Introduction to Biology Pt. 4: Genes and DNA

Introduction to Biology Pt. 4: Genes and DNA

When studying the life sciences, there are a lot of in-depth concepts to take in. Depending on the the type of science you are studying, biology vs. evolution, for example, you may even have to learn a handful of mathematical formulas to fully appreciate the material. Here, we are just having a light-hearted overview of the life sciences, so a light serving of sativa will do just fine.

In my experience, sativa helps me to not get lost in wordy texts (reading that is not broken up by graphics/tables or formulas) and keep my mind sharp and able to take in all relevant information. Grinding about 60mg (less than 1/4 of a 1g bud) of sativa and smoking just a small pinch of that for over a 3-5hr period is perfect for maintaining a healthy attention span for learning.

Black Flower Science Co. does not claim to be a medical professional and does not offer recommendations as a substitute for medical advice. All advice and recommendations are based on personal experience of the benefits of medical marijuana. If you are experiencing severe or declining mental health symptoms, please seek the advice of a medical professional.

A lot of what makes you unique from the next person is thanks to your genetic makeup. All of your cells contain many genes and this is what allows for extensive variation across all living creatures.

Even the smallest difference in DNA can make a world of a difference. Take for example humans and chimpanzees, they share 99% of their DNA with one another. That 1% difference is enough to make two completely different species. 

This article explores genetics and its role in diversity across all living creatures.

Genetics is the study of how an offspring’s characteristics can be traced to their parents. A genome is an individual’s entire collection of DNA including its genes which are the basic unit of heredity.  

Photo by Alexander Popov on Unsplash

Inheritance

Through his studies on pea plants, Gregor Mendel observed the concept of heritable units which we now call genes. He discovered the segregation of heritable traits when he noticed that a cross between a purple and a white pea plant yielded either purple and white offsprings and no color in between. 

These distinct forms of a gene are called alleles. A set of alleles is called a genotype and the observable traits that arise from this is called a phenotype. Organisms that have two copies of the same allele for a gene are homozygous for that gene and those that have different alleles are called heterozygous.

Organisms that are heterozygous for a certain gene tend to have one allele that is dominant, meaning its characteristics present itself in the phenotype. The other allele is recessive, because its qualities are not displayed. 

There are situations where alleles do not have complete dominance. In incomplete dominance, an intermediate phenotype is displayed. An example of this would be when the offspring between a red flower and a white flower has pink petals. In co-dominance, both alleles are presented such as when both red and white is present in the petals of an offspring. 

DNA provides the information that makes up life 

Deoxyribonucleic acid (DNA) is the molecular basis of genes. It is a chain made up of four nucleotides- adenine (A), cytosine (C), guanine (G), and thymine (T). The sequence of these four nucleotides holds genetic information. DNA is a double-stranded molecule that coils together into a double helix with preferential complementary pairing between nucleotides. A goes with T and C goes with G. 


Terpenes Infographic Print – 18×24

The central dogma of molecular biology

Simply put, the central dogma explains how genetic information is processed to create a product that the body can use, a protein. Following DNA replication, the processes of transcription and translation take place. 

Transcription creates an RNA copy of DNA using four ribonucleotides- adenine (A), cytosine (C), guanine (G), and uracil (U). RNA complementary matches to DNA, A goes with U and C goes with G. Next, translation occurs where the messenger RNA sequence produces a corresponding amino acid sequence to create a protein.

Cell division through mitosis and meiosis

Because a DNA sequence is super long, they have to be tightly coiled into chromosomes in order to fit inside cells. As an individual grows, their cells divide creating copies of their full genome. Mitosis is cell division to create two daughter cells that are genetically identical to their parent cells and the number of chromosomes within these cells are unchanged.

Meiosis is a type of cell division that produces gametes which are male or female reproductive cells. During meiosis, four cells are formed with one copy of each chromosome. When an egg is fertilized by a sperm, a fetus is formed with half of the mother’s and half of the father’s genetic information.  

Effects of genetic errors

There are multiple checkpoints during DNA replication and cell division, however sometimes errors slip through. These errors can affect an organism’s set of observable characteristics.  

Natural selection and evolution

Natural selection is the survival of the fittest. Since variation exists amongst all populations, situations may arise when organisms with certain phenotypes become better suited for an environment. In that case, a population with more genetic variation may be able to better ensure the continuation of their species.

The individuals that survive will mate with one another and breed offspring with favorable traits, resulting in evolution which is a population’s change of heritable traits over time. Evolution may then result in speciation, the formation of a new species.

Photo by National Cancer Institute on Unsplash

Manipulating DNA

Since it is understood that DNA contains the information needed to create life, researchers and innovators have taken advantage of this. Genetic engineering is the modification of an organism’s genes and has been used to solve a wide range of problems from medicine all the way to agriculture.

Model organisms

Model organisms have been used to learn more about other species that cannot be easily tested in the lab. Some of the most commonly used model organisms are yeast, the fruit fly, and mice. These organisms are practical for use because they are small and can breed in large numbers with shorter generation times compared to other species. 

Mice are model mammalian organisms and have made great contributions towards human research. About 97.5% of working DNA is shared between mice and humans. This similarity has allowed for research and vast discoveries in medicine including cardiac disease, gene therapy, cystic fibrosis, and so much more.

References 

Griffiths, A. J. F. (1970, January 1). Interactions between the alleles of one gene. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK21920/ 

Mayo, O., & BUeRGER, R. E. I. N. H. A. R. D. (1997). The evolution of dominance: a theory whose time has passed?. Biological Reviews, 72(1), 97-110. 

Torpy, J. M. (2008, March 19). Genetics: the Basics. Retrieved from https://jamanetwork.com/journals/jama/fullarticle/181643

Using Research Organisms to Study Health and Disease. (n.d.). Retrieved from https://www.nigms.nih.gov/education/fact-sheets/Pages/using-research-organisms.aspx


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