Chapter 17: Cellular Respiration and Fermentation Flashcards
what is cellular respiration?
cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from oxygen molecules or nutrients into adenosine triphosphate, and then release waste products.
what does cellular respiration include?
includes both aerobic and anaerobic respiration, but if often used to refer to just aerobic respiration
what is used to trace cellular respiration?
glucose
what is the chemical formula for cellular respiration?
C6H12O6 + 6O2 –> 6CO2 + 6H2O + energy (heat and ATP)
how is energy released in organic molecules?
the transfer of electrons during chemical reactions release energy stored in organic molecules
what is the energy released used to do?
synthesize ATP
what are chemical reactions that transfer electrons between reactants called?
oxidized-reduction reactions or redox reactions
what is oxidation?
a substances loses electrons
what is reduction?
a substance gains electrons
what are the two acronyms?
LEO and GER
in cellular respiration what is oxidized?
C6H12O6 and CO2
in cellular respiration what is reduced?
O2 and H2O
what type of molecules are good fuels?
organic molecules with an abundance of H (ex. carbohydrates and fats)
how can energy released be used in ATP synthesis?
as H with its electron is transferred to O2, energy is released that can be used in ATP synthesis
where are electrons transferred?
to NAD+ to neutralize it and make NADH.
what is NAD+ ?
a coenzyme
what does NAD+ function as during cell respiration?
an oxidizing agent
what does NADH represent?
represents stored energy that is tapped to synthesize ATP
where does NADH pass its electrons?
electron transport chain
what does the electron transport chain do?
passes electrons in a series of steps
how do electrons go down the chain?
O2 pulls electrons down the chain in an energy-yielding tumble
what is the energy-yielded used for?
to generate ATP
what are the two ways to make ATP?
oxidative phosphorylation and substrate-level phosphorylation
what is oxidative phosphorylation?
oxidizes glucose and makes ATP using the movement of electrons. electrons move because of a final electron acceptor at the end.
what is substrate-level phosphorylation?
uses enzymes to put ADP and PO4 together
what makes most of the ATP in cellular respiration? what percent? why?
oxidative phosphorylation. 90%. this is because it is powered by redox reactions.
what are the 4 steps in cellular respiration?
glycolysis, the link reaction, the Krebs cycle/ citric cycle, and oxidative phosphorylation
what is glycolysis?
sugar splitting
what happens in glycolysis?
glycolysis breaks down glucose using two ATP into two pyruvates, 2 NADH, and 2 ATP
what are pyruvates?
3 carbon molecules
where does glycolysis happen?
the cytoplasm
what are the 2 major phases of glycolysis?
- energy investment phase
2. energy payoff phase
does glycolysis require oxygen? what does this mean?
no. any living organism can make 2 ATP from glucose by glycolysis
what type of phosphorylation does glycolysis use to make ATP?
substrate-level
what happens in the link reaction?
in the presence of O2, the pyruvates enter the mitochondrion. the glucose is completely oxidized. the pyruvates are then converted into acetyl CoA. this then gets linked to the citric acid cycle.
what is acetyl?
a 2 carbon sugar- the pyruvate lost a carbon through CO2
what is CoA?
coenzyme A
how many layers does the mitochondria have?
2 - inner and outer
how much ATP is produced in the link reaction?
0
what does the link reaction produce in total?
2 acetyl CoA, 1 NADH, and 1 CO2
what does the citric cycle do?
completes the breakdown of pyruvate to CO2 and a few other products
where do hydrogen ions go?
NADH and FADH2 (gaining electrons)
how many carbons are present in the cycle prior to the acetyl CoA?
4 carbons - makes 6 carbon in total
where does energy come from in the Krebs cycle?
energy from broken bonds
how many times does the cycle happen?
two times
what useful products are created per cycle?
one ATP, 3 NADH, and 1 FADH2 per cycle
what is removed from the cell after the Krebs cycle?
CO2
how many steps does the cycle have?
