental and health complications.

Page 15: Alcohol as a Teratogen

Effects

• Alcohol consumption raises risks for Fetal Alcohol Spectrum Disorders (FASD), leading to cognitive and behavioral limitations.

Page 16: Tobacco and Its Effects

Health Risks

• Associated with various birth complications including low birth weight and respiratory issues due to reduced oxygen supply to the fetus.

Page 17: Illicit Drugs

Complications from Use

• Use can result in low birth weight, developmental challenges, and withdrawal symptoms in newborns post-birth.

Page 18: Exposure to Pollutants

Sources of Risk

• Lead, pesticides, and radiation can lead to significant developmental disabilities and birth defects.

Page 19: Sexually Transmitted Infections

Transmission Risks

• STIs like gonorrhea and HIV can severely impact fetal health and development, necessitating early detection and intervention.

Page 20: Maternal Health Considerations

Challenges

• Maternal age significantly impacts pregnancy risk. Older mothers have increased risks for genetic disorders while younger mothers can face complications like anemia.

• Positive outcomes are noted for older mothers, including improved educational and career opportunities.

Page 21: Preexisting Conditions

Complications from Gestational Diabetes and Hypertension

• Conditions increase risks for premature birth and associated complications.

Page 22: Weight Management

Recommended Guidelines

• Specific weight gain recommended based on pre-pregnancy body mass index to ensure healthy gestation.

Page 23: Prenatal Assessments

Routine Testing

• Involves ultrasound and genetic testing methods to identify potential complications early.

Page 24: Infertility and Treatments

Overview

• Infertility rates prompt various treatments, emphasizing the use of IVF and other assisted reproductive technologies.

Page 25: Complications of Pregnancy

Minor vs. Major Risks

• Overview of common pregnancy discomforts versus serious complications requiring medical intervention such as ectopic pregnancies and preeclampsia.

Page 26: Maternal Mortality

Concerns and Statistics

• Rising maternal mortality rates highlight preventable issues like infections and complications in the U.S.

Page 27: Preparation for Childbirth

Methods and Education

• Discusses effective methods for preparing parents for childbirth and the various philosophies guiding these practices.

Page 28: Stages of Vaginal Delivery

Process Breakdown

• Details stages of delivery from initial contractions to expulsion of the placenta, including indications for medical intervention.

Page 29: Assessing the Neonate

Apgar and NBAS

• Discusses the significance of APGAR scores and neurological assessments in evaluating newborn health post-delivery.

Page 30: Postpartum Concerns

Emotional Adjustments

• Reviews the emotional spectrum post-delivery, differentiating between typical experiences and significant disorders like postpartum depression.

Page 31: COVID-19 Impact on Pregnancy

Vaccination and Health Outcomes

• Details findings on COVID-19 vaccine immunogenicity in pregnant women and its effects on neonatal health.