1.5 Flashcards
What did Pasteur’s experiments demonstrate
hypothesized that cells must come from cells and he designed a falsifiable experiment
What did Pasteur do
He boiled nutrient broth in three swan neck flasks and then broke the neck of one flask to allow air to enter but left the other flask unbroken, the broth in the flask where the swan neck was not broken remained clear while the broth in the broken necked flask became cloudy as microbes grew and multiplied. In the third flask, Pasteur tilted the flask to expose the broth to the microbes in the curve of the swan neck.
What did Pasteur prove
spontaneous generation of cells and organisms does not occur on earth showing that the present conditions do not sustain the process (temperature, pressure, light)
What was the Miller -Urey experiment
they recreated the conditions of early earth in a closed system by including a reducing atmosphere (low oxygen) and high radiation levels, high temperatures and electrical storms. After running the experiment for a week, simple amino acids and hydrocarbons were found,
Providing, non-living synthesis of simple organic molecules was possible
What are the four conditions needed for life to emerge and persist
- simple organic molecules; amino acids, fatty acids and carbohydrates
- larger organic molecules; phospholipids and RNA and DNA, must be assembled from simpler molecules
- Organisms reproduce, so replication of nucleic acids must be possible
- Biochemial reactions require set conditions such as pH. Therefore self contained structures are necessary.
Pasteur proved
cells arise from pre-existing cells
the miller -urey experiment showed …
molecules essential to life could be produced in abiotic conditions
what does the endosymbiotic theory support
the idea that mitochondria and chloroplasts were themselves prokaryotes that were taken in by larger prokaryotes by endocytosis.
instead of being digested, the cels remained inside the host cells. The cells that could carry ut aerobic respiration and provide energy into their host cells evolved into mitochondria
prokaryotic cells that could convert light energy to chemical energy became chloroplasts and passed on sugars produced during photosynthesis to the host cell
What evidence supports the endosymbiotic theory
- have double membranes
- have circular naked DNA
- dna is formed as single chromosomes
- have 70s ribosomes
- divide by binary fission
- are susceptible to some antibiotics
how did mitochondria originate
from engulfed originally free-living proteobacteria
why do biologist suspect mitochondria came before chloroplasts
because all eukaryote shave mitochondria but not all have chloroplasts
What two things did miller and Urey find
amino acids and oily hydrocarbons
what happened in Pasteurs experiments
fungi and organisms did not appear in the boiled broth inside sealed swan necked flasks after prior exposure to air
