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
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
•Exam #3 W 12/5 at 7-8:30pmin 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
Crossing-Crossing-overover
Meiosis I
Meiosis II
4 Haploid cells, each unique
Meiosis:In humans, crossing-over and independent assortment lead to over 1 trillion possible unique gametes.(1,000,000,000,000)
Box 2.2
(Ind. Assort.)(Ind. Assort.)
Crossing over produces new allelic combinations
Fig 4.3
Homologouspair of chromosomes
Fig 4.10
Longer regions have more crossovers and thus higher recombinant frequencies
Some crosses do not give the expected results
=25%
8%9%41%42%
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
Fig 4.9
The probability of crossing over can be used to determine the spatial relationship of different genes
Double recombinants arise from two crossovers
Fig 4.11 Recombinant
Double recombinants can show gene order
Fig4.12
similar to pg 141
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 order and how far apart?
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
st ss e
14.6 m.u.
26.8 m.u.
12.2 m.u.
Put it all together…
Linkage map of Drosophila chromosome 2
Fig 4.13 and 20
Yeast chromosome 3
physical distance linkage
map
Recombination is not completely random.
PhenotypeGenotype
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
Fig 3.14+.16
Complexity of inheritance leads to genetic diversity.
Eye color: One trait controlled by multiple genes
Fig 6.7
Seven alleles and their interactions in leaf patterning of clover
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 genecontrollingmany traits
Mom = HS Dad = HS
H or S
H or S
HH
HS SS
HS possible offspring75% Normal25% Sickle-cell
Mom
Dad
Sickle-Cell Anemia S=sickle-cell
H=normal
Coincidence of malaria and sickle-cell anemia
Mom = HS Dad = HS
H or S
H or S
HH
HS SS
HS
possible offspringOxygen transport:75% Normal25% Sickle-cell
Malaria resistance:75% resistant25% susceptible
Mom
Dad
Sickle-Cell Anemia S=sickle-cell
H=normal
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 7-8:30pmin 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