The bicoid gene is a coordinate maternal-effect gene.
A female Drosophila heterozygous for a loss-of-function bicoid allele is mated to a male that is heterozygous for the same allele. What are the phenotypes of their progeny?

Question

The bicoid gene is a coordinate maternal–effect gene. A female that is homozygous for a loss-of-function bicoid allele is mated to a wild-type male. What are the phenotypes of their progeny?

Accepted Answer

Hi, everyone. Welcome back. Let's look at our next problem. If a female fly Andros, Sophal Melena Aster has two nonfunctional copies of the bio gene. So a homozygous loss of function, all and she mates with a wild type male with a normal bio bio jean. What would be the expected phenotype of their progeny? Choice? A normal anterior posterior patterning, the abnormal peripheral anterior patterning to c defects in head and anterior body segment develop and or choice d defects in the tail and posterior body segment development. Well, let's think about the role of that bio gene. The bio gene we can recall is a maternal fact, jean and that means those genes are active in the egg prior to fertilization and then they go on to establish the anterior posture axis of the embryo. So the entire load of this protein comes from the mother, not the father. So B coid is inherited only from the mother. In essence, in the case of our problem, that means that the mating with a wild type male won't be able to reestablish that function because all of the bi coid comes from the egg and therefore from the mother, the way it establishes that anterior posture axis of the embryo we can recall is by being expressed at higher levels in the anterior end of the egg and thus in the early embryo and at low levels in the posterior end. So our posterior segment, our and our tail of the embryo will not be affected so much because they normally have low levels of vico just in normal development. So we can eliminate to d defects in the tail and posterior body segment. We can also eliminate choice a normal anterior posterior patterning because you're missing this essential gene that actually sets up this pattern. So since we see this patterning established by expressing bi coid in high levels in the anterior end, we would expect choice A I mean, excuse me, choice C defects in the head and anterior body segment development because that's the precise areas where bio will be expressed in high levels. So that's where you're going to see the effects of its mutation. Choice B abnormal peripheral anterior patterning is not our answer because again, by quite establishes the distinction between anterior and posture ends, not anterior and peripheral meaning on the sides. So again, a female, a female opal who has two nonfunctional copies of the bi coid gene. If she mates with a wild type male, the expected phenotype of their progeny would be choice c defects in head and anterior body segment development. See you in the next video

The bicoid gene is a coordinate maternal–effect gene. A female that is homozygous for a loss-of-function bicoid allele is mated to a wild-type male. What are the phenotypes of their progeny?

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Key Concepts

Maternal Effect Genes

Bicoid Gene Function

Homozygous Loss-of-Function Alleles