BIOLOGY 111 1st Edition Lecture 18 Outline of Last Lecture I Epistasis II Pedigree Analysis III Inherited Disorders in Humans IV Chromosome Theory of Inheritance Outline of Current Lecture I Parental Type Offspring II Recombinant Type Offspring III Frequency of Recombination IV Linkage Map V Alteration of Chromosome VI Epigenetics Current Lecture Parental type offspring resemble the parents Recombinant offspring result of crossing over in Meiosis 1 On the same chromosome if there is no crossing over o all offspring are expected to match their parental types if there is crossing over in Meiosis 1 no crossing over occurs in Meiosis 2 o Parental type will be 50 o Recombinant type will be 50 if there are three genes on the same chromosome o parental type will be most common o recombinant will be intermediate o double recombinant will be the least amount Frequency of Recombination how many times you will see a cross over o if on different chromosomes they are 50 50 o if on same chromosome use equation below recombinants total offspring 100 recombination frequency linkage map a genetic map based on recombination frequency o the closer the genes are the less frequently they will recombine ex 1 map unit 1 recombination frequency o the further the genes are the more likely they will cross over 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 ex 10 map units 10 recombination frequency o maximum recombination frequency 50 map units you will not exceed 50 map units if you calculate 50 map units they are not on the same chromosome therefore they are not linked if they are on the same chromosome they will behave like unlinked genes even though they re on the same chromosome less than 50 map units they are linked Alteration of chromosome structure occurs during cell division o deletion removes a chromosomal segment a small piece of DNA is deleted whatever it was coding for you lose that function o duplication repeats a segment o inversion reverses a segment within a chromosome o reciprocal translocation switching with other chromosomes movement of a segment from one chromosome to a nonhomologous chromosome most often a nonhomologous chromosome exchanges fragments less often a nonreciprocal translocation occurs a chromosome transfers a fragment but receives none in return Translocations can move a gene to a new location and place it under control of different regulatory regions during mitosis Chromosome number and alterations o polyploid 3 or more sets of chromosomes diploid 2n triploid 3n tetraploid 4n o aneuploidy all abnormal chromosome numbers causing developmental and genetic abnormalities nondisjunction members of a pair of homologous chromosomes do not move apart properly during meiosis 1 or meiosis 2 o autosomal Trisonomy 21 Down syndrome Trisonomy 18 Edward syndrome Trisonomy 13 Patau syndrome o sex chromosome XXY Klinefelter XYY Jacobs XXX Triple X XO Turner Epigenetics o Genomic Imprinting occurs when the phenotype exhibited by a particular allele depends on which parent contributed the allele to the offspring it causes genes from one parent to be temporarily silent during early development by DNA packaging or methylation not mutation silence imprinted with a tag that says do not present yourself tags attach to certain types of genes these tags are what silent or activate a gene these tags are reversible silents a gene by adding methyl groups CH3 or they can change the histones proteins o if they tightly wind them expressing is suppressed o loosely wound more expression the phenotype changes accordingly to which genes are activated and which are silenced the phenotype depends on the male and female parents o ex a specific partial deletion of chromosome 15 prader willis syndrome from the father angelman syndrom from the mother cytomplasmic genes in mitochondira and chloroplasts o inherited only through the maternal linkage all mitochondrial DNA came from the mother o the sperm has mitochondria but its purpose is to create enough ATP to function the flagella to get to the egg o mitochondrial Diseases Lebers Neurogenic Maternal