Question

The combination of a host organism and its microbiome is known as a. a microbiome. b. a holobiont. c. a metagenome. d. a metabolome. e. both a and c.

Short answer

The correct answer is b. A combination of a host organism and its microbiome is known as a holobiont.

Step-by-step solution

Understand the question

The exercise requires finding out how a host organism and its microbiome are collectively known. The choices presented include a set of biological terms, namely, a microbiome, a holobiont, a metagenome, a metabolome, and a combination of microbiome and metagenome.

Define the terms

A microbiome refers to the collection of microbes in a specific environment, such as an organism's body. Holobiont describes an entity that includes a host and its symbiotic microbes. Metagenome refers to the genetic material present in an environmental sample. Metabolome represents the total metabolites and small molecules within a biological organism.

Compare the definitions with the question

After reviewing the definitions of the given terms, it becomes clear that 'holobiont' is the term that defines the combination of a host organism and its microbiome. None of the other terms are appropriate to use in this context.

Key concepts

Host Organism

A host organism is the main living entity that provides a habitat and resources for other smaller organisms, which are often called microbes. These microbes can include bacteria, viruses, fungi, and archaea. The host organism typically provides the necessary environment, nutrients, and security that the microbes need to survive and reproduce.
In biology, when discussing host organisms, it is crucial to realize their importance in sustaining life for various microbes. This interaction forms complex biological networks that are essential for numerous ecological and physiological processes. Host organisms can range from single-celled bacteria to complex multicellular organisms, like humans and plants.
The relationship between a host and its microbiome (the community of microbes living in and on the host) is critical to the health and functionality of the host. The presence and composition of these microbes are vital, as they help in processes such as digestion, protection against pathogens, and even influencing the host's immune response.

Microbiome

The term microbiome refers to the full collection of microorganisms that inhabit a particular environment. In the context of a host organism, the microbiome includes all the bacteria, viruses, fungi, and other microscopic entities living in symbiosis with the host.

• Microbiomes exist almost everywhere - from human skin and guts to soil, oceans, and even ice caps.
• These microbial communities are formed and influenced by both external factors (like diet, environment) and internal factors (like genetics and immune status of the host).

In humans, the gut microbiome is one of the most studied, given its significant effects on overall health and disease. It is intricately connected to myriad bodily functions, impacting metabolism, immune defense, and even mental health.
Understanding the microbiome has become an essential aspect of modern biological and medical research. Advances in technology, such as metagenomics, allow scientists to study these microbial communities in ways previously unimaginable.

Symbiotic Relationship

A symbiotic relationship refers to a close and long-term interaction between two different biological organisms. These interactions can be:

• Mutualistic, where both organisms benefit from the relationship.
• Commensalistic, where one benefits while the other is largely unaffected.
• Parasitic, where one organism benefits at the expense of the other.

The combination of a host organism and its microbiome represents a classic example of a symbiotic relationship. In many instances, this relationship is mutualistic. Microbes in the gut, for instance, help digest food, synthesize vitamins, and protect against pathogens, benefiting the host. In return, the host provides the microbes with nutrients and a stable environment.
This dynamic and interdependent relationship is not only crucial for the immediate health of the host but also plays a role in evolution and adaptation. It exemplifies the complex interactions that drive biological diversity and organismal survival.

Genetic Material

Genetic material refers to the substances that carry an organism's hereditary information. In the context of living organisms and their interactions, it predominantly involves DNA and RNA molecules.
The genetic material of a host organism is crucial because it encodes all the information required for its growth, development, and function. Every living cell within an organism contains a copy of this genetic blueprint. Genetic material also plays a significant role in the host's interaction with its microbiome.
Microbes also have genetic material, and this combined genetic pool within a host-microbiome system is sometimes referred to as a metagenome. Studying this can reveal insights into how microbes influence host traits and health. Techniques like metagenomics allow the detailed exploration of these genetic materials, enabling researchers to understand better how host-microbiome interactions can impact everything from metabolism to immune responses.