Cellular Respiration
Overview Heterotrophs obtain glucose from plants and plant matter. The goal is to convert food energy (glucose) into chemical energy! (ATP) Why would we do this?
The process by which glucose molecules (food) are broken down and converted it into chemical energy (ATP) is called cellular respiration. Cellular respiration is a series of chemical reactions that produces ATP. The cell can then use that ATP whenever it needs it!
Two types or categories for the chemical reactions that make up cellular respiration:
Aerobic respiration: requires oxygen Produces 36 ATP molecules from each glucose molecule.
Anaerobic respiration: does not require oxygen Produces 2 ATP molecules from each glucose molecule.
Some organisms are only capable of anaerobic respiration, however; others are capable of both
Check for Understanding What is the primary difference between aerobic and anaerobic respiration? Which one makes more ATP? Respiration breaks down glucose, where do our bodies get the glucose?
The type of cellular respiration that occurs most commonly in your body cells is aerobic respiration
Think about this Think of one specific piece of evidence that supports that your cells are aerobic. Be ready to share!
Three chemical reactions make up cellular respiration There are 3 reactions as we have 3 goals. 1)Break sugar down 2)Collect Hydrogens 3)Build lots of ATP!
Both aerobic and anaerobic respiration begin with glycolysis Glycolysis is the process by which glucose is converted (changed) by being broken apart. That catabolizing releases energy Glycolysis:
Vocab Tip! Glyco is a prefix that means sugar (glucose) in Latin! And lysis is a suffix that means to split in Latin So put it all together Glyco-(sugar) lysis-(breaks)
When glucose breaks we call the new compounds made; Pyruvate. Pyruvate is a three-carbon molecule that can be further broken down in the next reaction. Glycolysis occurs in the cytoplasm of the cell Glycolysis does NOT require oxygen so we call this process anaerobic.
Most of the energy is contained in the pyruvate molecules is released in the next stage.
Think about this. When we say energy is released where does that energy actually come from in a molecule or compound? Be ready to share!
A single glucose molecule that has undergone glycolysis will produce 3 things; NADH, 2 ATP and 2 pyruvate molecules.
Check for Understanding Where does glycolysis happen? Is it aerobic or anaerobic? What is needed for glycolysis? Where do those things come from? What is produced in glycolysis? Where do those things go?
Citric Acid Cycle (Also known as the Kreb s Cycle ) The pyruvate molecules produced by glycolysis are moved into the mitochondria and are the reactants (ingredients) for the Citric Acid Cycle.
Remember, we broke (catabolized) the glucose into 2 pyruvates and so now, in the Citric Acid Cycle we can break (catabolize) those pyruvates down even more! The Pyruvates are catabolize into NADH, ATP (from ADP+P) and CO2
Notice second taxi! Why is this needed here? AND how do our H taxis differ from those in a plant?
Check for understanding Where does Krebs Cycle occur? What is the other name for Krebs cycle? What is needed for Krebs cycle Where do those things come from? What is produced in Krebs cycle? Where do those things go?
Electron Transport Chain The process by which energy is transferred from NADH and FADH2 to ATP.
The movement of electrons on Hydrogen from NADH and FADH2 occurs along a special inner membrane of the mitochondrion, called the cristae.
The hydrogen & its electron connect to oxygen across the membrane and in so doing makes water molecules. The electron transport chain generates about 36 ATP molecules produced from each original glucose molecule.
Think about this. Why can t we leave hydrogen alone? Be ready to share!
Check for understanding Where does the ETC happen? Is it aerobic or anaerobic? What is needed for the ETC? Where do those items come from? What is the ultimate electron and hydrogen acceptor?
So think about this for 1 glucose you get about 36 ATP! That is an investment that pays off big!!!
Waste products of Cellular Respiration Carbon Dioxide Water Heat Where do each of these end up?
Anaerobic Respiration
Certain cells in our body can produce energy without oxygen, mainly our muscle cells. And only if we run low on oxygen for them! Anaerobic respiration is the process that releases energy from food molecules in the absence of oxygen. Through fermentation, anaerobic organisms and your cells can exist w/o oxygen by using the small amount of energy supplied by glycolysis.
Fermentation: The breaking of glucose in glycolysis and the recycling of NAD in the absence of oxygen. Only produces 2 ATP.
Two types of Fermentation:
Alcoholic fermentation (alcohol is a waste product) Lactic acid fermentation (lactic acid is a waste product) Quick check of understanding: Name a type of organism who does alcohol fermentation. And name an organism who does lactic acid fermentation.