Acquired and Inherited Traits

Introduction 

All living things can create new versions of themselves, and each of their cells contains a nucleus that contains chromosomes. Each of the 23 pairs of chromosomes in humans contains thousands of genes. The information that determines the personality or trait passed down from parent to child and shapes an individual’s identity can be carried by a gene. Because genes do not carry information about qualities, some traits are not passed down from parents. i.e., not DNA-encoded. These are acquired by repeated activities, injuries, illnesses, or other environmental factors and are not inherited. It might affect the organism’s general phenotype.

What are Acquired Traits?

A characteristic that emerges to alter the processes of development in an uncommon setting is known as an acquired trait. It contains traits that are both behavioral and physical.

Darwin, Lamarck, and Acquired Traits

Lamarck and Acquired Traits

  • According to Jean-Baptiste Lamarck, acquired characteristics can be passed down through the generations. He believed that organisms could change how they behaved in response to their surroundings and that the acquired traits might be passed down to their progeny. 
  • Giraffes, for instance, lengthen their necks to reach the leaves of higher trees for food. There is a chance that future generations of offspring will also have long necks. 
  • He therefore initially postulated that acquired attributes are passed down from parent to child, which may help the population’s young members to be environment friendly.

Let our expert teachers be your guide toward improving your grades and reaching your highest potential. For more help, you can refer to EVS Class 5 Lesson 21. Check out the video Lesson for a better understanding.

Darwin and Acquired Traits

  • Lamarck’s theory was initially accepted by Charles Darwin in his first book, Theory of Evolution. 
  • He held the view that a species does not evolve as a result of changes to an organism. 
  • The variations among members of the same species of organisms help them survive in the environment. 
  • He saw various instances in real life that demonstrated how someone could exercise, run, eat properly, and become healthy, but fitness is not passed down from parent to offspring. 
  • Later, when he had convincing proof that acquired qualities are not passed down to succeeding generations, he withdrew Lamarck’s idea.

Acquired Traits Examples

Acquired traits are received from the environment. The following are some examples of acquired traits: 

  • Example 1: It’s not necessary for a person born to be a bodybuilder to have incredibly huge muscles. Even after training and frequent exercise, the larger muscles are a learned trait; they cannot be passed from parent to child.
  • Example 2: An animal’s characteristics that determine its size, weight, and health are dependent on the food it consumes. It can alter the color of the animal’s body in some cases. Flamingos have white feathers at birth and eat larvae, algae, and shrimp for food. The presence of beta-carotene in algae and several other meals causes the bird’s feathers to turn pink. As a result, color is the acquired attribute in this case.

Inherited and Acquired Traits

Inherited traits Acquired traits These
These characteristics can be passed on from one generation to the next. These traits or characteristics evolved as a result of the environment’s response and are not passed down to subsequent generations. 
It can be developed from an individual’s birth. It may evolve throughout a person’s lifetime. 
Since it is somatic, evolution cannot benefit from it. Directly evolved through genetic variation.
These traits can be passed on through DNA inheritance. These traits can be learned and seen; they are not inherited.
Examples include color blindness, nose shape, hair, eye, and eye color Examples include losing muscular mass, losing a finger in an accident, losing body weight, and losing abilities. 

Purchased Traits

Characters or traits that have been acquired are those that have been purchased via particular efforts based on physical and environmental factors. Throughout a person’s lifetime, these traits develop. It could be a behavioral or physical characteristic.

Physical trait behavioralBehavioral traits
  • Hairstyle
  • Hair dyeing
  • Scars
  • Weight and height of the body
  • Broken bones
  • Tattoos
  • Dancing
  • Learning skills
  • Writing
  • Reading
  • Swimming
  • Painting
  • Playing games 

Inheritance Laws

Gregor Johann Mendel used his research on pea plants to explain the theory of inherited qualities. He said that the features in phenotype that are visible are known as dominant traits, and the traits in phenotype that are invisible are known as recessive traits.

