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(4) Genetics.docx

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York University
Natural Science
NATS 1675

GeneticsSecond half of chapter 18 and chapter 20CHAPTER 20 GENETICSINTROgenetics come from Greek to become somethingGenetics is the study of heredity Genetic include the transition of traits characteristics from generation to generation by birth as well as how traits are expressed It is also the study of heritable differences both how they originate and how they relate to an individuals genetic program Genetics is also concerned with the transition of traits in lineages refers to things like family trees pedigrees and successive generations Genetics is also the distribution of heritable traits within populations that make up a given speciesFebruary 10th 2014DNA chemical molecule that makes up genes The genes chromosomes DNA that are carried in the nucleusGenes are the basic units of inheritance More specifically they are the smallest segment of a chromosome that does for 1 whole protein on a polypeptide chain a piece ora part of a protein example is insulin The majority of proteins synthesized by genes function as enzymes Enzymes are chemical molecules that regulate the vast majority of the chemical processed that go on in our bodies Chromosomes are thread like structures found in the nucleus and almost all cells have a nucleus The x and Y chromosomes are the sex chromosomes The y chromosomes carry the gene for males MutationsAs genes are copied in the reproduction of an organisms errors are sometimes made and these errors are called mutations Mutation is the process of change in the genetic material DNA that determines the traits and characteristics of a species Causes of mutations are 1 accidents of nature 2 Certain chemical compounds 3 Viruses 4 Radiation a natural b industrial c medical d ultra violet uv Mutations are heritable errors that can be passed down from generation to generation It results in further variation between species but not all organisms within a species are equally suited for survival survival of the fittest For a species to change the mutation has to go through an entire population A mutation that survives even a 1 advantage may be incorporated into the population within 80 generations Genetic DiseasesGenetic diseases are the oldest most wide spread and the most burdens of all human afflictions Its estimated that 8 of all north American are affected by some disease involving disorders of hereditary disorder 80 of birth defects contain a genetic component The other 20 are the result of environmental factors such as infection drugs radiation physical injury etc to the fetus Examples are measles and drugs Other disease have been known to have a genetic component that can be passed on and not show symptoms till later in life Example is Heart Disease Familial Hypertension high blood pressure certain forms of arthritis diabetes certain cancers certain mental illnesses schizophreniamanic depressive illness bipolar Species is defined as populations of organisms that retain their individuality in nature because they are reproductively isolated from other species around themReproductive isolation includes both behaviour and geneticsHybrids Is an organism produced from two different species or two different genotypes Ex female horsemale donkey mule Female donkeymale horse Hinny Both the mule and Hinnys are hybrids but they cannot reproduce Every species has a very specific number of chromosomes GenotypeThe genetic makeup of an organism eg RR Rr or rr the combination of alleles at a particular locus or all loci Type of genes what type of genes the organism has that is its genotypeR rounds seeds in pea plantsr wrinkles seeds in pea plantsPhenotypeThe appearance of an organism with regard to an inherited characteristic trait or all inherited characteristicsThe phenotype is produced by the genotype in cooperation with the environment eg RRound pea seeds rwrinkled pea seeds How it looksLocus loci plLocation of a gene on a chromosomeLocus is sometimes used synonymously for geneFigure AAlleleA pair of genes that occupy corresponding positions on homologous chromosomesRememberit is homologous chromosomes that pair during prophase IAlleles are also 1 of 2 or more alternate forms of a gene that occupy a particular locus on homologous chromosomesFigure 181 ABO blood types is an example of 3 alternate forms of a gene found at a one locus within the population DominantA trait that appears in the phenotype whenever the allele gene for it is present in the genotype eg RR or RrRound seedsRecessiveA trait that appears in the phenotype only when 2 alleles for the trait are present in the genotype eg rrwrinkled seedsHomozygousAlleles of a gene on homologous chromosomes are alikeRememberit is homologous chromosomes that pair during Prophase I You can have homozygous dominant and homozygous recessive HeterozygousAlleles of a gene on homologous chromosomes are not alike Hybrid CarrierA heterozygous individual organism of normal phenotype who has a hidden recessive allele in its genotype and thus can transmit the recessive allele to offspringCarrier and heterozygous are synonyms however the term carrier can imply a possibly damaging or unwanted gene Example mother is the carrier of the colour blind trait You only use Dominant and Recessive when talking about homozygous not heterozygous The Father of Genetics is Gregor Mendel an Austrian monk who presented his research in 1865Mendels paper contained 3 major generalizations1 The Principle of Dominance2 The Principle of Segregation and3 The Principle of Independent Assortment or Recombination
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