Genetics: Homozygous vs Heterozygous

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Questions and Answers

What does it mean for an individual to be homozygous?

An individual is homozygous if they have two identical alleles at a specific locus on both chromosomes.

Provide an example of a homozygous dominant genotype and explain its implication.

An example of a homozygous dominant genotype is 'AA', which may lead to the expression of a dominant trait, such as red flowers.

What is the difference between homozygous recessive and heterozygous genotypes?

A homozygous recessive genotype has two identical recessive alleles (e.g., 'aa'), while a heterozygous genotype has one dominant and one recessive allele (e.g., 'Aa').

In the context of flower color, what would you expect from the genotype 'aa'?

'aa' is a homozygous recessive genotype that would result in white flowers. Signup and view all the answers

What phenotype is expressed by the heterozygous genotype 'Aa'?

The phenotype expressed by the heterozygous genotype 'Aa' is red flowers. Signup and view all the answers

Explain what is meant by allele composition at a locus.

Allele composition at a locus refers to the specific combination of alleles, either identical in homozygous individuals or different in heterozygous individuals, located at a particular position on chromosomes. Signup and view all the answers

What role do dominant and recessive alleles play in the expression of traits?

Dominant alleles typically mask the expression of recessive alleles, meaning when present, the dominant trait is expressed regardless of the other allele. Signup and view all the answers

How does the understanding of homozygous and heterozygous genotypes contribute to the study of inheritance?

Understanding these genotypes aids in predicting inheritance patterns and how traits may be passed down through generations. Signup and view all the answers

What genotype represents a homozygous dominant individual?

AA Signup and view all the answers

Which of the following statements about heterozygous genotypes is true?

They consist of two different alleles. Signup and view all the answers

If a plant has the genotype 'aa', what phenotype will it express?

White flowers Signup and view all the answers

What happens to the expression of the recessive allele in a heterozygous individual?

It is masked by the dominant allele. Signup and view all the answers

Which genotype indicates a plant with red flowers if 'A' is the dominant allele for red flowers?

Aa Signup and view all the answers

How are homozygous recessive genotypes represented?

aa Signup and view all the answers

Which of the following best describes a characteristic of homozygous individuals?

They possess two identical alleles. Signup and view all the answers

Which genotype is not indicative of homozygosity?

Aa Signup and view all the answers

Study Notes

Homozygous

An individual is homozygous for a gene when they have two identical alleles at a specific locus on both chromosomes.
Homozygous individuals can have either two dominant alleles (homozygous dominant) or two recessive alleles (homozygous recessive).
Example: If a gene determines flower color and the dominant allele (A) leads to red flowers, while the recessive allele (a) leads to white flowers, then:
- AA (homozygous dominant) = Red flowers
- aa (homozygous recessive) = White flowers

Heterozygous

An individual is heterozygous when they have two different alleles for a gene at the same locus.
One allele is dominant and the other is recessive.
The dominant allele masks the expression of the recessive allele.
Example: Using the same flower color example:
- Aa (heterozygous) = Red flowers (since the dominant allele A masks the effect of the recessive allele a).

Summary

Homozygous: Two identical alleles (AA or aa).
Heterozygous: Two different alleles (Aa).
These concepts are crucial for understanding inheritance patterns and how traits are passed down through generations.

Homozygous

Individuals have two identical alleles at a specific locus on both chromosomes.
Can be either homozygous dominant (both alleles are dominant) or homozygous recessive (both alleles are recessive).
Homozygous Dominant: Two dominant alleles (e.g., AA)
Homozygous Recessive: Two recessive alleles (e.g., aa)
In the example of flower color, AA results in red flowers and aa results in white flowers.

Heterozygous

Individuals have two different alleles for a gene at the same locus.
One allele is dominant and the other is recessive.
The dominant allele masks the recessive allele's expression.
Example: Aa (heterozygous) results in red flowers because the dominant allele A masks the recessive allele a.

Summary

Homozygous: Two identical alleles (AA or aa)
Heterozygous: Two different alleles (Aa)
Understanding these concepts is essential for comprehending inheritance patterns and how traits are passed through generations.

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Description

Test your knowledge on the concepts of homozygous and heterozygous alleles in genetics. This quiz covers definitions, examples, and the significance of these genetic variations. Perfect for biology students looking to reinforce their understanding of genetic traits.