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micro test 3
| Question | Answer |
|---|---|
| Basic structure of DNA | DNA is a double stranded helical structure omposed of nucleotides. ea nucleotide is a POSPHATE (which form the backbone) SUGAR(deoxyribose) & a nucleotide base. Has 2 strands |
| The 2 srands of DNA are _________and __________. and are held together by __________. | Complementry(C,G & A,T) Antiparallet (5-3 &3-5) they are directional. Held together by hydrogen bonds. |
| DNA has 2 types of bases which are? | Purines- A&G aka neucliotide bases (larger double-ring stuctures) PYRIMIDINES- T&C (neucliotide bases) smaller, single ring stucture. |
| Describe the basic structure of RNA | contains SUGAR RIBOSE (rather than deoxyribose) Contains Uracil instead of Thymine (U,T) Found in single stranded form |
| What are the 3 forms of RNA | mRNA-messenger RNA-carries info(ex blue eyes) most important tRNA-transfer RNA- carries amino acids to ribosomes rRNA-Ribosomal RNA-runs translation |
| What is DNA replication | A process in which DNA is copied |
| What is the process of DNA replication | Supercoiling: a characteristic of helical structures. must do this in order to get into cell. This is accomplished by 2 enzymes |
| Supercoiling is accomplished by what 2 enzymes? | Topoisomerase-unwinds the supercoils Helicase:seperates & unwinds strands |
| What are the 2 requirements for Replication? | Ample supply of neucleotides (A,T,C,G) A primer (template junction) A portion of DNA is paired w/a short piece of RNA called a primer--creating a mirror image) |
| DNA REPLICATION is performed by an enzyme called? | DNA POLYMERASE |
| What is DNA polymerase? | forms new strands of DNA using primer, temlate junctions as a guide DNA polymerase moves along the template strand in the 3-5 direction to create a new DNA strand in the 5-3 direction |
| What is proofreading? | During DNA polymerase mistakes can be made (mutations) it takes place at the primer (ex g mistakenly pairs w/ a T) |
| How are mutations removed | by exonuclease |
| Where does DNA replication start? | ORT- origin of replication. Replication is BIDIRECTIONAL |
| What is bidirectional | two replication forks move continuously around the chromosome. |
| What are CODONS? | Genetic code for amino acids which form proteins. |
| DEGENERATE(redundant) | when some codons code for the same amino acid |
| GENE | a segment of DNA that codes for a functional product (ex. protein) |
| What are the two features of a GENE | DNA & RNA and highly regulated |
| Transcription | the process by whech RNA is made from a DNA template |
| What are the 3 stages of translation? | Initiation-promoter(start) Termination-Stop sequence Elongation-RNA polymerase unwinds strands of DNA & synthesizes the RNA |
| with the parental strand what is the name of the daugher strand? | omplementary strand |
| Translation | The process by which proteins are made mRNA sends a message ORF-begins w/a start codon AUG an ORF ends w/ a stop codon UAA,UAG or UGA |
| Translation tRNA | attaches a specific amino acid at the acceptor arm, brings the ribosome to the anti-codon region |
| tRNa anti-codon base pairs with the? | mRNA codon Anti-codon bonds to the codon |
| rRNA makes up the globulare structure of? | Ribosome |
| What is polyribosome or polysome | more than one ribosome can move along th same messenger RNA |
| Where do peptide bonds form? | between amino acids while on the ribosome |
| What are the 3 sites of the Ribosome? | A site: tRNA brigs in new amino acid P site: tRNA holds the growing amino acid chain E site: tRNA exits the ribosome |
| Mutaions? | changes in DNA sequence Point or missense mutations Frameshift mutation |
| Point or Missense Mutaions means? | Nucleotide base change causes codon to code for wrong amino acid Point(normal mother) Missense(mutated mother-->mutated daughter) |
| What are Frameshift mutations? | Insertion of deletion of nucleotide base causes all following codons to shift their reading frame (lost likely will die) |
| How can DNA be damaged? | Esposure to chemicals (mutagens) |
| What are base analogs? | compounds w/ similar structure to A,C,G,T or U |
| What is genetic recombination? | Bacteria that can shuffle genes |
| What are the 4 ways genetic recombination can occur? | Transposition: w/in the same cell (jumping genes) Transformation: between cells (involves "naked" DNA Conjugation: between cells (occurs thru pilus) Transduction: between cells (uses bacterial virus phage) |
| Genes for resistance to disinfectants and enviornmental pressure are found on? | dissimilation plasmids |
| Where does DNA replication occur? | The Replication Fork |
| In the Replication Fork the double helix is________ and ___________. | unwound (topoisomerase) seperated(Helicase) |
