L10 FIRST CELLS

Question 1

How old are the oldest microorganisms?

Answer 1

3.6 billion years old.

Question 2

What were the 4 hypothesized stages of the creation of life?

Answer 2

1. The abiotic synthesis of small, organic molecules like AA and nitrogenous bases.
2. The joinging of these molecules into macromolecules.
3. These macromolecules became enveloped with membranes that contained them into Protocells.
4. Cell characteristic like self replication began evolving.

Question 3

Why is a protocell not a real cell?

Answer 3

While both are enclosed by a membrane, protocells do not exhibit all of the life characteristics and lack essential organelles.

Question 4

How many years ago was the earth formed?

Answer 4

4.6 billion years ago.

Question 5

Describe the conditions of the Hadean period.

Answer 5

The planet had just formed, and it was very hot and volcanic. The atmosphere was a reducing atmosphere unsustainable for most life.

Question 6

What is a reducing atmosphere?

Answer 6

An atmosphere made up mainly of CO2.
Reducing refers to the addition of electrons that allows the formation of simple molecules.

Question 7

Describe the Primordial Soup hypothesis.

+ who came up with it?

Answer 7

The Oparin-Haldane Primordial Soup hypothesis states that these 4 conditions must be met in order for synthesis or organic chemicals:

1. No free O2 (reducing CO2 atmosphere only)
2. A source of energy (either from heat of volcano, UV radiation, etc)
3. Chemical building blocks (IE ions, H2O, dissolved gases.)
4. A lot of time.

Question 8

Who tested Oparin & Haldane’s theory?

Answer 8

Miller.

Question 9

What is meant by abiotic synthesis?

Answer 9

Abiotic synthesis refers to the creation of simple organic molecules (non living).

Question 10

What were the results of Miller’s experiment?

Answer 10

He could recreate simple organic molecues like AA, nucleotide bases, sugar and lipids under similar atmosphere as Hadean period.

Question 11

How did polymers synthesize?

Answer 11

With the help of energy from hot sand/rock/clay.
Amino Acid/Nucleotide + Hot sand/clay/rock = Proteins/RNA

Question 12

What three life characteristics do protocells exhibit?

Answer 12

1. Capable of replicate
2. Capable of metabolozing
3. Canable of maintaining homeostasis

Question 13

The first genetic material was likely…

Answer 13

…RNA.

Question 14

Briefly describe RNA.

Answer 14

Single strand of genetic information that can easily flex into variety of shapes.

Question 15

What is ribozyme?

Answer 15

RNA enzymes that aid in RNA replication. They are self-replicating also.

Question 16

What is sedimentary strata?

Answer 16

Sedimentary strata: compressed layers of rock/sand/mud formed over time.

Question 17

By whom were protocells replaced by?

Answer 17

Prokaryotic cells, specifically autotrophics.

Question 18

Why is the fossil record biased? (2)

Answer 18

1. Species that were very abundant and widepsread were more likely to be fossilised
2. Species with hard body parts like bone skeledons were able to be better preserved.

Question 19

What is a stromalite?

Answer 19

Rock-like structure composed of cyanobacteria and sediment.

Question 20

When did prokaryotes dominate?

Answer 20

3.5 to 2.0 billion years ago.

Question 21

Whats the difference between photosynthesis and chemosynthesis?

Whats the molecule?

Answer 21

Light energ replaced by Hydrogen sulfide H2S.

Question 22

What did cyanobacteria do for the environment?

Answer 22

Convert CO2 to O2, catalyzing the oxygen revolution.

Question 23

Whe did eukaryotic life begin?

Answer 23

2.1 billion years ago.

Question 24

How did eukaryotes evolve from prokaryotes?

Answer 24

Through developed symbiotic relationships.

Question 25

What do all eukaryotic cells that prokaryotic/protocells do not have? (2)

Answer 25

1. Nucleus
2. Endomembrane system.

Question 26

What is endosymbiont theory?

Answer 26

The theory that eukaryotes arose from porkaryoes.

Question 27

What are the two organelles theorized to have been prokaryotes that formed symbiosis with other prokaryotes?

Answer 27

Mitochondria and chloroplasts.

Question 28

Who came first: mitochondria or chloroplast?

Answer 28

Mitochondria. Reasoning: Not all eukaryotic cells have chloroplasts, but they all have mitochondria.

Question 29

Name characteristics of mitochondrion and chloroplasts. (4)

Answer 29

1. About the size of bacterial cells
2. Have a double membrane
3. Have circular DNA
4. Have their own ribosomes & protein synthesis machinery.

Question 30

Briefly describe the entire sequence of events that lead to eukaryotes.

Answer 30

1. no free o2+energy+chemical blocks+time created simple molecules. these simple molecules formed macromolecules, then protocells, then prokaryotes, then prokaryotes formed symbionts with each other to greate eukaryotic cells.