BIO 002 Midterm #2

Immune system

Immune system

Tissues, cells, and molecules that mediate resistance to infections. Role of the immune system = Defense against microbes, Defense against the growth of tumor cells, and Homeostasis.

Immunology

Study of structure and function of the immune system.

Immunity

Resistance of a host to pathogens and their toxic effects.

Immune response

Collective and coordinated response to the introduction of foreign substances in an individual mediated by the cells and molecules of the immune system.

Homeostasis

A tendency to maintain a balanced or constant internal state, destruction of abnormal or dead cells.

Organs and Tissues, Cells, and Molecules

What makes up the Immune System?

Immune system organs/tissues

Skin as a barrier Tonsils and adenoids Thymus Lymph nodes Spleen Appendix Lymphatic vessels Bone marrow

Immune system cells

Lymphocytes, Monocytes, Macrophage and Granulocytes.

Lymphocytes

The two types of white blood cells that are part of the body's immune system. T-lymphocytes, B-Lymphocytes, plasma cells, and natural killer lymphocytes.

T cells Vs B cells

The main difference between T cells and B cells: T cells can only recognize viral antigens outside the infected cells. B cells can recognize the surface antigens of bacteria and viruses produce and secrete antibodies. Activating the immune system to destroy pathogens.

Immune system molecules

Antibodies, Complement system, and Cytokines (Interleukins and Interferons).

Complement proteins

Perform several functions: Serve as a marker to indicate the presence of a pathogen to phagocytic cells, such as macrophages and B cells, to enhance engulfment.

Cytokine

Any of various small regulatory proteins that regulate the cells of the immune system; they are released upon binding of PRRs to PAMPS.

Interleukins

Mediate interactions between white blood cells (leukocytes) and help bridge the innate and adaptive immune responses.

Interferons

Protein released by animal cells, usually in response to the entry of a virus. Nearby uninfected cells of impending infection, cause cells to start cleaving RNA and reduce protein synthesis, and signal nearby infected cells to undergo apoptosis.

Macrophage

Large, phagocytic cell that engulfs foreign particles and pathogens. Macrophages recognize PAMPs via complementary pattern recognition receptors (PRRs).

Neutrophils and Eosinophils

Small, phagocytic blood cells that mobilize during infection or tissue injury. Particularly important leukocytes that engulf large pathogens, such as bacteria and fungi.

Basophils

A circulating leukocyte that produces histamine. Also involved in allergy and hypersensitivity responses and induce specific types of inflammatory responses.

Anti-allergy medications are Anti-histamines

Hypersensitive immune response to harmless antigens, such as in pollen, often involves the release of histamine by basophils and mast cells.

Innate (non-adaptive) and Acquired (adaptive)

The Two types of immunity are?

Innate (non-adaptive)

First line of immune response, Relies on mechanisms that exist before infection, We are born with a fully formed innate immune system.

Acquired (adaptive)

Second line of response, relies on mechanisms that adapt after infection, handled by T- and B- lymphocytes.

Innate Immunity

Based on genetic make-up, relies on already formed components, has no memory, rapid response (Within minutes of infection), and not specific.

Barrier Tissues, Cells and Molecules

The Innate Immune system is made up of

Barrier Tissue

Exist at sites where the body interacts with the environment. Physically and chemically prevent pathogens and organisms from entering the body.

Key Cells in Innate Immunity

Include several types of circulating white blood cells (Leukocytes) and cells that reside in tissues. These cells use immune receptors to recognize pathogens. Ex) Dendric cell, mast cell, Neutrophil, Macrophage, Monocyte.

PAMPs (pathogen-associated molecular patterns)

Molecules associated with groups of pathogens that are recognized by cells of the innate immune system. Bind to a wide variety of threats. Molecular motifs commonly found on the outside of bacteria. Others include DNA and RNA from viruses that may be detected by cells that ingest them.

Peptidoglycan

A protein-carbohydrate compound that makes the cell walls of bacteria rigid. On Gram Positive Bacteria.

LPS (Lipopolysaccharide)

A molecule consisting of lipids and polysaccharide moieties that is a major component of the cell wall of gram negative bacteria.

Neutrophils

Migrate from the bloodstream to phagocytose and kill pathogens. Undergo programed cell death.

Macrophages

Phagocytose pathogens and dead cells and play a role in tissue repair.

Dendric cells

Phagocytose pathogens help activate the adaptive immune system.

Mass cells

Release large amounts of cytokines and other pro inflammatory mediators.

Pro-inflammatory mediators

Cytokines, chemokines, and histamine send signals to other innate immune cells and the cells of surrounding tissue to allow protein from blood into the tissue and interact with pathogens.

Sentinel Cells

Are always present in the tissues are the first to recognize and respond to an invading pathogen. When they recognize PAMPs they release pro-inflammatory mediators and stimulate blood vessels to become leaky.

Homeostasis is restored

As pathogens and dead cells are cleared. Monocytes migrate into the tissue, Macrophages also ingest dead cells.

Honey bees

Have both social and individual immunity. Compared to fruit flies, honey bees have only ~ 1/3 of the immune genes.

Information flows from DNA

Within a cell, DNA directs the production of RNA, which in turn directs the production of proteins.

Transcription

Follows the DNA base-pairing rules with one exception: Uracil (U) is used instead of thymine (T). Creates a molecule of RNA from a molecule of DNA.

Messenger RNA (mRNA)

The molecule that results from transcription is called? A type of RNA, serves as instructions for making a protein. Synthesized from DNA and attached to ribosomes in the cytoplasm.

DNA double helix separates.

During transcription, The RNA is processed to become messenger RNA, which then exits the nucleus via a nuclear pore.

Initiation

RNA synthesis begins after RNA polymerase attaches to the promoter.

Elongation

Using the DNA as a template, RNApolymerase adds free RNA nucleotides. Continues until the ribosome reaches a stop codon on the mRNA.

Termination

RNA synthesis ends when RNA polymerase reaches the terminator DNA sequence.

RNA transcript with cap and tail

Transcription, Addition of cap and tail, Introns removed, Exons spliced together

5' - 3' direction

Refers to the orientation of nucleotides of a single strand of DNA or RNA. Any single strand of DNA/ RNA will always have an unbound 5' phosphate at one end and an unbound 3' hydroxyl group at the opposite end.

Life Cycle of Human Coronaviruses

Enter host cells by first binding to cellular receptors. Viral genomic RNA is released and translated into viral polymerase proteins. The negative sense genomic RNA is synthesized. Viral RNA and nucleocapsid (N) structural protein are replicated, transcribed, or synthesized in the cytoplasm. Other viral structural proteins, iand envelope are transcribed then translated in the endoplasmic reticulum (ER) and transported to the Golgi.

RNA polymerase Vs RNA dependent RNA polymerase?

Template, DNA versus RNA. Input, Nucleoside Triphosphates. Product, RNA.

Translation

Takes place in the cytoplasm within ribosomes. Involves three kinds of RNA: rRNA, mRNA, and tRNA.