Mendel applied the following laws of inheritance to understand the inherited traits:

First Law: Law of Dominance

When two different character types exist in an adult, only one of them manifests in the F1 generation and is referred to as the dominant trait, while the other one does not manifest and is referred to as a recessive trait.

Second Law: Law of Segregation

Although one of the two is not visible in the F1 generation, the alleles do not mix and are retrieved as such in the F2 generation. This law is also known as the gamete purity law.

Third Law: Law of Independent Assortment

When two sets of traits are combined again, one pair of characters can be separated on its own during gamete development.

Summary

A characteristic that emerges to alter the processes of development in an uncommon setting is known as an acquired trait. According to Jean-Baptiste Lamarck, acquired characteristics can be passed down through the generations. Lamarck’s theory was initially accepted by Charles Darwin in his first book, The Theory of Evolution. Characters or traits that have been acquired are those that have been purchased via particular efforts based on physical and environmental factors.

Frequently Asked Questions

1. When Darwin published his first paper, why did he exclude Lamarck’s Hypothesis?
Ans. Lamarck’s concept was initially accepted by Darwin, but he eventually recognized the compelling evidence that acquired features are not inherited. He consequently deleted the incorrect claim regarding the acquired features.

2. What are Dominant and Recessive Traits?
Ans. Alleles that express their influence on a live organism’s phenotype are known as dominant traits, whereas alleles that do not express this influence are known as recessive traits.

3. Write down Five Traits one can Inherit from his Parents.
Ans.

  • Eye color
  • Height of tree
  • the Shape of nose
  • Color blindness
  • Blood group

4. In the Course of one’s Life, what Traits or Characteristics does one Acquire?
Ans. Learning abilities, huge muscles, singing, drawing, dancing, swimming, and a myriad of other acquired attributes can all be developed throughout a lifetime.

5. Explain Lamarck’s theory of Acquired Characteristics.
Ans. According to Lamarck, environmental factors can cause organisms to change their behavior or phenotype, and this change can be passed down to succeeding generations. For instance, the ability of the giraffe’s neck to extend to reach tree leaves is passed down to the offspring.

Accumulation of Variation During Reproduction

Introduction

There is no life on Earth without reproduction. For an organism to be classified as a living being, it must be able to reproduce. Reproduction of an individual requires replication of DNA, the molecular basis of life. Nature would not have been as diverse if all organisms reproduced asexually, and there would be no variation among populations. As a result of meiosis, living organisms can undergo variations, which maintain biological diversity and assist in adapting and evolving.

Heredity and Accumulation of Variation During Reproduction

Reproduction passes genetic information from parents to offspring, resulting in the offspring acquiring the same characteristics as their parents. This process is called heredity. Species or groups of organisms of a species may differ in some way due to variation. Variations in sexually reproducing species result from three genetic processes: mutations, independent segregation of chromosomes, and genetic recombination.

Let our expert teachers be your guide toward improving your grades and reaching your highest potential. For more help, you can refer to EVS Class 5 Lesson 21. Check out the video Lesson for a better understanding.

Mutations

Mutations are arbitrary alterations to an organism’s genes that can come from biological, chemical, or physical sources. Alleles which are different versions of the same gene are produced as a result of these modifications in various members of the same species. A mutation is passed down to the next generation in asexually reproducing organisms during mitosis. These changes are integrated into sexually reproducing organisms, nevertheless, where they then undergo further reorganization during sexual reproduction.

Independent Assortment of Chromosomes

Homologous chromosome pairs are found in diploid eukaryotes. Both members of the pair have separate sets of alleles, with one inheriting a set from the mother and the other from the father. These homologous chromosomal pairs divide during meiosis, and the individuals in each pair are then segregated into various daughter nuclei, giving rise to haploid gametes. The number of chromosomal pairs that each gamete acquires is random and unrelated to the other pairings. The resulting diploid individual possesses traits from both parents. This also explains the genetic variances seen in siblings, who all get their personalities from the same parents yet have distinct alleles.

