Part 2 - the Precambrian organic microfossil record Flashcards
(31 cards)
What is the cell envelope and what is its structure?
plasma membrane + cell wall
waste transport, and the location of metabolic processes.
What is the purpose of the (plasma) membrane? What about the wall?
Area of metabolic activity.
provides rigidity
What is the cell wall composed of?
peptidoglycan + - perplasmic space
Peptidoglycan is a complex molecule made up of chains of sugars (monosaccharides) and amino acids (peptides).
Periplasmic Space: Region between the cell wall and the cell membrane. It can contain various proteins and enzymes involved in different cellular functions
What do polysaccharide capsules do and what are their purpose in this topic?
They are made of polysaccharides.
they aid in capsule divide when the cell is ROUNDED.
What are polysaccharide sheaths?
The same as capsules but for nonrounded cells (Tubular).
sometimes they have pigment.
what is this?
pleurocapsales cyanobacteria - forms mother cell and divides inside.
What is the eukaryotic cell envelope?
plasma membrane that is rigidified by special lipids (sterols) in the bilayer. distinct chemical composition compared to bacterial peptidoglycan.
Autolysis is …. influenced by…
the enzymatic digestion of cells by the action of its own enzymes, and it mostly occurs in dying or dead cells.
influenced by hydrolytic enzymes.
summarize everything important in regard to Fossilization, molecular aspects
What is silification, what is the best way to preserve fossils and why is it important to fossil preservation?
Silicification is a process where silica (a form of silicon dioxide) precipitates and surrounds or replaces organic matter, such as the cells of microorganisms. This process often happens in environments rich in dissolved silica, like geothermal springs or the ancient oceans before the appearance of diatoms (a type of algae).
How does it happen?
Passive Precipitation: Silica molecules (Si(OH)4) in the environment start to bond with the surface of the cell wall.
Polymerization: These silica molecules link together, forming larger and larger chains.
Deshydration: Water molecules are released as the silica chains continue to grow, creating a stronger and more rigid structure.
Crystallization: Over time, these silica chains organize themselves into tiny crystals, further strengthening the structure.
Why is it important?
Silicification is a fantastic way to preserve ancient microorganisms as microfossils. The silica sheath protects the delicate cell structure from decay and allows scientists to study the morphology and even the chemical composition of these ancient life forms.
This happens in geyserites and we can see the past ecosystem.
Aside silicification, what is another good way to preserve microfossils?
Phosphatization
What is this image showing?
phosphatization with authigenic clays
what is this
possibly the oldest eukaryote, acritarch.
what is this and what was it taken with?
oldest gree algae, optical
What is this and what was it taken with?
oldest red algae , optical.
What is this and what was it taken with?
The oldest fungi, TEM left and SEM right
What is this and what was it measured with
cyanobacteria, optical top and clsm bottom
What is this
cynobac
What is this and what was it imaged with?
cynobac, optical
What is this
optical - more cynobacteria omg
except this time it is the oldest known lol
E. Belcherensis
What is this and why is it important?
Gunflint type microbiota as seen optically.
could represent S- metabolizing bacteria. could be oxygenic phototrophs.
What the fuck is this
optically captured archean filamentous sheaths.
What is this showing
Left - eukaryots right - cynobac
delta carbon 13 is lower in eukaryotes and higher in cyno bac.
shot in SIMS (Secondary Ion Mass Spectrometry)O
Metabolic isotope signatures are…
measured on total biomass of monospecific cultures ( = single species)
