Summary
The fusion of sperm and egg nuclei to form a diploid zygote.
In depth
The sperm binds the zona pellucida, the acrosome reaction releases enzymes, membranes fuse, and the egg's cortical granules harden the coat (block to polyspermy). Calcium waves activate the egg to complete meiosis II. Pronuclei fuse.
Fertilisation restores the diploid number and combines two genomes, and activates the egg metabolically. Only one sperm should enter, since polyspermy produces lethal extra chromosome sets.
Remember: the block to polyspermy has a fast electrical phase in sea urchins and a slow cortical reaction.
Frequently asked questions
What is Fertilisation?
The fusion of sperm and egg nuclei to form a diploid zygote.
Which area of biology covers Fertilisation, and how advanced is it?
Fertilisation is one of the 54 topics in Developmental Biology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Hedgehog Signalling, Zygote, Hox Genes.
Can you give an example of Fertilisation?
IVF bypasses natural steps by injecting sperm (ICSI).
What should I learn before Fertilisation?
Fertilisation is a Beginner topic, so no earlier topic is required. Other Beginner topics in Developmental Biology that pair well with it include Zygote, Embryo, Cleavage.
What topics are related to Fertilisation?
The closest topics to Fertilisation are Hedgehog Signalling, Zygote, Hox Genes, Epigenetic Reprogramming in Embryos. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Fertilisation?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Fertilisation. To practise the whole of Developmental Biology, use the Developmental Biology quiz.
How is Fertilisation different from Hedgehog Signalling?
Fertilisation: The fusion of sperm and egg nuclei to form a diploid zygote. Hedgehog Signalling: A morphogen pathway patterning the neural tube and limbs through Gli transcription factors. Read both side by side and note what each one explains.
How should I study Fertilisation 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 Hedgehog Signalling and explain the difference aloud. Finally, take the Developmental Biology quiz and come back to this page for any question you miss.