Revised 08 WORKSHEET BIO 208 Unit 2 Also review list of objectives, notes, textbook, and homework assignments 1. Animals can teach us genetics! Match Heterozygotes will exhibit two distinct proteins on their red blood cells A. Manx cat Show a dominant and recessive relationship B. Coat coloration in cats An allelic series C. Labrador retriever dogs A dominant homozygote is lethal D. Piebald spotting in beagles Coat coloration is determined by 2 distinct genes E. MN antigens Shows variable expressivity F. A and O blood alleles A qualitative, or continuous, trait G. Calico cat Females mosaics for X-linked heterozygous color genes H. Height of an individual 2. If Mendel only knew then what we know now. EPISTASIS CODOMINANCE PENETRANCE EXPRESSIVITY INDEPENDENT ASSORTMENT a. b. c. d. e. f. DOMINANCE INCOMPLETE DOMINANCE ALLELE RANDOM SEGREGATION The expression of both alleles of a heterozygous gene pair is called: The degree to which a genotype is expressed in the phenotype: The suppression of one gene by another non allelic gene : The % of individuals of a genotype that show the expected phenotype: Each gamete receives one allele of a gene : When a single gene heterozygous genotype results in a phenotype intermediate to the two alleles : g. The alleles of one gene pair are inherited independently from those of another gene pair : h. An alternative form of a gene: i. The expression of one allele to the exclusion of the other in a heterozygote: Revised 08 PED'IGREE, n. from L. pes,pedis, foot. Lineage; line of ancestors from which a person or tribe descends; genealogy. 3. Examine the pedigree below Why is this NOT a Y linked trait? Could this be an X – linked trait? Is this inherited in an autosomal dominant or autosomal recessive manner? How do you know for sure? I II III Which three modes of inheritance are possible for this trait. Show your reasoning by indicating possible genotypes for each individual I II 4. It is probable that a probability question is in the future From the cross AaBbccDdEeff X AABbCcDdeeFf what is the probability of obtaining the genotype AabbCcDDEeff in the progeny? 5. Epistasis with two genes! In horses, a dominant B will give the horse a black color, and a b will give the horse a chestnut color. However, when a dominant W is present in the second gene pair, the horse will be white no matter what. If the second gene pair is ww, then the horse will be the color of whatever the first gene pair is made of. If a heterozygous white (BbWw) mare is crossed with a heterozygous white (BbWw) stallion, what could the offspring's phenotype and genotype be? Revised 08 6. Fill in the disorder XY female XX male Patau syndrome Phenylketonuria a. b. c. d. e. f. g. h. i. j. k. l. Cri du Chat Down syndrome Anhydrotic ectodermal dysplasia Hemophilia Polydactyly Achondroplasia Alkaptonuria Male, small testes, infertility Female may not have ovaries or a uterus Female heterozygotes have patches of skin that lack sweat glands Inability to clot blood due to lack of a clotting factor Dominant allele results in extra fingers and toes Recessive allele prevents metabolism of phenylalanine Dominant allele affects cartilage growth needed for bone lengthening Retardation, higher risk of Alzheimer disease Babies usually do not live beyond a year, deaf, blind Microcephaly, abnormal larynx anatomy Metabolic disease part of phe pathway, black urine 5 disorders that can be detected by karyotype 7. And let’s not forget human sex….. Arrange in the correct chronological order: TDF, SRY, testosterone, male embryo, testes, Y chromosome 8. Fly sex………… In Drosophila sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. Female ratio is 1 or greater, while males have a ratio of 0.5 or less. Identify the sex of the following flies a. XY fly with 2 sets of autosomes ______________ b. XXY fly with 2 sets of autosomes ______________ c. XX fly with 3 sets of autosomes ______________ 9. AND……………Bird sex….. In birds, the male is the homogametic sex. Females are ZW. A dominant sex-linked allele, ZS gives silver feather color. Zs gives gold. Mate a silver female with a gold male. How can you identify male and female offspring by feather color alone? Revised 08 10. Who did it? a. ___________ Random X-chromosome inactivation Edwards b. ___________ Characterized trisomy 21 Klinefelter c. ____________Characterized trisomy 18 Barr d. ___________ Discovered independent assortment Mendel e. ____________ Chromosomal theory of inheritance Down f. ____________Characterized XXY males Sutton, Boveri 11. Do you know your numbers? a. b. c. d. e. f. g. h. number of chromosomes in a human diploid cell __________ number of chromosomes in a human haploid cell _____________ number of chromosomes in a human Turner syndrome cell __________ number of chromosomes in a human trisomic cell __________ number of chromosomes in a human triploid cell __________ number of chromosomes in a human cell with a Robertsonian fusion __ number of chromosomes in a human fertilized egg _______ number of chromosomes in a normal human sperm _______ 12. Ploidy, somy, and more Fill in: RECIPROCAL TRANSLOCATION MONOPLOID LOCUS MONOSOMY TRIPLOID TRISOMY TETRAPLOID BARR BODY a. Position a gene occupies on a chromosome ___________ b. X chromosome in mammals seen as heterochromatin __________ c. An aberrant chromosome number in which a normally diploid cell has 3 copies of 1 chromosome _________________ d. An exchange of non-homologous