PSYB32H3 Chapter Notes - Chapter 2: Triple X Syndrome, Gregor Mendel, Genetic Counseling
Document Summary
23 pairs of chromosome; 46 chromosomes; 1 sex pair and 22 autosomes. Chromosomes carry genetic info on the strands. Sperm and egg unite to form a zygote consisting of 23 pairs of chromosomes. Genetic variability comes from mixing of the chromosomes and crossing over. Dna: deoxyribonucleic acid; made up of nucleotides. Two crucial principles: there can more than one form of a gene called alleles, homozygous and heterozygous. If the organism is homozygous (tt): it will be tall. X chromosome is longer and carries more genes thus any recessive x-linked gene will automatically. Male: xy be expressed in males if they don"t have any counteracting dominant genes very likely. Many traits are determined by interactions of many pairs of alleles. Modifier genes: effect the expression of other genes indirectly. Is not likely to be passed on from parent to child. Improvement with treatments have increased the lifespan; 70% live into their 60"s.