Download College Prep Cellular Respiration Notes: H.B.3A.4 Harvesting

College Prep Cellular Respiration Notes: H.B.3A.4
Harvesting Chemical Energy
• The food you eat cannot be used by cells directly.
• Cells have only one usable energy form, ATP (adenosine triphosphate).
• Cellular Respiration is the complex process in which cells make ATP by breaking down organic compounds.
• Any food (organic) molecule, or nutrient, including carbohydrates, fats/lipids, and proteins can be processed and
broken down as a source of energy to produce ATP molecules.
• nutrients + oxygen  water + energy (ATP) + carbon dioxide
What is the ATP produced during cellular respiration used for?
• ATP can then release the energy for cellular metabolic processes:
– Active transport - Protein Synthesis - Muscle Contraction
What type of organism carry out cellular respiration?
• Autotrophs
– Use the glucose created during photosynthesis
• Heterotrophs
– Use organic compounds that are harvested from digestion
Cellular Respiration Occurs in Two Stages
• Step 1: Glycolysis
– Glyco = Sugar
-Lysis = To Break Apart
If Oxygen is available:
• Step 2: Aerobic Respiration : Aerobic = requires oxygen
– The two steps of aerobic respiration are:
1. Citric acid cycle or Krebs cycle
2. Electron Transport Chain
Where Does Cellular Respiration Occur?
 Glycolysis occurs in the cytoplasm
• The Krebs cycle occurs in the mitochondria
Review of Mitochondria Structure
• Smooth outer Membrane
• Folded inner membrane
• Folds called cristae
• Space inside cristae called the matrix
Many Reactions in Cellular Respiration are REDOX reaction
• A chemical reaction in which there is the transfer of one or more electrons from one reactant to another.
• Oxidation is the loss of electrons
• Reduction is the gain of electrons.
• Because the electron transfer requires a donor and an acceptor, oxidation and reduction always go together.
What Carries the Electrons?
• NAD+ (nicotinadenine dinucleotide) acts as the energy carrier
• NAD+ is a coenzyme
• It’s reduced to NADH when it picks up two electrons and one hydrogen ion
Glycolysis
• Breaks down glucose into 2 Pyruvate molecules (aka pyruvic acid)
• Anaerobic = Does not require Oxygen
• Carbon Dioxide is released
• Net of 2 ATP molecules are made
• Occurs in a series of reactions that are catalyzed by specific enzymes
Summary of Glycolysis ****THIS WILL BE ON THE TEST*****
Location
ATP USED
ATP created
Net ATP
Product
Cytoplasm
2
4
2
2 Pyruvates
The Kreb’s Cycle: A Little History
• Discovered by Hans Krebs in 1937
• He received the Nobel Prize in physiology or medicine in 1953 for his discovery
• Forced to leave Germany prior to WWII because he was Jewish
The Krebs Cycle
• Sometimes called the Citric Acid Cycle
• Requires oxygen = aerobic
• Takes place in the mitochondria
• Has a second step: Electron Transport Chain (ETC)
Summary Krebs Cycle
It takes two turns in the cycle to break down one molecule of glucose.
Location
Reactants
Products
Mitochondrial Matrix
Pyruvic acid
4CO2molecules
6NADH
2FADH2
2ATP
The Second Step: Electron Transport Chain (ETC)
• Most of the energy storing ATP molecules are formed during this step.
• Series of chemical reactions that combine hydrogen + oxygen to make water.
• CO2 is released as a waste product
• 34 ATP molecules produced
Adding up ATP
Step of Cell Respiration
Net number of ATP molecules
Glycolysis
2
Krebs cycle
2
Electron Transport Chain (ETC)
32
TOTAL:
36
Cellular Respiration Equation
• Does not represent all of the steps that occur during the process of aerobic respiration.
• C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
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One glucose molecule and six oxygen molecules are needed to produce six carbon dioxide molecules and six water
molecules.
Each of the reactants (glucose and oxygen) is used during different stages of aerobic respiration.
– Glucose used during glycolysis
– Oxygen used during Krebs Cycle and ETC
Each of the products (carbon dioxide and water) is formed during different stages of the process
The energy that is released is primarily used to produce approximately 32 to 36 of ATP per glucose molecule.
What Do Cells Do When Oxygen is not available?
• Cells can obtain energy through anaerobic respiration.
• An = not/without oxygen
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•
If there is no O2 available fermentation takes place
Fermentation is not as efficient as aerobic respiration
– ATP is produced in minimal amounts (2 ATP)
• There are two types of fermentation depending on the organism:
1. alcoholic fermentation
2. lactic acid fermentation
Why am I Sore: Lactic Acid Fermentation?
• Occurs in animal cells
• Ex. Muscle Tissue during vigorous exercise
• The pyruvic acid formed during glycolysis is broken down to lactic acid and energy is released
• Glucose  Pyruvic acid _Lactic acid _Energy
• Occurs so that the cell can have a continual source of energy
Alcoholic Fermentation
• Occurs in plant cells, yeast, and some bacteria.
• Glucose Pyruvic acid + _Alcohol_+ CO2 + Energy
• Sugars are converted into cellular energy and produce ethanol (alcohol)and carbon dioxide as metabolic wastes.
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This reaction occurs in the production of ethanol fuels, in the rising of bread dough, production of yogurt, pickles
and cheese.