Exam #3 W 12/5 at 7-8:30pm in ETC 2. 108 for the 9am class and ECJ 1 Exam #3 W 12/5 at 7-8:30pm in ETC 2.108 for the 9am class and ECJ 1.202 for the noon class Review T 12/4 at 5pm in WRW 102 Homework #4 due 12/3 (if needed) Bonus #2 is posted

Grades: A = 88.5+ B = 77.5 C = 65.5 Exam avg x 0.88 + homework + bonus = grade

Tracking two separate genes, for two separate traits, each with two alleles. Ratio of 9:3:3:1 Fig 3.4

Box 2.2 Crossing-over Meiosis: In humans, crossing-over and independent assortment lead to over 1 trillion possible unique gametes. (1,000,000,000,000) Meiosis I (Ind. Assort.) Meiosis II 4 Haploid cells, each unique

Crossing over produces new allelic combinations Fig 4.3

Homologous pair of chromosomes

Longer regions have more crossovers and thus higher recombinant frequencies Fig 4.10

Some crosses do not give the expected results

=25% 42% 41% 9% 8%

These two genes are on the same chromosome

By comparing recombination frequencies, a linkage map can be constructed = 17 m.u.

Another test

42 recombinants out of 381 offspring = 42/381 11% recombination

The probability of crossing over can be used to determine the spatial relationship of different genes Fig 4.9

Double recombinants arise from two crossovers Fig 4.11

Double recombinants can show gene order Fig 4.12

What is the relationship between these 3 genes What is the relationship between these 3 genes? What order and how far apart? similar to pg 141

What is the relationship between these 3 genes What is the relationship between these 3 genes? What order and how far apart? similar to pg 141

Double crossover similar to pg 141

Which order produces the double crossover?

Which order produces the double crossover?

We have the order. What is the distance? similar to pg 141

Recombinants between st and ss: (50+52+5+3)/755 =14.6% similar to pg 141

Recombinants between ss and e: (43+41+5+3)/755 =12.2% similar to pg 141

Put it all together… 26.8 m.u. st ss e 14.6 m.u. 12.2 m.u.

Linkage map of Drosophila chromosome 2

Recombination is not completely random. physical distance linkage map Yeast chromosome 3 Fig 4.13 and 20

It is rarely this simple. Genotype Phenotype Genes code for proteins (or RNA). These gene products give rise to traits… It is rarely this simple. Figs 1.15-17

The relationship between genes and traits is often complex Complexities include: Complex relationships between alleles Multiple genes controlling one trait One gene controlling multiple traits Environmental effects

The colors of peppers are determined by the interaction of several genes

Complexity of inheritance leads to genetic diversity. Fig 3.14+.16

Eye color: One trait controlled by multiple genes

Seven alleles and their interactions in leaf patterning of clover Fig 6.7

The relationship between genes and traits is often complex Complexities include: Complex relationships between alleles Multiple genes controlling one trait One gene controlling multiple traits Environmental effects

1 gene controlling many traits

Mom = HS Dad = HS Dad H or S possible offspring 75% Normal S=sickle-cell H=normal Sickle-Cell Anemia Mom = HS Dad = HS Dad H or S possible offspring 75% Normal 25% Sickle-cell HH HS H or S Mom HS SS

Coincidence of malaria and sickle-cell anemia

Mom = HS Dad = HS possible offspring Oxygen transport: 75% Normal S=sickle-cell H=normal Sickle-Cell Anemia Mom = HS Dad = HS possible offspring Oxygen transport: 75% Normal 25% Sickle-cell Malaria resistance: 75% resistant 25% susceptible Dad H or S HH HS H or S Mom HS SS

The relationship between genes and traits is often complex Complexities include: Complex relationships between alleles Multiple genes controlling one trait One gene controlling multiple traits Environmental effects

Next we will look at what DNA can tell us about the origins of Homo sapiens.

Exam #3 W 12/5 at 7-8:30pm in ETC 2. 108 for the 9am class and ECJ 1 Exam #3 W 12/5 at 7-8:30pm in ETC 2.108 for the 9am class and ECJ 1.202 for the noon class Review T 12/4 at 5pm in WRW 102 Homework #4 due 12/3 (if needed) Bonus #2 is posted