| In the Replication Fork the seperated strands are ____________ and are identified as __________ and _____________. | antiparallel and are identified as Leading strand and Lagging strand. |
| Leading strand | Replication moves toward replication fork |
| Lagging strand | moves away from replication fork |
| Okazaki Fragments | Lagging strand is replicated in pieces. Has its own short RNA primer. |
| Primase | Okazaki fragment created by an RNA polymerase |
| The Okazaki Fragent in filled in by the? | DNA polymerase |
| Okazaki fragments are linked together by? | DNA ligase |
| VIRUSE | obligate intracellular parasites. viruses infect bacteria ( bacteriophage or phage) |
| VIRION | an intact viral particle |
| Capsid | viral nucleic acid is surrounded by a protein called a capsid |
| capsid is made up of | capsomeres |
| besides capsids and capsomers a virus can also be surrounded by an? | Envelope |
| What type of nucleic acid can viruses contain? | RNA & DNA |
| What are RNA and DNA surrounded by? | capsomers and some are surrounded by envelopes |
| What is the VIRAL LYTIC CYCLE? | Attachment--->Penetration--->Uncoating--->Biosynthesis--->Maturation--->Release |
| What does the Viral Lytic cycle do? | produces the max # of virions. The result is cell death |
| Viral Lysogenic cycle | (ex. HIV goes doormant) known as the latent iinfection. Incorporates into hossts DNA. Host cell lives and continues to replicate along w/ viral genomes |
| A virus find its host cell thru? | randon collision |
| Lytic infections produce the max # of? | Virions |
| Host Range | are the cells abe to be infected |
| An envelope virus can fuse w/ the? | host cell membrane |
| Regarding the Envelope Virus the binding will take place where? | between viral envelope proteins and receptors |
| Define Accute Viral infection | rapid and self limiting |
| Define Persistand Viral infection | long term |
| Define latent viral infection | extreme versions of persistant infection |
| Define slow or transforming viral infections | complicated types of persistant infections |
| What is Cytopathology? | Cytopathic viruses that produce virions and kill host cells rapidly and produce max # of virions |
| What occurs during the incubation period of a viral infection? | some are short as days virus is replicating the host is beginning to respond |
| ex. of Accute viral ingecton | commond cold- assciated w/epidemics because of the short incubation period |
| Antigenic Variation(Acute infection) | Hosts that survive acute infections are immune for life(chicken pox) |
| Why do we not have a vaccine for the common cold? | Virions changing thier sturcture constantly |
| Antigenic drift involves what and results in what? | Involves smallchanges in virion structure and results from mutation |
| Antigenic shift involves what and is due to what? | involve major changes in virion structure and is due to the acquisition of new genes |
| General characteristics of a persistent latent infection? | no large scale production of virions-Reduced of no immune response-persistence of an intact viral genome so infections can reoccure as a provirus or extrachromosomal element |
| chronic | over and over |
| latent | viruses can be reactivated yrs after entry into host (ex shingles) |
| Cytotoxic T cells (CTL's) | are signaled by the immune systim to kill virally infected cells |
| Some viruses kill the ____ first allowing the virus to persist in the body longer | CTL's |
| 3 basic requirements for a viral infection | sufficient # of viruses present Access to susceptible & permissive host cells An ineffective hose immune response |
| 3 mian portals of entry for a virus | Respiratory(most common) Digestive Urogenital Tract |
| How can viruses enter thru the skin barrier? | usually by vector transmission or other animal bites |
| Viral transmission refers to? | the spread of the virus from one host to another |
| There are 2 patterns of viral transmission | human to human animal to human |
| Viruses can be transmitted via? | fomites, poor technique by health care workers, fecal-oral route |
| Viruria | transmission via urine |
| Virulence | the capacity of an infectoious organism to cause disease |
| attenuated | nonvirulent-----viruses cause little or no disease |
| 3 ways to measure viral virulence | LD50 how much virus is required to kill 50% of a subject population ID50- infect 50% PD50-Paralyze 50% |
| What are the 2 types of host? | susceptible- can infect and also transmil infection Immune-cannot be infected |
| What are the 2 vaccine developments? | Active immunization(antigen is administered and causes the onset of the immune response) Passive immunization(a performed antiviral product, such as antibody, is administered) |
| Oncogenic Viruses | are viruses and cancer ( can cause cancer in animals) |
| Protozoa | microscopic, single-celled eukaryotes |
| Helminths | macroscopes, multicelular worms |
