Biology 1202 Test 2 Microbes a cell so small that it can t be seen with the naked eye too small to be seen clearly without a microscope Prokaryotes range in size from 0 2 1 0 micrometers um a micrometer is to 1 1 000 000 of a meter the period at the end of a sentence is about 1000 um Unicellular eukaryotes range in size from 10 100 micrometers um Some prokaryotes are larger than the smaller eukaryotes but most of the time eukaryotes are bigger than prokaryotes Eukarya eukaryotes Bacteria and archaea prokaryotes Viruses are neither prokaryotes nor eukaryotes because they are non living things Order from smallest to largest viruses prokaryotes eukaryotes Other biological entities NOT considered organisms because they don t have all the characteristics of living organisms can t take in substances and excrete can t take in oxygen or carbon dioxide Viruses small 05 0 2 um and come in many different shapes 3 parts of a virus genome protein component membrane o 1 Genome genetic information can be either single stranded or double stranded DNA or RNA o 2 Capsid protein coat which surrounds and protects the genome all viruses need at least the genome and capsid to be considered a virus but some also contain an envelope o 3 Envelope membrane phospholipid bilayer which surrounds the capsid All viruses need to hijack cells to survive o highly specific for the organism it infects Types of viral genomes o ssRNA HIV o ssRNA influenza virus o dsDNA varicella zoster virus chicken pox shingles o current virus measles Bacterial virus steps host exit host o virus must find host bind to host enter host take over host replicate Three lines of defense against microbial attack 1 Nonspecific external barriers innate defenses if barriers are penetrated The Immune System the body responds with nonspecific external barriers o 1 External barriers skin mucous membranes A skin a physical barrier to microbial cells inhospitable environment for growth dry dead cells at surface Sweat sebaceous glands secreting acids and natural antibiotics like lactic acid B Mucous membranes of respiratory and digestive tracts well defined Secretions have antibacterial enzymes dirt caught in mucous moved by cilia C Stomach if microbes swallowed acids and protein digesting enzymes destroy them 2 nonspecific internal defenses innate defenses if nonspecific external defenses are insufficient the body responds with nonspecific internal defenses o A phagocytic cells white blood cells WBC in extracellular fluid amoeboid shape destroy microbes by phagocytosis Helps clean up areas of injury these cells specifically recognize these bad bacteria germs as its target and eats the bacteria through phagocytosis Targets things that are in the wound site that shouldn t be there Cleans up the wound site by identifying things Recognizes the bacteria internalizes the bacteria into its cell body and then destroys it acts like a janitor Attacks things that are not yet part of your cell yet o B natural killer cells WBC that destroys body cells infected by viruses and cancerous cells by punching HOLES in them Recognizes cells if there s something wrong with them If they have a virus within them or if they re cancerous cells How can you increase the rate of mutogenesis in your cells go out and get sunburned over and over again the longer you live the more likely you are to die of cancer Identifies viruses by proteins that are sticking out of the outside of the virus o C inflammatory response caused by large scale microbial invasion through wound Histamine released in response to damaged cells Histamine increased blood flow washes out wound Histamine increased blood flow inflammation red swollen Other chemicals attract phagocytes WBC engulf bacteria dirt tissue debris Blood clotting walls off wounded area Pus is just WBC dying Steps in which the inflammatory process takes place 1 Tissue damage carries bacteria into wound 2 Tissue is damaged 3 Wounded cells release chemicals that stimulate mast cells 4 mast cells to make store and release histamine 5 histamine increases capillary blood flow and permeability 6 Phagocytes leave capillaries and ingest bacteria and dead cells o D Fever response to microbes establishing major infection Low grade 100 102 F fevers beneficial o Stimulates immune response which coincides with iron complex in your blood o Most fevers at our age is good for you because its beneficial 1 slows down microbial reproduction 2 enhances immune system 3 Specific immune response acquired immunity reaction to specific type of microbe and provides future protection Involves 2 types of WBC called lymphocytes o B cells grow and mature in bone marrow from pre existing cells o T cells start in bone marrow but finish maturing in thymus o Humoral immunity targets invaders outside cells viruses bacteria fungi toxins by releasing cytokines o Helper T cells stimulates both humoral and cell mediated immunity o Cell mediated immunity targets defective body cells infected cells cancer cells transplants o B cells and T cells o Step 1 recognize the invader 1 Antibodies protein produced by a host to bind to and inactivate foreign particles act like door bell on your B cells that leads to the cell dividing over and over again made by B cells o unique binding site so can only bind to one antigen antibody and generating foreign intruder o binding of antigen to antibody shapes the shape of the cell and triggers the immune response o genes for antibody parts recombine during development taking parts of the gene to make particular sequence of amino acids result in a random assortment of antibodies o 20 000 genes in the human genome o not always one gene one protein a lot of genes can recombine during development such that some can be re modified to make more genes o when B cells bind to you in your body it gives the body a chance to get rid of them o B cells do not recognize self when matured immune system only recognizes non self do not want your immune system to recognize you otherwise they will destroy you o some will bind to body s own proteins immune system distinguishes self from non self by retaining only those immune cells that do not respond to the body s own molecules o body randomly makes 100 000 000 different antibodies what makes them different variable regions amino acid sequences are different can bind to different kinds of antigens depending of different kinds of amino acids that are present each different one binds to its own unique antigen up to
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