Chapter 9: Cellular Respiration & Fermentation

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