BIOL 100 Lecture Notes - Lecture 12: Mutation Rate, Meiosis, Zygote
Document Summary
Biology 100 - lecture 12 - genetic inheritance. Gametes like sperm and egg cells are haploid sex cells. A haploid cell has only one set of chromosomes known as 1n. In humans, each gamete has exactly 23 chromosomes, opposed to 46 in diploid cells. When two haploid cells fuse at fertilization, a diploid zygote is formed. A zygote is the first cell of a new organism. Cytokinesis occurs once in mitosis but twice in meiosis. During meiosis, chromosome pairs align randomly during metaphase i and separate during anaphase i. The chromosome replicates separate during anaphase ii. A mutation is a change in a cell"s dna sequence which means it is a change in the encoding of genes. However, the mutation rate is extremely low but it is a natural phenomenon. Mutations in chromosome structure can have major effects on an organism. Fertilization occurs when two haploid gametes fuse to form one diploid zygote.