Describe the process of crossing over and explain how it increases genetic diversity

Describe the process of crossing over and explain how it increases genetic diversity

A schematic diagram implying independent assortment

  • Independent Assortment of Chromosomes
  • Crossing Over
  • Quiz
    • Send Your Results (Optional)


Reviewed by: Mary Anne Clark, Ph.D.


The previous tutorial investigates the process of meiosis, where 4 haploid gametes are created from the parent cell. Half the genetic information from a parent is present in these haploids, which fuse with gametes of the opposite sex to create a zygote, with a complete chromosome complement that will create offspring after prolonged growth.

The process of meiosis increases genetic diversity in a species. The sex organs which produce the haploid gametes are the site of many occurrences where genetic information is exchanged or manipulated.

Independent Assortment of Chromosomes

Alleles for a particular phenotype determine what characteristic an organism will express, as with the following example where

  • Chromosome 1 contains an allele for blonde hair
  • Chromosome 2 contains an allele for brown hair
  • Chromosome 3 contains an allele for blue eyes
  • Chromosome 4 contains an allele for brown eyes

Describe the process of crossing over and explain how it increases genetic diversity

The top assortment to the left produces 2 blonde hair/blue eyes gametes while the below produces 2 brown hair/brown eyes gametes

Describe the process of crossing over and explain how it increases genetic diversity

The top assortment on the right produces 2 blonde hair/brown eyes gametes while the below produces 2 brown hair/blue eyes gametes

The above indicates that even though the two homologous chromosomes contain the same genetic information, the assortment of the chromosomes (the order they lie in) can determine what genetic information is present in each of the 4 gametes produced. With 23 chromosomes in a human gamete, there are 223 combinations (8388608 combinations)

A review of the Law of Independent Assortment and recombination (crossing over) in meiosis during gamete formation.
Credit: Biology Professor

Crossing Over

During meiosis, when homologous chromosomes are paired together, there are points along the chromosomes that make contact with the other pair. This point of contact is deemed the chiasmata and can allow the exchange of genetic information between chromosomes. This further increases genetic variation.

There are also many other ways in which genetic variation is increased in a species gene pool, all of which are described in the following pages.

The next tutorial investigates the work of Gregor Mendel, an Austrian monk famous for his work involving monohybrid and dihybrid crossing, alongside the continuation into looking at genetic diversity through meiosis and genetics in general.

Describe the process of crossing over and explain how it increases genetic diversity

CROSSING OVER AND INDEPENDENT ASSORTMENT – QUIZ (pdf)

CROSSING OVER & INDEPENDENT ASSORTMENT – QUIZ

Use this to evaluate the student’s familiarity with the core concepts in crossing over and independent assortment. It has two sections. The first is a fill-in-the-gaps test about crossing over and the second is a matching type about Mendelian Law of Independent Assortment.

Subjects: Genetics & Evolution
Lesson: Chromosomal Basis of Heredity
Grades: 9th, 10th, 11th, 12th
Type: Worksheet

Post navigation


You will also like...

Describe the process of crossing over and explain how it increases genetic diversity

New Zealand’s Unique Fauna

Meet some of New Zealand's unique fauna, including endemic insects, frogs, reptiles, birds, and mammals, and investigate..

Describe the process of crossing over and explain how it increases genetic diversity

Cell Structure

A typical eukaryotic cell is comprised of cytoplasm with different organelles, such as nucleus, endoplasmic reticulum, G..

Describe the process of crossing over and explain how it increases genetic diversity

ATP & ADP – Biological Energy

ATP is the energy source that is typically used by an organism in its daily activities. The name is based on its structu..

Describe the process of crossing over and explain how it increases genetic diversity

Gene Regulation in Eukaryotes

Learn about the general structure of a eukaryotic gene, the transcription factors, and post-transcriptional regulation....

How does crossing over increase genetic diversity quizlet?

In crossing over, genetic information is exchanged between homologous chromosomes. This exchange creates new combinations of genes, leading to increased genetic variation in the offspring.

What is the process of crossing over in biology?

Crossing over is a cellular process that happens during meiosis when chromosomes of the same type are lined up. When two chromosomes — one from the mother and one from the father — line up, parts of the chromosome can be switched. The two chromosomes contain the same genes, but may have different forms of the genes.