Forming a New Life - Chapter 3

Forming a New Life - Chapter 3

• Genetic Testing and Engineering: Genomics studies gene functions and interactions. Genetic testing raises ethical questions regarding testing children and potential predispositions to diseases.

• Guideposts for Study: Key topics include conception, multiple births, heredity in determining sex and traits, heredity/environment interaction, roles of heredity/environment in health/intelligence, and prenatal development stages.

• Conceiving New Life: Fertilization involves the union of sperm and ovum to create a single-celled zygote, also known as conception.

• Two Types of Multiple Births: Monozygotic (MZ) twins result from one egg and one sperm, sharing 100% of genes. Dizygotic (DZ) twins result from two eggs and two sperm, with 50% shared genes.

• Rise in Multiple Birth Rate: Factors include delaying childbirth and increased use of fertility drugs. Risks include pregnancy complications, premature delivery, and lower birth weight potentially leading to infant disability or death.

• Fetal Development: A presentation of fetal stages is referenced via a YouTube link. (Link omitted per instructions)

• Mechanisms of Heredity: DNA: This section details DNA structure (which is diagrammed in the slide)

• Determination of Sex: Sex is determined by the combination of sex chromosomes: XX for female and XY for male.

• Sex Determination (Chromosomes): Chromosomes are coils of DNA carrying genes. Autosomes are not related to sexual expression (22 pairs). Sex chromosomes (1 pair) determine sex - XX = female and XY = male.

• Dominant and Recessive Inheritance: Dominant traits are expressed with heterozygosity (only one dominant allele). Recessive traits require homozygosity (two recessive alleles).

• Trait Inheritance: Alleles are copies of genes, with homozygous (same copies) or heterozygous (different copies). Polygenic inheritance involves interactions of multiple genes to determine traits. This is a common pattern for most traits.

• Dominant-Recessive Inheritance: Tongue Curling Example: A diagram illustrates a tongue-curling example.

• Gene Expression: Genotype refers to the genetic makeup (alleles). Phenotype is the observable expression of that makeup. Multifactorial transmission means experience (environment) influences gene expression.

• Epigenesis: Epigenetic framework alters how cells "read" genes' DNA, impacting traits like cancer and illness. Environmental factors alter epigenetic markers.

• Inherited Defects: Defects can be dominant, recessive, or incomplete (partial dominance). Sickle cell anemia is an example of incomplete dominance.

• Sex-Linked Inheritance: Inheritance patterns related to sex chromosomes. The odds of inheriting an abnormal gene from a carrier mother are detailed (50/50 chance).

• Sex-Linked Defects: Examples include red/green color blindness and hemophilia. Traits impact males and females differently. Carriers may pass on a gene without being affected themselves.

• Chromosomal Abnormalities: Errors in cell division cause missing or extra chromosomes. These issues can affect either sex chromosomes or autosomes.

• Down Syndrome: Trisomy 21 (extra 21st chromosome) is the most frequent autosomal disorder. It tends to be associated with developmental challenges (moderate to severe).

• Genetic Counseling: Helps assess genetic defect risk in prospective parents, especially when there is already a child with a defect, a family history, or an ethnic background that has higher risk. Charts, like a karyotype, can reveal abnormalities.

• Behavioral Genetics: Focuses on how heredity and environment influence behavioral traits. Heritability measures the proportion of traits influenced by genetics in a population using statistical models(a formula is presented). Nature vs. nurture describes the debate on the relative contributions of these factors to traits.

• Measuring Heritability: Techniques include family studies (bio-relative trait sharing), adoption studies (adopted vs biological relatives), and twin studies (MZ vs DZ twin trait resemblance).

• Heredity & Environment: Working Together: Concepts like reaction range (potential trait variations) and canalization (heritable limitations on trait development) illustrate interplay between genetic makeup and environmental experience.

• Intelligence and Reaction Range: (A diagram illustrates the concept of reaction range for intelligence, demonstrating that phenotype intelligence can vary within a range defined by one's genotype.)

• Genotype-Environment (G x E) Correlations: Explains interactions between genes and environment - passive (parents' environments foster the trait), reactive (children evoke responses based on their traits), and active (choosing environments that best fit the traits).

• Nonshared Environment: Development is shaped by unique environmental factors each child experiences (accidents, illnesses, peer interactions).

• Traits Influenced by Heredity & Environment: Obesity, intelligence, school achievement, personality, and schizophrenia are examples of traits influenced by a combination of heredity and environment.

• Stages of Prenatal Development: This describes the germinal, embryonic, and fetal stages and their durations.

• Germinal Stage Development: Describes early cell division and attachment to the uterine wall in detail.

• Embryonic Stage Characteristics: Rapid development of organs and body systems during the embryonic stage. A risk of spontaneous abortion exists.

• Development During Fetal Stage: Key detail is continued development to fetal maturity.

• Maternal Factors: Teratogens (birth defects), maternal nutrition, weight, drugs/alcohol, nicotine, caffeine, illnesses, STDs, age and stress, and environmental hazards are factors that affect prenatal development.

• Paternal Factors: Exposure to environmental hazards that can negatively impact sperm and paternal age can also influence fertility

• Monitoring Prenatal Development: Ultrasound, amniocentesis, chorionic villus sampling (CVS), embryoscopy, and maternal blood tests are techniques used.

• Prenatal Care: Education, social services, and nutrition are aspects included in prenatal care. This care is not universally available or equally available between SES and ethnic groups.

• Preconception care: CDC physical examinations/vaccinations, risk screenings, and counseling.