Midterm 2 Study Guide Flashcards

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1
Q

When did Earth start to form?

A

4.6 billion years ago

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2
Q

When was the first evidence of photosynthetic cells?

A

3.2-2.5 billion years ago

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3
Q

During what period was there a reducing atmosphere?

A

Precambrian Period

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4
Q

What is a reducing atmosphere?

A

An atmosphere that contains compounds that remove oxygen from metals and other materials leaving little to no free oxygen

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5
Q

What produced the oxygen in a reducing atmosphere?

A

Photosynthetic bacteria

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6
Q

What are the two characteristics of the Precambrian Period?

A

1.) Life is mostly unicellular

2.) Reducing atmosphere where photosynthetic bacteria produced oxygen

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7
Q

What is the Heterotroph Hypothesis?

A

Life on earth developed through gradual chemical evolution of carbon-based molecules in a “primordial soup”

In this hypothesis, earth’s atmosphere was reducing, which allowed biochemically important compounds to be produced abiotically and to be concentrated. Early cells could then feed on these compounds

(The first cells were heterotrophic and fed on organic molecules that were not produced by cells)

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8
Q

Who proposed the Heterotroph HYpothesis?

A

Oparin

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9
Q

When was the atmosphere reducing?

A

4.2 billion years ago to 2.5 billion years ago

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10
Q

What did the rise of photosynthetic organisms do?

A

Change the atmosphere to oxidizing

This also ends the reducing atmosphere hypothesized to be suitable for the origin of life in the Heterotroph Hypothesis

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11
Q

What molecules tend to be mainly present in a reducing atmosphere?

A

H2, NH3, H2S, H2O, CH4

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12
Q

What molecules tend to be mainly present in an oxidizing atmosphere?

A

N2, O2, H2, CO2, NOx

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13
Q

In order to support the Heterotroph Hypothesis, who tested whether or not small organic molecules could be formed abiotically under specified conditions?

A

Miller and Urey (1935) and Joan Oro (1954)

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14
Q

What molecules were used in Miller and Urey’s experiment and what did they produce?

A

CH4 + NH3 + H2O + Energy

15% of the carbon in the system was used to produce organic materials and 5% of the materials produced are biochemically important

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15
Q

What molecules were produced in Oro’s experiment and what did they produce?

A

HCN + NH3 + Energy

Produced adenine

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16
Q

What are protocells?

A

Vesicles

17
Q

What are liposomes?

A

Small, fatty globules

18
Q

What are coacervate droplets?

A

Protein-based spheres that are common in solutions

19
Q

When can some properties associated with living organisms can emerge from nonliving organisms

A

When molecules interact and are organized into higher levels of order

20
Q

What are membranes made of?

A

Amphiphiles

21
Q

What are amphiphiles?

A

Molecules with parts that are hydrophilic and parts that are lipophilic (fat loving)

The hydrophilic head interacts with water solutes on the inside and outside of the cell

Hydrophobic/liphophilic tails are double layered

22
Q
A