Biological Foundations, Genetics, Prenatal Development, and Birth

Genetic Information and Development

• DNA stores genetic information, directing cellular activities and functioning as the blueprint for life.
• The blastocyst forms during the germinal stage of prenatal development, marking successful implantation into the uterine wall.

Gamete Formation

• Meiosis is the process that creates gametes (sperm and eggs) with half the normal number of chromosomes, essential for sexual reproduction.

SRY Gene Importance

• The SRY gene is crucial in prenatal development as it triggers the formation of male sex organs.

Genetic Disorders

• Cystic fibrosis is a recessive genetic disorder, requiring both copies of the gene to be mutated for the disease to manifest.
• Polygenic traits are influenced by multiple genes and environmental factors, contrasting with single-gene traits that arise from one gene.

Genetic Counseling

• The primary focus of genetic counseling is assessing the risk of genetic disorders, aiding parental decision-making without offering cures.

Chromosomal Disorders

• Down syndrome is associated with the presence of an extra twenty-first chromosome, leading to various physical and cognitive challenges.

Prenatal Diagnostic Techniques

• Amniocentesis is used to detect chromosomal abnormalities in the fetus and carries a higher miscarriage risk compared to ultrasound, which has the lowest risk.

Understanding Genetic Traits

• The term "range of reaction" describes potential phenotypes influenced by genetic and environmental interactions.
• Dominant gene disorders manifest with just one copy of the mutated gene from either parent, differing from recessive disorders which require both copies to be affected.

Role of the Placenta

• The placenta serves as a vital organ that facilitates nutrient and waste exchange between the mother and fetus, also producing hormones needed for fetal growth.

Prenatal Techniques and Traits

• Ultrasound is the diagnostic technique with the lowest risk of miscarriage, used primarily for monitoring fetal development.
• Haemophilia is an example of a sex-linked recessive trait, often associated with males due to its inheritance pattern.

Genomic Imprinting

• Genomic imprinting refers to the differential expression of a gene based on whether it is inherited from the mother or father, impacting development and phenotype.