Download Cellular respiration *vs

Cellular respiration –vsPhotosynthesis
You realize already that photosynthesis and
cellular respiration are opposites of each other
and both very necessary for life.
What is cellular respiration?
• When you and I eat---our body must digest the food so it can be used by
our body.
• It must be broken down very small to do this. It is broken down into tiny
“GLUCOSE” molecules:
•C6H12O6
We also need oxygen which we breath in…
• The oxygen travels from our lungs through our bloodstream into small
and then smaller and then smaller blood vessels until it reaches our cells.
Once the glucose and oxygen reaches our
cells-we have what we need for respiration.
• To even get more precise…the process starts in the cells’ cytoplasm
and is completed in the mitochondria. That is why we often refer to
the mitochondria as the POWERHOUSE of the cell---it supplies our
body with the energy.
So what does the mitochondria do—how the
power?
• The tiny organelle mitochondria takes one molecule of glucose (sugar)
and 6 molecules of oxygen and changes it into 36 molecules of ATP
which is energy for the cells to get things done.
Example: This is in an animal—such as you
and I:
• We eat some food……
• It begins to digest and breaks down into carbohydrate molecules:
Next the carbohydrate molecules will break down
into glucose molecules: Our body turns all sugars
into glucose which is what our body runs on.
Next step …
• 4 glucose molecules + oxygen from our breathing are converted in the
cells to energy in the form of ATP.
• Cellular respiration (a three stage process) converts glucose and
oxygen to ATP. ATP is the energy in a cell. This process converts
glucose and oxygen to ATP and releases carbon dioxide and water.
Here is the formula:
On your handout notice that 1 molecule of
glucose + 6 molecules of oxygen are changed into
about 36 molecules of ATP + 6 molecules of water
and 6 molecules of carbon dioxide.
Plants and Photosynthesis
• Photosynthesis creates glucose molecules (instead of eating).
• This glucose made in the plant is then used to fuel cellular respiration
in the plant cells. It is used to create ATP and fuels plant growth and
reproduction.
• The plants then provide carbohydrates to animals for their cellular
respiration. The cycle continues again and again and again.
• The formula in plants is:
Compare the equations side by side:
So what do we use ATP for?
• Our cells use ATP as the energy required so they can do their work.
This allows the body to function smoothly---to do work like: breathe,
circulate blood, digest, respond to stimuli, create new cells, repair and
grow, move our muscles, etc.,---everything you do uses energy.
There are 3 phases to convert glucose and
oxygen to ATP:
•1. Glycolysis: this process that takes 1
glucose molecule, in the cell’s cytoplasm
and breaks it down into 2 molecules of
pyruvate which is used in the Kreb’s cycle
(stage 2). This stage also releases 2 ATP and
2 water molecules. Also released are 2
•molecules of NADPH
(Helps the body make sugar later on)
Kreb’s Cycle:
• This is a very fancy biological cycle that basically goes through several
steps and generates 4 CO2 molecules and 2 ATP molecules. (There are
other molecules made but you do not need to know them at this
point. Here is a picture so you can see how complicated this gets:
The Electron Transport Chain (ETC) Stage 3
• This final stage is found in the mitochondria in animals and in the
chloroplasts in plants. It will release 32-34 ATP molecules which is
used as energy. Again, complicated and not for the scope of this class.
So—can energy be produced without oxygen?
YES!! It is called “Fermentation.”
• Sometimes we do not get as much oxygen to our cells as they prefer.
If you remember the word anaerobic—means w/o oxygen--fermentation is a form of anaerobic respiration.
• Because there is no oxygen for use the ATP for energy is much less.
This fermentation occurs in the cytoplasm of the cell and produces
only 2 molecules of ATP—Therefore, this is not as efficient of an
energy path to follow.
• So where does this fermentation occur—have you every been sore
after a hard workout or from playing a sport you have not done for a
long time? That muscle soreness is from your body not having enough
oxygen so you get lactic acid inside your muscles which = SORE!!
Where else do we see fermentation?
• It is used in the making of wine and beer. Yeast cells generate the ATP
from fermentation of the sugars in the fruit and grain (in the absence
of oxygen). Other foods are made that way also:
Conclusion:
• We need ATP to have our bodies run smoothly. We eat food for
bodies to digest and go through several cycles to make the ATP
molecules we need. This can be done with oxygen or without
oxygen—BUT, we get much more ATP (36) with oxygen than with
fermentation (2).
• The chemical equations for cellular respiration and photosynthesis
are complete opposites. We need what the plant throws out (O2) and
they need what our bodies throw out (CO2).
• It is a very complicated cycle—made simple in this PPT and your study
sheets. Study your diagrams and readings for your test.
Cellular Respiration Picture
Photosynthesis
OK then----Done 