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Snapdragon (1993)
IMDB rating: 3.40
Plot: Two men have already been killed during intercourse by a prostitute. The young Sargent Peckham is transferred from vice to homicide squad for the investigation. She asks her boyfriend, police psychologist David Stratton, for an analysis. Shortly after he’s introduced to amnesia patient Felicity, a stunningly beautiful blonde. She tells him of her nightmares, in which she kills her lovers. But since he’s got a crush on her, he doesn’t draw a connection to Peg’s case… not yet.
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Directors: Keeter Worth
Actors: Bauer Steven,McCoy Matt,Tigar Kenneth,Manetti Larry,Howard Rance,Monks Michael,O’Donohue John F.,Snyder Drew,Linger Phillip Troy,Chong Michael,Thriller,
The genetics of snapdragons?
Snapdragons (Antirrhinum) posses the pigment anthocyanin, which renders petals purple. Two pure anthocyanin-less Antirrhinum lines were developed, one in California and one in Holland. They looked identical in having no pigment at all, manifested as white flowers. However, when petals from the two lines were ground up together in buffer in the same test tube, the solution, which appeared colorless at first, gradually turned purple.
a)What could account for the production of the purple color in the test tube?
b)According to your explanation for part (a), what would be the genotypes for the two lines?
c)If the two white lines were crossed, what would you predict would be the phenotypes of the Fl and F2?
I am having trouble figuring out how to set up this problem. I assume there is an inhibitting gene preventing the pigment from being displayed, but I can’t work it out.
It would seem that two different gene products are required to convert a colorless compound into the purple pigment. The California plant and the Dutch plant have mutations in different genes. Genetically, the first plant might be AAbb and the second one aaBB. WHen you cross those, the F1 would all be AaBb, and the F2 would be 9 A_B_:3 A_bb:3 aaB_:1 aabb. Only the A_B_ plants would be purple, so you would see a 9:7 purple:white ratio in the F2.
hcbiochem | Feb 03, 2010
well for number a) you no that the antirrhinum is red,purple or simliar colors in the water because its a the soluble vacuolar pigment, the are all found on plant and some eukaryotic cells and some protist. so if it produce the purple color is in the test tube then that means there is water in there and it is caused by water, its soluble which you know break down in water and turn the solution to purple
for b)Homozygous, i guess i dont know this one
for c)if you going to be base on homozygous then the F1 generation will be all te same, as the parental generation (same phenotype) and then the f2 generation will will be 3:1 in phenotype which 3 will look like the parent and 1 will be different, (hmomzygous recessive
Mr. Liu | Feb 03, 2010
Haploinsufficiency each cultivar has only one fully functional allele (each has a second inactive allele) so each cultivar fails to produce enough gene product for the phenotype to penetrate, to be seen. Gene dosage is critical. Both alleles must be functional to produce enough product for the full phenotype.
These cultivars are both heterozygous: Pp
P produces pigment while p does not and Pp is not sufficient to appear purple.
Pp x Pp => 1PP – 2 Pp – 1pp
http://www.medterms.com/script/main/art. asp?articlekey=18474
Another possible answer is complementation: There is a biochemical pathway with several steps that manufactures the pigment. The two cultivars each have incomplete pathways, with mutant alleles, but are incomplete at different points. Each cultivar is expressing a homozygous recessive trait. The two petals placed together provide a complete set of metabolites for the final reactions to complete the pathway producing the pigment. If these cultivars are crossed the wild type coloration would be fully restored in the heterozygous F1 generation.
California has AAbb so produces functional enzymes to convert metabolites for one step while Holland has aaBB that makes the enzymes to convert the intermediate metabolite to the pigment.
http://en.wikipedia.org/wiki/Complementa tion_(genetics)
gardengallivant | Feb 03, 2010
