Cell Signaling, Cellular Defense, Human Immune System, Biomaterials

Flashcards covering cell signaling, cellular defense mechanisms, the human immune system, and biomaterials.

What is a ligand in cell signaling?

A chemical messenger that binds to a receptor on a target cell.

What is the role of a receptor in cell signaling?

A protein on a target cell that binds to a ligand, triggering a cellular response.

What is signal transduction?

The process of converting an original ligand signal into a cellular response in a target cell.

What happens in ion-channel linked receptor signaling?

A ligand creates an opening in the cell membrane where ions can pass through.

What is the function of autocrine signaling?

A cell self-stimulates by having a ligand bind to the same cell it originated from.

What is paracrine signaling?

A ligand travels by diffusion to local cells.

How does endocrine signaling occur?

Ligands travel through the bloodstream via blood/lymph vessels to target cells at a distance.

What are cytokines?

Hormones specifically for the immune system, composed of protein/short peptides.

What is a biofilm?

A community of microorganisms embedded in a self-produced matrix of proteins.

How does quorum sensing work in biofilms?

Regulation of gene expression in response to fluctuation in cell density of the colony.

What is EPS (extrapolymeric substance) in biofilms?

A matrix of excess proteins, carbs, lipids, etc. produced by a colony that keeps organisms trapped to a surface and protects the colony.

What is vibrio fischeri?

A species of marine bacteria capable of bioluminescence, which lives in symbiosis with the Hawaiian bobtail squid.

What are bacteriophages?

Viruses that exclusively infect prokaryotes, composed of proteins & RNA/DNA.

What is the lytic cycle?

A phage uses nucleic acids in bacteria to self-replicate until the cell lyses from overpopulation of phages.

What is the lysogenic cycle?

Phage DNA is incorporated into the bacterial genome and lies dormant until the bacteria undergoes stress, inducing the lytic cycle.

What are the pros and cons of phage therapy?

Pros: effective against resistant bacteria, more targeted than antibiotics. Cons: limited host range, can trigger immune response, identifying bacteria takes time.

What is an abortive infection system?

A programmed cell death system in prokaryotes that prevents further replication of viruses via apoptosis.

What is the function of restriction enzymes?

Cleaves DNA at specific (palindromic) sites where viral DNA is identified.

What is the CRISPR-CAS System?

Clustered Regularly Interspaced Palindromic Repeats. CAS9 uses guide RNA that recognizes complementary pairs of specific target sequence.

What is synthetic biology?

Redesigning organisms for useful human application, standardizing biology with a library of parts working in various organisms.

What are the types of threats the human immune system protects against?

Bacteria, viruses, allergens, cancerous cells, environmental pollutants.

What is immune tolerance?

How the immune system recognizes substances as threatening vs. something that can be tolerated.

What is an antigen?

Substance on the surface of pathogenic cells that trigger an immune response.

What is an allergen?

A harmless foreign antigen that still provokes an immune response.

What happens in autoimmune disorders?

The immune system attacks its own body.

Name some immune organs.

Lymph nodes, bone marrow, spleen, tonsils, appendix, lymph vessels, thymus, Peyer’s patches.

What is the role of lymph nodes?

Act as filters, trapping antigens where lymphocytes congregate.

Where are WBCs (white blood cells) produced?

Bone marrow and spleen.

What is the innate immune system?

First line of defense, includes physical barriers and phagocytes.

What is stress in materials science?

Force applied to the surface area of a material, measured in megaPascals.

What is strain in materials science?

Deformation in response to stress in a material.

What is strength/elasticity?

Resistance to permanent deformation or total failure.

What is plasticity/ductility?

Ability of a material to undergo permanent deformation.

What is toughness?

Ability of a material to absorb energy and deform without fracturing.

What is the adaptive immune system?

Antigen-specific, more complex immune response involving B-cells and T-cells.

What are stem cells?

Cells that haven’t differentiated yet and can become any needed cell type based on cytokine signals.

What is the role of cytokines in the immune system?

Small signaling proteins used to determine what stem cells differentiate into.

What is the function of B-cells?

Responsible for secreting antibodies that mark antigens for destruction by phagocytes.

What is the role of T-cells?

Recognize antigens on the surface of infected/cancerous cells.

What are the functions of Helper T-cells and Killer T-cells?

Helper cells stimulate B-cell production and coordinate immune response. Killer cells recognize infected/cancerous cells and directly kill them.

Describe the 'whole inactivated virus' vaccine platform

A virus that is no longer capable of replicating.

Describe the 'live-attenuated virus' vaccine platform

A virus that is alive, but less infectious after incubation in other organisms.

How do protein subunit vaccines work?

Protein subunit: portion of a virus that generates same immune response

How do viral vector vaccines work?

Transgenic virus containing the gene to express antigen of target virus

What are biomaterials?

Materials designed to replace parts of a living system, found in a biological system, or synthetic materials mimicking biological systems.

What is hierarchical structure?

Number of levels where same recognizable structure is repeated, theme through multiple layers.

Examples of hard vs. soft biomaterials?

Hard biomaterials: bone, teeth, nails. Soft biomaterials: skin, organs, muscles.

What is multifunctionality in biomaterials, and give an example?

Multiple functions in one biomaterial, e.g., bones have a hard exterior resisting compression, while bone marrow produces blood cells.

What is Young's Modulus?

Young’s modulus: Stress / Strain, slope of SS plot during linear region, high YM = stiffer material.

What are the benefits to using protein fibers as biomaterials?

Lightweight, biodegradable, biocompatible, inexpensive, widely available

Why is spider silk so strong and tough?

ASM-INCBED, effect of non-covalent bond generating internal friction.

What is the structure of amyloid fibers?

Beta sheets, a secondary structure of proteins.

What are composite materials?

Composed of several substances, allows strength against multiple loading modes.

What does it mean for a material to be anisotropic?

Material has different loading capacity in different directions.

What does it mean for a material to be isotropic?

Exhibits properties uniformly in all directions.