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Suppose that blue flower color in a plant species is controlled by two genes, A and B. The dominant alleles A and B specify proteins that function in the pathways shown below. The A and B proteins are both required to make blue pigment from a colorless precursor. A and B proteins also independently inhibit the production of blue pigment from a different colorless precursor; that is, the presence of either protein A or protein B is sufficient to prevent blue pigment production from precursor 2. The recessive mutant alleles a and b specify no protein. Two different pure-breeding mutant strains with white flowers were crossed, and complementation was observed so that all the F were blue.
a. | What are the genotypes of each white mutant strain and the F1? |
b. | If the F1 are selfed, what would be the |
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Chapter 3 Solutions
ND STONY BROOK UNIVERSITY LOOSELEAF GENETICS: FROM GENES TO GENOMES
- In wheat, aleurone cells form a thin layer of the seed coat that is critical to early gene expression in plant development. The color of this layer of cells is controlled by two alleles of a gene [colored aleurone (R) is dominant to colorless (r)]. A second gene is known to control the color of leaf tips [green leaf tip (G) is dominant to yellow (g)]. Two plants, each heterozygous for both characteristics, are test crossed to homozygous recessives, and their progeny are combined to produce the following totals: colored green 102 colored yellow 98 colorless green 103 colorless yellow 97 a) Use chi-square analysis to test these data for an independent assortment of the two characteristics (table provided). Please show work, how your expected values are calculated, and explain what your results indicate about the data. b) You decide to be cautious in your analysis, and decide to analyze the progeny from each of the crosses individually (instead of adding them together as shown above).…arrow_forwardIn a species of tree, seed color is determined by four independently assorting genes: A, B, C, and D. The recessive alleles of each of these genes (a, b, C, and d) produce abnormal enzymes that cannot catalyze a reaction in the biosynthetic pathway for seed pigment. This pathway is diagrammed as follows: A White precursor Yellow ----Orange----- Red --- Blue When both red and blue pigments are present, the seeds are purple. Trees with the genotypes Aa Bb Cc Dd and Aa Bb Cc dd were crossed. (a) What color are the seeds in these two parental genotypes? (b) What proportion of the offspring from the cross will have white seeds? (c) Determine the relative proportions of red, white, and blue offspring from the cross.arrow_forwardWould you simply answer the question for me, i saw many answers for it but still not sure. The flower color of genetically identical hemp plants (clones) is purple when the flowers develop under cold environment (30 °C). Describe in detail a molecular mechanism that could explain how these two groups of genetically identical plants differ in their gene expressions to produce different flower colors?arrow_forward
- Feather color in parakeets is produced by the blending of pigments produced from two biosynthetic pathways shown below. Four independently assorting genes (AA, BB, CC, and DD) produce enzymes that catalyze separate steps of the pathways. For the questions below, use an uppercase letter to indicate a dominant allele producing full enzymatic activity and a lowercase letter to indicate a recessive allele producing no functional enzyme. Feather colors produced by mixing pigments are green (yellow + blue) and purple (red + blue). Red, yellow, and blue feathers result from production of one colored pigment, and white results from absence of pigment production. What is the genotype of a pure-breeding purple parakeet strain? Express your answer as combination of allelic symbols. Example: AaBBccDd.arrow_forwardYou conduct an experiment to study the expression of the S protein through the tissues of your favorite plant (Arabidopsis thaliana). The morning of the experiment you inject in the leaves a messenger RNA that codes for the synthesis of a single protein made of two parts that are attached to each other: the functional S protein and a red fluorescent protein tag (RFP). You perform two cross sections of the same root, one section at the start of the experiment (time = Oh; corresponding to the time of injection) and one section in the afternoon (time = 8h). Through fluorescent microscopy you observe a change in the coloration inside the cells of the root's central tissues (as indicated by the arrows): from no coloration (time = Oh) to red (time = 8h). • The cells of the central tissues in the roots do not have nuclei or ribosomes. How can you explain this change of coloration? Please provide a cellular feature that can lead to this. • What is one advantage of using an RFP-tag in an mRNA?…arrow_forwardThe flower color of genetically identical hemp plants (clones) is purple when the flowers develop under cold environment (30 °C). Describe in detail a molecular mechanism that could explain how these two groups of genetically identical plants differ in their gene expressions to produce different flower colors?arrow_forward