chromosomes __________ e. An aberrant chromosomal condition in which a cell has 1 copy of a chromosome and 2 copies of all others __________ f. An individual possessing 4 sets of chromosomes ____________ 13. Deletion, Translocation, Inversion, Duplication, OR Mosaicism? a. __________ Involved in 46, 5pb. __________ May result in a position effect which affects gene expression c. __________ May result in pseudodominance of an allele which is normally recessive to a dominant allele d. __________ Two genetically distinct populations of cells in a single individual e. __________ Will result in abnormal gamete formation (more than one answer) f. __________ Involved in familial Down syndrome g. __________ Lethal if it occurs in the same region of two homologous chromosomes Revised 08 h. __________ No loss or gain of genetic material is involved (2 answers) i. __________ Cell will have 45 chromosomes j. __________ Increase of genetic material, may be tandem or reverse k. __________ 46, XX/45, X (one individual) 14. Fill in the blanks on the pathway for phenylalanine metabolism. The arrows represent a mutant enzyme (and corresponding gene) that does not function in the pathway. a. Name of disease ________________ b. Why disease kills brain cells ____________ c. Name of pigment ______________ d. Black urine disorder name ________ 15. MORE?? a. When true-breeding tall stem pea plants are crossed with true-breeding short stem pea plants, all of the ______ plants, and 3/4 of the ______ plants had tall stems. Therefore, tall stems are dominant b. A genetic cross between two F1-hybrid pea plants having yellow seeds will yield what percent green-seeded plants in the F2 generation? Yellow seeds are dominant to green. c. To identify genotype of yellow-seeded pea plants as either homozygous dominant (YY) or heterozygous (Yy), you could do a test cross with plants of genotype ___. d. What is the probability that a woman with cystic fibrosis (an autosomal recessive disease) and normal male whose parents are homozygous dominant have a child with cystic fibrosis? e. Why is it not possible for a colorblind man (XcY) who mates with a normal woman (XCXC) to have a colorblind son? Revised 08 f. Maple syrup disease is a rare genetic (inherited) disease. This disorder of metabolism causes the baby’s urine to assume the odor of maple syrup. Two individuals, heterozygous for the disease (phenotypically normal) have 10 children. How many children are expected to exhibit the disorder? g. In Mendel's experiments, if gene for tall (T) plants was incompletely dominant over gene for short (t) plants, what would be the result of crossing two Tt plants? h. A genetic cross of inbred snapdragons with red flowers with inbred snapdragons with white flowers resulted in F1-hybrid offspring that all had pink flowers. When the F1 plants were self-pollinated, the resulting F2-generation plants had a phenotypic ratio of 1 red: 2 pink: 1 white. The most likely explanation is: i. A woman with type A blood and a man with type B blood could potentially have offspring with which of the following blood types? j. A pea plant is heterozygous for both seed shape and seed color. S is the allele for the dominant, spherical shape characteristic; s is the allele for the recessive, dented shape characteristic. Y is the allele for the dominant, yellow color characteristic; y is the allele for the recessive, green color characteristic. What will be the distribution of these two alleles in this plant's gametes? k. Which of the following genetic crosses would be predicted to give a phenotypic ratio of 9 :3:3: 1? SSYY x ssyy or SsYy x SsYy or SSyy x ssYY or ssYY x ssyy l. In a dihybrid cross, AaBb x AaBb, what fraction of the offspring will be homozygous for both recessive traits? m. Following a SsYy x SsYy cross, what fraction of the offspring are predicted to have a genotype that is heterozygous for both characteristics? n. In a dihybrid cross, SsYy x SsYy, what fraction of the offspring will be homozygous for both traits? o. Hemophilia in humans is due to an X-chromosome mutation. What will be the results of mating between a normal (non-carrier) female and a hemophiliac male? p. A human female "carrier" who is heterozygous for the recessive, sex-linked trait causing red-green color blindness has a child with a normal male. What proportion of their male progeny will have red-green color blindness? q. A human female "carrier" who is heterozygous for the recessive, sex-linked trait red color blindness, marries a normal male. What proportion of their female progeny will show the trait? Revised 08 r. A rooster with gray feathers is mated with a hen of the same phenotype. Among their offspring, 15 chicks are gray, 6 are black, and 8 are white. What is the simplest explanation for the inheritance of these colors in chickens? What offspring would you predict from the mating of a gray rooster and a black hen? s. A man has six fingers on each hand and six toes on each foot. His wife and their daughter have the normal number of digits. Extra digits is a dominant trait. What fraction of this couple's children would be expected to have extra digits? t. A woman has the rare (hypothetical) disease called bent fingers. She has children with a normal man, and all of their sons but none of their daughters have bent fingers. What is the mode of inheritance of bent fingers? a. Autosomal recessive b. Autosomal dominant c. X-linked recessive