Genes work in?

AIIMS Nagpur NO - 2018

Pathology & Genetics

Easy

Appeared in: AIIMS Nagpur NO - 2018

Explanation

Genes in diploid organisms, such as humans, exist and function as pairs.
These pairs are known as alleles, and they are located at the same position (locus) on homologous chromosomes.
For each gene, one allele is inherited from the mother and the other from the father.
The interaction between the two alleles in a pair determines the specific genetic trait (phenotype) that is expressed.

Option A: Genes are the underlying instructions that determine traits; they do not function 'in' traits. A trait is the resulting characteristic.
Option C: While some traits are controlled by the interaction of multiple genes (polygenic inheritance), the fundamental unit of gene function is a pair of alleles at a specific locus.
Option D: In diploid organisms, somatic (body) cells have two sets of chromosomes, meaning genes are paired. Genes operate singly only in haploid cells.

Visual 1: Diagram: A pair of homologous chromosomes showing a specific gene locus with two different alleles (heterozygous) labeled.
Visual 2: Infographic: A simple chart illustrating the difference between genotype (e.g., AA, Aa, aa) and phenotype (e.g., brown eyes vs. blue eyes).
Visual 3: Flowchart: A diagram showing how one allele is passed from the mother and one from the father during fertilization to form a new gene pair in the offspring.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Mechanism of Gene Function and Inheritance as background academic context rather than a clinical decision trigger.
Understanding that genes work in pairs is crucial for genetic counseling. It helps predict the risk of offspring inheriting genetic disorders, especially recessive conditions like cystic fibrosis or sickle cell anemia, which require two copies of the faulty allele.
This principle is the basis for carrier screening, where individuals are tested to see if they carry one copy of a recessive gene for a particular disorder.
What if? If a person inherits two different faulty alleles for the same gene (known as being a compound heterozygote), they can still develop the genetic disorder. This shows that the function of both alleles in the pair is critical for health, not just whether they are identical.

How to Approach the Question

Identify the core concept of the question, which is the fundamental functional arrangement of genes in living organisms.
Recall the basic principles of genetics, specifically that sexually reproducing organisms like humans are diploid.
Connect the term 'diploid' to its meaning: having two complete sets of chromosomes, with one set inherited from each parent.
Deduce that if chromosomes come in pairs, the genes located on them must also exist and function in pairs.
Evaluate the given options: 'Pairs' directly corresponds to this diploid nature. 'Traits' are the result of gene function, not the arrangement itself. 'Group' and 'Single' are less accurate for describing the basic unit of inheritance in diploid organisms.

Concept Tested & Keywords

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