PROKARYOTES
CLICKERS OUT ! GET READY TO USE THEM
STAND UP NOW WITH CLICKERS IN HAND
WHEN I GIVE THE SIGNAL, HOLD YOUR BREATH AS LONG AS YOU CAN. I will count the time off. When you can’t hold your breath any longer, Sit down and punch in the time in seconds that you held your breath. It will be in increments of 10 seconds
Let’s review who the prokaryotes are Bacteria are responsible for one of the greatest events in the earth’s history The Oxygen Revolution There are 2 major concerns to deal with: How did we go from an anaerobicaerobic environment? What metabolic changes were involved ? Let’s review who the prokaryotes are
EUBACTERIA & ARCHAEBACTERIA PROKARYOTES EUBACTERIA & ARCHAEBACTERIA
WHAT ARE PROKARYOTES? Single cells No nuclear membrane Cell Wall Single circular chromosome No organelles such as mitochondria, chloroplasts, ER, or Golgi. ~60 Phyla of Prokaryotes
LUCA= Last Universal Common Ancestor CLASSIFICATION Prokaryotes LUCA= Last Universal Common Ancestor
Comparing Eubacteria & Archaebacteria 9+2
LUCA= Last Universal Common Ancestor CLASSIFICATION LUCA= Last Universal Common Ancestor
Domain Archaea. Kingdom Archaebacteria Includes Extremophiles e.g. Methanogens e.g. Halophiles e.g. Thermophiles Yellowstone National Park
Domain Bacteria Kingdom: Eubacteria Simplest organisms Smallest Oldest (>3.5 BYA) Originated in an anaerobic environment (i.e. without O2)
Prokaryotes Are Everywhere
Bacteria Are Everywhere Human body composition: 10 trillion human cells 100 trillion bacterial cells (90% of the cells in your body aren’t human) Bacterial species living in human: 5,000—35,000 species in the intestine 300--500 species in the mouth 120 species on the skin
Exist as parasites Exist as mutualists Exist as commensals We’re a walking ecosystem Exist as parasites Exist as mutualists Exist as commensals
We’re a walking ecosystem Total of microbial genes is 100x greater than human genome. Our systems are linked together as a superorganism. We can’t live without the other. They produce vitamins we require B, H, and K. They manipulate our immune system.
Plaque and tartar in teeth Biofilm in catheters
Reproduction in Prokaryotes Binary fission (Not mitosis)
Genetic Variability in bacteria
Plasmids Plasmids = extra chromosomal DNA capable of independent replication Numbers: 1- thousands Important in horizontal or lateral gene transfer Some carry antibiotic resistance genes
Genetic Exchange in bacteria Conjugation Pili attachment
Variability in Prokaryotes via Mutation—high rate/unit time because of high speed of reproduction. Conjugation Transduction Transformation DNA is transferred between organisms Horizontal Gene Transfer Can Genes be passed between Kingdoms?
Horizontal Gene Transfer Bacteria sp1 Bacteria sp2 Bacteria Fungi (yeast) Bacteria Plants Fish Bacteria Bacteria Insects Bacteria Nematode worms Greatly speeds the rate of evolution
The Oxygen Revolution
What is the Evolutionary Sequence of the Prokaryotes? Hints from the energy transfer systems. 2 types of Energy Capture: 1) Heterotrophic= breaking down organic molecules to get energy (ATP) 2) Autotrophic= using non-organic molecules (self-feeders) to get energy. a) Chemotrophic = chemosynthetic b) Phototrophic = photosynthetic Which was first?
Could chemosynthesis be the energy source for the first bacteria? 12H2S + 6CO2 C6H12O6 (=carbohydrate) + 6H2O + 12S Purple sulfur bacteria Bacteria living in the hydrothermal vents
Simple Photosynthesis in Green Bacteria Light H2S + CO2 C6H12O6 + S + ATP Bacteriochlorophyll No chloroplasts 1 Photosystem H2S is source of H+ and e- Sulfur is released Anaerobic process –No O2
Photosynthesis Blue-Green Bacteria Chlorophyll a -No chloroplasts but Ch a is on internal membranes in cytoplasm. 2 photosystems - Does best in low 02 (10%) - Can use H2O instead of H2S Light H2S + CO2 C6H1206 + S + ATP H2O + CO2 C6H1206 + O2 + ATP Light This is the beginning of the Oxygen Revolution
Complex Photosynthesis in Plants Light H20 + CO2 C6H1206 + 02 + ATP --Uses chlorophyll a and b to capture light in the chloroplast --2 photosystems- ATP --H2O is source of H+ and e- --02 is released
1) Chemosynthesis Inorganic chem. reactions (H2S) S (Anaerobic) 2) 1 Photosystem Photosynthesis Green Bacteria (Bacterial chlorophyll) (H2S) S (Anaerobic) 3) 2 photosystems photosynthesis Blue green bacteria (Chlorophyll a) (H2S or H20) S or O2 OXYGEN REVOLUTION BEGINS 4) Plant Photosynthesis (H2O) O2 2 Photosystems Chlorophyll a & b
Heterotrophic Nutrition Could heterotrophic nutrition be first— in organic soup? Heterotrophic Nutrition Glucose (6C) 2 ATP 2 Pyruvic Acid (3C) Alcohol (2C) Lactic Acid (3C) Acetic Acid (2C) Pyruvic Acid (3 C)
Heterotrophic Nutrition Glucose (6C) 2 ATP 2 Pyruvic Acid (3C) Glycolysis (Splitting of glucose) Most organisms can do this suggesting it evolved early Anaerobic Only a small amount of energy released Occurs in the cytoplasm Incomplete breakdown of glucose Alcohol (2C) Lactic Acid (3C) Acetic Acid (2C) Pyruvic Acid (3 C)
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