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Prokaryotic Life Characteristics Reproduction Evolution Structure A bacterium such as E. coli has the basic structure typical of most prokaryotes: cell wall, cell membrane, and cytoplasm. Some prokaryotes have flagella that they use for movement. The pili are involved in cell-to-cell contact. The cell walls of eubacteria contain peptidoglycan. Characteristics Small – Few micrometers in length Unicellular No nucleus No membrane bound organelles May have flagella for movement Characteristics Energy- How do bacteria acquire energy? Prokaryotes can be autotrophs or heterotrophs -Autotrophs: -Self producers, by sunlight or organic chemicals -Chemoautotrophs -Photoautotrophs -Heterotrophs: - Consumes energy from other organisms Bacterial Reproduction Binary Fission - Parent cell splits into two identical daughter cells Conjugation - Sharing genetic information - Results in genetic variation Binary Fission Video Video Did you know? Fun Facts • There are 10 times more bacterial cells living on and in you, than your own body cells. • You have more bacterial DNA than human DNA on you. • All the bacteria living in/on you weighs about the same as a human brain. Binary Fission-Asexual Reproduction What must happen first before the cell can divide? -Conjugation (sexual) : swapping genes over a bridge between two bacteria Think: Which of these two types of reproduction is more beneficial and why? Do they both have advantages? Think Question Cell Enlargement Vs. Cell Division What’s the Difference? Prokaryotic Cell Cycle G1- Gap 1 Phase Growth S- Synthesis of DNA (DNA Replication) G2- Gap 2 Phase The bacterial cell prepares to divide Evolution Prokaryote success depends on various selective pressures Like other organisms, if prokaryotes can survive their environment they will then survive and reproduce Obstacles that bacteria have to overcome: – Temperature – Food – Chemical balance – Antibiotics – Antimicrobials Evolutionary Success Rapid reproduction time – Successfully passing on genetic information from parents to offspring Diversity - FOUND EVERYWHERE - Air, soil, water, on plants, animals, and humans! Examples of Bacterial Evolution: Bacterial resistance to antibiotics - As bacteria evolves, medicine also needs to evolve in order to effectively treat the bacterial infections - Mrsa – Methicillin-resistant Staphylococcus aureus (MRSA) infection is caused by a strain of staph bacteria that's become resistant to the antibiotics commonly used to treat ordinary staph infections. – Most MRSA infections occur in people who've been in hospitals or other health care settings, such as nursing homes and dialysis centers Example of Bacteria Evolution Resistance to antimicrobials (hand sanitizer) - Formulas constantly change to keep up with bacteria evolution - Knocks out the weak bacteria - Strong bacteria survive, and these go on to reproduce Evolution of antibiotic resistant bacteria Bacteria can share genetic content. This is why bacteria are so successful: the sharing of advantageous traits may enable evolving species to become even more successful. Successful Evolution • Bacteria can reproduce very rapidly! – E. coli can reproduce in just 20 minutes! • Environments exert natural selection on populations causing them to change. Evolution of Prokaryotes • http://ed.ted.com/lessons/how-antibioticsbecome-resistant-over-time-kevin-wu Evolution of Prokaryotes • http://ed.ted.com/lessons/how-antibioticsbecome-resistant-over-time-kevin-wu