Immunology, Human Microbiome, and Microbial Ecology

Comprehensive practice flashcards covering introductory immunology, the human microbiome, and principles of microbial ecology based on the lecture notes.

What is hematopoiesis?

The process of making new blood cells, including both white and red blood cells.

What is the scientific name for white blood cells?

Leukocytes.

How do the innate and adaptive immune systems differ in their ability to recognize microbes?

The innate immune system has limited ability to "see" microbes with only a few hundred receptors, while the adaptive immune system has a vast, highly specific repertoire of over $10^{13}$ receptors.

What is an epitope?

The specific part of an antigen that an immune cell recognizes as foreign.

Which cells and proteins are key components of the skin's innate defense?

Keratinocytes, macrophages, mast cells, and proteins such as complement and antimicrobial proteins.

What substances do mast cells release to cause vasodilation and increased vascular permeability?

Histamine and cytokines.

What are the stages of the leukocyte adhesion cascade?

The process where leukocytes adhere to and migrate through blood vessel walls, facilitated by adhesion molecules and cytokines.

Which enzymes are involved in the "respiratory burst" during phagocytosis to kill microbes?

NADPH oxidase and Myeloperoxidase produce reactive oxygen species (ROS) such as $H_2O_2$ and hypochlorous acid ($HClO$).

What is somatic recombination?

The process in B and T cells where genes are rearranged to create unique receptors, allowing for vast diversity without a massive genome.

What is the primary difference in peak response time between primary and secondary antibody responses?

The primary response lag is usually $5-10$ days, while the secondary response lag is much faster at $1-3$ days.

Which T cell type induces apoptosis in infected or cancerous cells?

Cytotoxic ($CD8+$) T cells.

Match the T helper cell to its principal target: Th1, Th2, and Th17.

Th1 targets macrophages; Th2 targets eosinophils (for helminths/allergies); Th17 targets neutrophils (for extracellular bacteria/fungi).

Which antibody isotype is associated with mucosal immunity in the gastrointestinal and respiratory tracts?

$IgA$.

Which antibody isotype is involved in defense against helminths and allergic reactions?

$IgE$.

What are the four dominant phyla found in the human digestive tract?

Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria.

How does the microbiota of breastfed infants differ from bottle-fed infants?

Breastfed infants primarily develop $Bifidobacterium$ populations, while bottle-fed infants have a mixture of coliforms, $Clostridium$, and $Staphylococcus$.

Which bacterium is primarily associated with sebaceous (oily) skin sites and acne?

$Cutibacterium acnes$.

What are the five stages of biofilm development?

1. Reversible attachment, 2. Irreversible attachment, 3. First maturation phase, 4. Second maturation phase, and 5. Dispersal phase.

What role does $Helicobacter pylori$ play in the stomach?

It is a Gram-negative bacterium that can colonize the mucosa, causing gastritis, ulcers, and gastric cancers; it is considered a Class I carcinogen.

What is dysbiosis?

The disruption of homeostasis between the microbiome and the host, linked to diseases like IBD, asthma, and cancer.

Which bacterium is a pathobiont associated with colorectal cancer and periodontal disease?

$Fusobacterium nucleatum$.

What did Sergei Winogradsky discover regarding the bacterium $Beggiatoa$?

He discovered chemolithotrophy, where cells used sulfur ($H_2S$) as their sole respiratory source.

In a Winogradsky column, which organisms are typically found in the top Oxic Zone?

Cyanobacteria (oxygenic phototrophs) and heterotrophic bacteria.

What is the difference between vertical and horizontal symbiont transmission?

Vertical transmission occurs from parent to offspring (e.g., in eggs), while horizontal transmission is acquired from the environment.

What benefit does the squid $Euprymna scolopes$ receive from its symbiosis with $Aliivibrio fischeri$?

Counter-illumination for camouflage during nocturnal activity.

What is the Coral Probiotic Hypothesis?

The idea that corals can adapt to environmental stress and pathogens through changes in their symbiotic microbial community (the holobiont).

What is kleptoplasty in the sea slug $Elysia chlorotica$?

The ability to feed on algae ($Vaucheria litorea$) and maintain active chloroplasts in its digestive tract for up to 11 months.

What is the "wolfpack hypothesis" regarding $Myxococcus xanthus$?

Cells move as swarms toward prey to increase the density of hydrolytic enzymes needed to lyse the prey.

How do shark microbiomes relate to their environment according toRecent research?

Shark microbiomes are distinct from the surrounding seawater and vary by both shark species and anatomical location.

According to the bat microbiome study, what was a potential factor in shaping their gut microbiome?

Diet (e.g., whether the bat is an insectivore or a frugivore).