BIO1 - The physical basis of living systems Flashcards
Why is water important for life? What properties make it so special?
Water is extremely important for life, as it is a solvent with many special properties. First of all, it is a very polar solvent, which means that it creates strong bonds with other polar molecules/substances. Furthermore, it has a high “special energy” which means that it takes a lot of energy to increase the temperature of water by one degree. I.e. sweating is a great way of cooling the body, as the expended heat is transferred easily with the water (high heat loss). Furthermore, water has a density anomaly, which means that solid water (ice) is less dense than its liquid counterpart. I.e. lakes and oceans do not freeze from the bottom up. Rather the water freezes from the top down, which creates an insulated environment for marine life in the winter.
What are the requirements for life as we know it?
Life as we know it require 3 things
Liquid water
An energy source
Temperatures compatible with biomolecules
What are the basic characteristics of living systems and why are viruses often not
considered alive?
Viruses are often not considered alive, since they need a host cell to reproduce.
i.e. pr. NASA’s definition, life must be self-sustaining and capable of Darwinian evolution. A virus is technically neither unless it has a host cell.
How can we remotely find signs of life on exoplanets?
One way of remotely finding signs of life on exoplanets is through spectroscopy of a given planet’s atmosphere. Finding co-existence on gases that would not co-exist at equilibrium (such as methane and oxygen) is indicative of life, as life is the only mechanism that we know of that disturbs equilibrium.
What are examples of how living organisms can generate large-scale geological
structures?
Coral Reefs: Coral polyps build massive calcium carbonate structures (e.g., Great Barrier Reef).
Stromatolites: Cyanobacteria form layered sedimentary rocks (e.g., Shark Bay).
Coal and Peat: Plant matter compresses into coal deposits (e.g., Appalachian coal fields)
What is the role of ATP? How much of it are we producing? Be able to perform simple stoichiometric calculations of energy conversion.
ATP is responsible for the transport of energy in living organisms. The energy from ATP comes from the cleavage of a phosphate group in the molecule. The potential energy from the bond can then be used to move the body.
A normal person uses between 75kg to 150kg of ATP per day. That’s why ATP is constantly being reproduced from ADP and phosphate by anabolism (building complex molecules to store energy)
What forms of energy does life use and how is energy stored in live cells?
Light energy (photons, used for photosynthesis in plants)
Energy-rich inorganic compounds (chemolithotrophy)
Energy-rich organic compounds (chemoorganotrophy)
Potentially gradients in chemical species and temperatures in the environment. (postulated for early organisms)
What is an argument for the RNA-world hypothesis of the origin of life?
1 RNA stores information and has catalytic activity
2 RNA plays a key role in all forms of life as we know it
Which basic properties of living systems are constrained by physical laws.
Body size of animals, Height of trees and the size of living cells.
What is a dissipative structure, and why are dissipative structures relevant for understanding life?
Dissipative structures are self-organizing structures that increase entropy
It has been postulated that life itself is a dissipating structure, and that evolution is simply the result of an attempt to maximize entropy production.
How can diffusion lead to pattern formation?
While diffusion usually leads to a decrease in concentration over time, diffusion coupled with reactions and unequal diffusion coefficients can lead to pattern formation and oscillation (Allan Turing was the first to propose this). I.e. it does not necessarily reduce concentration locally.
Give examples of biological properties governed by universal scaling laws.
Metabolic rates, Lung volume, Respiratory Frequence and much more.
How do biological magnetoreception and temperature sensing work?
We currently do not know how magnetoreception works, but there are two theories:
Magnetite in the brain. Magnetite is the strongest magnetic material, and it is postulated that this is the only mineral that would allow animals to register the very tiny variations in the earth’s magnetic field.
The presence of a protein called cryptochrome in the eyes of animals allows them to see magnetic fields.
Thermoreceptor Proteins: Proteins like TRP channels in sensory nerve endings respond to specific temperature ranges (hot, cold, or harmful extremes).
What is chemotaxis?
A chemotaxis as the movement of an organism in response to a chemical stimulus.
This stimulus can either attract or repel the organism. This response is a processing of information to ensure survival and reproduction of the organism.
