20 Viruses and Prokaryotes Bacteria

Transcription

1 20 Viruses and Prokaryotes Bacteria

2 Classifying Prokaryotes Prokaryote unicellular organisms that lacks a nucleus Most abundant and widespread organisms on Earth Divided into two groups

3 Bacteria (Eubacteria true bacteria ) Large group, contains the typical bacteria Found almost everywhere Archaea (ancient) rare, live in harsh conditions (salty, hot, little oxygen, etc.) More closely related to Eukaryotes than bacteria

4 Structure and Function Size range from 1 5 micrometers Structure: Consists of a cell wall surrounding a cell membrane and inner cytoplasm Some may have an additional cell membrane outside of wall, to protect cell Pili short hairs on surface that anchor cell to surfaces or other bacteria

5

6 Movement: some bacteria move, while others do not move at all Flagella long tail that corkscrews to propel bacteria Slime bacteria secretes a slime on which they glide

7 Prokaryote Shapes: Bacilli (s. bacillum) rod-shaped bacteria Cocci (s. coccus) sphere shaped bacteria Spirilla (s. spirillum) spiral shaped bacteria

8 Nutrition: Prokaryotes take in food molecules and release the energy through cellular respiration or fermentation, or both depending on the environmental conditions Some may use photosynthesis or chemosynthesis to make carbohydrates (food)

9 Growth and Reproduction: Binary fission process of asexual reproduction, in which cell divides in half to create two new daughter cells Performed in favorable conditions Bacteria divide very quickly, some in just 20 minutes

10 Endospore cell forms a thick internal wall to enclose DNA and some cytoplasm Remains dormant for long periods of time Performed in harsh conditions

11 Adaptation without sexual reproduction, bacteria can still develop variation, which contributes to their adaptation and evolution Mutation random mutations between divisions are inherited by daughter cells

12 Conjugation two bacteria exchange genetic info Hollow bridge connects bacteria, and plasmids move from one cell to the other Helps to increase variation, develop adaptations to new conditions

13

14 Importance of Prokaryotes Prokaryotes perform many jobs that are important for the balance of ecosystems and function of individual organisms, or helping to make our lives better

15 Decomposers break down dead organisms, causing decay Releases the nutrients and other materials back into the environment, to be used by other organisms (ex: actinomycetes)

16 Producers photosynthetic bacteria make up the largest population of primary producers in the ocean, forming the base of many food webs (ex: cyanobacteria)

17 Nitrogen fixers: bacteria live in soil or on roots of plants and convert atmospheric nitrogen (N 2 ) to a form that is usable by other organisms, ammonia (NH 3 ) (ex: Rhizobium)

18 Human Uses: bacteria produce many foods and perform functions that make our lives easier Produce foods such as yogurt, cheeses, etc. Synthesize drugs via genetic engineering, such as hormones like insulin Digest pollutants and wastes such as petroleum (oil spills)

19 Bacterial Diseases Pathogen microorganisms (virus or bacteria) that cause disease Louis Pastor French chemist who first showed that bacteria can cause disease

20 Bacteria cause disease by destroying living cells or releasing chemicals that disrupt homeostasis Damaging Host Tissue Bacteria may destroy cells/tissue directly or cause an immune response that destroys areas of tissue Ex: Tuberculosis causes immune response that destroys areas of the lungs

21 Releasing Toxins chemicals (toxins) are released by bacteria disrupts the normal function of cells Ex: diphtheria cause of deadly food poisoning called botulism

22 Controlling bacterial growth: Washing hands and surfaces to remove bacteria Using chemical solutions called disinfectants to kill bacteria Store food at temperatures low enough slow bacteria growth Cook foods to a certain temperature to kill bacteria Sterilize objects or surfaces by heating them to 100ºC to kill bacteria

23 Preventing bacterial Diseases Vaccine: weakened or killed bacteria or inactivated toxins to build body s immunity to that pathogen Treating bacterial diseases Antibiotics: drugs that attack bacterial infections by blocking growth and reproduction

24 Review 1. What are the two groups of prokaryotes? 2. Name 3 structures that are found on the outside of bacteria. 3. Give one function/importance of bacteria. 4. What is a vaccine? 5. How do bacteria act as producers? 6. Name the two methods of movement used in bacteria.