| What is the basic characteristic of a Helmith? | bilateraly symmetrical, various lengths. covered by touch cuticle have suckers hooks, plates for attachment) |
| Protozoans(cysts) | facultative anerobes, heerotrophs, sexual and asexual |
| Multiple hosts can be divided into | difinitive(where sexual reproduction occurs) intermedidate(where asexual reproduction occures |
| Protozoan parasite | Sporozoans: intracellular parasite altenate sexual & asexual reproduction --causes malaria |
| Malaria (plasmodium) is transmitted by? | Mosquito bite |
| Malaria cycle? | sexual life cycle beins w/ bite (blood) male fertilizes female inside mosquito gut it forms an oocyst filled w/sporozites into mosquito body Sporozites penetrates mosquito salivary glands |
| Sporozites move to the________ and____________ reproduce to form____________, which infect & destroy red blood cells | liver asexually Merozites(infect and dstroy RBC) |
| Symptoms of Malaria | fever, shivering, anemia, dark urine, enlarged spleen, elusions, death |
| What is Malarial proxysm | cycling of symptoms ~successful treatment requires destruction of al the parasites in all its forms....based on some form of quinine(GIN) |
| Toxoplasmosis | is an obligate intracellular parasite (ex house cats) |
| When discussing toxoplasmosis who is the definitive host and who is the intemediate host | house cats and humans |
| Amebiasis( Entamoeba histolytica) | obligate intracellular parasite. passed from host to host as cysts uses fecal oral route live in the colon where they feed on the bacteria multiplying and defecating out during diarrhea. which for cysts during defecation. |
| Amebiasis can survive | envirnmental pressures (temp,chlorine) |
| Intestinal Nematodes | Pinworms- small asymptomatic infections cycle takes about 2 wks |
| Tissue Nematodes | can induce disease in tissue, blood, lymph system. and can live for yrs in subcutaneous tissues and lymph vessels ~caused by parasites |
| Explain Enterobiasis | Pinworms.A ubiqutous parasite of humans most infections are in children (daycares) They attach to lg intestines. females migrate down to perianal itssie o lay eggs. Eggs stick to towels, bedding, inhaled or swallowed. hatch in upper intestine and cycle b |
| Trichinosis | from eating undercooked meat worms mature 24-48 hrs after ingestion Larval invasion starts 1 wk later Lasts 1-6 wks |
| Cestodes | (tapeworms) are hermaphroditic can ve make or female can ve acquired from eating undercooked meat (cow eats feces) |
| Define innate immunity | nonspecific. immediatly available, w/out memory |
| define adaptive | specific. takes several to develop, has memory. |
| what activates your innate immunity | responses are triggered by damage to cell or tissue |
| what activates your adaptive immune response | memory- adaptive immune response remembers any "specific" pathogens & respond quickly & powerfully |
| Why is your skin such an effective barrier to pathogen entry? | ~the skin is covered w/normal microbial flora ~entry requires break in skiin |
| How does mucus act as a barrier to pathogen entry? | mucus traps microorganisms |
| What is the mucociliary escalator? | Moves the mucus (which traps microorganisms) up the oral cavity where it can be swallowed or expectorated |
| How does the lachrymal apparatus protect the eye from pathogen entry? | it causes tears fo fluch across the eye |
| what does saliva contain that is inhibitory towards microbial growth? | Lysozyme(an enzyme that breaks down bacterial cell walls) IgA-(an immunoglobulin that participates in your adaptive immune response |
| What is sebum and how does it protect agains pathogens? | Sebum- forms a protective layer on th skin. it makes skin SLIGHTLY ACIDIC which inhibits microbal growth |
| How does persperation protect agains pathogens? | ~fluches them from the skin ~contains lysozyme (an enzyme that breaks down bacterial cell walls) |
| How does gastric juice protect agianst pathogens? | The harsh chemical enviornment limits microbial growth |
| How does urine protect against pathogen entry? | ~its acidic ~its fluching action prevents attachment |
| Define Antigen | any substance that triggers an immune response |
| What are toll-like receptors and what is their function? | ~molecules located o the surface of cells that defend the body ~These receptors bind to antigens found on pathogens |
| Why does a patient's complete blood count tell youabout possible infection | the number correlates with the stage of infection |
| What is the basic function of neutrophils | They "sense" that an infection has occured and migrate to the area of infection (chemotaxis) to destrop invading infectios organisms |
| What is the basic function of basophils(a type of WBC) | They carry recetors or IgE upon binding to IgE, they release histamine as part of the inflammatory responce |
