Symbiosis Notes

Symbiosis

• In ecosystems, many populations live in symbiosis, which is the relationship of organisms that live in very close contact with one another.
• The word \"symbiosis\" comes from the Greek word for \"living together.\"
• Close relationships are symbiotic relationships.

Symbiosis and Microbiomes

• Humans and all the organisms in our microbiomes live in symbiosis.
• Together, humans and their microbiomes form an ecosystem.
• Human bodies are like islands that support the life of all the organisms on the island, and these organisms support us.

Impact of Microbes on Human Development

• In human bodies, different microbes release chemicals that affect our development.
• The microbiome impacts various aspects of human health:
  • Bones
  • Heart and blood vessels
  • Digestion
  • Brain and behavior
  • Immune system
  • Skin

Three Types of Symbiosis

• Mutualism: Both populations benefit from the relationship.
• Commensalism: One population benefits, and the other is neither harmed nor helped.
• Parasitism: One population benefits, but harms the other. Organisms that make us less healthy are parasites.

Types of Relationships with Microbiome Communities

• Humans have all three types of symbiotic relationships (mutualism, commensalism, and parasitism) with their microbiome communities.
• The most common type of relationship is commensalism, where microbes don't bother us but benefit from the food, water, and shelter our bodies provide.
• Example: Staphylococcus and streptococcus bacteria living on the surface of human skin engage in commensalism with us.

Mutualism Example

• Example of mutualism: Green bacteria makes the enzyme lactase, and pink bacteria makes the amino acid tryptophan.
• Each type of bacteria benefits from the product of the other, increasing their chances of survival by living nearby each other.

Pathogens and Parasitism

• Pathogens are microbes that cause disease.
• Pathos means \"illness,\" and -gen means \"to give rise to.\"
• Pathogenic microbes are sometimes called \"germs.\"
• Pathogens are parasites: they benefit by reproducing on our bodies, while we suffer because we get sick as our immune systems try to kill them.