PSYCH 1XX3 Chapter Notes - Chapter Development Module 2: Sensation Seeking, Twin Study, Phenotypic Trait
5 Mar 2018
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Zygote-single cell (46 chromosomes, 23 from each parent) Our chromosomes contain between 30 000 to 40 000 genes. Genotypes can express into different forms of phenotypes. The expression of a trait is determined by a single pair of alleles ex//hair type (curly or straight) Homozygous: when two alleles have the same effect on the phenotype. Heterozygous: when two alleles have a different effect on the phenotype. When the expression of a trait is determined by the interaction of multiple genes ex//intelligence and temperament. When the expression of a trait is determined equally by two dominant alleles ex//blood type. Genes are expressed on the x chromosome ex//colour blindness and haemophilia. No single gene can account for most complex behaviours. Two alleles are both expressed, to produce an intermediate or combined phenotype. The phenotypic expression of the recessive allele occurs less frequently in females relative to males, who only have one x chromosome.
