Question

Describe why, in order to be considered living, an object must contain DNA or another substance that has the same capabilities.

Short answer

Living organisms need DNA or similar molecules for genetic storage and function.

Step-by-step solution

Understanding DNA's Role in Living Organisms

DNA, or deoxyribonucleic acid, is a molecule that contains the instructions needed for an organism to develop, survive, and reproduce. It stores genetic information and is responsible for passing traits from one generation to the next. DNA is essential for the regulation, management, and reproduction of cells.

Alternative Biological Molecules with Similar Functions

Not all living organisms rely solely on DNA for genetic information. Some viruses use RNA as their genetic material. RNA, like DNA, has the capacity to store genetic instructions, replicate, and control cellular functions but in a single-stranded form.

The Importance of Genetic Material

To be considered living, an object must be capable of growth, reproduction, and the continuation of its species, which requires a mechanism for storing and transmitting genetic information. DNA or molecules like RNA provide the necessary blueprint for these processes.

Defining Life with Genetic Material

The presence of DNA or similar molecules is a critical criterion for life because it ensures that an organism can perform essential functions such as cellular organization, homeostasis, metabolism, growth, adaptation, and response to stimuli.

Key concepts

DNA and RNA

DNA and RNA are both critical nucleic acids that serve as the blueprint of life. DNA, or deoxyribonucleic acid, has a double-helix structure and is found primarily in the nucleus of cells. It contains the genetic instructions that guide the development, functioning, and reproduction of living organisms. RNA, or ribonucleic acid, is usually single-stranded and plays several roles, including messenger RNA (mRNA), which carries genetic information from DNA to the ribosome, where proteins are synthesized.
Both DNA and RNA are made of long chains of nucleotides, which are the building blocks of nucleic acids. Nucleotides consist of a sugar, a phosphate group, and a nitrogenous base. In DNA, the sugar is deoxyribose, while in RNA it is ribose. The bases include adenine, thymine, cytosine, and guanine for DNA, with uracil replacing thymine in RNA.

• DNA: Double-stranded, main storage of genetic information.
• RNA: Single-stranded, involved in protein synthesis and sometimes genetic storage in viruses.

These molecules are crucial for carrying and expressing genetic information, thus facilitating growth and reproduction.

Criteria for Life

For an object to be considered living, it must meet certain criteria centered around the concept of life. These criteria are based on biological principles and include characteristics such as cellular organization and complexity. Life must be able to maintain homeostasis, which is the regulation of internal conditions to remain stable and vital.
Life involves metabolism, which refers to the chemical processes that occur within a living organism to maintain life. Metabolism includes anabolic (building up) and catabolic (breaking down) reactions. Another criterion is the ability to grow and develop, meaning that living things undergo growth by increasing in size or cell number.
Reproduction is also a key feature, allowing organisms to produce new individuals, thus ensuring the continuation of species. Additionally, living organisms must be capable of responding to environmental stimuli and adapting to changes, allowing evolution over time.

• Cellular organization and complexity.
• Ability to maintain homeostasis.
• Metabolic activity.
• Growth and reproduction.
• Response to stimuli and adaptation.

These characteristics are essential for defining life and are largely facilitated by genetic material like DNA and RNA.

Genetic Information Transmission

Genetic information transmission is a fundamental process that ensures the inheritance of traits from one generation to the next. This process is vital for the survival and evolution of species. It involves the accurate copying and distribution of genetic material during the processes of cell division, such as mitosis and meiosis.
During these processes, DNA is replicated to ensure that each new cell receives an exact copy of genetic information. RNA plays a crucial role as well, especially mRNA, which is central in translating genetic codes into proteins essential for various functions.
Errors in genetic information transmission can lead to mutations, which may sometimes result in beneficial adaptations or negative effects. The efficiency and precision of this transmission process are what enable organisms to preserve necessary functions and develop new traits. DNA repair mechanisms are also in place to correct any mismatches during replication.

• DNA replication ensures genetic continuity.
• mRNA translates genetic codes into proteins.
• Mutations can lead to positive or negative adaptations.
• DNA repair mechanisms help maintain genetic integrity.

This transmission of genetic material is essential for life as it allows for the persistence and innovation of life forms through successive generations.