1Null alleles
A DNA sequence variation that prevents a gene from producing a functional product.
2What begins in Zygotene?
Homologous chromosomes connect at the telomeres. Synaptonemal complex begins to form.
3Silent alleles
An allele that has no detectable product, and so is not expressed in a phenotype.
4Leaky alleles
Mutation that makes an incompletely functioning product.
5What occurs in Pachytene?
The synaptonemal complex is complete, and both homologous chromosomes have fully synapsed. Crossing over occurs.
6What occurs in Leptotene?
Chromatin begins to condense
7What occurs in Diplotene?
The paired homologous chromosomes are separated slightly. Chiasmata structures can be seen between nonsister chromatids.