A Summary of Heredity and Genes
Introduction
Heredity is the process via which the traits and characteristics of a parent are passed on to their offspring. Traits like eye color, height, facial structure, and hair color are some of the heritable traits. Genes are the primary storage units of heritable traits and characteristics. Heredity is dependent on genes which are the basic physical units of heredity. Thus every individual acquires two copies of each gene with each one of them being inherited from each parent. The genes that a child inherits from both parents are known as the organism’s genotype. Even though most of the genes are the same, at least less than one percent is unique of the genes also known as alleles are unique to the individual, and they play a significant role in determining the unique physical traits of the individual. Therefore it is crucial to identify how the genetic information is passed on to the offspring of a family. In this article, I summarize the biological workings of heredity.
Heredity and Genes
Mendelism
Gregor Mendel in 1865 attempted to provide a scientific explanation of heredity. Mendel in his experiments with peas in his garden argued that heredity is dependent on genes that segregate; parents transmit half of their genes and different sets of genes to each offspring. Mendel also identified that unlike twins, siblings do not receive the same heredities. The heredity of humans which is dependent on sexual reproduction was also depicted as having unique hereditary traits despite having the genetic resemblance. It is true that some genes are active in affecting our cell formation and thus may be active in some organs and tissue and also inactive in others. This means that the environmental factors and the genetic makeup affect the passage of diseases from parents to the offspring.
The Heredity Process
The cell is the basic unit of an organism. Thus from the biological perspective, the genes are responsible for carrying the physiological traits from the parent to the offspring. Genes are composed of a chemical called deoxyribonucleic acid and are linked to each other in a chain structure known as chromosomes. Thus the gene acts as the blueprint for the development of the human traits with special reference to the unique features of the parents while the DNA carries the information that determines the traits in protein form. The characteristics in the parents are passed on to the offspring through DNA which is a molecule that is crucial for encoding the genetic information. Deoxyribonucleic acid is responsible for encoding the genetic information and thus the designated carrier of the transferrable traits and characteristics from the parents to the offsprings.
In a nutshell, the genetic material passed from the parents to the offspring as a result of sexual reproduction. The genetic composition of each of the parents’ traits is enabled by genes and thus hereditary is dependent on genes which are the carriers of the genetic material. A gene being the fundamental unit of inheritance makes up a DNA sequence which is, in other words, the genetic material in heredity. An offspring inherits chromosomes that contain the genes of the parents. Chromosomes exist in pairs, and thus a human chromosome has a total of 46 chromosomes in 23 pairs each from each parent. It is crucial to note that the 23rd pair of chromosomes determines the sex of the offspring and is thus referred to as the sex chromosome.
Chemical Bases
The DNA has at least four types of bases that are interchangeable while the base arrangement along the DNA structure depicts the specific information regarding the traits and characteristics that are transferrable. Genes are also composed of unique codes known as chemical bases. These chemical bases Adenine, Thymine, Cytosine, and Guanine are like the alphabetical words that affect the composition of the genes. Indeed these chemical bases make up the DNA which then acts as the blueprint for the development of the human body and particular traits. Therefore, before cell division begins, the DNA is copied into the cells such that each chromosome will inherit a trait from one of the parents. Therefore the portion of the DNA that specifies a specific trait is known as a gene. The differences in genetic composition thus result due to the building and development of a variety of proteins and amino acids which determines the physical traits such as the color of the hair or the blood type of the offspring. The gene is the custodian, and the primary determinants of the hereditary process are determined by the interaction of the genes and the environmental factors. For example, one might have the genetic trait of being overweight, but environmental factors such as the availability of food and factors such as exercise.
Genotypes and phenotypes
A genotype is the genetic composition of particular inherited traits and is determined by the composition of alleles which is a gene that determines the uniqueness of the traits. Thus a genotype is a genetic makeup within the genes that ultimately affect the traits of the offspring. Thus the genotypes can only be determined as a result of biological tests, but cannot be observed physically. Therefore an example of genotypes is the genes that determine the transferrable traits such as eye color, height or the color of hair.
On the other hand, a phenotype is the observable physical features that can be seen as a result of the genes that have been passed on to the offspring. An example is a height, color of the eyes and color of the hair. Phenotypes are highly dependent on the genes and also the environment. Genotypes thus remain constant all through the life of individuals, but as a result of the environmental changes as well as behavioral differences so does phenotypes. Most of our cells are diploid meaning that each cell of our body contains two sets of 23 chromosomes except the sex chromosomes which are considered haploid. After the process of fertilization, the sperm cells combine with the egg cells to form a new organism. This cell has the 46 chromosomes which are 23 chromosomes from the sperm cell and 23 chromosomes from the egg cell. Each of the 23 chromosomes has the genetic material from both parents, and hence via the genes the traits that are from each parent can be passed down from the genetic material of the parents, and this is the reason in most families there is the aspect of resemblance in terms of eye color, nose shape and height.
Genetic Mutations
Disorders can also be passed on to the offsprings from the parent. The pattern of inheritance can be altered by the alteration of a single gene. The inherited conditions can be inherited via the autosomal dominant, autosomal recessive, the X linked dominant, or the X linked recessive. Thus conditions are affected by a variety of environmental factors such as exposure to risk factors to certain disease as also genetic composition. The degree of complex traits being inherited is hard to predict as the genetic makeup cannot be determined either. On the other hand, the dominant traits only have a single copy of the genes to manifest. An example of this trait is the rolling of the tongue.
Indeed, when genes mutate, it leaves a permanent mark on the composition of the DNA of a person. Some mutations are beneficial while others are harmful. Therefore it is crucial to identify harmful traits within the family line in advance to have the upper hand in dealing with any upcoming issues. Thus only the changes in DNA in the egg or the sperm cells can be passed on to the child from the parent. Even though our bodies can cause harmful mutations, the original stable genetic composition of our genes are not affected. This explains how a harmful mutation such as cancer happens. Thus it is crucial to access genetic tests to gain an understanding of the hereditary diseases to plan.
Genetic Variations
Genetic variations are the unique differences in the genetic composition in each. Variation explains the reason individuals exhibit a variety of traits. Variations are supposed to allow the aspect of adaptability in humans which is crucial for the survival of the human species in different environmental conditions. Changes in environmental factors such as habits, exposure to chemicals and body exercise can hence affect our genes either positively or negatively.
Conclusion
In conclusion, heredity is a crucial process that explains the aspect of species resemblance. The process of heredity is dependent on genes which carry the genetic information from one generation to another. Environmental factors and genetic characteristics may affect the genetic composition either negatively or positively as a survival measure by our bodies. The genes of our bodies are stable but also at risk from environmental factors such as exposure to toxic chemicals. Thus we should ensure that we are aware of our genetic composition via genetic tests to determine and mitigate any threats that may arise from our environment. Heredity is a natural phenomenon that is meant to ensure the sustainability and safe development of the human species.