| What is the basic function of eosinophils? | Normally small numbers circulate in the blood but increase in cases of parasitic infection Primary defense to parasitic infection (produce powerful enzymes that attack parasites |
| What is the basic function of monocytes and what do they differentiate into? | ~are guided to the site of tissure damage ~Differentiate into powerful phageocytic macrophages at site of infection |
| What are the 3 types of macrophages? | ~those derived from macrophages ~wandering macrophages (move throughout the body) ~Resident (fixed) macrophages (stay in specific loctions ex. kidney, spleen, joints, lungs) |
| What is the basic function of the cytokines and chemokines? | Cytokines-regulate inflammatory & immune response Chemokines-promotes migration of monocytes, lymphocytes and neutrophils to area of infection |
| Define diapedesis | migration from blood to tissue |
| What is the basic function of mast cells, dendritic cells and natural killer cells? | Mast-responsible for allergic responses & parasitic infection (WBC that releases histamine(cytokins) during an allergic reaction Dendritic-regulate both the innate & adaptive immune response NKC-Destroy virus infec.cells bacter.,fungi,parasites |
| What is perforin? | An enzyme released by cytotoxic cells that lead to the destruction of target cells (destroys cell walls so pathogens die) |
| Define chemotaxis | (moves toward invader) A non random movvement of an organism toward or away from a chemical |
| What are the 5 steps of phagocytosis? | 1. chemotaxis 2. Adherence 3. Ingestion 4. Digeston 5. Excretion |
| Define pseudopodia | encelope the cell |
| Define phagosome | a vessicle that forms around the pathogen |
| Define phagolysosome | Phagosome that fuses w/ a lysosome |
| Define inflammation | the normal physiological response to trauma which helps destroy pathogens. Also involved in itssue repair and replacement |
| What are the symptoms of inflammation | Redness, pain, heat, swelling |
| Define vasodilation | key to inflammation. involves local reaction (swelling, pain) delivers clotting elements |
| What are some benefits of blood clotting in agents in terms of contolling an infection | walls of the affected are & can prevent the spread of infection |
| Define fever | a systemic rise in body temp |
| What chemicals trigger fever | caused by pyrogens Exogenous(bacterial toxins produced by bacteria) Endogenous(produced by host) |
| Why is fever beneficial? | it speeds host defenses, inhibits growth of pathogens, denatures bacterial protein toxins. Drains energy & forces patient to rest |
| What does the complement system consist of? | about 30 serum proteins (produced in liver) |
| What is the final result of the complement system? | Membrane Attack Complex (MAC) |
| What activates the classical complement pathway? | anibody-antigen complex |
| What activates the alternative complement pathway? | Factor B, Factor D, Factor P |
| What activates the lectin-binding complement pathway? | carbohydrate mannose(not in humans & found on the surface of certain bacterial pathogens and parasites |
| Define opsonization | The process by which microorganisms are rendered more attracctive to phagocytes by being coated w/ antibodies & or C3b |
| Define membrane attack complex | C5-C9 (drills holes in pathogen cell wall |
| What is the function of interferon? | moves to uninfected neighboring cells causes them to produce antiviral proteins makes uninfected cells resistant to infection |
| Define Virus? | obligate intracellular parasites (can't live outside a cellular host) |
| Define bacteriophage(phage) | bacteria that can be infected by viruses |
| Define productive infection | an infection where the virus can replicate itself |
| Define Virion | an intact viral particle |
| Define capsid | a protein coat that surrounds a viral nucleic acid |
| Define capsomere | ea. capsid is made up of capsomeres |
| Define envelope | some viruses can also be further surronded by an envelope |
| What type of nucleic acid can viruses contain? | DNA or RNA (single & double strand) |
| Explain viral lytic cycle | 1. Attachment 2. Penetration 3. Uncoating 4.Biosynthesis 5. Maturation 6. Release The final outcome is that the host cell flls w/ virions & bursts (cell dies) |
| Explain viral lysogenic cycle (latent infection) | A viral genome is inserted into a host chromosome & is now referred to as the provirus. The "hidden virus" replicates along w/ the host cell chromosome. At some later time, the provirus can leave the host cell chromosome & initiate lytic infection. |
| Define provirus | the product of a viral genome being inserted into a host chromosome |
| Define latent | anothe term for lysognic |
| How does a virus find its host cell? | thru randon collision (lytic infections produce the max. number of virions to increase adds of finding a host |
