1. 12.4 Early Single-Celled Organisms Updates: Unit 3 Test today! Homework: –Read 13.3, 13.2 –Unit guide 13.3 # 1-3, 13.2 #1-3 due Wednesday Unit 4 quiz 1 Friday

2. 12.4 Early Single-Celled Organisms LEQ: How do organisms in ecosystems transform matter and energy? Activator: life as we know it –What process does this formula represent? –Why does life as you know it depend upon this formula? Key terms – endosymbiosis, producer, autotroph, chloroplast, aerobe, consumer, heterotroph, mitochondria

3. 12.4 Early Single-Celled Organisms Microbes have changed the physical and chemical composition of Earth. The oldest known fossils are a group of marine cyanobacteria. –added oxygen to atmosphere –deposited unique minerals

4. 12.4 Early Single-Celled Organisms Fossilized stromatolites provide evidence of early life.

5. 12.4 Early Single-Celled Organisms Producers transform non-living matter and energy into life. Producers get their energy from non-living resources. –autotrophs make their own chemicals for food (left). –Chemotrophs use chemosynthesis to produce chemicals as an energy source (right).

6. 12.4 Early Single-Celled Organisms Photosynthetic eukaryotes have chloroplasts. –Photosynthesis converts sunlight into energy-rich carbon molecules –Chloroplasts convert solar energy to chemical energy. Contain their own DNA

7. 12.4 Early Single-Celled Organisms Consumers get their energy by eating the carbon molecules of organisms; alive or dead –heterotrophs - feed off of different things.

8. 12.4 Early Single-Celled Organisms Bacteria, Archaea and eukaryotes are widespread on Earth. Cells can be grouped by their need for oxygen. –obligate anaerobes are poisoned by oxygen –obligate aerobes need oxygen –facultative aerobes can live with or without oxygen

9. 12.4 Early Single-Celled Organisms Mitochondria and chloroplasts were once free living cells. –Mitochondria (pl.) supply energy to eukaryotic cells. –most require oxygen –Contain their own DNA

10. 12.4 Early Single-Celled Organisms Eukaryotic cells evolved through endosymbiosis. Endosymbiosis is a relationship in which one organism lives within the body of another. –Mitochondria (all), chloroplasts ( eukaryotic producers)

11. 12.4 Early Single-Celled Organisms Events could have occurred near-simultaneously step-wise How did eukaryotic cells evolve?

12. 12.4 Early Single-Celled Organisms Microbes play important roles in ecosystems. Prokaryotes have many functions in ecosystems. –photosynthesize –recycle carbon, nitrogen, hydrogen, sulfur –fix nitrogen (right)

13. 12.4 Early Single-Celled Organisms 1) Which of the following terms describes an organism that consumes many types of food? A) autotroph B) heterotroph C) producer D) anaerobe 2) Which of the following organelles is essential for photosynthesis in eukaryotes? A) mitochondria B) nucleus C) lysosomes D) chloroplasts 3) Organisms that are able to produce their own energy from the Earth’s chemistry are called: A) consumers B) decomposers C) producers D) aerobes 4) An organism that requires oxygen to survive is called a(n): A) aerobe B) producer C) anaerobe D) consumer 5) Which of the following organelles was once a free-living cell? A) mitochondria B) chloroplasts C) nucleus D) A and B

14. 12.4 Early Single-Celled Organisms Summary: What beneficial roles to microorganisms play in our world? What similarities do mitochondria and chloroplasts share? What is endosymbiosis?