concept 9.5: fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen

what does cellular respiration depend on

the ability for oxygen to pull electrons down the electron transport chain

how does glycolysis produce ATP

by coupling with anaerobic respiration or fermentation

what cells in the body utilize fermentation

yeast cells and muscle cells

what is different about the electron transport chain in anaerobic respiration

they use a final electron acceptor that is not oxygen, can be SO4 2- or hydrogen sulfide

how does glycolysis oxidize glucose

oxidizes glucose to pyruvate without O2 or electron transport chain

what is the oxidizing agent used in glycolysis

NAD+

does glycolysis need O2 to be present

can occur with or without O2

how many ATP does glycolysis produce by substrate level phosphorylation

net 2 ATP

how does NAD+ become NADH under aerobic conditions

by transforming electrons to the electron transport chain

what are the two types of fermentation

alcohol fermentation and lactic acid fermentation

what occurs in achohol fermentation

pyruvate is converted to ethanol in two steps

what are the two steps involved in pyruvate being converted to ethanol

the first step releases CO2 from pyruvate

the second step produses NAD+ and ethanol

what occurs in lactic acid fermentation

pyruvate is reduced by NADH, forming NAD+ and lactate as an end product with NO net release of CO2

does lactic acid fermentation release and CO2

no CO2 released

what is lactate/ lactic acid converted back to after lactic acid fermentation

the lactate/lactic acid is converted back to pyruvate when oxygen levels are restored

what is lactic acid fermentation used to do

to make cheese and yogurt

is it true that human muscle cells only produce lactate when O2 is short supply

it is not true

what are the similarities between fermentation and anaerobic respiration

both use glycolysis to oxidize glucose and use that chemical energy from food

in all three, NAD+ is the oxidizing agent that accepts electrons during glycolysis

what is a major different in the mechanisms used to oxidize NADH and NAD+

in fermentation, an organic molecule acts as the final electron acceptor

in cellular respiration the electrons are transferred to the electron transport chain

another different between fermentation and cellular respiration

fermentation produces 2 ATP by substrate level phosphorylation

cellular respiration gets up to 32 ATP by oxidative phosphorylation

what are obligate anaerobes

carry out fermentation or anaerobic respiration and cannot survive in the presence of O2

what are facultative anaerobes

they can survive using either fermentation or cellular respiration and these pyruvates create a form in the metabolic road leading to alternative catabolic routes

what are some facultative anaerobes

include yeast and many bacteria

what is the evolutionary significance of glycolysis

ancient prokaryotes are thought to have used glycolysis long before there was oxygen and the pathways occurred in the cytosol and didn’t need membrane bound organelles

when did oxidative phosphorylation evolve

after atmospheric O2 became abundant