Lecture 14 Flashcards
7 characteristics shared by cellular lifeforms
Display order
Harness and utilize energy
Reproduce
Respond to stimuli
Exhibit homeostasis
Grow and develop
Evolve
Why aren’t viruses not defined as living
Missing:
-don’t have Ribosomes (rely on living cells to manufacture their proteins and replicate their RNA)
- don’t have their own metabolism(don’t respire or carry out photosynthesis)
- cannot complete their lifecycle without living cells (but neither can some living organisms, including many parasites)
How old is the earth
4,600,000,000
4.6 billion years
We know this be evaluating the decay of uranium into lead
Earths current atmosphere
High concentration of O2 oxidize the electrons in electron rich molecules
This leaves relatively low atmospheric hydrogen, carbon dioxide, ammonia, and methane
Current atmosphere is classified as an oxidizing atmosphere
Current atmosphere is classified as what type
Oxidizing atmosphere
Earths early atmosphere
Opalin-Harlan hypothesis states macromolecules making up all life must have been produced via abiotic synthesis from a reducing atmosphere made of simple gases:
Hydrogen, co2,ammonia,methane, very little oxygen
These small molecules enter into reactions that yield larger more complex organic molecules
Miller-Uray did what
Experimental validation of Oparin Haldane Hypothesis of abiotic formation of life-critical molecules
Miller Uray experiment
Simulated earths early atmosphere
Boiled water
Vapor travels up
Electrodes
Spark discharge
Inorganic molecules simulate earths early atmosphere
Water out
Condenser
Water in
Water droplets
Water containing organic compounds
Liquid water in trap
Why did miller uray experiment boil water then condense it?
To simulate water cycle on earth
What does lack of O2 and O3 mean in miller uray experiment
Energetic UV light also my with lightning provide energy needed to form more complex biologically important molecules
What life molecules did miller uray find
Urea
Lactic Acid
Acetic acid
Formic acid
Miller uray experiment repeated over decades
Resulted in all components of life
Lipids. Sugars. Nucleotides
- these are all monomer. Life is made of polymers (proteins. Sugars. Etc)
-since polymers are created using dehydration synthesis this needs a catalyst
-it’s hypothesized clay must have acted as this catalyst
We have complex molecules. What do we need for life
1st. Mechanism to store information
2nd. Energy transfer to enable work
3rd. Compartmentalization to keep work local and enhance reactionsq
Ribozymes
RNA can act as catalysts called ribosymes
Critical for control of gene expression:
-removal of introns from newly synthesized rna
-cleaving mRNA (messenger RNA) to cause them to break apart
-just like proteins RNA nucleotide order defines shape which then defines function
-Altman and cech- Nobel prize in chemistry 1989
Why is ribosome considered a ribosyme
RNA can act as enzymes called ribosymes.
Catalytic component of the ribosome that joins individual amino acids is itself and RNA molecule
Where did RNA come from
Hypothesized RNA might have started out as self replicating
But ribosymes aren’t as efficient for catalysis than an enzyme
This is because enzymes can be more specialized than ribosymes
This is because proteins are made from 20 different amino acids while RNA consists of chains of only 4 nucleotides
Hypothesized RNA might have catalyzed formation of small proteins
Once proteins are made it becomes simpler to use dna
The sugar deozyribose is hard to make with ribosomes but makes for a much stabler molecule
Why is DNA desirable
Extremely stable ( can recover DNA 1000s of yrs old). RNA degrade within minutes
The double strand provides an extra copy of the correct information
RNA contains uracil, DNA contains thymine. Because C->U mutation is common in DNA it allows for error checking and repair
Citric acid cycle
Key component to cellular respiration
Electrons released during oxidation used later in the respiratory pathway to generate ATP
Synthesizes precursor molecules- building blocks for amino acids and fatty acids
Where the first cell membranes lipid?
No. They were inorganic
Might have been NiS of FeS to compartmentalize rxns
Allowed for segmentation of H+ ion concentrations to do work. This would be achieved naturally in these highly compartmentalized inorganic containers
This would allow for natural phosphorylation of ADP to ATP
