Chapter 8.4, Problem 38AQP

a.

Summary Introduction

To explain:

The number of chromosomes in individual with allotriploidy including species I and II.

Introduction:

The chromosomal mutations not only involve the change in the structure of chromosome rather it also includes a change in the number of chromosomes. Aneuploidy is the gain or deletion of one ormore individual chromosome. Polyploidy refers to a gain of the whole set of chromosomes. Polyploidy is of two types, namely- autopolyploidy and allopolyploidy.

Explanation of Solution

Allotriploidy arises when a diploid gamete fuses with haploid gamete. There are two possibilities through which allotriploid can form. One possibility is that it inherits $\text{1n}$ from species I and $\text{2n}$ from species II, then the number of chromosomes will be as follows:

$\begin{array}{c}\text{Number of chromosomes in species I, 2n}=\text{8}\\ \text{n}=\frac{\text{8}}{\text{2}}\\ \text{n}=\text{4}\end{array}$

$\begin{array}{c}\text{Number of chromosomes in species II, 2n}=\text{14}\\ \text{Number of chromsomes in allotriploid species}=\left(\begin{array}{l}\text{1n of species I}\\ +\text{2n of species II}\end{array}\right)\\ =\text{4}+\text{14}\\ =\text{18}\end{array}$

The number of chromosomes in allotriploid individual including species I and species II if it inherits $\text{1n}$ from species I and $\text{2n}$ from species II is $18$.

Another possibility is that it inherits $\text{2n}$ from species I and $\text{1n}$ from species II, then the number of chromosomes will be as follows:

$\begin{array}{c}\text{Number of chromosomes in species I, 2n}=\text{8}\\ \text{Number of chromosomes in species II, 2n}=\text{14}\\ \text{n}=\frac{\text{14}}{\text{2}}\\ \text{n}=\text{7}\end{array}$

$\begin{array}{c}\text{Number of chromsomes in allotriploid species}=\left(\begin{array}{l}\text{2n of species I}\\ \text{+n of species II}\end{array}\right)\\ =\text{8+7}\\ =\text{15}\end{array}$

The number of chromosomes in allotriploid individual if it inherits $\text{2n}$ from species I and $\text{1n}$ from species II is $15$.

b.

Summary Introduction

To explain:

The number of chromosomes in individual with autotetraploidy in species II.

Introduction:

The chromosomal mutations not only involve the change in the structure of chromosome rather it also includes a change in the number of chromosomes. Aneuploidy is the gain or deletion of one orthe more individual chromosome. Polyploidy refers to a gain of the whole set of chromosomes. Polyploidy is of two types, namely- autopolyploidy and allopolyploidy.

Explanation of Solution

Autotetraploidy results when there occurs four copies of the whole set of chromosomes in individuals. The autotetraploid individual in species II will have a following number of chromosomes.

$\begin{array}{c}\text{Number of chromosomes in species II, 2n}=14\\ \text{n}=7\\ \text{4n}=\text{4}\times 7\\ \text{Number of chromosomes in autotetraploid individual of species II}=\text{28}\end{array}$

The number of chromosomes in autotetraploidindividual of species II will be $28$.

c.

Summary Introduction

To explain:

The number of chromosomes in an individual with trisomy in species I.

Introduction:

The chromosomal mutations not only involve the change in the structure of chromosome rather it also includes a change in the number of chromosomes. Aneuploidy is the gain or deletion of one ormore individual chromosome. Polyploidy refers to a gain of the whole set of chromosomes. Polyploidy is of two types, namely- autopolyploidy and allopolyploidy.

Explanation of Solution

Trisomy is the addition of a single chromosome in the whole set of chromosomes. Addition of single chromosome refers to the gain of one extra homologous copy of individual chromosome. Trisomy is represented as $\text{2n}+\text{1}$. The number of chromosomes in trisomicindividual of species I will be:

$\begin{array}{c}\text{Number of chromosomes in species I, 2n}=\text{8}\\ \text{Number of chromosomes in trisomic individual of species I}=\text{2n}+\text{1}\\ =\text{8}+\text{1}\\ =\text{9}\end{array}$

The number of chromosomes in trisomicindividual of species I will be $9$.

d.

Summary Introduction

To explain:

The number of chromosome in individual with monosomy in species II.

Introduction:

The chromosomal mutations not only involve the change in the structure of chromosome rather it also includes change in the number of chromosomes. Aneuploidy is the gain or deletion of one ofmore individual chromosome. Polyploidy refers to gain of whole set of chromosomes. Polyploidy is of two types, namely- autopolyploidy and allopolyploidy.