Chromosomal crossing over the homologous chromosomes undergoes an event called “chromosomal crossing over” just before the separation of homologous chromosomes occurs, which causes the recombination of genes on the chromosomes. Recombination involves the exchange of alleles from one chromosome’s homologue with those from the other. The likelihood of variation is increased in sexually reproducing organisms by chromosomal crossing over.

Why is it Important to have Variations?

The expansion of a population’s gene pool requires variation. Increased genetic diversity results from it. In actuality, the foundation of the entire evolutionary history of the planet is inheritance in combination with the variation of the inheritable genes (i.e., “descent with modification”). 

Heredity and variations are the basis for

  • Diversified generations of the same lineages
  • The evolutionary advantage in adverse conditions
  • Adaptations of organisms 
  • Evolution of new species 
  • For tracing the evolutionary history and classification of an organism’s

Molecular Basis of Inheritance (DNA and RNA)

Mendel’s research with garden peas laid the groundwork for genetics. He was aware that each “factor” had two “variants,” only one of which was passed down from each parent to the offspring, and that each “variant” was responsible for the features observable in organisms. But he didn’t know what this element was. Some ground-breaking studies, such as those conducted by Fredrick Griffith in 1928, Averty, MacLeod, and McCarty in 1944, and Hershey and Chase in 1952, provided unmistakable proof that the DNA, not RNA or proteins, is the molecular foundation of inheritance.

The cornerstone for the continuation of life is the nucleic acids DNA and RNA. The information is stored in the DNA as genes, which are transferred from one generation to the next. The phenotypic characteristics of an individual vary depending on what allele (a variant of a specific gene) is present on the chromosome.

Differences Between the DNA and the RNA:

DNA RNA 
Comprises two polynucleotide strands, coiled around a common axis in a right-handed manner The RNA molecule is a single polynucleotide strand 
Adenine pairs with thymineCytosine pairs with guanine Adenine pairs with uracilCytosine pairs with guanine 
Contains a deoxyribose sugar Contains a ribose sugar 
Carries hereditary information in the form of nucleotide segments known as genes Translates the gene transcripts (mRNA) from DNA into proteins

Summary 

Reproduction passes genetic information from parents to offspring, resulting in the offspring acquiring the same characteristics as their parents. Mutations are arbitrary alterations to an organism’s genes that can come from biological, chemical, or physical sources. Recombination involves the exchange of alleles from one chromosome’s homologue with those from the other. The phenotypic characteristics of an individual vary depending on what allele (a variant of a specific gene) is present on the chromosome.

 Frequently Asked Questions

1. What are the Factors that Determine the Sex of a Human?
Ans. The sex chromosomes in humans control gender. Males have one X from the mother and one Y from the father, making up the XY sex chromosome combination, whereas females have the XX chromosome pair (one X chromosome from each parent).

2. Do all Characters Always Pass Down from Both Parents?
Ans. No. Some characteristics, and particularly some diseases, can be sex-related and be found on the sex chromosomes. In addition, we are aware that mitochondria contain their DNA. The mother alone is the exclusive source of this mitochondrial DNA. All other nuclear features are passed down through both parents.

3. What is meant by Somatic Variation?
Ans. Genetic material is either inherited or acquired by an offspring from its parents. However, the somatic (non-gametic) cells of the developing zygote may develop mutational alterations that are not integrated into the germline. These characteristics won’t be passed down to the person’s descendants.

4. Is there a chance of Genetic Variation Whenever there is a Crossing-Over?
Ans. On the non-sister chromatids of a homologous pair, the identical allele of a gene may cross over. Crossover may occur in this situation, but unless the alleles on the two chromosomes are distinct, no new variation will result.

5. What are Sex-Linked Traits? Give an Example.
Ans. Traits controlled by a sex chromosome gene or allele are known as sex-linked traits. X-linked recessive conditions are twice as common in females as in males: if 1 in 20 males in a population is red-green colourblind, then 1 in 400 females will be reversed colourblind.