8 steps, each catalyzed by a specific enzyme
what exactly happens when the acetyl CoA goes into the Krebs cycle?
the acetyl group combines with oxaloacetate, which forms citrate. the next 7 steps decompose the citrate into oxaloacetate, making it a cycle
is oxaloacetate regeneratable?
yes
where do the NADH and FADH2 go from the Krebs cycle?
the electron transport chain
what are NADH and FADH2?
they are electron carriers
what does the electron transport chain do?
powers ATP synthesis via oxidative phosphorylation
what two things does the electron transport chain do?
oxidative phosphorylation and chemiosmosis
what type of phosphorylation does the Krebs cycle use to make ATP?
substrate level
are NADH and FADH2 high or low energy molecules?
high
what is necessary in the electron transport chain for it to occur?
O2 at the end as an electron acceptor
where does the electron transport chain happen?
the inner membrane (cristae) of the mitochondria
what is the chain mostly made of?
most of the chain components are proteins, which exist in multiprotein complexes
what do the proteins in the chain do?
they alternate reduced and oxidized states as they accept and donate electrons
what happens to the electrons in the chain?
electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O
what are cytochromes?
redox-active proteins, each with an iron atom
does the chain itself generate ATP?
no
what happens to H+ ions in the chain?
proteins cause the H+ to get pumped out from the mitochondrial matrix to the intermembrane space
how does H+ go to the O2 acceptor?
through ATP synthase. ATP synthase is a protein complex that uses exergonic flow of H+ to drive phosphorylation of ATP
what is chemiosmosis?
movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient.
what is the H+ gradient called in the chain/ chemiosmosis?
proton motive force, emphasizing its capacity to do work
how does energy stored in the H+ gradient help ATP synthesis?
the energy stored in a H+ gradient across a membrane couples the redox reactions of the electron transport chain to ATP synthesis
where does phosphate come from?
when the body does work, phosphate enters the cytoplasm
how much ATP is made in total in the process of cell respiration?
32 ATP
what percent of energy from glucose is transferred to ATP?
34%
what is fermentation?
metabolic process that produces chemical changes in organic substances through the action of enzymes
how is ATP produced if O2 isn’t available?
glycolysis is used
what can glycolysis do if there is no oxygen present?
either fermentation or anaerobic respiration
what does anaerobic respiration use when no oxygen?
uses an electron transport chain with a final electron acceptor other than O2 (ex. sulphate)
what does fermentation use when no oxygen?
uses substrate level phosphorylation instead of electron transport chain to generate ATP
what does fermentation consist of?
fermentation consists of glycolysis plus reactions that regenerate NAD+ which can be reused by glycolysis
what are the two types of fermentation?
alcohol fermentation and lactic acid fermentation
is fermentation efficient?
no
what happens in alcohol fermentation?
the glucose is broken down into two pyruvates. these are converted into ethanol in two steps. the first steps releases CO2 from the pyruvate, and the second step reduces acetaldehyde into ethanol.
in general what happens in alcohol fermentation?
glucose into pyruvates, which go to ethanol. in the process of converting ethanol it produces CO2 and NAD+, as well as 2 NADH and 2 ATP
when is alcohol fermentation used?
it’s used in brewing, wine making, and bread making by yeast.
when does lactic acid build up?
in muscle cells, when they are overused.
what happens in lactic acid fermentation?
pyruvates are reduced by NADH, forming lactate as an end product, with no release of CO2.
what uses lactic acid fermentation?
fungi and bacteria is used to make cheese and yogurt. human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce.
in general explain lactic acid fermentation.
glucose is converted into 2 pyruvates. it is then converted into two lactate, and releases NAD+. then it is converted into lactic acid, which is when O2 is running out. 2 NADH and 2 ATP is produced.
does fermentation, aerobic, or anaerobic respiration use glycolysis?
all
does fermentation, aerobic, or anaerobic respiration use NAD+? how does it use it?
all. NAD + is the oxidizing agent that accepts electrons during glycolysis
what are the types of electron acceptors in fermentation vs. cellular respiration?
organic molecule, O2
how much ATP does cell respiration produce vs. fermentation?
cell resp- 32 ATP/ glucose molecule
fermentation- 2 ATP/ glucose molecule
what are obligate anaerobes?
carry out only fermentation or anaerobic respiration because they cannot survive the presence of O2.
what are facultative anaerobes?
they can survive using either fermentation or cellular respiration. (ex. yeast and bacteria)
what does a pyruvate do in a facultative anaerobes?
it is a fork in the metabolic road. this leads to two alternative catabolic routes
what is the evolutionary significance of glycolysis?
