Exchange of segments between homologous chromosomes in prophase I that creates new allele combinations.
In prophase I, homologous chromosomes pair (synapsis) and exchange segments at chiasmata. At least one crossover per chromosome pair helps them align properly. The exchange makes recombinant chromatids, giving new allele combinations.
Crossovers are catalysed by enzymes that cut and rejoin DNA precisely.
Exchange of segments between homologous chromosomes in prophase I that creates new allele combinations.
Crossing Over is one of the 54 topics in Genetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Allele, Linked Genes, Monohybrid Cross.
It separates linked alleles so offspring can differ from both parents.
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Crossing Over. Intermediate topics assume the Beginner vocabulary.
The closest topics to Crossing Over are Allele, Linked Genes, Monohybrid Cross, Law of Independent Assortment. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Crossing Over. To practise the whole of Genetics, use the Genetics quiz.
Crossing Over: Exchange of segments between homologous chromosomes in prophase I that creates new allele combinations. Allele: One of the alternative versions of a gene found at the same position on a chromosome. Read both side by side and note what each one explains.
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 Allele and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.
One of the alternative versions of a gene found at the same position on a chromosome.
🧬 GeneticsGenes close together on the same chromosome tend to be inherited together instead of assorting independently.
🧬 GeneticsA cross following one gene with two alleles, giving a 3:1 phenotype ratio in the F2 generation.
🧬 GeneticsAlleles of different genes are distributed to gametes independently when the genes lie on separate chromosomes.
🧬 Genetics