| Define host range | refers to the range in which the virus can infect a host (helps the virus to know which host it is able to reside in) Virus recognizes host cell molecules which can be used as viral receptors to determine HOST RANGE of the virus |
| Receptor mediated edocytosis | virus viral capsid (non-enveloped virus) bond with the receptors of a host cell. then is broght into the host cell surronded by a host membrane called the ENDOSOME |
| How does an envelope virus enter its host cell? | The viral envelope is essentially a plasma membrane that can fuse w/ the host cell membrane & release viral genomes into host cell |
| How does a double stranded DNA Virus go thru transcription & translation in order to produce the proteins need to synthesize more viruses? | One strand of viral DNA is transcribed into mRNA, mRNA codes for new viral components (capsomer proteins). The viral genome has the same configuration as host DNA so recplication is easy. Viral replication is performed by the host cell machinery |
| How does a single standed DNA go through replication, transcription & translation? | The viral strand is used as a template to make a complementary copy of DNA. This uses the host cells DNA polymerase & the copy is transcribed into mRNA & also used to make new copies of the viral genome |
| How does a provirus replicate itself? | once the viral genome is inserted into a host chromosome (the provirus), the hidden provirus replicates along w/ the host cell chromosome. |
| What is an RNA dependent polymerase & where does it come from? | RNA dependent polymerease are required to make viral mRNA & replicate genomes. Viruses must carry their own. |
| How is a double stranded RNA virus genome replicated, Transcribed & translated | Replication & Transcription are bases on complementary base pairing & the use of templates. Genomes contain one (+) strand & one (-) strand. Durind infection the (-) strand is copied into mRNA by RNA polymerase. Each is used to make new double stand geno |
| Retrovirus & Reverse transcription | Retroviruses are RNA viruses that cotain the enzyme REVERSE TRANSCRIPTION, which converts RNA to DNA. RETROVIRUSES cause latent infections (ex. HIV) |
| Intracellular trafficking | 1st step to maturation. Some viral components are synthesized in the cytoplasm & some in the nucleus. Transported thru the cell by hose cell microtubules to the assembly sites. Viral proteins travel from assembly site to cell membrane in vesicles. |
| What part of a virus go into the final assembly of a new virus? | non-enveloped viruses- formation of subunits for capsid, assembly of capsid & associatiion of viral genome w/ion capsid Enveloped viruses |
| Envelope viruses include? | all of the same as the non-enveloped with addition to the assembly of a viral envelope |
| What is the difference between concerted assembly & sequential assembly? | in concerted assembly, the virion is assembled while the viral genome is being symthesized in sequential assembly, the viral genome is insereted into already assembled capsid |
| How are the new viruses released from their host? | non-envelope viruses use LYSIS(causes cell death) envelope viruses use budding, which allows host cell to live for a while |
| What is an efficient way for viruses to spread from host to host while avoiding detection by the immune system? | Some use tight junctions, some form syncytia (coming together in masses) and some produce decoy virions (empty capsids or non-infectious virions) to confuse & distract host defenses. some viruses incorporate host proteins as a type of camouflage |
| What is the basic life cycle of a trematode? | live for decades in human tissue & blood vessecles ~eggs are excreted from human host ( needs H2O to hatch)~Hatching releases larvae called Miracidia(penetrate snails(intermediate host)~Miracidia develop into cercariae(tails)burrow into human skin or plan |
| Define Mycology | study of fungi---diseases caused by fingi are called mycoses |
| Define Mycoses | Fungal infections on outer skin or hair (superficial mycoses) |
| What are the basic characteristics of fungi? | eukaryotes,heterotrophs, grow in mold or yeast but some are DIMORPHIC and grow in both |
| Mold and yeast are 2 forms of what? | fungal infections |
| Define cutaneous/mucocutaneous mycoses | Associated w/ skin, eyes, sinuses, ears, vagina any opening of the body |
| What is meant by superficial mycoses | skin or hair |
| Example of Keratitis | ringworms |
| What is Subcuaneous Mycosis | Locolized primary infection penetration wound Rare disease |
| Deep mycosis | usually seen in immunocompromised patients acquired by deep inhalation of fungi use of contaminated medical equipment |
| what is histoplasmosis | caver's disease |
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