Explanation of Solution

Monosomy is the loss of one of the copies of the homologous chromosome. It is represented as $2\text{n}-1$. So the number of chromosomes in individual with monosomy in species II will be as follows:

$\begin{array}{c}\text{Number of chromosomes in species II, 2n}=\text{14}\\ \text{Number of chromosomes in monosomic individual of species II}=\text{2n}-\text{1}\\ =\text{14}-\text{1}\\ \text{=13}\end{array}$

The number of chromosome in individual with monosomy in species II will be $13$.

e.

Summary Introduction

To explain:

The number of chromosome in individual with tetrasomy in species I.

Introduction:

The chromosomal mutations not only involve the change in the structure of chromosome rather it also includes change in the number of chromosomes. Aneuploidy is the gain or deletion of one ofmore individual chromosome. Polyploidy refers to gain of whole set of chromosomes. Polyploidy is of two types, namely- autopolyploidy and allopolyploidy.

Explanation of Solution

Tetrasomy is the acquiring of two nonhomologous chromosomes. It is represented as $\text{2n}+\text{2}$. So the number of chromosome in tetrasomic individual will be

$\begin{array}{c}\text{Number of chromosomes in species I, 2n}=\text{8}\\ \text{Number of chromosomes in tetrasomic individual of species I}=\text{2n}+2\\ =\text{8}+2\\ =10\end{array}$

The number of chromosome in individual with tetrasomy in species I will be $10$.

f.

Summary Introduction

To explain:

The number of chromosome in individual with allotetraploidy including species I and species II.

Introduction:

The chromosomal mutations not only involve the change in the structure of chromosome rather it also includes change in the number of chromosomes. Aneuploidy is the gain or deletion of one ofmore individual chromosome. Polyploidy refers to gain of whole set of chromosomes. Polyploidy is of two types, namely- autopolyploidy and allopolyploidy.

Explanation of Solution

Allotetraploidy arises when a diploid gamete fuses with diploid gamete or a haploid gamete fuses with triploid gamete. The number of chromosomes in allotetraploid if it inherits $\text{2n}$ from species I and $\text{2n}$ from species II will be as follows:

$\begin{array}{c}\text{Number of chromosomes in species I, 2n}=\text{8}\\ \text{Number of chromosomes in species II, 2n}=\text{14}\\ \text{Number of chromosomes in allotetraploid}=\text{2n}+\text{2n}\\ =\text{8+14}\end{array}$

$\text{Number of chromosomes in allotetraploid}=22$

There are two possibilities through which allotetraploid can form. The first possibility is that it inherits $\text{3n}$ from species I and $\text{1n}$ from species II, then the number of chromosomes will be as follows:

$\begin{array}{c}\text{Number of chromosomes in species I, 2n}=\text{8}\\ \text{n}=\frac{\text{8}}{\text{2}}\\ \text{n}=\text{4}\\ \text{3n}=\text{12}\end{array}$

$\begin{array}{c}\text{Number of chromosomes in species II, 2n}=\text{14}\\ \text{n}=\frac{\text{14}}{\text{2}}\\ \text{n}=\text{7}\end{array}$

$\begin{array}{c}\text{Number of chromosomes in allotetraploid}=3\text{n}+1\text{n}\\ =12+\text{7}\\ =\text{19}\end{array}$

The number of chromosomes in allotetraploid individual if it inherits $\text{3n}$ from species I and $\text{1n}$ from species II will be $19$.

The second possibility is that it inherits $\text{1n}$ from species I and $\text{3n}$ from species II, then the number of chromosomes will be as follows:

$\begin{array}{c}\text{Number of chromosomes in species I, 2n}=\text{8}\\ \text{n}=\frac{\text{8}}{\text{2}}\\ \text{n}=\text{4}\end{array}$

$\begin{array}{c}\text{Number of chromosomes in species II, 2n}=\text{14}\\ \text{n}=\frac{\text{14}}{\text{2}}\\ \text{n}=\text{7}\\ \text{3n}=\text{21}\end{array}$

$\begin{array}{c}\text{Number of chromosomes in allotetraploid}=1\text{n}+3\text{n}\\ =4+21\\ =25\end{array}$

The number of chromosomes in allotetraploid individual if it inherits $\text{1n}$ from species I and $\text{3n}$ from species II will be $25$.

Conclusion:

Autopolyploids are produced because of mistakes which might occur during mitosis or meiosis which results in the production of extra sets of chromosomes. Aneuploidy can be defined as the increase or decrease in the individual chromosome number. Aneuploidy might arise because of the loss of chromosome during mitosis or meiosis or nondisjunction of homologous chromosomes or sister chromatids. There are four types of aneuploidy, namely- nullisomy, monosomy, trisomy, and tetrasomy.