PSYC 3206 Lecture Notes - Lecture 2: Fetus, Quantitative Trait Locus, Lactase
Document Summary
Lactose (milk sugar) is digested by lactase, and enzyme produced by every baby. Most humans (~65%) stop producing lactase after early childhood. Each person has 23 pairs of chromosomes (usually: 22 pairs are autosomes sex chromosomes are the 23rd pair (i. e. xy is a boy and xx is a girl, generally) Gene: the biochemical instructions carried on strands of dna. Alleles: variations of genes: homozygous: alleles are the same, heterozygous: alleles are different. Ge(cid:374)otype: a perso(cid:374)"s co(cid:373)plete set of ge(cid:374)es. Phenotype: observable features that result from the interaction between genes and the environment. Single-gene inheritance: some traits are controlled by a single gene, examples: pku, sickle cell. Polygenic inheritance: a trait is affected by multiple genes, examples: personality, intelligence twins. **y chromosome normally has sry gene from conception to birth. Prenatal development: changes that turn a fertilized egg into a newborn baby. Essential life systems (respiration, digestion, and vision) finish developing. The fetus experiences tastes and hears sounds.