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Cards In This Set
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Describe the genetic material, cell division and metabolism of pro. and euk. cells.
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Prokaryotic
G.M: circular DNA, not membrance bound - singular chromosome in genome C.D: not by mitosis or meiosis Metabolism: anaerobic (do not need 02 for cellular respiration) Eukaryotic G.M: membrane-bound - several chromosomes C.D: mitosis and meiosis Metabolism: most are aerobic (need O2) |
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List some characteristics of viruses.
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- a container (capsid) of nucleic acid
- has DNA to copy itself but cannot live independently outside of cells (therefore, must live off a cell) - it is not cellular (no organelles) - cause disease = food shortages, illnesses |
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Why are viruses not considered alive? Why might they be?
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- not alive because:
1. not cellular 2. too different from cells - alive because: 1. have genetic material 2. reproduce |
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How do scientists classify viruses?
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- by size and shape of capsid
Ex. T4 virus has a head and tail HIV virus has spherical shape - by types of diseases they cause |
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Bacterialphage
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Virus that affects bacteria
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Explain the reproduction of viruses.
a. The lytic cycle |
Lytic Cycle
1. Attachment (by protein receptors) 2. Entry and Injection (of DNA into host cell) 3. Provirus Formation (DNA becomes part of h.c. chromosome) 4. Replication (host cell makes viral parts) 5. Assembly (viral parts are put together) 6. Release (host cell breaks open) |
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B. The lysogenic cycle
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After provirus formation stage of lytic cycle, cell divides by mitosis with viral DNA.
-provirus leaves host's chromosome - starts replicating - provirus/lysogenic cycle can be activated any time |
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Provirus
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Host chromosome combined with viral DNA
- can be activated by temperature, stress etc. |
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What is a retrovirus?
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an RNA virus that inserts its DNA into a host cell to duplicate
- usually, DNA sends message via mRNA which goes out into cytoplasm and tells organelles to make certain proteins - a retrovirus contains enzyme called reverse transcriptase (does opposite) Ex. HIV |
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Prion
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- a disease-causing agent, only one without RNA or DNA
- infectious particle that damages brain cells - can recuit other other cells - proteins normally found in body but become diseases when they convert to harmful particles Ex. mad cow disease, scrapie in sheep |
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How do researchers use viruses to copy genes?
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- they insert gene into virus
- virus enters host cell and makes it copy itself - each new virus now has that gene |
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What are the different forms of bacteria and archaea?
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1. Cocci (spherical)
2. Bacilli (rod-shaped) 3. Vibrios (comma-shaped) 4. Spirilla (helical-shaped, shorter) and Spirochetes (helical-shaped, longer) |
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Aggregrations
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Unicellular bacteriua and archaea group together in chains, spheres, etc.
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Methanogenesis
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process in which CH4 is produced by archaea
- arc. are anaerobic (don't need O2), can survive in cow guts - happens during final stages of decomposition |
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Photosynthetic bacteria
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cyanobacteria
- account for most of atmospheric O2 - sun + CO2 + water = sugar + oxygen |
