glycolysis and cellular respiration
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Glycolysis and Cellular Respiration . What is Photosynthesis?. Glucose. A key energy-storing molecule: Nearly all cells metabolize glucose for energy Other organic molecules are converted to glucose for energy harvesting. Overview of Glucose Breakdown. - PowerPoint PPT PresentationTRANSCRIPT
Glycolysis and Cellular Respiration
What is Photosynthesis?
Glucose
A key energy-storing molecule:Nearly all cells metabolize glucose for energy
Other organic molecules are converted to glucose for energy harvesting
Overview of Glucose Breakdown
C6H12O6 + 6O2 6CO2 + 6H2O + ATP + (heat E)
Glucose Breakdown The main stages of glucose
metabolism are: Glycolysis
Cellular respiration
Glycolysis Glycolysis
Occurs in cytosol Does not require oxygen Breaks glucose into pyruvate Yields two molecules of ATP per molecule
of glucose
Fermentation If oxygen is absent fermentation
occurspyruvate is converted into either
lactate, or into ethanol and CO2
If oxygen is present, cellular respiration occurs
Cellular RespirationOccurs in mitochondria (in
eukaryotes) In cytosol (in prokaryotes)
Requires oxygenBreaks down pyruvate into carbon
dioxide and waterProduces an additional 32 or 34 ATP
molecules, depending on the cell type
Summary of Glycolysis
Each molecule of glucose is broken down to 2 molecules of pyruvate.
A net of 2 ATP and 2 NADH molecules are formed.
Fermentation Occurs under anaerobic conditions Pyruvate is converted into lactate or
ethanol and CO2
Fermentation does not directly produce more ATP
But is necessary to regenerate NAD+, which must be available for glycolysis to continue
Fermentation Some cells ferment
pyruvate to form acids Human muscle cells can
perform fermentation Anaerobic conditions
produced when muscles use up O2 faster than it can be delivered (e.g. while sprinting)
Lactate (lactic acid) produced from pyruvate
Fermentation Some microbes ferment pyruvate to other
acids (as seen in making of cheese, yogurt, sour cream)
Some microbes perform fermentation exclusively (instead of aerobic respiration)
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Fermentation Yeast cells perform
alcoholic fermentation
Glucose is fermented to ethanol and CO2
Cellular Respiration
Occurs within mitochondria in eukaryotic cells
Electron Transport Chain Most of energy in glucose is stored in
electron carriers NADH and FADH2 Only 4 total ATP produced per glucose after
complete breakdown in the Krebs Cycle NADH and FADH2 deposit electrons into
electron transport chains in the inner mitochondrial membrane
Electrons join with oxygen gas and hydrogen ions to make H2O at the end of the ETCs
Chemiosmosis1. Energy released from electrons as they are
passed down the ETC2. Released energy used to pump H+ across
inner membrane H+ accumulate in intermembrane space
3. H+ form a concentration gradient across the membrane (a form of stored energy)
4. H+ flow back into the matrix through an
ATP synthesizing enzyme
Chemiosmosis Flow of H+ provides energy to link 32-34
molecules of ADP with phosphate, forming 32-34 ATP
ATP then diffuses out of mitochondrion and used for energy-requiring activities in the cell
Influence on How Organisms Function
Metabolic processes in cells are heavily dependent on ATP generation
Muscle cells switch between fermentation and aerobic cell respiration depending on O2 availability
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The End