Summary
Mother's mRNAs deposited in the egg, such as bicoid in Drosophila, set up the embryo's polarity.
In depth
Offspring phenotype depends on the mother's genotype, not their own. Examples: bicoid, nanos, and oskar in flies. Maternal mRNAs are localised in the oocyte.
Maternal mRNAs and proteins in the egg direct early development before zygotic genes turn on. They are transcribed in nurse cells and localised by motor proteins.
Key idea: the mother's genotype can determine the embryo's early phenotype.
Maternal effect genes are expressed in the mother's ovary, and their mRNAs or proteins are loaded into the egg, so the offspring's phenotype depends on the mother's genotype rather than its own. They set up polarity before the embryo's genome is active.
In Drosophila, bicoid mRNA is anchored at the anterior pole and its protein diffuses to form a gradient that activates head and thorax genes; nanos is at the posterior and torso at the ends. A bicoid-deficient mother produces embryos without head and thorax, even if the embryos carry a functional gene.
Example: snail shell coiling direction is determined by the maternal genotype.
Remember: it is not cytoplasmic inheritance, but maternally supplied products.
Frequently asked questions
What is Maternal Effect Genes?
Mother's mRNAs deposited in the egg, such as bicoid in Drosophila, set up the embryo's polarity.
Which area of biology covers Maternal Effect Genes, and how advanced is it?
Maternal Effect Genes is one of the 54 topics in Developmental Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Zygote, Body Axes Formation, Morphogens.
Can you give an example of Maternal Effect Genes?
If a bicoid mutant mother lays eggs, the embryos lack heads.
What should I learn before Maternal Effect Genes?
Work through the Beginner topics in Developmental Biology first, such as Fertilisation, Zygote, Embryo, then return to Maternal Effect Genes. Intermediate topics assume the Beginner vocabulary.
What topics are related to Maternal Effect Genes?
The closest topics to Maternal Effect Genes are Zygote, Body Axes Formation, Morphogens, Cell Fate Determination. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Maternal Effect Genes?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Maternal Effect Genes. To practise the whole of Developmental Biology, use the Developmental Biology quiz.
How is Maternal Effect Genes different from Zygote?
Maternal Effect Genes: Mother's mRNAs deposited in the egg, such as bicoid in Drosophila, set up the embryo's polarity. Zygote: The single cell formed at fertilisation that divides to become an embryo. Read both side by side and note what each one explains.
How should I study Maternal Effect Genes step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Zygote and explain the difference aloud. Finally, take the Developmental Biology quiz and come back to this page for any question you miss.