{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

set2 extensions mendelian - BIOL 239 Modifications of...

Info iconThis preview shows pages 1–17. Sign up to view the full content.

View Full Document Right Arrow Icon
Modifications of Mendelian Ratios Chapter 4 pp 62 - 82 BIOL 239 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2 Posted to LEARN Required online Videos 1 through 3 must be viewed by midnight Jan 26 (tutorial 2) Video 4 must be viewed by midnight Feb 2 (tutorial 3) Online quiz for tutorial 4 must be completed by Feb 23 midnight (available Feb 10) Video 5 must be viewed by midnight Mar 9 (tutorial 8) -let me know if you have any submission problems
Background image of page 2
Dominance is not always complete ! Incomplete dominance : The F 1 hybrid resembles neither purebred parent (often an intermediate phenotype) Codominance : Alternative traits are both visible in the F 1 hybrid 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Different dominance relationships X X X X Complete Complete Incomplete Codominant Parent 1 phenotype Parent 2 phenotype AA aa A 1 A 1 Aa Aa aa AA A 2 A 2 A 1 A 2 A 1 A 1 A 2 A 2 A 1 A 2 A is dominant to a a is recessive to A A is dominant to a a is recessive to A A 1 and A 2 are incompletely dominant A 1 and A 2 are codominant 4
Background image of page 4
Incomplete dominance Genotype and phenotype ratio is 1:2:1 Phenotype ratio is reflection of genotype ratio ! Snap dragons 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Incomplete dominance: Among snapdragons there is a gene which produces flower pigment (a protein). The allele A r produces the wild type red pigment and The allele A w produces white (lack of red pigment). When red ( A r A r ) plants are crossed with white ( A w A w ) plants the resulting F1 are pink ( A r A w ). This is because only one “dose” of red pigment is produced (from A r ), resulting in pink o ff spring that do not resemble either of their parents. Note* it is proper to designate incompletely dominant or co-dominant alleles as both uppercase 6
Background image of page 6
7 Codominance Neither is dominant or recessive to each other Shows same genotype and phenotype ratio as incomplete dominance: 1:2:1
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
What is the mode of inheritance of coat colour ? 8
Background image of page 8
What is the mode of inheritance of coat colour ? 9
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
What is the mode of inheritance of coat colour ? 10
Background image of page 10
What is the mode of inheritance of coat colour ? 11
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Multiple alleles of a single gene e.g., ABO blood groups 12
Background image of page 12
Codominance: The gene controlling the cell surface sugars responsible for the ‘ABO’ blood grouping system is a multiple allele system in which I A and I B are co- dominant to each other but they are both dominant to the i allele. Allele I A attaches a sugar di ff erent to that of allele I B and allele i does not attach the sugar at all. Heterozygotes I A I B have both types of sugars on their cell surface. Phenotype (blood type) Possible genotype A B AB O 13
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Codominance is described by phenotype Blood type A B AB - codominant A sugar (A antigen) Lipid stalk B sugar (B antigen) A and B sugars X = O No sugar Blood type A X = A ( i is recessive) 14
Background image of page 14
I A = makes enzyme A to add A sugar I B = makes enzyme B to add B sugar i = no enzymes - no sugars added I A I B = both enzymes to add both A + B sugars single gene ( I ) with altered alleles ( I A + I B + i ) I A + I B are codominant to each other and dominant to i Polymorphic gene as the 3 alleles are commonly found 15
Background image of page 15

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Variations on complete dominance are
Background image of page 16
Image of page 17
This is the end of the preview. Sign up to access the rest of the document.