PSYCH 1XX3 Lecture Notes - Lecture 2: Phenotypic Trait, Y Chromosome, Egg Cell
13 Jan 2017
School
Department
Course
Professor
Document Summary
Segments of dna comprise genes, which provide chemical code for development. Zygote quickly divides into billions of different cells. Each parent can produce millions of genetically distinct offspring. Monozygotic twins: genetically identical, same sperm and ovum. Dizygotic twins: share 50% of genes, different sperm and ovum. Males determine the sex of the child: females carry two x chromosomes, males carry an x and a y chromosome. The 46 identical chromosomes in each of your cells translates into the genes that make up your genotype. The expression of the genotype into observable traits and characteristics is called the phenotype. Phenotype: the expression of an individual"s genotype in terms of observable characteristics. Genotypes can express into different forms of phenotypes: children from same parents might have different eye colour. Four main patterns of genetic expression: simple dominant-recessive inheritance, polygenetic inheritance, codominance, sex-linked inheritance. Dominant allele is expressed in the phenotype. Recessive allele not expressed but still heritable.
