Transcript CellularRespirationglycolysis

Cellular Respiration
Chapter 7 pgs 131-147
Food to energy
Harvesting Chemical Energy
• From photosynthesis
we get carbohydrates
(glucose)
• Cellular respiration:
Breaking down the
carbohydrates
(glucose) to make ATP
and NADH
– NADH is an electron
carrier
• Starts with glycolysis
– Glyco = sugar
– Lysis = breaking
– Breaking down sugars
What happens after Glycolysis?
• Chemicals can take
one of two pathways
– Anaerobic (no oxygen
present) fermentation
• Makes no ATP, but
keeps the cycles going
– Aerobic respiration
• Makes a lot of ATP
Glycolysis
• 1 six carbon
glucose broken
down into 2
three carbon
pyruvic acid
molecules
• Happens out in
the cytoplasm
What
happens
next
depends on
whether
there is
oxygen
present or
not.
Fermentation
• If there is no oxygen some cells can
convert pyruvic acid into other compounds
and get some more NAD+
• No ATP is made, but the NAD+ can keep
Glycolysis going to make a little ATP
• 2 kinds of fermentation: Lactic acid
fermentation and Alcoholic
Fermentation
Lactic Acid Fermentation
• Converting pyruvic acid to Lactic
acid
– A.K.A. milk acid
• Bacteria are used to do this to get
cheese, yogurt, and sour cream
• Under heavy exercise you use up
Oxygen faster than you can
replace it
– Lactic Acid builds up and the acidity
causes fatigue, pain and cramps.
Alcoholic Fermentation
• Yeast convert pyruvic acid
into ethyl alcohol
• They break a CO2 off of
pyruvic acid
• The 2 carbon sugar left
behind forms ethyl alcohol
• Basis of wine and beer
industry, and bread making
Efficiency of Glycolysis
• Compare the kilocalories of Glucose with
the kilocalories in the ATP that is made.
• The 2 ATP molecules made during
glycolysis receive only 2% of the energy in
glucose
– Where does the rest go?
• It’s still in pyruvic acid
• This small amount of energy is enough for
bacteria, but more complex organisms
need more of glucoses energy.
Objectives
• Define Cellular respiration
• Describe the major events in glycolysis
• Compare and contrast lactic acid
fermentation and alcoholic fermentation
• Calculate the efficiency of glycolysis