Heredity unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
Law of independent assortment
Pedigree analysis
Nondisjunction
Genotype vs phenotype
Carrier
Multiple alleles
Cytoplasmic inheritance
Interpreting error bars
Dihybrid cross
Epistasis
Monohybrid cross
Polygenic inheritance
Short answer 1. Define or explain: Interpreting a chi-square result
3 ptsShort answer 2. Define or explain: Sex-linked inheritance
3 ptsShort answer 3. Define or explain: Wild type vs mutant
3 ptsShort answer 4. Define or explain: Mean, standard deviation, standard error
3 ptsFree response
4 ptsThe ald gene of fruit flies encodes the ALD protein, which associates with both the centromeres of chromosomes and the protein filaments produced during meiosis. Without functional ALD protein, gamete-producing cells enter anaphase I before homologous chromosomes are correctly aligned, and the resulting gametes do not contain the correct numbers of chromosomes. Scientists generated four mutations in ald — ald1, ald3, ald23, and del (a deletion of the gene) — and studied gamete-forming metaphase cells from flies homozygous for the wild-type allele (WT/WT) and from flies heterozygous for different combinations: WT/del, ald1/del, ald3/ald23, ald23/del. FIGURE 1A. PERCENT OF GAMETE-FORMING METAPHASE CELLS CONTAINING ALD-ASSOCIATED FILAMENTS (± error bar) WT/WT 63 ± 19 WT/del 77 ± 12 ald1/del 12 ± 5 ald3/ald23 5 ± 2 ald23/del 0 FIGURE 1B. AMOUNT OF ALD PROTEIN PRODUCED (band thickness; a thicker band means more protein) WT/WT thick band — the greatest amount WT/del medium band — roughly half the WT/WT amount ald1/del medium band — the same thickness as WT/del ald3/ald23 thin band — less than WT/del ald23/del no band — no detectable ALD protein
(a) Based on Figure 1A, identify the fly genotype in which the average percent of metaphase cells with ALD-associated filaments is close to 12%.
(b) Based on Figure 1B, describe the difference in ALD protein production between gamete-forming metaphase cells of flies with the genotype ald3/ald23 and flies with the genotype ald23/del.
(c) Scientists hypothesize that gamete-forming metaphase cells can produce a normal amount of ALD-associated filaments even when they produce about half as much ALD protein as the wild-type cells produce. Use the data in Figures 1A and 1B to support the scientists’ hypothesis.
(d) For gamete-forming metaphase cells of the WT/del and ald1/del flies, explain why the phenotypes observed in Figure 1A differ even though the amount of ALD protein produced (Figure 1B) does not.