Inheritance: Reproduction

Overview of Reproduction

Reproduction is the process by which organisms produce more of their own kind.
It can take two forms: asexual reproduction and sexual reproduction.

Asexual Reproduction

Asexual reproduction involves only one parent and leads to offspring that are genetically identical to the parent. This is known as producing clones.
Some organisms that reproduce asexually include bacteria, some plants, and some animals such as the starfish.

Sexual Reproduction

Sexual reproduction involves two parents, each contributing half of their genes to the offspring. This results in offspring that are genetically different from each other and from their parents.
Human beings, as well as many plants and animals, reproduce sexually.

The Inheritance Aspect in Reproduction

The process of inheritance begins in sexual reproduction with the formation of gametes, which are the eggs in females and sperm in males.
Each gamete contains half the number of chromosomes of a regular cell in the body. These are known as haploid cells.
When a female gamete and male gamete unite during fertilisation, they form a zygote. This zygote is a diploid cell, because it contains a full set of chromosomes: half from the mother and half from the father.

Variation and Inheritance

Genetic variation among the offspring is introduced during sexual reproduction due to the mixing of genes from both parents.
Alleles are different versions of a gene that are found at the same place on a chromosome.
The inheritance of specific traits can be predicted using Punnett squares, showing the possible combinations of alleles that can occur.
Dominant alleles display their effects even if the individual only has one copy of the allele. However, a recessive allele only shows its effects if the individual has two copies of the allele.
In some traits, both alleles can have an effect on the phenotype, leading to co-dominance. In these cases, the individual exhibits a blend of the two traits.

Natural Selective Pressure and Evolution

Over time, certain traits can become more prevalent in a population due to natural selection. Organisms with traits that increase their chance of survival and reproduction are more likely to pass on these traits to future generations.
Over many generations, this can lead to evolution, or the development of new species.
Evolution is driven by mutation (random changes in DNA), non-random mating, gene flow, genetic drift, and the selective pressure exerted by the environment.

Always remember that the study of inheritance and reproduction helps us understand a wide range of phenomena – from individual family traits to the diversity of life on earth.