AP Biology Chapter 19 Flashcards

Viruses

5726244394	Virus	-smaller and simpler than eukaryotes -technically nonliving b/c cannot reproduce/carry out metabolic activity outside host cell	0
5726244395	Capsid	-protein shell enclosing viral genome -built from capsomere protein subunits -usually have few types of proteins making up capsid	1
5726244396	Viral Envelopes	-membranous envelope surrounding capsids of many animal viruses -derived from membranes of host cells -contain host cell phospholipids and membrane proteins -contain viral proteins and glycoproteins	2
5726244397	Bacteriophage (Phage)	-viruses that infect bacteria -capsids w/ elongated icosahedral heads w/ DNA -protein tail piece w/ fibers by which phages attach to bacterium attached to head	3
5726244398	Host Range	limited variety of host cells each type of virus can affect	4
5726244399	Viral Reproduction	1. virus binds to host cell and enters uncoated, releasing viral DNA and capsid proteins 2. viral genome encodes proteins to have host reprogram cell to copy viral nucleic acid and replicate viral genome 3. meanwhile, host enzymes transcribe viral genome into viral mRNA, which host ribosomes use to make more capsid proteins 4. viral genomes and capsid proteins self-assemble into new virus particles, which exit cell to infect other cells and spread viral infection	5
5726244400	Lytic Cycle	-phage reproductive cycle that culminates in death of host cell 1. Attachment: page uses tail fibers to bind to specific receptor sites on surface bacteria 2. Entry of phage DNA and degradation of host DNA: sheath of tail contracts, injecting the phage DNA into cell and leaving empty capsid outside -> cells DNA hydrolyzed 3. Synthesis of viral genomes and proteins: phage DNA directs production of phage proteins and copies of phage genome w/ host enzymes 4. Assembly: 3 separate sets of proteins self-assemble to form phage heads, tails, and tail fibers; genome packaged in capsid as head forms 5. Release: phage directs production of enzyme that damages bacterial cell wall -> fluid enters -> cell swells and bursts, releasing 100-200 phage particles	6
5726244401	Virulent Phage	phage that reproduces only by lytic cycle	7
5726244402	Lysogenic Cycle	phage reproductive cycle w/ replication of phage genome w/o destroying host 1. phage DNA incorporated on site of bacterial chromosome -> prophage 2. bacterium reproduces normally, copying prophage and transmitting it to daughter cells 3. many cell divisions -> large population of infected bacteria	8
5726244403	Temperate Phage	phage capable of using both modes of reproduction in bacteria	9
5726244404	Prophage	phage DNA incorporated w/ bacterial DNA	10
5726244405	Reproductive Cycle of Lipid Enveloped RNA Virus	1. glycoproteins on viral envelope bind to specific receptor molecules on host cell, promoting viral entry into cell 2. capsid and viral genome enter cell-digestion of capsid by cellular enzymes releases viral genome 3. viral genome functions as template for synthesis of complementary RNA strands by viral envelope 4. new copies of viral genome RNA made using complementary RNA strands as templates 5. complementary RNA strands also function as mRNA, translated into capsid proteins (in cytosol) and glycoproteins for viral envelope (ER, Golgi) 6. vesicles transport envelope glycoproteins to plasma membrane 7. capsid assembles around each viral genome molecule 8. each new virus buds from cell, envelope studded w/ viral glycoproteins embedded in membrane derived from host cell	11
5726244406	Retrovirus (Class VI)	-RNA animal virus w/ most complex reproductive cycles -have reverse transcriptase enzyme	12
5726244407	Reverse Transcriptase	enzyme that transcribes RNA template to DNA	13
5726244408	HIV	-Human Immunodeficiency Virus -retrovirus causing AIDS	14
5726244409	AIDS	Acquired Immunodeficiency Syndrome	15
5726244410	HIV Reproductive Cycle	1. envelope glycoproteins enable virus to bind to specific receptors on certain white blood cells 2. virus fuses w/ cell's plasma membrane-capsid proteins removed, releasing viral proteins and RNA 3. reverse transcriptase catalyzes synthesis of DNA strand complementary to viral RNA 4. reverse transcriptase catalyzes synthesis of second DNA strand complementary to first 5. double stranded DNA incorporated as provirus -> permanent resident of cell 6. proviral genes transcribed into RNA molecules-serves as genomes for next viral generation and as mRNAs for translation into viral protein 7. viral proteins include capsid proteins, reverse transcriptase, and envelope glycoproteins 8. vesicles transport glycoproteins to cell's plasma membrane 9. capsids assemble around viral genomes and reverse transcriptase molecules 10. new viruses bud off host cells	16
5726244411	Vaccine	harmless variant of pathogen that stimulates immune system to mount defenses against harmful purposes	17
5726244412	Emerging Viruses	viruses that are new to medical scientists/suddenly appear b/c: 1. mutation of existing viruses -> new strains of disease -> epidemics 2. dissemination of viral disease from small, isolated human population-can be due to technological and social factors (radiation, travel, blood transfusion, sexual promiscuity, drugs, etc...) 3. spread of existing virus from other animals	18
5726244413	Epidemic	huge outbreak of disease	19
5726244414	Pandemic	global epidemic	20
5726244415	Viroid	-circular RNA molecules that infect plants -replicate in host plant cells using host enzymes instead of encoding proteins -cause errors in regulatory system that control plant growth -> stunted growth, abnormal development	21
5726244416	Prion	-infection proteins that cause many degenerative brain diseases of many animals -mostly transmitted w/ food-incubation 10+ years -virtually indestructible propagate by: -misfolded versions of normal brain proteins -contact w/ normal folded protein -> normal gets abnormal shape -chain rxn of misfolding -> cellular malfunction, brain degeneration	22