Introduction to Biology. Lecture 9
Alexey Shipunov
Minot State University
February 3, 2017
Shipunov (MSU)
BIOL 111
February 3, 2017
1 / 27
Outline
1
Where we are?
Photosynthesis
2
Archean eon
First Life
First fossil cells
3
Cell
Prokaryotic cell
How to be a prokaryote
Shipunov (MSU)
BIOL 111
February 3, 2017
2 / 27
Outline
1
Where we are?
Photosynthesis
2
Archean eon
First Life
First fossil cells
3
Cell
Prokaryotic cell
How to be a prokaryote
Shipunov (MSU)
BIOL 111
February 3, 2017
2 / 27
Outline
1
Where we are?
Photosynthesis
2
Archean eon
First Life
First fossil cells
3
Cell
Prokaryotic cell
How to be a prokaryote
Shipunov (MSU)
BIOL 111
February 3, 2017
2 / 27
Where we are?
Photosynthesis
Where we are?
Photosynthesis
Shipunov (MSU)
BIOL 111
February 3, 2017
3 / 27
Where we are?
Photosynthesis
Photosynthesis
light, chlorophyll
CO2 + H2 O −−−−−−−−−−−−−→ carbohydrates + O2
Two stages:
A
B
Light-dependent: production of energy (ATP) and photolysis of
water
Light-independent: assimilation of CO2 into carbohydrates
Then carbohydrates are partly converting into lipids; with addition
of N—into amino acids; with addition of N and P—into nucleotides
Shipunov (MSU)
BIOL 111
February 3, 2017
4 / 27
Where we are?
Photosynthesis
ATP
Universal energy source in the cell, “universal currency”
ATP → ADP + P + energy
Shipunov (MSU)
BIOL 111
February 3, 2017
5 / 27
Archean eon
First Life
Archean eon
First Life
Shipunov (MSU)
BIOL 111
February 3, 2017
6 / 27
Archean eon
First Life
Oxygen and iron
Initially, Earth atmosphere contained no oxygen
Photosynthetic oxygen oxidized free iron into quartzite-like rocks
contained hematite and other iron minerals
New iron was always replenished from ocean water
However, ≈2000 Mya, when Proterozoic eon started, almost all
iron went deeper into mantle and core
Shipunov (MSU)
BIOL 111
February 3, 2017
7 / 27
Archean eon
First Life
Wheeler Peak, NV
Shipunov (MSU)
BIOL 111
February 3, 2017
8 / 27
Archean eon
First Life
Hematite
Shipunov (MSU)
BIOL 111
February 3, 2017
9 / 27
Archean eon
First Life
From oxygen oases to oxygen revolution
In Archean, photosynthesis could only produce local “oxygen
oases”
But when no free iron was available anymore, atmosphere started
to accumulate oxygen
When oxygen reached 1% (Pasteur point), aerobic life started
This was the oxygen revolution which allowed cells to obtain
energy via respiration
Shipunov (MSU)
BIOL 111
February 3, 2017
10 / 27
Archean eon
First Life
Fermentation versus respiration
carbohydrates → CO2 + ethanol + 2 ATP
carbohydrates + O2 → CO2 + H2 O + 38 (!!!) ATP
Which is better? Do not forget however that oxygen is highly
poisonous and destructive molecule.
Shipunov (MSU)
BIOL 111
February 3, 2017
11 / 27
Archean eon
First fossil cells
Archean eon
First fossil cells
Shipunov (MSU)
BIOL 111
February 3, 2017
12 / 27
Archean eon
First fossil cells
First and second
Stromatolites: microbial mats from (mostly) cyanobacteria
(photosynthetic bacteria)
Metallogenium and others: proteobacteria (e.g., aerobic
metal-oxidizing bacteria)
Shipunov (MSU)
BIOL 111
February 3, 2017
13 / 27
Archean eon
First fossil cells
Fossil stromatolite
Shipunov (MSU)
BIOL 111
February 3, 2017
14 / 27
Archean eon
First fossil cells
Oldest stromatolite: Isua, Southern Greenland
3.7 Myr!
Shipunov (MSU)
BIOL 111
February 3, 2017
15 / 27
Archean eon
First fossil cells
Pesent-day stromatolite (Shark Bay, Australia)
Shipunov (MSU)
BIOL 111
February 3, 2017
16 / 27
Archean eon
First fossil cells
Present-day iron-oxidizing bacteria
Shipunov (MSU)
BIOL 111
February 3, 2017
17 / 27
Archean eon
First fossil cells
Fossil Metallogenium
Shipunov (MSU)
BIOL 111
February 3, 2017
18 / 27
Archean eon
First fossil cells
First life
In Archaean, cyanobacteria (fossilized as stromatolites) were first
Photosynthesis changed the atmosphere
Aerobic life respires to obtain more ATP
Shipunov (MSU)
BIOL 111
February 3, 2017
19 / 27
Cell
Prokaryotic cell
Cell
Prokaryotic cell
Shipunov (MSU)
BIOL 111
February 3, 2017
20 / 27
Cell
Prokaryotic cell
Prokaryotic cell
Shipunov (MSU)
BIOL 111
February 3, 2017
21 / 27
Cell
Prokaryotic cell
Main components of prokaryotic cell
Cell wall
Membrane
Cytoplasm
DNA
Ribosomes
Membrane folds and pockets
Vesicles
Flagella
Shipunov (MSU)
BIOL 111
February 3, 2017
22 / 27
Cell
How to be a prokaryote
Cell
How to be a prokaryote
Shipunov (MSU)
BIOL 111
February 3, 2017
23 / 27
Cell
How to be a prokaryote
How to make energy
Two ways:
Cell respiration and other destructive processes make ATP for all
cell
Photosynthesis and other synthetic processes make ATP (but
later, they spend it)
Shipunov (MSU)
BIOL 111
February 3, 2017
24 / 27
Cell
How to be a prokaryote
How to make proteins
To build factory, we need energy (see before) and also need machines.
These are proteins. To build machines from scratch, we need
instruction books. This is DNA. To work with instructions, it is better to
keep them in library but copy only some pages for immediate use.
These are RNAs.
DNA and RNA contain four types of nucleotides
The sequence of nucleotides is a cypher
Each tree nucleotides will encode amino acid (“genetic code”)
Ribosomes translate triplets into amino acids and make proteins
Shipunov (MSU)
BIOL 111
February 3, 2017
25 / 27
Cell
How to be a prokaryote
Summary
Bacteria were first
Photosynthesis changed the atmosphere
Aerobic life respires to obtain more ATP
Prokaryotic cells are simplest cells
Shipunov (MSU)
BIOL 111
February 3, 2017
26 / 27
Cell
How to be a prokaryote
For Further Reading
Photosynthesis.
http://en.wikipedia.org/wiki/Photosynthesis
(introduction)
Cellular respiration.
http://en.wikipedia.org/wiki/Cellular_respiration
(introduction)
Shipunov (MSU)
BIOL 111
February 3, 2017
27 / 27