BIO1 - The physical basis of living systems Flashcards
*Why is our atmosphere important to life on earth?
- Oxygen: respiration
- Protect from radiation
- Greenhouse gas effect, maintaining suitable temperature
*What are requirements for life as we know it?
1) Liquid water
2) An energy source
3) Temperatures compatible with biomolecules
Extra that may have helped for life on earth to develop:
1) Magnetic field and a dense atmosphere to protect from radiation
2) Large gas planets in our solar system to protect us from comets, asteroids etc.
3) a large moon
*What are the basic characteristics of living systems?
Life on earth is characterized by:
1) a peculiar out of equilibrium state (If an equilibrium state is one in which nothing seems to be happening, i.e., “equilibrium is death,” then a key distinction of all living systems is that they operate out of thermodynamic equilibrium, which requires that
they constantly burn energy, obtained from photosynthesis or metabolism, to stay alive.)
2) evolution
3) cellular organization.
*Why are viruses often not considered alive?
- Lack of cellular structure. Instead they consist of genetic material surrounded by a protein coat.
- No evolutionary process
*What features of our solar system/planet are particularly favourable for life?
- Distance from the Sun => Goldilocks zone => liquid water, right temperatures for water to exist in its liquid state => essential for various biological processes.
- Atmosphere composition (oxygen)
- Magnetic field
- Ozone layer
- Stable orbit
*How can we remotely find signs of life on exoplanets?
- Spectroscopy of exoplanets atmospheres. James Webb space telescope can look for evidence of life through measuring the gas composition of exoplanet atmospheres.
Looking for out of equilibrium compositions, such as the simultaneous presence of methane and oxygen.
*What are examples of how living organisms can generate large scale geological structures?
Coral reefs, massive underwater structures formed by the accumulation of calcium carbonate exoskeletons secreted by coral polyps over time
*What is osmosis?
Osmosis is a major physical force that life has to deal with.
Osmosis is the movement of solvent molecules (usually water) across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. The goal of osmosis is to equalize the concentration of solute on both sides of the membrane, but the solvent (water) moves to achieve this equilibrium
Osmosis in very high salt concentrations for instance the death sea. A living organism in the death sea; The water will try to leave the organism to dilute the death sea.
*How do organisms adapt to osmotic stress?
Organisms adapt to osmotic stress by regulating internal ion concentrations, producing compatible solutes, and adjusting cell membrane permeability. They may also employ water retention mechanisms and structural adaptations to minimize water loss. These strategies help maintain cellular homeostasis and prevent damage from fluctuations in external osmolarity.
by accumulating or releasing solutes, thereby attenuating water fluxes. Those solutes include inorganic ions (often K+), and organic molecules denoted “osmolytes”
Living cells often fight osmotic pressure by accumulating high
concentrations of soluble small molecules inside the cell, such as such as
polyols (glycerol, arabitol, mannitol, and glucosylglycerol), low-molecular-
weight nonionic carbohydrates (sucrose, trehalose, and glucose), free amino
acids and their derivatives (proline, glutamate, glycine, γ-aminobutyrate,
taurine, and β-alanine), etc.
*What is the role of ATP?
ATP stores and carries energy within cells. It consists of a molecule of adenosine linked to three phosphate groups. The high energy bonds between these phosphate groups can be broken, releasing energy that cells can use for variuos cellular activities
*What forms of energy does life use and how is energy stored in live cells?
The different forms of energy life can use:
1) Light (photosynthesis, not at the origin of life)
2) Energy rich inorganic compounds (chemolithotrophy). for example pyrite - FeS2
3) Energy-rich organic compounds (chemoorganotrophy)
4) potentially gradients in chemical species and temperature in the environment
(postulated for early organisms)
*What is an argument for the RNA-world hypothesis of the origin of life?
RNA can both store information AND has catalytic activity.
RNA plays a key role in all forms of life (mRNA, tRNA, ribosome)
This hypothesis is the most widely accepted theory about the origin of life.
The RNA-world hypothesis proposes that before DNA or proteins existed, RNA molecules served as both the genetic material and catalysts for early life forms. This hypothesis suggests that RNA played a fundamental role in the origin of life by storing genetic information and catalyzing chemical reactions, thus bridging the gap between simple molecules and the complex biological systems we see today
*Which basic properties of living systems are constrained by physical laws? (Hvilke grundlæggende egenskaber ved levende systemer er begrænset af fysiske love)?
1) Gravitation force affects: the body size of land and marine animals as well as the height of trees. F scales with length^3.
2) Diffusion of substances or heat affects the size of living cells, as diffusion t scales with length^2. Cells must maintain a size that allows for efficient exchange of substances and heat across their membranes, which imposes limits on their size.
3) Limited available energy supply/density affect the size and metabolic activity of organisms
4) Fluid transport through capillarity or pressure driven flow affects the design and functioning of biological structures, such as blood vessels, respiratory systems, and vascular plants.
*Why can marine animals grow larger than land animals?
The buoyancy (opdrift) of water enables ocean animals to grow to greater sizes than land animals, which need legs sturdy (solide) enough to support them
*Why are dissipative structures relevant for understanding life?
Dissipative structures are self organising structures that are maintained through the
dissipation of energy (entropy increase)
Dissipative structures are crucial for understanding life because they explain how living systems, unlike inanimate objects, actively maintain order and complexity far from thermodynamic equilibrium. Living organisms continuously dissipate energy, producing entropy in their surroundings while organizing and adapting to their environment. This concept helps elucidate the dynamic, self-organizing, and non-equilibrium nature of life, emphasizing the emergence of complexity, information processing, and adaptability in biological systems
Living things are always changing, but they manage to stay stable and organized. Dissipative structures show how systems can stay stable even when they’re constantly changing.
