**Contents**show

## How many varieties of gametes are possible in cells that do not cross over?

In a cell with just two pairs of homologous chromosomes, like the one at right, random metaphase orientation allows for 2^{2} = 4 different types of possible gametes. In a human cell, the same mechanism allows for 2^{23} = **8,388,608 different types** of possible gametes. And that’s not even considering crossovers!

## How many different types of gametes are produced when there is crossing over?

If crossing over occurs between the two genes, an exchange of alleles is produced between the homologous chromosomes. We therefore obtain 50% “parental” gametes and 50% “recombined” gametes, further divided in **four types** of gametes from the point of view of allele separation.

## How many different genetic combinations are possible in the first part of meiosis because of Independent Assortment?

When these chromosome pairs are reshuffled through independent assortment, they can produce **eight possible combinations** in the resulting gametes: A B C.

## Does crossing over occur for every chromosome every time gametes are produced?

No, it is **a random event** which means that it happens sometimes, but not all the time. When does independent assortment occur? Metaphase I and Metaphase II.

## How many different combinations of alleles are possible among the gametes?

Since each parent has four different combinations of alleles in the gametes, there are **sixteen possible combinations** for this cross.

## What are the gametes that would be formed for the following genotype AA?

An individual with the genotype Aa can make two types of gametes: **A and a**. Since this is a random process, the individual will, on average, make equal numbers of each gamete.

## How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism?

Exactly two maternal and two paternal chromosomes always move to each of the two poles. The first to move influences all the others. They align and assort independently to form any of **16 different combinations**.

## What is the number of possible gametes that can be formed due to independent assortment of chromosomes?

32. Since humans have 46 chromosomes or 23 homologous pairs, what is the number of possible gametes that can be formed due to independent assortment of chromosomes? The number of possible combinations of maternal and paternal chromosomes in the resulting gametes is **223**, or about 8.4 million.

## How many possible gamete types can be generated through the process of crossing over alone?

from an original cell that contains a diploid number of 46 (2n=46)? 3. How many possible gamete types can be generated through the process of crossing over alone?

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Mitosis (begins with a single cell) | Meiosis (begins with a single cell) | |
---|---|---|

# nuclear divisions | 1 | 2 |

# daughter cells produced | 2 | 4 |

_{#}_{chromosomes}_{in} daughters |
46 | 23 |