biology EXAM #3 pt. 3 Flashcards
Living cells require a
All heterotrophs, including us, obtain
Energy flows into an ecosystem as
source of energy from the outside to perform their many tasks
energy for our cells by eating plants and other consumers
sunlight and leaves as heat
Coupled reactions:
Anabolic pathways are coupled with
Catabolic pathways release
Electron transfer plays a
catabolic pathways as source of energy to perform work.
stored energy by breaking down complex molecules
major role in these pathways
These processes are central to cellular respiration
The breakdown of organic molecules is
Fermentation is a
Aerobic respiration consumes
Anaerobic respiration is similar to
exergonic
partial degradation of sugars that occurs without O2
organic molecules and O2 and yields ATP
aerobic respiration but consumes compounds other than O2
COMPLETE Cellular respiration includes both
Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the _____
formula of cellular respiration
aerobic and anaerobic respiration but is often used to refer to aerobic respiration
sugar glucose
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy (ATP + heat)
Redox reactions transfer
In oxidation, a substance
In reduction, a substance
Na + Cl Na+ + Cl-
Here, Na is
electrons from one reactant to another by oxidation and reduction
loses electrons, or is oxidized. It is called reducing agent because it is the electron donor.
gains electrons, or is reduced. It is called the oxidizing agent because it is the electron acceptor.
Na is oxidized or reducing agent and Cl is reduced or oxidizing agent.
Oxidation and reduction always
The electron donor is called
The electron acceptor is called
go hand in hand
the reducing agent, it reduces the electron acceptor
the oxidizing agent, it oxidizes the electron donor
Instead of fully transferring electrons, some redox reactions :
Oxygen (O) atoms are very ________; they :
what constitutes a redox reaction?
For example, electrons are not completely transferred in the redox reaction between methane and O2
change electron sharing in covalent bonds
electronegative; they attract electrons and do not share them equally
The partial “gain” of electrons by O atoms and the partial “loss” of electrons by their bonding partners
Some redox reactions do not completely:
They change :
exchange electrons
the degree of electron sharing in covalent bonds
Photosynthesis
-formula
Hydrogen atoms are transferred from :
_________ is required and this comes in the form of :
Chloroplasts convert solar energy to ______ which is then used along with ___________ to:
energy + 6CO2+6H2O C6H12O6 + 6O2
water to carbon dioxide and glucose is formed
Energy; form of light energy from the sun
solar energy to ATP;
with hydrogen to reduce carbon dioxide to glucose
During cellular respiration, the fuel (such as glucose) is ________-, and O2 is ________
Organic molecules with an abundance of hydrogen are:
Energy is released as
the fuel (such as glucose) is oxidized, and O2 is reduced
excellent sources of high-energy electrons
the electrons associated with hydrogen ions are transferred to oxygen, a lower energy state
During cellular respiration, glucose is __________ and oxygen is _______
co2 is ______ and h2o is _______
Complete oxidation of a mole of glucose produces _____ kcal of energy (____ in the form of ATP)
This energy is used to form ____
glucose is oxidized and oxygen is reduced
co2 is oxidizes and h20 is reduced
686 kcal of energy; 262
ATP
Catabolic pathways yield energy by:
oxidizing (loss of H+ or e-) organic fuels (Glucose is oxidized thus converted to CO2 and O2 is reduced and converted to H2O)
cellular respiration
Is the most:
Consumes:
Yields how much ATP ?
