Bacteria was discovered in the 1600’s by - Anton van Leeuwenhoek (Lay vun hook) - Dutch merchant,...
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Transcript of Bacteria was discovered in the 1600’s by - Anton van Leeuwenhoek (Lay vun hook) - Dutch merchant,...
CH 9, SEC 2 BACTERIABacteria was discovered in the 1600’s by
- Anton van Leeuwenhoek (Lay vun hook) - Dutch merchant, made microscopes as hobby- looked at teeth scrapings one day, noted wormlike organisms (not able to see details of organisms due to microscope not strong enough)
Bacteria- single celled organisms
Cell Structure- prokaryotes- genetic material inside cytoplasm, no nucleus- most have rigid cell wall, like plant cell, with cell membrane inside - Flagellum
- long, whiplike structure to help cell move (like a propeller)
- not all bacteria have flagella (moved by air, water, objects)
- some have many flagella
Cell Sizes & Shape- bacteria come in many different sizes- strep throat bacterium are from 0.5 – 1 micrometer in diameter- Basic shapes of bacteria
- spherical, rodlike, or spiral- determined by chemical makeup
Food & Energy - bacteria live in different environments (hot vs cold adaptability) - *All bacteria must have food and ability to break down food for energy
- Obtaining Food- some bacteria: autotrophs, make own
food by capturing sun light or from chemical substances
- some bacteria: heterotrophs, consume other organisms or food from other
organisms (consume milk, meat, decaying leaves) - Respiration
- bacteria need energy- most need oxygen to break down food into energy (respiration)- Escherichia coli living in intestines do
not need oxygen for respiration
Reproduction- *when bacteria have enough food, right temperature, & suitable conditions, they thrive and reproduce frequently - Under ideal conditions, some bacteria can reproduce every 20 minutes- Asexual Reproduction
- reproductive process that involves only one parent & produces offspring identical to parent
- binary fission: cell duplicates genetic material, then divides into 2 separate cells
- Sexual Reproduction- two parents combine genetic
material to produce new organism, which differs from parents
- Conjugation - one bacterium transfers some
genetic material to another bacterium
through a threadlike bridge; after
transfer, cells separate - results in bacteria with new
combinations of genetic material
- Endospore Formation- when conditions are no longer favorable for bacteria to grow, some survive by forming
endospores - Endospore - small, rounded, thick-walled, resting cell
that forms inside a bacterial cell - Endospores can survive without nutrients - They are resistant to ultraviolet radiation, desiccation, high temperature, extreme freezing and chemical disinfectants-Common anti-bacterial agents that work by destroying vegetative cell walls don't work on endospores- commonly found in soil and water, where they may survive for long periods of time
- Endospores can survive for many years- Clostridium botulinum (bacteria that
causes botulism) produce heat-resistant endospores that can survive in improperly canned food
- because they’re light, a breeze can carry them to new places; if suitable conditions, opens up & bacterium grow & multiply
Not all bacteria are harmful- *Bacteria are involved in oxygen & food production, environmental recycling & cleanup, and in health maintenance & medicine production
- Oxygen Production- autotrophic bacteria produce oxygen,
scientists think autotrophic bacteria were responsible for first adding oxygen to Earth’s atmosphere billions of years ago
- distant offspring of the bacteria help keep oxygen levels in the air stable - Food Production
- cheese, sauerkraut, pickles (from bacteria)
- some bacteria causes food to spoil; heating & refrigerating slow down food spoilage
- Pasteurization - heating food to a temperature high enough to kill most harmful bacteria without changing taste of food - named after inventor: Louis Pasteur
Decomposers- organisms that break down large chemicals in dead organisms into small chemicals- nature’s recyclers- decomposing bacteria break down chemicals in dead leaves- nitrogen-fixing bacteria live in soil & certain root plants; convert nitrogen gas from air into nitrogen products plants need for growth
- Environmental Cleanup- some bacteria convert poisonous
chemicals in oil into harmless substances - Health & Medicine
- bacteria in intestines help with digestion of food
- compete with harmful bacteria for space & prevent them from attaching to intestines
- 1970; first medicine-producing bacteria made. Human insulin made by manipulating bacteria’s genetic material