Transcript Genetics
Genetics 2.1 What is Genetics 2.2 Inheritance 2.3 DNA 2.4 Mutations and Disease 2.5 Genetic Technologies 2.1 What is Genetics • Genetics is the science of inheritance • Genetic information is carried on chromosomes in the nucleus of every cell • Chromosomes contain sequences of DNA called genes • Genes are the instructions for making proteins 2.1 What is Genetics • A chart depicting the chromosomes possessed by an individual is called a karyotype • Gender is determined by the 23rd pair of chromosomes called the sex chromosomes (XX or XY) • Karyotypes are commonly made after amniocentesis 2.1 What is Genetics • Chromosomes must be replicated and distributed during cell division • Mitosis: the division of autosomal cells into two identical diploid daughter cells • Meiosis: the division of sex cells to make four haploid gametes 2.1 What is Genetics • Fertilization is the combining of two haploid gametes to make a diploid zygote • By selectively breeding livestock and crops humans have altered naturally occurring species to suit our needs 2.2 Inheritance • Gregor Mendel worked with pea plants to discover the basic rules of heredity • Every trait is controlled by two alternate forms of a gene called alleles • One allele may be dominant while the other is recessive 2.2 Inheritance • A Punnett square can be used to determine the probable outcomes from a single trait cross • Important definitions: genotype, phenotype, heterozygous, homozygous • Human blood types illustrate other mechanisms of inheritance 2.2 Inheritance • Sex-linked inheritance involves alleles carried on the X chromosome (colour blindness and hemophilia 2.3 DNA • DNA: deoxyribonucleic acid • DNA is a double helix consisting of paired nucleotides • The order of nucleotides determines the sequence of amino acids in a protein • DNA is self replicating using a semiconservative process 2.4 Mutations and Disease • A mutation is a change is the sequences of bases in a DNA molecule • Mutations can be substitutions, additions or deletions • Addition and deletion mutations are called frameshift mutations 2.4 Mutations and Disease • Some mutations result in genetic disease • If the mutation is recessive then it is possible for a person to be a carrier of the disease • The frequency of mutations are increased by mutagens • Some mutagens are carcinogens 2.4 Mutations and Disease • A pedigree chart can be used to determine the type of inheritance of a genetic disease, to determine the genotypes of individuals and to identify carriers • Royal family pedigree chart 2.5 Genetic Technology • Genetic technologies include: • Transgenics: using recombinant DNA technology to modify the proteins produced by an organism (AKA genetic engineering or genetically modified organisms) • Gene therapy: replacing a defective gene to cure a disease 2.5 Genetic Technology • DNA fingerprinting: cutting DNA into fragments and creating a unique profile for an individual