Each ATP =
prevalent and efficient catabolic pathway
oxygen and organic molecules such as glucose
(32-34)
7.3 kcal
About 34% of the energy in a glucose molecule is:
(7.3*32)/686 Kcal = 40% 34% efficiency
The rest = unused energy lost as heat
transferred to ATP during cellular respiration, making approximately 38 ATP
One catabolic process, fermentation is a:
The biproducts:
Yields how much ATP ?
partial degradation of sugars that occurs without oxygen
lactate-us, lactic acid, alcohol yeast-beer/wine or bacteria -tequila, citric acid…
(2)
To keep working cells must________________– remember coupled reactions:
Catabolic pathways yield ________ due to the transfer of _________
regenerate ATP
anabolic and catabolic reactions simultaneously
energy; electrons
Cellular respiration oxidizes __________ in a series of steps
Electrons from organic compound are usually first transferred to ______, which is a ________
glucose
NAD+, a coenzyme
Each electron travels with a ________—thus, as a ______ ______
proton; hydrogen atom
Hydrogen atoms are usually first passed to _______ _______, rather than directly to ____
electron carriers, rather than directly to O2
As an electron acceptor, Nicotinamide adenine dinucleotide, NAD+ functions as an :
Each NADH (the reduced form of NAD+) represents:
oxidizing agent during cellular respiration
stored energy that is tapped to synthesize ATP
NADH,
First – picks up the
If electron transfer is not stepwise….
electrons removed from food, then it passes the electrons to the electron transport chain
a large release of energy occurs (explosion), as in the reaction of hydrogen and oxygen to form water
the electron transport chain passes:
then, uses the energy from the electron transfer to:
NADH up to (how much ATP)
FADH2 up to (how much ATP)
electrons in a series of steps instead of in one explosive reaction
form ATP (26-28 ATP by means of oxidative phosphorilation)
2.5 ATP in Oxidative phosphorilation
1.5
NADH passes electrons to the :
O2, the _____ _______ ______, captures the:
The energy yielded is used to:
electron transport chain where they are transferred in a series of redox reactions, each releasing a small amount of energy
final electron acceptor; electrons and the hydrogen nuclei (H+), forming H2O
regenerate ATP
Respiration is a cumulative function of
three (four) metabolic stages
The process that generates almost 90% of the ATP is called … because…
A smaller amount of ATP is formed in ________ and the _________ by :
oxidative phosphorylation because it is powered by redox reactions
formed in glycolysis and the citric acid cycle by substrate-level phosphorylation
overview of cellular respiration
Oxidation of glucose to carbon dioxide, water, and energy
Exergonic reaction used to
4 phases of respiration are required for complete oxidation of glucose:
Oxidation involves the
drive ATP synthesis which is endergonic
glycolisis, preparatory reaction, citric acid cycle, electron transfer chain
removal of hydrogen atoms from substrates by redox coenzymes NAD+ and FAD
Glycolysis breaks down
Glycolysis occurs in the _______ and has:
1)
2)
Glycolysis occurs whether or not
glucose into two molecules of pyruvate
occurs in the cytoplasm and has two major phases:
Energy investment phase
Energy payoff phase
O2 is present
Glycolysis:
Transition rxn:
The citric acid cycle completes the
Oxidative phosphorylation is driven by:
breaks down glucose into two molecules of pyruvate (in cytoplasm
2 pyruvate to 2Acetyl CoA (cytoplasm –matrix)
breakdown of glucose
the electron transport chain and generates ATP
Both glycolysis and the citric acid cycle can
generate ATP by substrate-level phosphorylation
Glycolysis harvests energy by
Glycolysis means:
Breaks down glucose into
Occurs in the
oxidizing glucose to pyruvate
“splitting of sugar”
pyruvate
cytoplasm of the cell
All of the carbon originally present in glucose is
Glycolysis does not release any ____, and occurs whether or not ___ is present
accounted for in the two molecules of pyruvate
CO2, and occurs whether or not O2 is present
After pyruvate is oxidized, the citric acid cycle…
Most of the energy in glucose remains
In the presence of O2, pyruvate enters a
completes the energy-yielding oxidation of organic molecules
stored in the pyruvate molecules produced by glycolysis
mitochondrion (in eukaryotic cells), where the oxidation of glucose is completed
Before the citric acid cycle can begin, pyruvate must be:
This step is carried out by :
(3)
converted to acetyl coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle
a multienzyme complex that catalyzes three reactions:
1)Oxidation of pyruvate and release of CO2
2)Reduction of NAD+ to NADH
3)Combination of the remaining two-carbon fragment and coenzyme A to form acetyl CoA
