The Earth is pretty old. Our current, best estimate is that it is 4.54 billion years old, plus or minus 50 million years. Since then, however, a lot has happened. To help clarify the Earth’s timeline, geologists have divided the Earth’s history into various eras and periods. Each division of time represents a change in something, which happened on the planet. Learn more about the Earth’s history and geologic time scales, on this episode of Everything Everywhere Daily.  This episode is sponsored by the Tourist Office of Spain In Spain, you can find accommodations like you can find everywhere else: hotels of all luxury levels and even hostels. However, you also find something in Spain that you can’t find everywhere: Paradores. A Parador is a luxury accommodation usually in a refurbished historic building, like a monastery or a castle, or in a modern building with a panoramic view.  There is an official network of over 90 Paradores scattered all over the country in every region.  In my many trips to Spain, I’ve stayed at several Paradores, and it is always a unique experience that adds an extra cultural element to every trip. I’ve stayed at ones in Guadalupe, Cáceres, and Costa Brava. You can research visiting one of the many Paradores in Spain before your next visit by going to Spain.info.  Once again, that is Spain.info. The Earth is so old, that to make sense of its history, geologists have come up with divisions. These divisions are very broad and cover millions to billions of years, depending on what the division is. Each division also has subdivisions that can themselves be further subdivided. The three primary temporal divisions of Earth’s history are eons, eras, and periods.  An eon is a very broad division of history, and there have really only been three eons. The Archean, which goes from the formation of the Earth to about 2.5 billion years ago. The Proterozoic, which goes from 2.5 billion years ago to about 540 million years ago, and the Phanerozoic, which goes from 540 million years ago to today.  There is also sometimes a fourth eon called the Hadean which would be from the formation of the Earth to 4 billion years ago, but it is really hard to study that period by itself, so it is often just lumped with the Archean.  I actually studied geology and geophysics for several years, and the use of eons seldom came up. Occasionally you would hear about the Archean, but the other eons are so broad as to not generally be useful.  The Archean is the period where continents started to form and the very simplest life began. The Proterozoic is the eon where oxygen appeared, up to the beginning of complex multi-cellular life. In the Archean and Proterozoic, there is little to nothing in the way of fossils, because there was nothing that could become fossilized yet. There are some fossilized stromatolite beds, which are mats of bacteria, but that is about it.  The rest of this episode will focus on the Phanerozoic Eon. That is whe

1. 1

2. ATTENDANCE

3. PRAYER

4. KREB’S CYCLE
A process whereby the pyruvic acid in Glycolysis diffuses into a
cellular organelle called mitochondrion that hosts a large
surface area of respiration to occur.
The pyruvic acid is then subjected to more enzymes which
break it down into a 2 carbon compound that is always present
in the cycles, which in turn combines with oxygen present in
aerobic respiration, releases CO2. hence the need for animals
to breath out and expel this CO2. Enzymes oxidize the carbon
compounds and transport the hydrogen atoms to the electron
transport chain (cytochrome system)

5. ELECTRON TRANSPORT CHAIN
- also known as hydrogen carrier system, which happened in the cristae
of the mitochondria, where the reduced hydrogen carries transport
hydrogen atom, some of the coenzymes A are transferred to the next
coenzymes B, which is then oxidize and in turn released hydrogen and
energy is made available.
The released atom binds with 2 oxygen atoms, which in turn produces
water, a by-product of respiration. Overall, from 1 glucose plus 6 O
produces 6 CO , 6 H O, and a net gain of 36 ATP (Figure 6.7).
Therefore, the ultimate goal of cellular respiration is to take
carbohydrates from the food we eat, disassemble them into
glucose molecules, and then use this glucose to produce energy-rich
ATP molecules that will be utilized in all metabolic activities by the cells
of our body.

6. When oxygen is not present (anaerobic
respiration), the pyruvic acid is broken down
into 2 carbon dioxide gas, which causes bread
dough to rise, and 2 ethyl alcohol (ethanol) in
plant cell, which is used in the wine and beer
making or 2 lactic acid in animal cell, which
causes muscles fatigue. Anaerobic cellular
respiration known as fermentation process.
Process in which glucose is broken down in the
absence of oxygen to supply a cell with energy.
This process produces only two ATP and is
much less efficient than glycolysis

7. FERMENTATION
When oxygen is not present,
glycolysis is followed by a different
pathway, called fermentation.
Fermentation releases energy from
food molecules in the absence of
oxygen. There are two types of
fermentation, alcoholic and lactic
acid fementation.

8. Alcoholic fermentation. Yeasts and other few
microorganism uses alcoholic fermentation,
forming ethyl alcohol , carbon dioxide and water.
Pyruvic acid + NADH alcohol + CO2 + NAD
Alcoholic fermentation causes to rise. When the
yeast on the dough runs out of oxygen, it begins to
ferment, giving of bubbles of CO2.
+

9. Lactic acid fermentation. In many cells, the pyruvic acid
that accumulate as a result of glycolysis can be
converted to lactic acid. This process regenerates NAD
so that glycolysis can continue.
Pyruvic acid +NADH Lactic acid + NAD
Lactic acid is produced in your muscles during rapid
exercise when the body cannot supply enough oxygen
to the tissues. Without enough oxygen, the body is not
able to produce all of the ATP that is required. When you
exercise vigorously, the muscles quickly run out of
oxygen. The muscles cell rapidly begin to produce ATP
by lactic acid fermentation. The build-up of lactic acid
causes a painful, burning sensation.

10. TABLE 6.2 DIFFERENCES BETWEEN AEROBIC AND
AN ANAEROBIC RESPIRATION
Aerobic respiration Anaerobic respiration
Occurs in the presence of oxygen Occurs in the absence of oxygen
Complete breakdown of organic food Incomplete breakdown of organic
food
All hydrogen atoms in the glucose are
replaced
All hydrogen atoms in the glucose are
not replaced
Releases relatively large amount of
energy
Releases relatively small amount of
energy
Waste products are carbon dioxide
and water
Produces carbon dioxide and ethanol
in plants, and lactic acid in animal