Astrobiology - Structure of Life

What is the name for ordinary matter?

Baryonic matter

What forms protons and neutrons?

Quarks

What is a nucleon?

Protons and neutrons

What is kB?

Boltzmann constant

Equation linking kB, energy and temperature

E = kBxT

What is plasma?

Hot ionised gas

What are the CHNOPS elements?

Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur

Why is Silicon not found in life?

Bonds strongly to Oxygen

Where is Silicon found in life?

Phyloliths in plants (provides stability)

Are amino acids in life right or left handed?

Left (except glycine)

Are sugars in life right or left handed?

Right

Why might ammonia be a good solvent for life?

Dissolves chemicals, high heat of vapourisation, high heat capacity

How big are eukaryotes?

10-100 um

How big are prokaryotes?

1-10 um

Why is having only one phylogenetic tree sig?

Suggests life only evolved once (life is unusual)

What is the 'mesh' called that protects cells?

Peptidoglycan

What enzyme unwinds the DNA dbl helix?

topoisomerase

Why are microbes not 'simple life'?

have chemotaxis, can move, same evolution period

What shows an absorption on a graph?

A dip/trough

What is an emission spectra?

photons produced by an energised gas, element or molecule

What is a protoplanetary disk?

Planet forming regions of dust around stars

How hot is the outer disk of a protoplanetary disk?

10K

How hot is the inner disk of a protoplanetary disk at 10AU?

100K

How hot is the inner disk of a protoplanetary disk at 1AU?

1000K

What happens at the inner disk of a protoplanetary disk?

Ice evaporates

What is present on the outer disk of a protoplanetary disk?

Frozen molecular gas on dust grains

What type of molecules are formed in protoplanetary disks?

Complex molecules (sugars and bases)

What evidence is there for the formation of complex molecules in protoplanetary disks?

Molecules present on asteroids (left over material from planet formation)

What are grains in space?

Solid silicaceous/carbonaceous material with ice on exterior

Why are grains significant for chemistry?

Solid surface for reactions

Why is chemistry difficult in space?

Low temperatures and pressures

What are PAH's?

Polycyclic aromatic hydrocarbons

Why are PAH's significant?

Stable

What can PAH's react to form?

Complex, ringed carbon compounds (e.g. fullerenes and quinones)

Define catabolism

Process of an organism obtaining energy and raw materials from nutrients.

Define anabolism

Process of an organism using energy and raw materials for biosynthesis

Define metabolism

Processes of catabolism and anabolism

Prefix for organisms that obtain energy from light

Photo

Prefix for organisms that obtain energy from chemical compounds

Chemo

Prefix for organisms that obtain Carbon from CO2

Auto

Prefix for organisms that obtain Carbon from organic compounds

Hetero

Prefix for organisms that obtain Carbon from both CO2 and organic compounds

Mixo

What order are proteins in the ETC in?

Increasing electronegativity

What does electron movement generate?

Free energy

What is pmf?

Proton motive force

Equation linking pmf, water potential, R, T, F and pH?

pmf=△waterpot. - (2.3RT/F)(△pH)

How is pmf generated?

Pumping protons across a membrane

What is the final electron acceptor in anaerobic respiration?

Inorganic Molecules (not oxygen)

What is the final electron acceptor in aerobic respiration?

Oxygen

Example of an organism uses nitrates as its final electron acceptor?

Pseudomonas

What is another name for a chemoautotroph?

Chemolithotroph (rock eater)

What does anoxygenic photosynthesis use?

Sulfur (or sulfide)

Example of an organism that uses anoxygenic photosynthesis

Chlorobium

What is the word used to describe a reaction with a negative free energy change?

Exergonic (energy given out)

What is the word used to describe a reaction with a positive free energy change?

Endergonic (energy taken in)

What is the word used to describe a reaction with a free energy change of zero?

Equilibrium

Equations for Gibbs Free Energy change

△G = -nFE and △G = -2.303(pE)

What is pE analogous to?

pH

Equation for pE

pE = EF/2.303RT

Where on the electron tower are the best electron donors (oxidisers) found?

Top/higher (more negative value)

Define phylogeny

Evolutionary history of a species or group of species.

What area of science classifies organisms and determines their evolutionary relationships?

Systematics

Define analogy

Similarity due to convergent evolution

Define homology

Similarity due to common ancestry

What is a good molecule to analyse to determine evolutionary relationships?

rRNA (highly conserved)

What can phylogenetic tree branches represent?

Number of genetic changes OR chronological time

What is the name for the technique that allows predictions about features of a common ancestor?

Phylogenetic bracketing

What are the three methods of horizontal gene transfer (HGT)?

Transformation, transduction and conjugation

Where does genetic info come from in transformation HGT?

Environment

Where does genetic info come from in transduction HGT?

Microbes via an agent (e.g. a virus(bacteriophages))

Where does genetic info come from in conjugation HGT?

A pilus from one bacterium to another (usually plasmids)

What can HGT lead to?

Antibiotic resistance

What domain are most extremophiles from?

Archea

What temperature range can Tardigrades endure?

151 to -200 degrees celcius

What pressure range can Tardigrades endure?

Vacuum to 1200x atm

How long can Tardigrades survive without water?

10 years

What radiation can Tardigrades endure?

1000x more ionising

What are organisms that live in hot environments called?

Thermophiles (50-80 degrees), Hyperthermophiles (80+ degrees)

What are organisms that live in salty environments called?

Halophilic

What is an adaptation to a hot environment?

Modified cell membrane compositions to prevent increased fluidity

What is an adaptation to a cold environment?

Double bonds to prevent close packing and so increase membrane fluidity

What is an adaptation to a saline or dry environment?

Control of water loss and cell dormancy to overcome issues with osmotic pressure and water availability

What are most extremophiles (energy and carbon source)?

Chemolithotrophs

What is the name for organisms that live in multiple extreme environments?

Polyextremophiles

How could extremophiles be used in space?

Oxygen production, nitrogen fixation

Why are hydrogen bonds used between bases in DNA?

Require little energy to overcome (replication easier)

What type of bonds are more common in extreme environments?

Covalent and Ionic (strong)

Why is water's negative melting curve on phase diagrams significant?

Ice floats so water environment more stable below

What is degenerate matter?

Free, non-interacting particles (more dense than a solid)

Where is degenerate matter found?

White dwarfs, neutron stars

Why is carbon the basis of life?

Bonds to itself (chains), stable bonds

Why is water a good solvent?

Polar (dissolves ions), abundant, stable

Why is radiation important for chemistry?

Transfers energy

Why does HGT make building phylogenetic trees difficult?

Gene transfer between non-related organisms