Foundations of Development

• DNA (deoxyribonucleic acid)


  • Chemical that carries inherited instructions for the development of all cellular forms of life
  • Substance of which genes and chromosomes are made
• Genes


  • Segments of DNA that consist the genetic code which the cellular machinery “reads”
  • Functional units of heredity
• Chromosomes


  • Coils of DNA that consist of genes
  • Store and transmit genetic information
  • 2 main types: Autosomes and Sex chromosomes
• Human genome is the complete sequence of genes in the human body
• Every cell in the normal human body has 23 pairs of chromosomes (46 chromosomes in total)
• Gametes only have 23 single chromosomes
• Meiosis is the cell division that lets the sex cells (sperm (X or Y) and ovum (X only)) contain 23 single chromosomes
• Zygote is formed through the union of the sperm and ovum which lets humans have 46 chromosomes
• Chromosome 23: XX for females and XY for males
• Undergoes mitosis (cell division for non-sex cells) that creates a genetic duplicate of the original cell
• Mutations are permanent alterations in genes or chromosomes that may produce harmful characteristics
• Monozygotic (Identical) twins: One zygote that divides into two or more fetuses
• Polyzygotic (Fraternal) twins: Multiple fetuses produced by two or more zygotes
• Dizygotic twins: Two zygotes that may produce two or more fetuses
• Trizygotic twins: Three zygotes that may produce three or more fetuses
• Fission: partial splitting of a fertilized egg
• Genotypes and Phenotypes: Multifactorial Transmission
• Epigenesis: Environmental Influence on Gene Expression
• Genetics

  • Alleles: Two or more alternative forms of a gene that occupy the same position on paired chromosomes and affect the same trait
  • Forms the genotype
  • Homozygous: Possessing two identical alleles for a trait
  • Heterozygous: Possessing two differing alleles for a trait
• Dominant inheritance: When a child receives different alleles, only the dominant one is expressed
• Recessive inheritance: When a child receives identical recessive alleles, resulting in expression of a non-dominant allele
• Recessive inheritance: Autosomal diseases include Cooley’s anemia, Cystic fibrosis, Phenylketonuria (PKU), Sickle cell anemia, Tay Sachs Disease, X-linked diseases like Duchenne muscular dystrophy, Hemophilia, Diabetes insipidus, Red-green color blindness
• Dominant inheritance: Autosomal Diseases include Huntington’s Disease, Marfan syndrome
• Chromosomal Abnormalities include Down Syndrome (chromosome 21), Sex chromosome abnormalities like XYY, XXX (Triple X), XXY (Klinefelter syndrome), XO (Turner syndrome), Fragile X
• Genotypes and Phenotypes
• Genotype: Genetic makeup of a person, containing both expressed and unexpressed characteristics
• Phenotype: Observable characteristics of a person
• Sex chromosome abnormalities

  • XYY
  • XXX (Triple X)
  • XXY (Klinefelter syndrome)
  • XO (Turner syndrome)
• Genotypes


  Genetic makeup of a person, containing both expressed and unexpressed characteristics
• Phenotypes


  Observable characteristics of a person
• Epigenesis


  Mechanism that turns genes on or off and determines functions of body cells
• Epigenesis


  Development resulting from ongoing, bidirectional exchanges between heredity and all levels of the environment
• Reproductive Choices


  • Artificial insemination
  • Assisted Reproductive Technology (ART)
  • In vitro fertilization (IVF)
  • Cryopreservation of gametes or embryos
  • Fertility medication
  • Traditional surrogacy (sperm is introduced in a surrogate)
  • Gestational carrier (embryo is implanted in a surrogate)
• Genetic Counseling


  1. Clinical service that advises prospective parents of the chances of their children acquiring hereditary disorders through history taking and physical examinations including genetic testing

  2. Helps couples choose the best course of action based on the risks and their family goals
• Recommended individuals for genetic counseling
• Prenatal Diagnostic Methods

  1. Amniocentesis

  2. Chorionic villus sampling (CVS)

  3. Embryoscopy/Fetoscopy

  4. Ultrasound (sonogram)

  5. Maternal blood analysis

  6. Ultrafast magnetic resonance imaging (MRI)

  7. Preimplantation genetic diagnosis

  8. Umbilical cord sampling (cordocentesis)
• Adoption trends
• 1 out of 6 children are orphaned, abandoned, or neglected in the Philippines in 2021. Only 237 children are adopted every year (Rohei Foundation, 2021)
• RA 11642 of 2022: Domestic Administrative Adoption and Alternative Child Care Act
• Environmental Contexts

  • Family
  • Neighborhoods and Schools
  • Cultural Context