What is life

Question 1

what are requirements to be alive (4)

Answer 1

maintain internal homeostasis
respond to external stimuli
consume and produce energy
reproduce and have a form of heredity

Question 2

Maintain Homeostasis

Answer 2

cell must be able to maintain interior conditions (temp, pH, concentration of things) in the face of changing external conditions
membranes, proteins, energy consumption maintain

Question 3

External Stimuli

Answer 3

change in environment external to the organism, response can be physical or chemical

Question 4

Consume and Produce Energy

Answer 4

uses ATP in mitochondria to produce energy

Question 5

Reproduction and Heredity

Answer 5

through DNA or RNA
pass on info between generations

Question 6

Evidence for LUCA (4)

Answer 6

all extant life
is carbon-based
has similar enzymes
passes heredity info through DNA or RNA
has same chemistry of amino acids and nucleic acids (conformations)

Question 7

Primordial Soup Theory

Answer 7

monomers first
lightning or UVs entering the empty atmosphere facilitated the production of small organic monomer compounds
monomers swam around, eventually formed complex organic compounds (polymers for early cells)

no real explanation for how

Question 8

RNA World Theory

Answer 8

RNA first, can act like protein and DNA, things essential for life

Question 9

Deep Sea Hydrothermal Vent Theory

Answer 9

method to create energy first

Alkaline water from vents meets slightly acidic oceanic water, creates a proton (energy) gradient like membranes

semi-porus rocks had different concentrations building up on either side, leads to electrical potential
–> energy –> monomers and polymers

Question 10

Fossilization and its limits

Answer 10

organism dies –> no oxygen for decomposition + sedimentation –> molecules eventually replace by minerals

not equally likely in all environments, marine environments with hard parts most likely

Question 11

Chemical evidence

Answer 11

comparing carbon isotope rations ratios can suggest existence of photosynthesis in the environment (but can’t provide evidence for early forms of life)

Question 12

Molecular Clock

Answer 12

estimates divergence of two species by calculating and comparing the mutation rates in DNA over time, only works sometimes

Question 13

Stromatolites

Answer 13

colonies of bacteria
primitive photosynthesizers
deposit minerals on the lowers edges and leave behind large fossils
not the first
3.4Ga

Question 14

what did the first life likely look like?

Answer 14

simple cells
simple forms of energy generation - photosynthesis evolved much later
simple form of heredity - divided by mitosis

Question 15

Anaerobic Respiration

Answer 15

life evolved here, no free oxygen

Question 16

The great oxygenation event
~2.7GYA

Answer 16

bacteria began producing oxygen as a waste product
thought to be responsible for a significant increase in output of oxygen
oxygen began to bind to everything, created banded iron formations

Question 17

Aerobic Respiration

Answer 17

most forms of life found a way to protect themselves from oxygen
could produce much more energy to use than aerobic cells