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Advanced Biology Prokaryotes. Chapter 28. The first cells (28.1). Isotopic Data Carbon-12 is found in microfossils This is used for carbon dating of organisms and carbon fixation Pathways include: Calvin Cycle (photosynthesis) Krebs Cycle (cellular respiration) Hydrocarbons biomarkers. - PowerPoint PPT Presentation
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Chapter 28
ADVANCED BIOLOGYPROKARYOTES
The Earth formed approximately 4.5 billion years ago
The first fossil formations found on Earth are dated to 3.5 billion years ago Microfossils
Fossil form of microscopic organisms
Isotopic Data Carbon-12 is found in
microfossilsThis is used for carbon
dating of organisms and carbon fixation Pathways include:
Calvin Cycle (photosynthesis)
Krebs Cycle (cellular respiration)
Hydrocarbons biomarkers
THE FIRST CELLS (28.1)
Abundant amounts of prokaryotes – ~10% identified
New techniques to identify w/o culturing
Two groups: Archae and
Eubacteria
Prokaryotes are the oldest form of life.
They have a simple structure and
They are also the most abundant form of life on Earth Cyanobacteria
(photosynthetic) changed Earth’s atmosphere to be able to produce oxygen
PROKARYOTIC DIVERSITY (28.2)
Found in deep sea caves, volcano rims and inside glacier formations
Some Archae are extremophiles – extreme environments such as hot springs, geysers, toxic gases and extreme cold (Anartica)
Extremes may indicate earth’s conditions 3.5 bya
PROKARYOTES CAN LIVE ANYWHERE
Prokaryotes Unicellular Cell size – vary
≤1ųm up to 750 ųm Single circular chromosome Plasmids Binary Fission – asexual Horizontal gene transfer No internal compartments –
ribosomes differ Flagella – single fiber – spin Oxygenic and anoxygenic chemolithitrophic
Eukaryotes Unicellular and
multicellular Cell size – normally
≥10ųm Membrane bound nucleus Mitosis – sexual Genetic Diversity via
Mutations Membrane bound
organelles Flagella and cilia
w/microtubules – whiplike Photosynthesis release
oxygen
PROKARYOTE VS. EUKARYOTE
Prokaryotes Eukaryotes
Plasma membrane in both but differs in glycerol link to hydrocarbon chains
Cell Wall– Peptiglycan in Eubacteria but not in Archae
DNA Replication differs by place of origin and proteins
Gene Expression – Archae may have more than one RNA polymerase
ARCHAE VS. EUBACTERIA
CLASSIFICATION
Classification of prokaryotes were gram staining and observations such as: Can photosynthesize Mobility Unicellular or colonies Spores or binary fission Whether it is pathogenic
Now classified by evolutionary means using DNA analysis
Three basic forms:Rod shaped (bacillus)
Sperical shaped (coccus)
Spiral shaped (spirillum or spirochetes)
PROKARYOTE CELL STRUCTURE (28.3)
Cell wall determines cell shapeLack cell wall, no particular cell shape
FlagellaChainsColoniesBranching
filaments
CELL STRUCTURE
Cell wall basically contains peptidoglycan with a polymer that forms a strand of crosslinked polysaccharides with peptide chains
Archae may have pseudomurein or pseudopeptidoglycan
CELL WALL
Click icon to add picture
Gram + will stain purple
Thick Peptioglycan so traps crystal violet
Gram – will stain pink
Multiple layers does not trap crystal violet but will show the red dye
GRAM STAINING
CapsuleGel type outer layer
Allows for adherance and evasion from immune system
Flagella Structure that allows movement connected at cell wall and spins – made of protein flagellin
OTHER STUCTURES
Pili Hairlike structure that allows movement (gram-), attachment and exchange of genetic information
EndosporesDormant stage in prokaryotes
Thick wall formed when environmental stress
Stay dormant for days to centuries Examples: Tetanus or
anthrax
Internal membranesRespiratory membranes – photosynthesis
Nucleoid Double stranded circular DNA (nucleoid region)
Plasmid – replicating circular DNA (small)
RibosomesSmaller than Eukaryote ribosomes
Different proteins and RNA
Antibiotics will bind to these ribosomes blocking protein synthesis
INTERNAL STRUCTURES
Prokaryotes reproduce asexually
Exchange DNA throughConjugation - transfer plasmids (F+/F- )
Transduction transformation
CONJUGATION
PROKARYOTIC GENETICS (28.4)
TransductionDNA transfer from one bacterium to another via a virus
Transformation (Griffith) – Cell death causes lysis that releases fragments of DNA into the environment where another bacteria incorporates it into its genetic material
Plasmids can have resistant genes incorporated E.coli found in digestive tract of humans vulnerable
Due to its rapid reproduction a mutation in a bacterium can spread rapidlyMedia growth (Nutrient Agar) Auxotroph – need
supplement MRSA and VRSA
ANTIBIOTIC RESISTANCE AND MUTATIONS
Intake of energy and carbon – 4 Ways: Photoautotrophs Chemolithoautotro
phs Photoheterotrophs Chemoheterotroph
s
Photoautotrophs – sunlight to build from carbon dioxide
Chemolithoautotrophs – oxidize inorganic substances such as ammonia to nitrite
Photoheterotrophs – Sunlight for energy and other molecules for carbon
Chemohetertrophs – carbon and energy from other molecules
PROKARYOTIC METABOLISM (28.5)
Infective diseases by bacteria killed over 20% of US children before age 5 before the discovery of antibiotics by Pasteur and Koch
Bacteria can infect by various methods such as droplets in air, feces or pests
See Table 28.1 on page 561.
HUMAN BACTERIAL DISEASE
Prokaryotes can cause harm but there are some that are beneficialBacterial decomposers along with fungi put C, N,P, S back into the soil
Fixation during nutrient cycling of carbon and nitrogen
Symbiotic relationshipsMutualism – nitrogen fixation or digestion
Commensalism - live outside of organism without harming
Parasitism - infection
BENEFICIAL PROKARYOTES
Genetic EngineeringHuman genes can be inserted into bacterium to produce human proteins such as insulin
Biofactories for enzymes, vitamins, antibiotics and industrial compounds
BioremediationRemoving pollutants from water, air and/or soil
Bacterium used in wastewater treatment plants to breakdown raw sewage.
Future development in removing toxic waste