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.
Environmental effect on phenotype
Punnett square and probability
Barr body and X-inactivation
Multiple alleles
Pleiotropy
Monohybrid cross
Dihybrid cross
Mean, standard deviation, standard error
Law of independent assortment
Linked genes
Interpreting a chi-square result
Degrees of freedom in chi-square
Short answer 1. Define or explain: Genotype vs phenotype
3 ptsShort answer 2. Define or explain: Test cross
3 ptsShort answer 3. Define or explain: Incomplete dominance
3 ptsShort answer 4. Define or explain: Pedigree analysis
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.