Jessica Exam 2 Essay Flashcards
Select a source of energy that is not known to be utilized by any form of life on earth. Describe the energy that could possibly be used and how it would work. In addition, if the potential source of energy that you selected has any deleterious effects, describe the protections life forms would possess to protect themselves while using this source of energy.
thermal energy, hydrothermal vents, temperature gradients between vacuoles and cell plasma, changes in membrane motility to change electric potential, inefficiency, moving across sharp environmental gradients, convection and an elongated body
Carbon can be considered a “Goldilocks-type” of element for life. Name and describe at least three characteristics of carbon that makes it ideal for “life as we know it”.
most oxidized and most reduced are moderately reactive gases compared to silicates and silane, use in redox reactions, pi bonds
One of the critical environmental parameters for life to occur is that there must be a liquid solvent present. Describe the reasons why life needs a liquid solvent.
dissolve some compounds and allow them to react, stabilize others, buffer against temperature fluctuations, dense enough to maintain concentrations of reactants
The article, “Chance and Necessity in Biochemistry: Implications for the Search for Extraterrestrial Biomarkers in Earth-like Environments” written by Davila and McKay, explores how there can be life based on carbon but not on the same biochemistry that we are familiar with on Earth. Explain how this can be.
Abiotic nitrogenous bases and amino acids, specific particular isomers of 20 aa’s and 5 nitrogenous bases, abiotic amphiphilic molecules and Earth-specific phospholipids, chirality and L-amino acids in proteins, frozen accident
In the hypothesis paper of Limaye et al., “Venus’ Spectral Signatures and the Potential for Life in the Clouds”, the authors present the case that life could occur in the clouds and possess metabolisms based on the use of iron and sulfur. Discuss their justifications for these ideas.
sulfur compounds (sulfuric acid, sulfur dioxide), carbon dioxide, water, phosphorus, iron chloride
moderate temperatures and pressures, particles float for months
airborne cells present in Earth’s atmosphere, life in acidic CO2-dominated iron environments that fix CO2 and N2 and get energy from sulfur redox reactions and iron
How might you recognize evidence of past habitability on Mars?
atmosphere, liquid water, plate tectonics, potential energy sources
What clues or biosignatures might you look for?
complex organic molecules, chirality, biogenic heat, fluid inclusions in salt crystals preserving life for hundreds of millions of years, iron oxide inclusions
Do you think it will be easy to decide which rocks to sample for return to Earth?
nope
