bio unit 2 lesson 11 (cellular respiration/ fermentation)

cellular respiration

catabolic pathways of aerobic (O2) and anaerobic (no O2) respiration, which break down organic molecules and use an electron transport chain for the production of ATP

producers

use energy from sunlight to convert CO2 —> carbohydrates and O2 (photosynthesis)

• then use these carbohydrates to generate

  • ALL biological molecules (carbs/lipids/proteins/nucleic acids) they need ATP and (CO2, a byproduct)

consumers

must regularly eat to acquire organic compounds and then transform them into ATP (and CO2, a byproduct)

anaerobic 

• catabolic pathway for organic molecules

• inorganic molecules (other than oxygen) accept electrons in an electron transport chain

• ultimately produces a decreased amount of ATP

aerobic

• catabolic pathway for organic molecules

• uses oxygen as the final electron acceptor in an electron transport chain 

• ultimately produces large quantities of ATP

• most efficient catabolic pathway and is carried out in most eukaryotic cells and many prokaryotic organisms 

coupled reactions

aerobic respiration couples the breakdown of organic molecules (carbohydrates, fats, proteins) with the production of ATP

• couples an exergonic reaction (the breakdown of complex molecules) with an endergonic reaction (the production of ATP)

oxidation

losing electrons 

• complete or partial loss of electrons from a substance in a redox reaction

reduction 

gaining electrons

• complete or partial addition of electrons to a substance in a redox reaction 

• adding electrons reduces the amount of positive charge 

reducing agent

the electron do not

(loses an electron— becomes oxidized)

oxidizing agent

the electron acceptor

(gains an electron —itself becomes reduced)

redox reaction

the combination of a reduction reaction and an oxidation reaction

mitochondria

site of cellular respiration

• found in both plants and animals 

• double membrane 

cristae

folds of the inner membrane 

matrix 

semi-fluid portion of the interior

glycolysis

occurs in the cytoplasm (anaerobic)

pyruvate oxidation (link reaction)

occurs in the matrix of the mitochondria

citric acid cycle (Krebs cycle)

occurs in matrix of the mitochondria

Oxidative phosphorylation

occurs across the Cristae (aerobic)

electron transport chain 

series of protein complexes in the inner mitochondrial membrane that generates a proton gradient to produce ATP during cellular respiration

pyruvate

vital metabolic compound produced from glucose during glycolysis and serves as a key fuel for energy production in a mitochondria, also acting as an antioxidant and precursor or various anabolic processes 

NADH

substrate level phosphorylation

ATP is made by this in glycolysis

• enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate 

  • occurs in glycolysis and citric acid cycle- but NOT the electron transport chain 

Coenzyme A (CoA)

Acetyl CoA

Decarboxylation

FADH2

Oxaloacetate

ATP Synthase

Chemiosmosis 

‘final electron acceptor’ (e.g. oxygen)

proton-motive force

fermentation

recycling of NAD+ drives glycolysis to repeat, making 2 ATP each time

lactic acid (lactate) fermentation

• (lactate)

  • animals (human muscle cells)

  • some bacteria (Lactobacillus yogurt)

• actic acid can build up in our muscles, causing the burning sensation from strenuous exercise 

• once aerobic conditions can be met again, the lactic acid is broken down and the ‘burn’ dissipates 

alcoholic fermentation 

(ethanol +CO2)

• yeast (beer, wine, bread)

• other bacteria