1. COLEGIO SAN PATRICIO - HIGH SCHOOL<br />BIOLOGY GUIDE - 4th Period<br />Hybrids: Offspring that result from crosses between true-breeding parents with different traits.<br />Mendel concluded that traits are inherited from the parents to the offspring through ‘factors’<br />When Mendel crossed true-breeding tall plants with true-breeding short plants, all the offspring were tall because the allele for tallness is dominant (and all of them had it).<br />In the P (parent) generation, a tall plant was crossed with a short plant. Short plants reappeared in the F2 (second) generation because the allele for shortness and the allele for tallness segregated when the F1 (first generation) plants produced gametes.<br />The principles of probability can be used to predict the traits or characteristics of the offspring produced by genetic crosses.<br />A Punnett square shows the possible results of a genetic cross, the genotypes of the offspring, the alleles in the gametes of each parent.<br />Meiosis results in the formation of four genetically different haploid (1N) cells.<br />Linked genes are found on the same chromosome.<br />DNA contains a series of nucleotides composed of: deoxyribose (5C sugar), a phosphate group, nitrogenous base (Cytosine, Guanine, Adenine or Thymine)<br />DNA replication results in two DNA molecules, each with one new strand and one original strand.<br />RNA contains a series of nucleotides composed of: ribose (5C sugar), a phosphate group, nitrogenous base (Cytosine, Guanine, Adenine, Uracil).<br />Types of RNA involved in protein synthesis: messenger RNA, transfer RNA, ribosomal RNA.<br />Transcription: process that takes place in the nucleus of the cell, where a molecule of mRNA (a blueprint of the DNA) is produced.<br />Translation: process that takes place in the ribosome, where tRNA decodes the information in mRNA, to produce amino acids and assemble specific proteins. <br />Codons: groups of three nitrogenous bases that code for one specific amino acid.<br />Gene mutations: insertion, deletion, substitution.<br />Chromosomal mutations: translocation, deletion, insertion, inversion.<br />Karyotype: shows homologous chromosomes, autosomes, sex chromosomes.<br />A Pedigree chart can be used to: determine whether a trait is inherited or not, show how a trait is passed from one generation to the next, determine whether an allele is dominant or recessive.<br />Genotype: genetic information, genes/alleles of an organism. Phenotype: physical characteristics of an organism.<br />Autosomes: chromosomes that contain the information for somatic cells (all the body, except for sex cells). Sex chromosomes: chromosomes that determine the gender of an organism. Homologous chromosomes: paired chromosomes.<br />Chromosomes 21 and 22 have unstable sites where rearrangements can occur and result in a mutation.<br />Barr body: condensed X chromosome that is inactive.<br />Heterozygous: Organisms with two different alleles for the same trait. Homozygous: Organisms with the same genes for a specific trait.<br />Inbreeding, Genetic Engineering, Hybridization, Transformation, Selective Breeding (main purpose).<br />Blood groups, Colorblindness, Sickle-cell disease, Hemophilia, Tay-Sachs, Huntington – how they are transmitted, dominance, incomplete dominance, codominance. <br />