it is thought to have been used way before there was even oxygen in the atmosphere. so as O2 increased, the evolutionary advantage increased. it is a very old process.
what do catabolic pathways do to electrons?
funnel electrons from many kinds of organic molecules into cellular respiration
what type of cell does glycolysis happen in?
prokaryotic and eukaryotic
what type of cell does the link reaction happen in?
eukaryotic
what type of cell does the Krebs cycle happen in?
eukaryotic
what type of cell does oxidative phosphorylation happen in?
eukaryotic
what type of cell does alcohol fermentation happen in?
yeast
what type of cell does lactic acid fermentation happen in?
bacteria and muscle
where in the cell does glycolysis happen?
cytoplasm
where in the cell does the link reaction happen?
mitochondria
where in the cell does the Krebs cycle happen?
mitochondria
where in the cell does oxidative phosphorylation happen?
mitochondria
where in the cell does alcohol fermentation happen?
cytoplasm
where in the cell does lactic acid fermentation happen?
cytoplasm
is O2 needed for glycolysis?
no
is O2 needed for the link reaction?
yes
is O2 needed for the Krebs cycle?
yes
is O2 needed for oxidative phosphorylation?
yes
is O2 needed in alcohol fermentation?
no
is O2 needed in lactic acid fermentation?
no
is CO2 released from glycolysis?
no
is CO2 released from the link reaction?
yes
is CO2 released from the Krebs cycle?
yes
is CO2 released from oxidative phosphorylation?
no
is CO2 released from alcohol fermentation?
yes
is CO2 released from lactic acid fermentation?
no
does glycolysis transfer electrons to NADH/ FADH2?
yes
does the link reaction transfer electrons to NADH/ FADH2?
yes
does the Krebs cycle transfer electrons to NADH/ FADH2?
yes
does the Krebs cycle transfer electrons to NADH/ FADH2?
yes
does oxidative phosphorylation transfer electrons to NADH/ FADH2?
no
does alcohol fermentation transfer electrons to NADH/ FADH2?
yes
does lactic acid fermentation transfer electrons to NADH/ FADH2?
yes
does glycolysis involve an electrons transport chain?
no
does the link reaction involve an electrons transport chain?
no
does the Krebs cycle involve an electrons transport chain?
no
does oxidative phosphorylation involve an electrons transport chain?
yes
does alcohol fermentation involve an electrons transport chain?
no
does lactic acid fermentation involve an electrons transport chain?
no
what type of phosphorylation does glycolysis use?
substrate level
what type of phosphorylation does the link reaction use?
n/a
what type of phosphorylation does the Krebs cycle use?
substrate level
what type of phosphorylation does oxidative phosphorylation use?
oxidative phosphorylation
what type of phosphorylation does alcohol fermentation use?
substrate level
what type of phosphorylation does lactic acid use?
substrate level
how many ATP are produced in glycolysis?
2 ATP
how many ATP are produced in the link reaction?
0 ATP
how many ATP are produced in the Krebs cycle?
2 ATP (1 per turn)
how many ATP are produced in oxidative phosphorylation?
26 - 35 ATP
how many ATP are produced in alcohol fermentation?
2 ATP
how many ATP are produced in lactic acid fermentation?
2 ATP
explain glycolysis in a sentence.
glucose is broken into 2 pyruvate in the cytoplasm in order to produce 2 ATP and transfer electrons to NAD+, reducing it to NADH
explain the link reaction in a sentence.
pyruvate is converted into acetyl CoA in the mitochondria, releasing a CO2, and creating the reactant necessary for the Krebs cycle.
explain the Krebs cycle in a sentence.
Acetyl CoA joins with oxaloacetate to form a 6 carbon sugar that cycles through a series of reactions that produces ATP, makes NADH and FADH2 as electron carries, and releases CO2 as a waste product to the environment all while generating a 4 carbon sugar.
explain the electron transport chain in a sentence.
NADH and FADH2 transfers electrons to the electron transport chain which results in the pumping of H+ into the intermembrane space and eventually passing these electrons to O2 to reduce it to H20
explain chemiosmosis in a sentence.
H+ ions that were pumped into the intermembrane space flow down their concentration gradient through ATP synthase, generating a lot of ATP and providing H for the reduction of O2 to H2O.
