Transcript Slides - people.vcu.edu

Quantitative Traits
Quantitative Traits
Fraction of Population
Distribution of Corn Ear Lengths
50
40
30
20
10
0
P
F1
F2
0
10
20
Length of Corn Ears (inches)
30
Mendelian Explanation of a
Quantitative Trait
Dihybrid Cross: (H1 h1 H2 h2) x (H1 h1 H2 h2)
H1 H2
H1 h 2
h 1 H2
h1 h2
H1 H2 H1 H1 H2 H2 H1 H1 H2 h2 H1 h1 H2 H2 H1 h1 H2 h2
H1 h2 H1 H1 H2 h2 H1 H1 h2 h2 H1 h1 H2 h2
H1 h1 h2 h2
h1 H2 H1 h1 H2 H2 H1 h1 H2 h2 h1 h1 H2 H2
h1 h1 H2 h2
h1 h2 H1 h1 H2 h2
h1 h1 h2 h2
H1 h1 h2 h2
h1 h1 H2 h2
Very small : Small : Medium : Large
1
4
6
4
: Very
Large
1
Study Question 3
How many discrete lengths would you
predict to be possible if there were four
identical Height genes?
Complementation
Multiple Infection
Multiplicity
of Infection
Phage/Hosts
Complementation
Failure to Complement
Complementation
Study Question 4
•5 mutants of phage T2
•Mutants forms tiny plaques
•Complementation tests
- coinfect E. coli with pairs
Coinfection
#1 with #2
#1 with #3
#1 with #4
#1 with #5
#2 with #3
#2 with #4
#2 with #5
#3 with #4
#3 with #5
#4 with #5
•How many genes are required for
the wildtype phenotype?
Plaque Size
wildtype
wildtype
tiny
wildtype
tiny
wildtype
wildtype
wildtype
wildtype
wildtype
Study Question 5-7
Cross female #34 extra hairy x male #43 (Curly hair)
Possible genotypes of parents?
Genotypes of F1 progeny?
One gene hypothesis
#34: EE x #43: CC
EC
Two gene hypothesis
#34: EE ++ x #43: ++ CC
Two gene hypothesis/one X-linked
#34: XEXE++ x #43: X+Y CC
E+ C+
X+XE C+
XE Y C+
Recombination
Nicked
One
Homologous
Other
Recombination
strand
strands
strand
nicked
chromosomes
break
invades
complete
other pair
chromosome
Recombination
No change (sequences are identical except
for sites of mutation)
Recombination
Two novel DNA’s, different from parents
Complementation vs
Recombination
Complementation
Recombination
acts through protein
acts through DNA
temporary
permanent
efficient
rare
useful to define genes
useful to map genes