BIO 171 1st Edition Lecture 4Outline of Last Lecture I. Organization of DNA Within CellsII. Cell Division III. The Eukaryotic Cell Cycle IV. Phases of Mitosis V. MeiosisVI. Multicellular Organisms Outline of Current Lecture I. Meiosis/Multicellularity Cont. II. Mutations *Didn’t get to Mendel’s Laws (will cover in Lecture 5)*Current LectureMeiosis/Complex Multicellularity Cont. -Meiosis (germ cell division resulting in four haploid gametes) increases genetic variation in several waysoMaternal/paternal chromosomes recombine (crossing over)-Chiasmatahold the homologous chromosomes together so DNA exchange can happen between the non-sister chromatids -This creates unique chromosomes that contain both maternal and paternal DNAoHomologous chromosomes assort independently -Chromosomes can separate during meiosis (both I and II) in many different combinations, and each separates independently from the nextOne human can make gametes with 8 million different combinations of chromosomes -This creates unique gametes oMale and female gametes (sperm and egg) combine randomly during fertilization -This creates unique zygotes These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.One male and one female can create 70 trillion different zygotes during fertilization alone-Complex multicellular organisms are mostly Eukaryotes (some Bacteria, but very few) Mutations -= "Mistakes" in one's DNA that ultimately lead to changes in protein production -Mutation also increase genetic variation among individuals and organisms -Some can be beneficial, some have no effect, and some can be harmful-Types of mutations:oSmall scale mutations -Point mutations (including nonsense, missense, and silent)= when a single nucleotide is exchanged for anotherNonsense mutation= when there is an early stop codon in the sequence,causing it to end prematurely and lack necessary amino acids Missense mutation= single nucleotide changes resulting in a changed amino acid Synonymous (silent) mutation= when a nucleotide sequence is changed,but it doesn't effect the amino acid that is produced (multiple codons can translate to the same amino acid)-Insertion/Deletion= insertion or removal of one or more extra nucleotides oLarge scale mutations -Frame-shift mutations= when nucleotides are inserted or deleted (not in multiples of three)-Inversion= an entire section of DNA (or codon) is reversed/flipped -Translocation= DNA is swapped between two non-homologous chromosomes (chromosomes that express different genes)-Nondisjunction= the failure of homologous chromosomes or sister chromatids to separate during anaphase I and II causing an extra chromosome (or aneuploidy) in one's