Chapter 25 & 27 Flashcards
What are the four steps hypothesized to have brought life about
- Abiotic synthesis of organic molecules
- Formation of organic polymers - repeating units
- Formation of Protocells: membrane-bound, cell precursors
- Formation of ribozymes: protein enzymes made of RNA
How was the early Earth atmosphere like
- Organic molecules formed from simpler molecules
- Energy for reactions from lightning/UV radiation
- Oceans were full of organic molecules (primordial soup)
______ processes could have produced the early building blocks of life
Abiotic
Why are bogs good fossil repositories
- Low oxygen
- Low water flow
- Acidic soils
- inhibit microbial and fungal activity
What are two methods to age fossils
- Carbon-dating
- Radiometric dating
The geological record is divided into ______, _______, ______, and ______ _____
Hadean, Archaean, Proterozoic, Phanerozoic, Eons
Approximately how long did the first three Eons add up to
4 Billion years
How long have we been in the Phanerozoic Eon, and what has arisen since
600 Million years, Multicellular Eukaryotic Life
What three era’s is the Phanerozoic Eon divided into
- Paleozoic Era
- Mesozoic Era
- Cenozoic Era
What occurred in the Archaean Eon
First prokaryotes arose 3.5 BYA, only life form from 3.5 BYA to 2.1 BYA
Oxygen Revolution
O2 producing photosynthesis became dominant, allowed organisms to gain energy from the sun and enabled cellular respiration
Wha occurred in theProterozoic Eon
Single-celled eukaryotes arose 1.8 BYA, evolved via endosymbiosis
What is endosymbiosis
When a prokaryotic cell engulfed another cell, and evolved the mitochondria
What occured in the Proterozoic Eon
Multicellular Eukaryotes evolved 1.3 BYA, which gave way to algae, plants, animals, and fungi
What occured during the Paleozoic eon
Cambrian explosion, which is marked by the sudden appearance of fossils
Continental Drift
The slow movement of Earth’s continents as the underlying mantle moves.
What are some consequences of Continental Drift
- Reduction in shallow water habitats
- Colder and drier climate inland
- Changes in climate w/ movement away from the poles
- Changes in ocean circulation patterns (global cooling)
The break of Pangaea lead to ______ ______
Allopatric speciation
Permian Mass Extinction
- Occurred 252 MYA
- Separates Paleozoic & Mesozoic Era’s
- Lasted 5 MY, wiped 95% of marine animals
- Caused by Volcanism, leading to global warming, and decrease in oceanic oxygen
Cretaceous Mass Extinction
- Occurred 65.5 MYA
- Separates Mesozoic & Cenozoic Era’s
- Happened in 10k yrs
- 75% of species (terrestrial plants & animals) went extinct
Adaptive Radiation
The evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities (new niches, little competition)
What are Prokaryotes
Single-celled organisms that make up the Bacteria & Archaea domains
What’s special about Prokaryotes
- Adapted to diverse/extreme environments
- Most abundant organism on Earth
- First organism to inhabit Earth
- .5-5 um in length (vs 10-100um eukaryotes)
Hypertonic
Net movement of water out of the cell, more solute outside
Hypotonic
Net movement of water into the cell, more solute inside
Isotionic
Osmotic equilibrium, no net movement, solute concentrations are equal inside and outside
most prokaryotes _____ water and ____ in _____ environments
Lose, burst, hypertonic
peptidoglycan
a network of sugar polymers cross-linked by polypeptides
Archaeal walls contain ________ and proteins, and lack __________
polysaccharides, peptidoglycan
Gram-positive
Simple walls, with large amounts of peptidoglycan
Gram-negative
Complex walls with outer membrane, contains lipopolysaccharides and less peptidoglycan
Why are gram-negative bacteria more resistant to bacteria
Antibiotics target peptidoglycan, which gram-negative bacteria contain very little of in their membrane
Capsule V.S. Slime layer
Capsule bacteria are dense and well-defined, Slime-layer bacteria are not well organized
Endospores
Copies of bacterial chromosome surrounded by a multilayered structure produced when water/nutrients are lacking in bacteria
Fimbriae
hairlike appendages that allow prokaryotes to stick to their substrate or other bacteria
Pili
Longer (than Fimbriae) appendages that pull bacteria together and allow the exchange of DNA
Flagella
Tail-like structure used for movement
Plasmids
Rings of independently replicating DNA in prokaryotes
What are some key features of Prokaryote reproduction
- They are small
- Reproduce by binary fission
- Short generation times
Binary Fission
asexual reproduction where identical (except mutations) cells are produced
Transformation
When prokaryotic cells incorporate foreign DNA from surroundings
Transduction
When phages (bacteria infecting viruses) carry genes from one host to another
Conjugation
The process of two prokaryotic cells transferring DNA through a Sex Pili
R Plasmids
Plasmids that carry antibiotic resistance genes.
Phototrophs
Cells that obtain energy from light
Chemotrophs
Cells that obtain energy from chemicals
Autotrophs
Require CO2 as fuel source
Heterotrophs
Require organic nutrients (often created by autotrophs) to make the organic compounds
Obligate aerobes vs Obligate anaerobes vs Facultative anaerobes
Aerobes require O2 for cellular respiration, while Anaerobes are poisoned by O2; Facultative can use O2 if present, if not they use fermentation or anaerobic respiration
Nitrogen fixation
Prokaryotes that convert N2 to ammonia (NH3)
Heterocyst
Cells that prevent oxygen penetration in colonies