- The flower color of genetically identical hemp plants (clones) is purple when the flowers develop under cold environment (<14 °C) and white when they develop under hot environment (>30 °C). Describe in detail a molecular mechanism that could explain how these two groups of genetically identical plants differ in their gene expressions to produce different flower colors?arrow_forwardIn roses, the synthesis of red pigment is produced by two steps in a pathway. gene O magenta intermediate - gene P colorless intermediate- red pigment What would the phenotype be of a plant homozygous for a null mutation of gene P? What would the phenotype be of a plant homozygous for a null mutation of gene Q? What would the phenotype be of a plant homozygous for null mutations of genes P and Q? magenta red Match a genotype to each strain. colorless Strain P locus Q locus homozygous null mutation of gene P homozygous null mutation of gene Q homozygous null mutations of genes P and Q Answer Bank plp PIP What F2 ratio is expected from crossing a plant that is homozygous for a null mutation of gene P with a plant that is homozygous for a null mutation of gene Q? Assume independent assortment. 9 colorless : 4 magenta : 3 red 9 red : 4 colorless : 3 magenta O 9 red : 4 magenta : 3 colorlessarrow_forwardAurora AAurora A is a protein that acts as a kinase (transfers phosphates to molecules). Many types of cancer cells, including breast cancer cells, have higher than normal levels of this protein.Expressions of Aurora A genes in normal breast tissues (n = 10), normal tissues adjacent to tumors (n = 12) and breast tumors (n = 14).Scientists studying the production of Aurora A protein in normal frog cells observed that the amount of this protein in the cells changed throughout the cell cycle.Scientists tested chemicals that block Aurora 2 to see if they could be used as anti-cancer drugs. They found that some of the candidate drugs did slow the growth of cancer cells in cell culture in the lab. But when they tested these drugs in cancer patients to see if the drugs could slow the growth of solid tumors, they found that the benefit to patients was small when compared to the development of severe side effects such as anemia (low red blood cell count) and leukopenia (low white blood cell…arrow_forward
- In roses, the synthesis of red pigment is by two steps ina pathway, as follows:colorless intermediate gene Pmagenta intermediate red pigment gene Qa. What would the phenotype be of a plant homozygousfor a null mutation of gene P?b. What would the phenotype be of a plant homozygousfor a null mutation of gene Q?c. What would the phenotype be of a plant homozygousfor null mutations of genes P and Q?d. Write the genotypes of the three strains in parts a, b,and c.e. What F2 ratio is expected from crossing plants fromparts a and b? (Assume independent assortment.)arrow_forwardA complex biochemical pathway is shown below, along with the alleles that either promote or inhibit each step of the pathway leading to a phenotype. Gene A has alleles A and a, B has alleles B and b, and so forth. Genes B and C are duplicate dominant epistatic lethal as heterozygotes (i.e. Bb Cc are lethal). Genes D and E are duplicate dominant epistatic (i.e. dd eg = desired phenotype). If I were to cross AA Bb cc Dd Ee with aa BB Cc Dd e, (i) (ii) What proportion of all offspring don't show the phenotype? What proportion of offspring survive? Gene A Gene B B Gene D a Gene C Gene Earrow_forwardThe cystic fibrosis gene encodes a chloride channel protein necessary for normal cellular functions. Let us assume that if at least 5% normal channels are present, the affected individual has mild symptoms of cystic fibrosis. Having less than 5% normal channels produces severe symptoms. At least 50% of the channels must be expressed for the individual to be phenotypically normal. This gene has various mutant recessive alleles: Predict the percent of functional channels and severity of symptoms for the following genotypes: a. heterozygous for CF100 b. homozygous for CF100 c. heterozygous, with one copy of CF100 and one of CF3 d. heterozygous, with one copy of CF1 and one copy of CF3arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning
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