Before the citric acid cycle can begin, pyruvate must first be converted to
Loss of
acetyl CoA, which links the cycle to glycolysis
two C molecules in the form of CO2
The citric acid cycle, also called ___________, completes the:
The citric acid cycle oxidizes:
Takes place in the:
Substrate level phosphorilation
Loss of
the Krebs cycle
energy-yielding oxidation of organic molecules
organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn
matrix of the mitochondrion
4 C molecules in the form of CO2
The citric acid cycle has
The acetyl group of acetyl CoA joins the cycle by
The next seven steps :
The NADH and FADH2 produced by the cycle relay
eight steps, each catalyzed by a specific enzyme
combining with oxaloacetate, forming citrate
decompose the citrate back to oxaloacetate, making the process a cycle
electrons extracted from food to the electron transport chain
Oxygen is taken in by breathing
Digested food contains glucose
Oxygen and glucose are carried to cells by the bloodstream
Glucose and oxygen enter cells where respiration occurs
Carbon dioxide is taken by the bloodstream to the lungs
leer
for glucose:
2C acetyl group from prep reaction combines with a 4C molecule to produce 6C citrate
Oxidation of citrate by removal of hydrogens
Produces 3 NADH and 1 FADH2 per cycle
Produces 1 ATP by direct substrate phosphorylation per cycle
Cycle turns twice per glucose
Total yield:
6 NADH, 2 FADH2, 2 ATP, 4 CO2
Following glycolysis and the citric acid cycle,
These two electron carriers donate electrons to the _______________, which :
NADH and FADH2 account for most of the energy extracted from food
electron transport chain, which powers ATP synthesis via oxidative phosphorylation
Molecules of the electron transport chain are
The membrane is folded into
In prokaryotes, the electron transport chain is
embedded in the inner mitochondrial membrane (cristae) in eukaryotic cells
cristae to increase surface area for electron transport chains
embedded in the plasma membrane
Most of the chain’s components are _____, which exist in :
Electrons drop in ___________ as they :
Electron carriers alternate between:
proteins; multiprotein complexes
free energy as they go down the chain and are finally passed to O2, forming H2O
reduced and oxidized states as they accept and donate electrons
Electrons are transferred from NADH or FADH2 to the
Electrons are passed through a number of
The electron transport chain generates
It breaks the :
electron transport chain
proteins to O2
no ATP directly
large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts
In the electron transport chain, electrons from NADH and FADH2 :
A series of
lose energy in several steps
redox reactions
NADH and FADH2 donate electrons to
At the end of the chain, electrons are passed to:
different electron acceptors early in the chain
oxygen, forming water
At certain steps along the electron transport chain, electron transfer causes
H+ then moves
protein complexes to pump H+ from the mitochondrial matrix to the intermembrane space
down its concentration gradient back across the membrane, passing through the protein complex ATP synthase
The resulting H+ gradient stores … and drives…
stores energy and drives chemiosmosis in ATP synthase
Chemiosmosis is referred to as a
Is an
proton-motive force
energy-coupling mechanism that uses energy in the form of a H+ gradient across a membrane to drive cellular work
ATP synthase is the
enzyme that actually makes ATP
During cellular respiration, most energy flows in this sequence:
About __% of the energy in a glucose molecule is ….., making about # ATP
The rest of the energy is lost as
glucose → NADH → electron transport chain → proton-motive force → ATP
34% ; transferred to ATP during cellular respiration; 30-32
heat
cellular respiration old
3: glycolisis, citic acid cycle, oxidative/electron trans…/chemi
new
4:glycolisis, pyruvate oxidation, citic acid cycle, oxidative/electron trans…/chemi
There are three reasons why the number of ATP is not known exactly:
Photophosphorylation and the redox reactions are not directly coupled; the ratio of NADH to ATP molecules is not a whole number
ATP yield varies depending on whether electrons are passed to NAD+ or FAD in the mitochondrial matrix
The proton-motive force is also used to drive other kinds of work
Fermentation and anaerobic respiration enable cells to
Most cellular respiration depends on
Without oxygen,
In that case, glycolysis
produce ATP without the use of oxygen
electronegative oxygen to pull electrons down the transport chain
the electron transport chain will cease to operate
couples with anaerobic respiration or fermentation to produce ATP
Anaerobic respiration uses an…
, for example, ______.
