Post on 15-Apr-2022
Chapter 9: Cellular Respiration & Fermentation
9.1 Cellular Respiration: An Overview
Org need food for NRG to carry out cell’s activities
Calories: measures food NRG
1 cal = heat needed to raise 1 g H2O 1○ C
1000 calories = 1 kilocalorie or 1 dietary Calorie
Cells use diff molecules of food
Fats: 9 cal of NRG/g
Proteins: 4 cal of NRG/g
Carbs: 4 cal of NRG/g
Cells break down food
gradually
1. Chemical NRG & Food
Releases NRG from food in presence of O2
6 O2 + C6H12O6 6 CO2 + 6 H2O + NRG
A. 3 Stages of Cellular Respiration
1. Glycolysis: in cytoplasm, breaks glucose, little ATP
2. Krebs Cycle: in mito, cont to break down, little ATP
3. ET Chain: inner mem of mito, Most NRG production
B. Oxygen & NRG
O2 required at end of ET chain NRG = O2 demand
Aerobic Pathway: requires O2 (krebs & ET Chain, Cell Resp))
Anaerobic Pathway: w/out O2 (glycolysis, fermentation)
2. Overview of Cellular Respiration
Photosynthesis Cellular Respiration
Removes CO2 in atm Puts CO2 into atm
Releases O2 into atm Uses O2 to release NRG from food
Occurs only in: plants, algae, Occurs in: anmls, plants, fungi,
some bact protists, most bact
3. Comparing Photosynthesis & Cellular Respiration
9.2 Process of Cellular Respiration
Anaerobic (With or W/out O2); quick proces
Occurs in cytoplasm
1 Glucose (6C) 2 Pyruvic Acid (3C)
A. ATP Production
Input 2 ATP to start rxn = produces 4 ATP; net gain of 2 ATP
B. NADH Production
NAD+ accepts pair of high-NRG
electrons to make NADH
1. Glycolysis—Stage 1
Named after Hans Krebs (biochemist) 1937
Aerobic
Occurs in Mitochondrion fluid matrix
Series of chem rxn mainly involving C compounds
Pyruvic Acid (3C) gets broken down into CO2 thru series of rxns
2. Krebs Cycle—Stage 2
A. Citric Acid Production
As cycle begins, it takes pyruvic acid (3C)Acetyl-CoA + 4C = Citric Acid (6C) 5C 4C (back to start)
Also known as Citric Acid Cycle b/c 1st comp formed
B. NRG Extraction
1 ATP/cycle turn (2 Pyruvic Acids = 2 turns = 2 ATP made)
E- carriers accept High NRG e-: NADH & FADH2
Products made in Krebs: CO2 (by product, exhale out)
2 ATP
NADH Help generate huge amt of ATP
FADH2 in ET Chain
Occurs in inner membrane of mitochondria
High NRG e- (from Krebs: NADH/FADH2) & carrier proteins to convert ADP into 32 ATP
O2: final e- acceptor (H2O)
3. Electron Transport & ATP Synthesis
Glycolysis = 2 ATP
Krebs = 2 ATP
ET Chain = 32-34 ATP
about 36-38 ATP
Human Diet
Includes complex carbs, to lipids, to proteins
Enters into Glycolysis & Krebs in several places
Compared to a furnace = gen NRG (ATP) from about any food source
= releases heat NRG
4. The Totals
9.3 Fermentation
Anaerobic process (w/o O2)
Begins w/Glycolysis in cytoplasm
Releases NRG from food by making ATP
2 types: Alcoholic & Lactic Acid
1. Fermentation
9.3 Fermentation
Used by Yeast & other microorg.
Pyruvic Acid + NADH Alcohol + CO2 + NAD+
Uses: causes bread dough to rise (CO2 bubbles = air spaces in bread)
alcoholic beverages, root beer
A. Alcoholic Fermentation
Most org go thru Lactic Acid Ferm
Pyruvic Acid + NADH Lactic Acid + NAD+
Uses: bact = cheese, yogurt, buttermilk, sour cream (sour taste), pickles, sauerkraut
Humans: Use for rapid burst of act, strenuos act
O2 is low or depleted causing sore muscles
B. Lactic Acid Fermentation
Humans have 3 main NRG sources
1. ATP already in muscles
2. ATP from Lactic Acid
3. ATP from Cellular Respiration
In footrace, use all 3 sources
A. Quick NRG (short race)
ATP avail few sec
Uses stored ATP Glycolysis + Lactic Acid Fermentation
Must repay O2 debt (heavy breathing)
B. Long-Term NRG
Use Cellular Respiration to make big amt ATP
Releases ATP at slower rate
Pathway: stored glycogen (15-20 min) then stored fat
2. Energy & Exercise