BIOLOGY 111 1st Edition Lecture 16 Outline of Last Lecture I. Meiosis II. Sexual ReproductionIII. Phases of Meiosis IV. Genetic VariationOutline of Current LectureI. Mendelian GeneticsII. Segregation of AllelesIII. Phenotype and GenotypeIV. Law of independent assortment V. Probability FormulasCurrent LectureMendelian Genetics- cross fertilization - the cross of two different specimens (instead of self-fertilization)- parental generation - first (original) generation- F1 - first generation (offspring of parentals)- F2 - second generation (offspring of F1)...- experiment o Parental: cross fertilization of purple and white flowerso F1: there was a dominance in purple, so all offspring were purple.He self-fertilized to create F2.o F2: white shows back up in small ratio to purple - Alleles - are different variations of the same gene encoding the same character (account for variations inherited)o for each character, an organism inherits two alleles, one from each parent o different individuals can have different alleles at this locuso dominant alleles - masks the presence of another allele [A- (AAThese 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.or Aa) o recessive alleles - are masked and reveal themselves only when the organism has two copies of that allele (aa)o heterozygous - individual has two different alleles (Aa)o homozygous - individuals alleles are identical (AA or aa)- locus - is the "address" or location of a particular gene (allele) on a chromosome - segregation of alleles - two alleles for a heritable character, segregate(separate) from each other, so that only one allele is carried by each sperm or egg)o inheriting even one copy of a dominant allele is effective o if offspring showed the recessive trait, they would have two copies of the recessive allele o this explains the 3:1 segregation ratio in the F2 generation - phenotype is the physical appearance - genotype is genetic composition - Monohybrid cross (focuses on one character)o a cross between parents that differ in a single gene pair (AA X aa)o phenotype is 3:1 [3 dominant: 1 recessive (i.e. 3 purple to 1 white flower)]o genotype is 1:2:1 (1 homozygous dominant: 2 heterozygous dominant: 1 homozygous recessive)- a test cross is a way of testing if a genotype was homozygous dominant or heterozygous- law of independent assortment - each pair of alleles segregrate independently of each other pair of alleles during gamete formation (this law only applies to genes on different, nonhomologous chromosomes)- dihybrid cross (based on two characteristics)o cross parents that differ by two pairs of alleles (AABB X aabb)o phenotype is 9:3:3:1 (9 double dominant: 3 recessive and dominant: 3dominant and recessive: 1 double recessive) i.e. 9 yellow round peas: 3 green round peas: 3 yellow wrinkled peas: 1 green wrinkled pea- combination of gametes is o YyRrTtPPo 2*2*2*1= 8o or 2^n (n is number of possible gametes)- Laws of probability P=[(number of times an event occurs) / (total numberor possible outcomes)]- Product rule (multiply the possibilities of each product) **AND** is keywordo probability that two or more independent events will occur isequal to the product of their individual probabilities o ex. what is the probability of having 3 girls in a row?  the chances of having a girl is 1/2  chances of having three girls is (1/2)*(1/2)*(1/2) = 1/8o ex 2. an offspring with Aadd if the parents are (AaDd X AaDd) Aa: (1/2) dd: (1/4) (1/2)*(1/4) = 1/8- Sum rule (add up the possibilities of each event) **OR** is keyword o probability that one of two or more mutually exclusive events willoccur is the sum of probabilities of possible outcomes o add the probabilities (1/4 + 1/4) = 1/2o probalbility of having YYRR or yyrr from a YyRr X YyRr cross YY: (1/4) RR: (1/4)- YYRR (1/16) yy: (1/4) rr: (1/4)- yyrr (1/16) (1/16) + (1/16) = 2/16 = 1/8o probability of having aaDd or aaDD- Mendels interpretationo Heritable factor (genes) – responsible for character inheritance - Mendels Lawso Law of segregation (for monohybrid cross) Phenotype ratio 3:1  Genotype 1:2:1o Law of independent assortment (for dihybrid cross)Phenotype ratio 9:3:3:1- incomplete dominance o traits appear to blend in F1 generation o ex. crossing a red and white flower gives pink offspringo not enough encoding to signal for complete dominance- co-dominant allelso 2 alleles affect the phenotype equally and separately o instead of blending, both characteristics appear in equal amounts o ex. in red blood cells, there are four types that each give a different phenotype A is dominant, could be homozygous or heterozygous dominant B is dominant, could be homozygous or heterozygous dominant  AB (codominant, A and B are equally dominant, neither masks the other) - universal recipient because it has all themarkers, allowing it to recognize type A, B, or O blood O is homozygous recessive for both A and B, considered a universal donor because it does not have any markers, allowing it to be recognized by all types of blood, BUT only type O blood can donate to type O blood  Rh factor genes are inherited in dominant/recessive fashion - Rh+ (Rh is present) = dominant- Rh- (Rh is absent) = recessive - Polygenic characters - characters controlled and expressed as a combined expression of two or more genes o quantitative characters that vary continuously throughout a population (i.e. skin color, height...) are usually encoded - Multifactorial character - in addition to genetic factors, there are environmental factors (i.e. diet) as wello depression exhibits multifactorial inheritance (genes plus stressful environment)  altered protein function can affect