some organisms use a sulfate ion (SO42-) as a final electron acceptor
In this case, H2S (hydrogen sulfide) is made as a by-product instead of H2O
Fermentation uses
electron transport chain with a final electron acceptor other than oxygen; for example, sulfate
substrate-level phosphorylation instead of an electron transport chain to generate ATP
Glycolysis can produce ATP:
Couples with:
with or without oxygen, in aerobic or anaerobic conditions
fermentation to produce ATP
Fermentation consists of
Two common types are
glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis
alcohol fermentation and lactic acid fermentation
In alcohol fermentation, ___________ is converted to ___________ in two steps:
1)
2)
Alcohol fermentation by yeast is used in brewing, winemaking, and baking
pyruvate is converted to ethanol in two steps:
1)The first step releases CO2 from pyruvate
2)The second step produces NAD+ and ethanol
In lactic acid fermentation, _______ is reduced by ________, forming:
Lactic acid fermentation by some fungi and bacteria is used to make cheese and yogurt
Human muscle cells use lactic acid fermentation to
pyruvate is reduced by NADH, forming NAD+ and lactate as end products, with no release of CO2
generate ATP during strenuous exercise when O2 is scarce
Both fermentation and cellular respiration use glycolysis to
Fermentation and cellular respiration differ in their
Another difference is the
Fermentation produces (ATP)
Cellular respiration harvests ATP by oxidative phosphorylation, # ATP.
This sums up to # ATP total in aerobic respiration
oxidize glucose and other organic fuels to pyruvate
final electron acceptor
amount of ATP produced per glucose molecule
2 ATP by substrate-level phosphorylation
26-28 ATP
30-32 ATP
Obligate anaerobes carry out
Yeast and many bacteria are ______________, meaning:
fermentation or anaerobic respiration and cannot survive in the presence of O2
facultative anaerobes, meaning that they can survive using either fermentation or cellular respiration
Glycolysis is
Early prokaryotes likely used glycolysis to produce ATP before
Used in both cellular respiration and fermentation, it is the
This pathway occurs in the
an ancient process
O2 accumulated in the atmosphere
most widespread metabolic pathway on Earth
cytosol so does not require the membrane-bound organelles of eukaryotic cells
Glycolysis and the citric acid cycle connect to:
Catabolic pathways :
-Funnel…
-Proteins used for fuel must be …
-Nitrogenous waste is excreted as…
many other metabolic pathways
-electrons from many kinds of organic molecules into cellular respiration
-digested to amino acids and their amino groups must be removed in a process called deamination
-ammonia (NH3), urea, or other products
Fats are digested to
Fatty acids are broken down by
An oxidized gram of fat produces more than twice as much ATP as an
glycerol and fatty acids
beta oxidation and yield acetyl CoA, NADH, and FADH2
oxidized gram of carbohydrate
The body uses small molecules to
These small molecules may come directly from
build other substances
food or through glycolysis or the citric acid cycle
Cellular respiration:
Feedback inhibition is the
Is controlled by
If ATP concentration drops, ______________; if there is plenty of ATP, ______________
Catabolism is controlled by
most common mechanism for metabolic control because it prevents wasteful production
allosteric enzymes at key points in glycolysis and the citric acid cycle
respiration speeds up; ………., respiration slows down
regulating the activity of enzymes at strategic points in the pathway
Certain electron carriers in the electron transport chain
In this way, the energy stored in a H+ gradient across a membrane couples the
The H+ gradient is referred to as a
accept and release H+ along with the electrons
redox reactions of the electron transport chain to ATP synthesis
proton-motive force, emphasizing its capacity to do work
