CH 24 TEST STUDY Flashcards
When did Earth form, and when did prokaryotes first appear in the fossil record?
Earth formed 4.6 billion years ago, and prokaryotes appeared 3.5 billion years ago
Which two domains represent the most abundant organisms on Earth?
Bacteria and Archaea are the most abundant organisms.
What is the Oparin Haldane hypothesis?
The Oparin-Haldane hypothesis suggests
that organic molecules formed from simpler ones using energy from lightning and UV radiation.
Describe the 1st stage n the hypothesis of production of the first simple cells.
organic molecules formed from simpler molecules by using energy from lightning and UV radiation (oparin-haldane hypothesis)
Describe the 2nd stage in the hypothesis of production of the first simple cells.
Joining of these small molecules into macromolecules (synthesis of macromolecules). RNA monomers have been spontaneously produced from simple molecules without enzymes or ribosomes.
Describe the 3rd stage in the hypothesis of production of the first simple cells.
Packaging of molecules into PROTOCELLS - fluid filled vesicles with a membrane like structure formed spontaneously in water.
Describe the 4th stage in the hypothesis of production of the first simple cells.
Origin of self replication molecules RNA. Ribozymes (RNA molecules) can copy themselves. Natural selection would have favored RNA molecules that were more stable therefore replicating the most would have left the most descendants.
What kind of cell are prokaryotes?
Unicellular or colonial
What size are prokaryotic cells?
0.5-5 micrometers whilst eukaryotic cells are 10-100 micrometers in diameter
Differ in structure between gram positive and gram negative prokaryotic cells.
Gram Positive =
-PURPLE
-thick layer of peptidoglycan
Gram Negative=
-PINK
-thin layer of peptidoglycan
-outer membrane of lipopolysaccharide
What did the ‘primitive soup’ refer to in early Earth conditions?
‘Primitive soup’ referred to Earth’s early oceans.
These oceans contained organic molecules.
Which experiment tested the Oparin-Haldane hypothesis, and what was the result?
The Miller-Urey experiment tested it and resulted in the formation of organic molecules.
How did RNA monomers form in the early Earth environment?
RNA monomers spontaneously formed from simple molecules without the need for enzymes.
Why is RNA significant in early life formation?
RNA has catalytic properties, allowing it to self-replicate and act as a precursor to DNA
What are protocells, and how did they form?
Protocells are fluid-filled vesicles with membrane-like structures that formed spontaneously in water.
What role did lipid bilayers play in early protocells?
Lipid bilayers provided a stable, enclosed environment for organic molecules in protocells.
Why is RNA believed to be the first genetic material?
RNA could both store genetic information and catalyze reactions, unlike DNA
What are ribozymes, and why are they important?
Ribozymes are RNA molecules with catalytic properties, capable of self replication
How did natural selection play a role in the early evolution of RNA molecules?
RNA molecules that were most stable or replicated faster were favored by natural selection.
What evidence supports RNA as the first nucleic acid over DNA?
RNA can act as both genetic material and a catalyst (ribozymes), unlike DNA.
How could RNA’s catalytic properties have contributed to the origin of life?
RNA’s ability to catalyze reactions would allow it to self-replicate and evolve.
What is the key structural structural difference between gram-positive and gram-negative bacteria?
Gram-POSITIVE bacteria have a thick peptidoglycan layer
What is the primary role of the capsule in bacteria?
The capsule PROTECTS the bacterium and helps it ADHERE to surfaces
How do fimbriae help bacteria in their environment?
Fimbriae allow bacteria to stick to surfaces or to other bactera
