eco unit 2 lesson 9

giant impactor theory

Currently, the leading explanation for where the moon came from is the idea that a small planet ran into Earth some time during its formation(4.45 bya), and the leftover debris formed the moon

hadean eon

(4.6bya-3.8bya)

Accretion of the earth from celestial debris
- Frequent celestial collision events
- Formation of the moon
- Formation of early atmosphere by de-gassing
- Water vapor condenses into liquid, forming
ancient seas

Archean Eon

3.8 bya

Beginning of the geologic record

3.5 bya Oldest fossils of cells appear
(stromatolites)

origin of life
2.7 bya Oxygen is produced in oceans,
forming oxide compound

law of superstition

younger rocks are closer to the
surface, and contain younger fossils; older rocks and
older fossils are deeper

Radioactive decay

involves the loss or gain of subatomic particles
or the emission of electromagnetic energy (radiation), resulting in
one isotope being transformed into another.

Half life

represents how long it takes for ½ of a parent isotope to
decay into daughter (a constant)

characteristics of life

organization

energy use and metabolism

maintenance of internal constancy

reproduction, growth, and development

irritability and adaptation (response to environment))

how did the first cells evolve

formation of monomers

linking monomers into polymers

retention of biomolecules in a membrane

evolution of self replication

Criticism of Miller-Urey experiment

Non-reducing gases were emitted from the experiment. Demonstrated the organic formation of simple biomolecules

monomer: amino acids

Polymer: polypeptide

Monomer: Nucleotide

polymer: nucleic acid

Monomer: Simple Sugars

Polymer: polysaccharide

amino acids into polypeptides IN the cell

ribosome builds polypeptides off messenger RNA

amino acids into polypeptides OUTSIDE the cell

Polypeptides can form on dry, hot clay

nucleotides to nucleic acids IN the cell

DNA or RNA polymerase builds new strands of nucleic acids, using a pre-existing strand as a template

nucleotides to nucleic acids OUTSIDE the cell

can form on clay (like polypeptides)

Sugars into Polysaccharides

-Remains an ongoing challenge
- On wet-dry clay, polysaccharides form chaotic
branching patterns, resulting in a “tar” like substance.

Liposomes

- Can grow and shrink through
osmosis
- Stable in water
-Can divide, and fuse with other
liposomes
- Can store energy in the form of
a membrane potential

Proteinoid microspheres

- Can bud and divide
- Allow water in and/out of the cell by osmosis
- Can fuse with other proteinoid microspheres,
combining their innards
- Are stable in water
- Can absorb some molecules through their membranes

Protobiont (literally “first life”):

a membrane-bound
sphere that can divide, fuse, absorb stuff, and carry stuff
around inside. Thought to be the proto-type of the cell.

RNA

Ribose sugar backbone

Usually single-stranded (OH makes double-stranded unstable)

Single strands can fold to make complex shapes, which can perform functions

Can replicate without enzymes

DNA

Deoxyribose sugar backbone

always double-stranded

Doesn’t fold into weird shapes. Just double helices

requires enzymes

RNA world hypothesis

self-replicating
RNA molecules were precursors to the current DNA and
protein-based systems of life, since RNA can store
information and replicate without the assistance of proteins;
DNA can not.

4 domains of life

eukaryote

bacteria

archaea

NCLDVs