Chapter 29, Problem 1RQ

Match each of the following key terms (a–i) with its description below: Key:

a. alleles

b. autosomes

c. dominant allele

d. genotype

e. heterozygote

f. homozygote

g. phenotype

h. recessive allele

i. sex chromosomes

____ (1) genetic makeup

____ (2) how genetic makeup is expressed

____ (3) chromosomes that dictate most body characteristics

____ (4) alternate forms of the same gene

____ (5) an individual bearing two alleles that are the same for a particular trait

____ (6) an allele that is expressed whether in single or double dose

____ (7) an individual bearing two alleles that differ for a particular trait

____ (8) an allele that must be present in double dose to be expressed

Summary Introduction

To review:

The key terms in column A with their description in column B.

Column A	Column B
Alleles	Genetic makeup
Autosomes	How genetic makeup is expressed
Dominant allele	Chromosomes that dictate most body characteristics
Genotype	Alternate forms of the same gene
Heterozygote	An individual bearing two alleles that are the same for a particular trait
Homozygote	An allele that is expressed whether in single or double dose
Phenotype	An individual bearing two alleles that differ for a particular trait
Recessive allele	An allele that must be present in double dose to be expressed
Sex chromosome

Introduction:

Heredity refers to the transfer of characteristics or traits from one generation to another generation by different means of reproduction. Genetics is the branch of biology, in which heredity is studied.

Explanation of Solution

Alleles: Genes are the DNA (deoxyribonucleic acid) segments that code for proteins. The alleles are the alternate form of a gene that is located on the homologous chromosome at the same locus. So, (a) can be correctly matched with (4).

Autosomes: Autosomes and allosomesor sex chromosomes are the two types of chromosomes. The autosomes are the chromosomes that do not determine the sex of an organism. These are involved in the determination of the body characteristics. So, (b) can be correctly matched with (4).

Dominant allele: The allele that suppresses or masks the expression of another allele is known as a dominant allele. It is represented by a capital letter. These alleles are expressed when present in either single dose or in a double dose. So, (c) can be correctly matched with (6).

Genotype: The genetic makeup of a person is known as a genotype. It determines the properties or characteristics called phenotype of an individual. So, (d) can be correctly matched with (1).

Heterozygote: Heterozygote refers to an individual that have two alternative forms or alleles of a gene or genes, which are different for a particular trait. Thus, it produces varying offspring. So, (e) can be correctly matched with (7).

Homozygote: Homozygote refers to an individual, who possess two identical alleles for a specific gene coding for a particular trait, one of which is inherited from each of the parents. So, (f) can be correctly matched with (7).

Phenotype: The physical characteristics of a trait is known as phenotype. It is defined by the genetic makeup or genotype of an organism. So, (g) can be correctly matched with (2).

Recessive allele: The allele, whose expression is masked by the dominant allele is known as a recessive allele. They can be expressed when present in double dose are represented by the lowercase alphabets. So, (h) can be correctly matched with (8).

Conclusion

Column A	Column B
Alleles	(4) Alternate forms of the same gene
Autosomes	(3) Chromosomes that dictate most body characteristics
Dominant allele	(6) An allele that is expressed whether in single or double dose
Genotype	(1) Genetic makeup
Heterozygote	(7) An individual bearing two alleles that differ for a particular trait
Homozygote	(5) An individual bearing two alleles that are the same for a particular trait
Phenotype	(2) How genetic makeup is expressed
Recessive allele	(8) An allele that must be present in double dose to be expressed
Sex chromosome