Flashcards
Bio 212 Final Defense
Flashcards do conjunto (23)
- 1PathogenAny entity capable of causing a disease such as a microbe virus or prion
- 2AntigenToxin or foreign substance which induces an immune response in the body especially the production of antibodies
- 3Innate ResponseWhite blood cells can recognize pathogens and phagocytize them
Broad groups of pathogens recognized by Pattern Recognition Receptors
Toll-like receptors (TLRs) receive a molecular signal when pathogen group is present - 4Inflammatory ResponseInflammation is a process that ensures that components of the innate and adaptive immune systems arrive at the site of pathogen entry to prevent further entry.
1. Pathogen enters a wound.
2. Platelets release blood-clotting factors.
3. Injured tissue releases cytokines, which recruit immune system cells. Macrophages patrols first
4. Mast cells secrete histamine, dilating blood vessels and making them more permeable.
5. Recruited neutrophils and macrophages remove pathogens by phagocytosis.
6. Chemical signals are released that stimulate tissue repair.
Lots of fluid = swelling
Lots of blood = swelling and blood
Recruited cells are receptors = pain - 5Two main lymphocytesLymphocytes are produced in bone marrow
• T lymphocytes (T Cells) mature in thymus
• B lymphocytes (B Cells) mature in bone marrow - 6Structure of T cell receptorT-cells have T-cell receptors called TCRs antigen must be presented with APC
• T-cell receptors (TCRs) proteins do not bind antigens directly.
• Antigen-presenting cells (APCs) present pieces of antigen to the T-cell.
• Grab antigen from blood and broken into small pieces and given to T-cell receptor
- 7Structure of B cell receptorB-cells receptors are essentially antibodies which can directly bind an antigen
- 8Activation of T cellT Cell activation requires APC
APCs are phagocytes. Dendritic cells are important antigen-presenting phagocytes.
• Dendritic cells ingest antigens by phagocytosis.
• Enzymes break antigen into fragments.
• Fragments are loaded onto two kinds of Major Histocompatibility Proteins (MHC): class I and class II.
• MHC protein presents the fragments on the cell surface. - 9Activation of B cellB-Cell activation is a multi-step process
• B-cell receptor binds to matching antigen.
• The antigen is internalized, fragmented, and presented on MHC Class II proteins.
• The presenting B-cell interacts with an activated T-helper cell that recognizes the same antigen.
• The T-helper cell releases cytokines that activate the B-cell.
• The activated B-cell divides, generating multiple clones of itself.
• Some of the clones differentiate into plasma cells, which release antibodies in the blood.
• Memory cells stay for the rest of your life - 10What do T cell produceT-cells can be CD4+ or CD8+
• CD8+ cells recognize antigens presented on MHC Class I proteins. CD8+ cells become cytotoxic T-cells.
- Cytotoxic T-cells kill pathogen-infected cells.
• CD4+ cells recognize antigens presented on MHC Class II proteins. CD4+ cells become helper T-cells.
- Helper T-cells activate B-cells and cytotoxic T-cells.
**Why people with HIV do not have an immune system** - 11What do B cell produceAntibodies
- 12Overview of T cell and B cell
- 13Humoral RespinseHumoral response [B-cells]
• Acts on extracellular pathogens.
• Involves antibodies and other cells.
• Only attack pathogen in the fluid of the body - 14Cell-mediated responseCell-mediated response [T-cells]
• Acts on intracellular pathogens. (Inside of cell)
• Involves phagocytic cells and cytotoxic T cells.
• Requires cell-to-cell contact.
• T cell is sacrificed to kill the pathogen - 15Primary and secondary immune responseThe primary immune response occurs the first time the antigen is encountered.
A secondary immune response occurs if the same antigen enters the body again.
• A secondary immune response is possible because some of the activated T- and B-cells during the primary response differentiate into memory cells.
When memory cells encounter the antigen again, they quickly mount an immune response. - 16How do vaccines relate to immunological memoryImmunological memory is the basis of vaccination
• A vaccine contains/generates antigen from a pathogen or contains a killed or weakened version of the pathogen itself.
• After vaccination, the body mounts a primary immune response that produces memory cells.
• If a second infection occurs later, these memory cells respond quickly and eliminate the threat before illness appears. - 17What types of pathogens attack bacteria, protists, and fungi?Phagocytic unicellular eukaryotes ingest bacteria and protists
Viruses called bacteriophages infect and kill bacteria.
Fungi can be infected by viruses (mycoviruses)
Virus called virophages infect and kill protist - 18What is the role of biofilms in bacterial defenseThe first line of defense for bacteria
- 19Restriction/Methylation System• The restriction/methylation system:
- Restriction endonuclease: recognizes a specific sequence in DNA and cuts both DNA strands wherever it finds the sequence.
- Methylation enzyme: recognizes the same specific sequence as the endonuclease. It scans bacterial DNA and protects it from the endonuclease by methylating it (adds —CH3).
- Viral DNA is not methylated, so it can be cut by the endonuclease.
Dual of enzymes
1. Restriction endonuclease (nuclease cuts DNA or RNA)
a. Endo: cuts DNA and RNA from middle
b. Exo: cuts DNA from the ends
2. Methylation enzyme (protects DNA from restriction enzyme)
a. Adds methyl to DNA
Both these enzymes’ recognitions the same sequence - 20CRISPR systemBacteria have multiple defenses against bacteriophages (DNA editing)
CRISPR provides a specific defense against bacteriophages - 21Hypersentive ResponseWhen damaged by pathogen PLANTS undergo HR response
• Stomata close, keeping out pathogens.
• Toxins targeting the pathogen are produced in specific location.
• Cell walls are reinforced to prevent pathogen movement.
Cells in the infected area rapidly die by programmed death to “starve” the pathogen - 22Systemic Acquired ResponseHormones released during the HR trigger a slower response called the systemic acquired resistance. (SAR)
SAR is initiated by methyl-salycilate (MeSA) (high alert)
• MeSA is derived from salicylic acid (same compound found in aspirin).
• MeSA acts locally (where it is produced at site) and globally (throughout the entire plant).
• MeSA is transported to other parts of the planet through the phloem.
• MeSA stimulated the expression of at least 15 genes known as the pathogenesis-related genes (PR genes). - 23Secondary MetabolitesMany plants employ chemical defenses
•Plant tissues are often protected by secondary metabolites: organic molecules produced by plants but not involved in normal metabolic activities
•Secondary metabolites are investigated for possible drug development.
•Examples of secondary metabolites include aspirin, taxol, caffeine, nicotine, morphine, codeine, cocaine
oCaffeine and nicotine are alkaloids that disrupt the nervous systems of plant-eating insects and vertebrates.
oFlavorful oils in peppermint and lemon repel insects.
oPitch oozing from pines and firs contains toxins.
oTannins bind to digestive enzymes and sicken herbivores from oak.
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- Biology FlashCards sobre Bio 212 Final Defense , criado por Meranda Clark em 30-04-2022.
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- Meranda Clark · abr 2022
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- Criado por Meranda Clark · 30 abr 2022
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