Bacteria Chapter 7.2

POINT > Describe bacterial cells POINT > Describe how bacteria get energy POINT > Explain how bacteria reproduce POINT > Describe the role of bacteria in nature POINT > Identify diseases caused by bacteria

POINT > Describe bacterial cells Current world population: 7,200,000,000 Bacteria cells in human body: 100,000,000,000,000 Human body has 10x more bacteria cells than human cells!

POINT > Describe bacterial cells Bacteria are prokaryotes: no nucleus Bacteria have a circular DNA in the cytoplasm Bacteria have a cell wall outside the cell membrane Some bacteria have flagella for movement

POINT > Describe bacterial cells Bacteria have three shapes: Rod-shaped RoundSpiral

CHECK: Do bacteria cells have a nucleus? What are three shapes of bacteria cells? Do bacteria have a cell wall?

POINT > Describe how bacteria get energy Some bacteria are autotrophs: they make their own food from sunlight energy or chemical energy Some bacteria are heterotrophs: they get energy from other organisms

POINT > Describe how bacteria get energy Some bacteria are aerobic: they use oxygen to perform respiration Some bacteria are anaerobic: they cannot live in oxygen

POINT > Explain how bacteria reproduce Bacteria reproduce asexually by binary fission The cell grows, copies its DNA and divides Some bacteria divide very rapidly (every twenty minutes) 1 cell > 1000 cells in 3 hours

POINT > Explain how bacteria reproduce Bacteria reproduce sexually by conjugation Bacteria cells exchange DNA through pili Sexual reproduction increases variation in bacteria

POINT > Explain how bacteria reproduce When conditions become poor (no food, dry, too cold or too hot) bacteria can produce endospores Endospores are single cells that can survive freezing, heat and no food for months or years

CHECK: What is asexual reproduction in bacteria called? What is sexual reproduction in bacteria called? What is an endospore?

POINT > Describe the role of bacteria in nature Bacteria are very important to life Bacteria produce much of the oxygen we breathe Bacteria are used to make cheese and yogurt Bacteria are decomposers: break down dead organisms

POINT > Describe the role of bacteria in nature Bacteria help us digest food Bacteria produce vitamins our bodies need Bacteria in our stomach protect us from harmful bacteria

POINT > Identify diseases caused by bacteria Bacteria cause many human diseases: Cholera from unclean water Plague killed about 1/3 of Europe population, almost half of China’s population (1300’s) Tuberculosis kills 2,000,000 every year Strep throat

POINT > Identify diseases caused by bacteria Bacterial diseases can be treated with medicines called antibiotics: ex. penecillin Some bacteria are becoming resistant to antibiotics Antibiotic resistance is a growing problem worldwide We can prevent many bacterial diseases with vaccines, washing hands, drinking clean water, and cooking foods completely

CHECK: What are two diseases caused by bacteria? What is an antibiotic? What is antibiotic resistance? What is a decomposer?

Homework: Read 7.2 pages S.A. page 225 #1-4 GRAS pages (All)