Exam 1 Flashcards by Jessica Brooks

What is the major reason we think life will be found elsewhere?

Statistics, the total number of possible exoplanets

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Describe the likely first life (not LUCA)

single-celled prokaryotes based on RNA

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Why do we want to find life as a global entity?

much less likely to be a contamination event

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Vernadsky

geology and biology are fundamentally indistinguishable, the line between living and non-living is not very clear

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Lovelock - Gaia hypothesis

once life is established, it would respond to the changing environment to ensure that it continues

living, self-regulating, homeostatic system

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Miller and Urey

mimicked conditions on early Earth with electrodes and inorganic compounds

solution became cloudy with organic molecules, including amino acids

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What is the predominant form of life on Earth?

prokaryotes

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What would a methane-based solvent change about life?

may be based on silicon instead of carbon

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What would a non-water solvent change about life?

upside-down lipid bilayer (hydrophobic exterior)

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Why would life need constant habitats?

to maintain life

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Why would life need variable habitats?

resources are not depleted, waste products do not build up, produces natural selection

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What is the “life as a process” defn of life?

something that consumes energy to maintain its organization (lower entropy, build biomass)

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What is the textbook defn of life?

a self-sustaining bounded local environment in disequilibrium with its environment

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Why does life require “some” fidelity?

fidelity is required so life can continue and make more cells, mistakes are required to produce variety for evolution to act upon

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Defn of metabolism

the sum of all the chemical reactions that occur within the cell

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Describe anabolism

consuming energy to build things up

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Describe catabolism. How is the way life performs this process different than non-life?

releasing energy by breaking things down, life can use a number of steps to control the release of energy and reduce the amount of energy wasted

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Describe autopoiesis

self-creation powered by the controlled consumption of energy; the process of making more biomass

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What are the two life-specific parts of reproduction?

start with raw materials and use anabolic reactions to form monomers, polymers, and a cell

have an evolutionary history

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What is the unique chemistry of life on Earth?

nitrogen, carbon, oxygen, hydrogen, sulfur, phosphorus

Earth’s crust is mainly silicon

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Types of life - Darwin life

emphasis on the capacity for organisms to adapt to their environment and change through time

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Types of life - Haldane life

emphasis on metabolism and maintenance, if organisms are decreasing entropy and processing the chemical reactions that make up life

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Types of life - Carl Woese life

he used the r16s (small subunit rRNA) gene to develop the phylogeny of life that moved us from 5 kingdoms to 3 domains

Types of life - synthetic life

wetware; taking living cells and genetically modifying them

Types of life - virtual life

software; AI or life contained within the machine

Types of life - mechanical life

hardware; life that cannot build new versions of itself from raw materials

Types of life - Paul Davies "dark life"

life that does not rely on sunlight for energy and instead uses chemicals such as hydrogen sulfide or ferrous iron

Origin of life - Panspermia

Francis/Crick, life came from elsewhere, does not explain where that life came from

Origin of life - Primordial Soup

dilute solutions on earths surface where life could use lightning or UV radiation from the sun as energy and the water and simple organic molecules brought by asteroids; requires cycles of freezing or desiccation

Origin of life - Deep Sea Vents

hydrogen sulfide and other inorganic compounds that can serve as sources of energy; would also be hard to concentrate reactants and retain products; iron/sulfur chimney structures as catalysts

Thermal beginning of life

thermophiles are at the root of the tree of life; may indicate support for deep sea vents or just that thermophiles are the most likely to survive the early bombardment of Earth

8 steps for life (list)

source of energy, polymerization, formation of a membrane, info-polymers, RNA, DNA, statistically re-occurring of effective and efficient metabolites, proteins

What are some compounds found on early Earth? What sort of atmosphere did we have?

hydrogen, nitrogen, carbon dioxide, ammonia, cyanide, formaldehyde, hydrogen sulfide reducing atmosphere

How much energy does the reaction of hydrogen and oxygen yield?

237.14kJ

What are the three ways ATP can be produced?

electron acceptor chains, substrate level phosphorylation, electron pair bifurcation

Describe LUCA

contains DNA and proteins; proto-cell with a cell membrane; small size

Age of universe

14 BYA

First elements

hydrogen and helium, combine for nuclear fusion in protostars

Formation of earth

4.46 BYA, heavy elements closer to sun, lighter elements further away

Age of first life, description

3.5-3.8 BYA, bacterial mats / stromatolites found in Australia

Age of anoxic photosynthesis, description

3.4 BYA, used hydrogen sulfide before water

Age of rock evidence for the release of oxygen

2.3-2.4 BYA, oxygen reacted with ferrous iron to make banded iron formations, allowed for aerobic respiration and multicellular life

Age of first cyanobacteria

2.7 BYA

Age of red/brown algae

1.2 BYA

Why has increased complexity favored?

movement and increased specialization

Evolutionary significance of stable environments

stabilizing selection with fewer extreme phenotypes, low diversity

Evolutionary significance of changing environments

preference for extreme phenotypes, causes speciation and high diversity

Meaning of inclusive fitness

the heredity of genes is the most important; even if you die, close relative may survive and pass on your genes

Minimum temperature, adaptations

-10/-15*C, increased branched fatty acids and cholesterol in membranes

Maximum temperature, adaptations

121*C, disulfide protein bonds, lipid monolayer and/or ether bonds, reverse gyrase

Minimum pH, adaptations

below 0, use electrons from ferrous iron to balance protons in the environment

Maximum pH, adaptations

around 11, use sodium pumps for ATP production

Essay ? - Nelson Conrad 1999, three categories of life

physicists - use light/heat, chemists - use chemical energy, biologists - use other organisms

Essay ? - Mariscal and Doolittle 2018, defining life

all defns of life suck, choose what you like best

Essay ? - Jeffares et al 1998, RNA world

DNA - double stranded, deoxyribose sugars, thymine | Proteins - shorter reaction times, more functional groups, precise tertiary structure, small substrates

Essay ? - Darwin's pond

favor hydrolysis, cycles of desiccation or freezing

Essay ? - Upper temperature limit

121*C, disulfide bonds, lipid monolayer and/or ether bonds, reverse gyrase