Chapter 21 - Defining Life & Its Origins

Question 1

emergent properties (of life)

Answer 1

New property that forms when simpler objects associate to increase the complexity of the resulting combination.

Question 2

Protobionts

Answer 2

The term given to a group of abiotically produced organic molecules that are surrounded by a membrane or membranelike structure.

They are microspheres composed of inorganic and organic molecules trapped inside of a lipid bilayer membrane

Question 3

ribozyme

Answer 3

ribozyme is a ribonucleic acid (RNA) enzyme that catalyzes a chemical reaction. The ribozyme catalyzes specific reactions in a similar way to that of protein enzymes

Question 4

heterotrophs

Answer 4

An organism that acquires energy and nutrients by eating other organisms or their remains.

Question 5

autotrophs

Answer 5

An organism that produces its own food using CO2 and other simple inorganic compounds from its environment and energy from the Sun or from oxidation of inorganic substances.

Question 6

endosymbiosis

Answer 6

A symbiotic association in which one symbiont or partner lives inside the other.

Question 7

endomembrane system

Answer 7

In eukaryotes, a collection of interrelated internal membranous sacs that divide a cell into functional and structural compartments.

Question 8

7 characteristics exhibited by life

Answer 8

1. display order
2. harness and utilize energy
3. reproduce
4. presond to stimuli
5. exhibit homeostasis
6. grow and develop
7. evolve

Question 9

4 hypothesized steps to evolution of life

Answer 9

1. Formation of polymers and monomers
2. Self-replication of RNA
3. Association between amino acids and nucleotides
4. Formation of membrane-enclosed compartments
5. Development of metabolic pathways

Question 10

Miller-Urey Experiment (abiotic formation of molecules)

Answer 10

The Miller–Urey experiment was a chemical experiment that simulated the conditions thought at the time to be present on the early Earth and tested the chemical origin of life under those conditions

demonstrated that organic molecules can be synthesized under conditions simulating primordial Earth

Question 11

reducing atmosphere

Answer 11

hydrogen (h2)
carbon dioxide (CO2)
ammonia (NH3)
methane (CH4)

Question 12

organic compounds formed by Miller experiment

Answer 12

urea, amino acids, lactic, formic, acetic acids

Question 13

key events in timeline of life

Answer 13

1. arrival of stardust containing elements C,N,O, and H
2. accumulation of Co2 in atmosphere and liquid h20
3. Appearance of sugars such as glucose
4. spontaneous assembly of polysaccharides (multiple monomers “simple sugars”
5. appearance of self-replicating RNA
6. first occurence of DNA-encoded protein synthesis
7. first appearance of endomembrane system

Question 14

age of planet

Answer 14

`4 billion years ago

Question 15

Oparin-Haldane hypothesis

Answer 15

life arose gradually from inorganic molecules, with “building blocks” like amino acids forming first and then combining to make complex polymers.

early atmosphere was a reducing atmosphere because of the presence of large concentrations of molecules such as hydrogen, methane, and ammonia. These molecules contain an abundance of electrons and hydrogen, and they would have entered into reactions with one another that would have yielded larger and more complex organic molecules.

uv light reaching earth in absence of oxygen, and lightning provided energy to drive formation of biological molecules

Question 16

When cyanide and formaldehyde were added to the simulated primitive atmosphere in Miller’s apparatus, what other building blocks were formed?

Answer 16

amino acids; fatty acids; the purine and pyrimidine components of nucleic acids; sugars such as glyceraldehyde, ribose, glucose, and fructose; and phospholipids

Question 17

3 hypothesis of initial abiotic synthesis

Answer 17

reducing atmosphere, deep-sea vents, and extraterrestrial origins.

Question 18

clay hypothesis

Answer 18

demonstrate that the formation of short nucleic acid chains and polypeptides can be synthesized on a clay surface

polymerization in absence of enzymes