Session 6 Biology Study Guides

In a certain pecie of plant, the diploid number of chroma ome i 4 (2n = 4). Flower color i controlled by a ingle gene in which the green allele ( G) i dominant to the purple allele (g). Plant height i controlled by a different gene in which the dwarf allele (D) i dominant to the tall allele (d). Individual of the parental (P) generation with the genotypes GGDD and ggdd were cro ed to produce F1 progeny. Chromo omc 1 Chromo. ome 2 In a certain species of plant, the diploid number of chromosomes is 4 (2n = 4). Flower color is controlled by a single gene in which the green allele (G) is dominant to the purple allele (g). Plant height is controlled by a different gene in which the dwarf allele (D) is dominant to the tall allele (d). Individuals of the parental (P) generation with the genot es GGDD and dd were crossed to produce F1 progeny. (a) ,co,nstruct a diagram below to depict t I e our possi e normal products of meiosis that would be produced by the F1 progeny. Show the chromosomes and the allele(s) they carry. Assume the genes are located on different chromosomes and the gene for flower color is on chromosome 1. { 1 point) G D G d g D g d Co1n:struct dia1gram (1 point) 1 • Di1 agram m·ust include, all of the i following:: o Each cell has one und�plicated chromosome 1 (with G or g)� o Each ce11 has one unduplicated chromosome 2 (with D or d) o Genotype combinations should be:: GD, G1d, gD gd. 1• 1, G D G d g D g d (c) If the two genes were genetically linked, describe, how the proportions of phenotypes of the 1esulting offspring would most likely differ from those of the testcross betwee,n an F1 in1dividual and a ggdd individual. (1 point) Identify diff1erence (1 point) • • • The majority/greater than 50 percent would have the parental plant phenotypes Greater than 2G percent would be green dwarf plants and ,greater than 2G percent would be purple tall plants Less than 25 percent would be green tall plant.s and less than 25 p-ercent would be purple dwarf plants Both mitosis and meiosis are forms of cell division that produce daughter cells containing genetic information from the parent cell. (a) .Describe TWO, events that are common to both mitosis and meiosis that ensure the resulting daughter cells inherit the appropriate number of chromosomes. Description (1 point 1each;: 2 poi, n.ts maximum), • • • • • • • Spindle elements (microtubules) form/attach to chromosomes C'h romatin condenses Alignment of chromosomes across center of cell prior to chromosome separation Separation of chromatids/centromer1es to daughte1 cells G2/M checkpoint occurs in both processes Replication or synthesis of DNA precedes mitosis/meiosis Cytokinesis separates daughter cells after mitosis/meiosis (b) The genetic composition of daughter cells produced by mitosis differs from that of the daughter cells produced by meiosis. Describe TWO features of the cell division processes that lead to these differences. Feature Description (1 point each row; 2 points maximum) Mitosis Meiosis Number of divisions/ number of resulting cells 1 clivisiun/ 2 cells resulL 2 clivisiuus/ 4 cells resulL Ploidy of daughter cells • • • • Chromatids separate Occurs Not in meiosis I/only in meiosis II Crossing over Does not occur Occurs Homologous chromosomes separate/independently Does not occur Occurs assort • Same as parent cell Diploid (2n-->2n or n-->n) • Half of parent cell Haploid (4n-->2n; 2n-->n) The pyruvate dehydrogenase complex {PDC) catalyzes the conversion of pyruvate to acetyl-CoA, a substrate for the Krebs (citric acid) cycle. The rate of pyruvate conversion is greatly reduced in individuals with PDC deficiency, a rare disorder. (a)1 Identify the cellular lo r cation where PDC is :mo1st active. Identification I point • Mitochondria • Mitochondria] matrix The pyruvate dehydrogenase complex {PDC) catalyzes the conversion of pyruvate to acetyl-CoA, a substrate for the Krebs {citric acid) cycle. The rate of pyruvate conversion is greatly reduced in inciividuals with PDC deficiency, a rare disorder. {b) Make a claim about how PDC deficiency affects the amount of NADH produced by glycolysis AND the amount of NADH produced by the Krebs (citric acid) cycle in a cell. Provide reasoning to support your claims based on the position of the PDC-catalyzed reaction in the sequence of the cellular respiration pathway. Claim Glycolysis No change • • • Krebs cycle Decrease • Reasoning Glycolysis continues; PDC is not needed . Glycolysis occurs before conversion of pyruvate to acetyl-CoA. The Krebs cycle is greatly reduced/slowed down if there is no/less acetyl-CoA .. The Krebs cycle occurs after conversion of pyruvate to acetyl-CoA . (c) PDC deficiency is caused by mutations in the PDHAl gene, which is located on the X chromosome. A male with PDC deficiency and a homozygous female with no family history of PDC deficiency have a male offspring. Calculate the probability that the male offspring will have PDC deficiency. X X V xx xv X xx xv Calculation ( 1 point) • • The probability of inheritance is O . The offspring cannot/will not have PDC deficiency .