Milestone Minutes Genetics Week 3 Write notes in your Milestone Journal and answer the practice questions. Genetics DNA and RNA are molecules essential for the transmission of genetic information. DNA is a double stranded helix, contains the sugar deoxyribose, A-T & G-C RNA is single stranded, contains the sugar ribose, A-U & G-C, produces proteins DNA replication (copying)occurs prior to mitosis during the cell cycle Mitosis stages: prophase, metaphase, anaphase, telophase Mitosis results in two genetically identical daughter cells, occurs in autosomal cells, diploid (asexual) Meiosis results in four genetically different gametes (egg & sperm), haploid (sexual) Recombination of genetic material (crossing over) occurs during anaphase 1 & 2 of meiosis Mendel was the father of genetics and put forth laws concerning heredity. Law of Dominance -dominate alleles (capital letter) suppress recessive alleles (lowercase letter) Law of Segregation -during fertilization gametes randomly pair to produce four sets of alleles (monohyrid) TT=homozygous dominant, Tt=heterozygous, tt=homozygous recessive Genotype is the combination of alleles, Phenotype is the physical expression of alleles Law of Independent Assortment -genes for traits are inherited independently of each other (dihybrid) Segregation & Independent Assortment allow only one allele a gene to be present in the gametes Alterations (mutations) can occur during meiosis and change the genetic code. Some environmental factors are mutagenic (sunlight, chemical waste, radiation, toxins) Insertion-addition of one or more nucleic bases in the genetic sequence, changes reading frame Deletion-removal of one or more nucleic bases in the sequence, changes reading frame Substitution-switch of one or more nucleic bases in the genetic sequence, no change to reading frame Nondisjunction- failure of homologous chromosomes to separate during anaphase of meiosis Trisomy- condition of having an extra chromosome (Down Syndrome) DNA technology can change the genetic makeup of an organism. Recombination-moving genes from one organism to another (crosspollination/Hybrids) Genetic Engineeringusing organisms for beneficial purposes (insulin production, fighting viruses) Complete the practice questions in your journal.