Ch. 9 Cellular respiration and fermentation
what is the structure of NAD+?
The molecule consists of two nucleotides (adenine and nucotinamide) joined together at their phosphate groups.
catabolism is linked to work by
a chemical drive shaft--ATP
NAD+
a coenzyme thatcycles easily between oxidized (NAD+) and reduced (NADH) states, thus acting as an electron carrier
An electron transport chain consist of
a number or molecules, mostly protiens, built into the inner membrane of the mitochondria of eukaryotic cells and the plasma membrane of aerobically respiritng prokaryotes
electron transport chain
a sequence of electron carrier molecules (membrane protiens) that shuttle electrons down a series of redox reactions that release enrgy used to make ATP
the most prevalent and efficient catabolic pathway is
aerobic respiration
cellular respiration is usually refer to _why?
aerobic respiration because of the relationship of that process to organismal respiration (animals breath oxygen)
cellular respiration includes which processes?
anaerobic and aerobic processes
At the "bottom" of the electron transport chain what happens?
at the lower-energy end O2 captures these electrons along with hydrogen nuclei (H+), forming water
What holds back the flood of electrons to a lower energy state?
barrier of activation
The main energy-yielding foods,_,are reservoirs of_
carbohydrates and fats electrons associated with hydrogen
The waste products of cellular respiration,which are_,are the raw materials for photosynthesis
carbon dioxide and water
Insted of energy being released and wasted in a single explosively step, electrons_
cascade down the chain from one carrier molecule to the next in a series of redox reaction, losing a small amount of energy with each step until they finally reach oxygen (terminal electron aceptor)
anaerobic respiration
catabolic pathway in which inorganic molecules other than oxygen accept electrons at the "downhill" end of the electron transport chains
aerobic respiration
catabolic pathway, using oxygen as the final electron acceptor in an electron transport chain and ultimately producing ATP.
The breakdown of organic molecules is _... and is_
catabolism exergonic
a redox reaction that moves electrons closer to oxygen, therefore releases
chemical energy that can be put to work
aerobic respiration is similar to_, in which who provides the fuel for respiration? who is the exhaust of this process?
combustion of gasoline food carbon dioxide and water
catabolic pathways _move flagella, pump solutes across membranes, polymerize monomers, or perform cellular work
do not directly
Some redox reactions change the degree of
electron sharing in covalent bonds
who plays a major role in the catabolic pathways?
electron transfers
Each "downhill" carrier is more_than the previous electron carrier, and thus capable of oxidizing, its "uphill" neighbor, with _ at the bottom of the chain
electronegative oxygen
At key steps of the series of steps in cellular respiration, _are stripped from the glucose
electrons
Organic compounds possess energy as a result of the arrangement of...
electrons in the bonds between their atoms
ATP is the immediate_for almost all organism function... life's currency!
energy source
Hydrogen is transferred from glucose to oxygen, but the _of the electron changes as _.
energy state hydrogen (with its electron) is transferred to oxygen
Matabolic pathways are controlled by
enzymes
who will low the barrier of activation energy in glucose? what allows this?
enzymes allows the sugar to be oxidized in a series of steps
who can carry aerobic respiration?
eukaryotic and prokaryotic cells
the breakdown of glucose is endergonic or exergonic?
exergonic
ex of catablic process
fermentation
Where does all the energy utlimately comes from?
from the sun
Compounds that can participate in exorgenic reactions can act as
fuels
Cells require_to perform their many tasks
transfusions of energy from outside sources
Electrons lose_of their potential energy when they are transferred from glucose to NAD+
very little
NAD+ is a derivated of
vitamin niacin
Life is
work
Some energy taken out in catabolic pathways from the chemical storage of molecules can be used to_; the rest is dissipated as_
work heat
Catabolic pathways_due_
yield energy to the transfer of electrons down energy gradients
from NAD+ and NADH, who is the reduced form?
NADH
what is the free energy change when one mole of glucose is breakdown?
-686 kcal per mole of glucose descomposed
What are some examples that imply the use of energy?
-Assembling polymers -Pumping substances across the plasma membrane -Moving -Reproducing
Energy flows into a systems as_and leaves as_
-Flows into as sunlight -Exits as heat
3 Key pathways of cellular respiration
-GLYCOLYSIS -THE CTRIC ACID CYCLE -OXIDATE PHOSPHORYLATION
Electrons transfer from NADH to oxygen is _reaction, which the energy is released_; What the e- transport chain allows for is _
-exergonic -explosively -gradual "fall" of electrons, and conversion of that energy to a usable form (proton gradient).
there are two important differences when cellular respiration is bringing the electrons stored on NADH to oxygen, what are these?
1st- In cellular respiration, the hydrogen reacts with oxygen is derived from organic molecules rather than H2. -2nd-Instead of occuring in one explosive reaction, respiration uses an electron transport chain to break the fall of electrons to oxygen into several energy-releasing steps.
If we supply energy by igniting glucose how much energy it releases?
686 kcal of heat per mole of glucose
Reduction
A substance gains electrons, or is reduced
Oxidation
A substance loses electrons, or is oxidized
Cellular respiration yields
ATP
to keep working, the cell must REGENERATE its supply of_from_
ATP ADP + Pi
Cellular respiration formula
C6H12O6 + 6O2----->6CO2 + 6H2O + Energy (ATP + heat)
_breaks the fuel produced in phototsynthesis (oxygen and organic molecules) generating_
Cellular respiration ATP
How does NAD+ trap electrons from glucose and other organic molecues?
Enzymes called Dehydrogenases removes a pair of hydrogen atoms (2 electrons and 2 protons) from the substrate (glucose), thereby oxidizing it. The enzyme delivers 2 electrons and 1 proton to coenzyme, NAD+.
In cellular respiration formula, who of the reactants becomes reduced?
oxygen
what the electron transport chain does?
It PUMPS H+ across the inner membrane creating a H+ gradient (potential energy).
What process produces the most NAD+ during respiration?
the oxidation of NADH
Who is the most versatile electron acceptor in cellular respiration and functions in several redox steps during breakdown of glucose?
NAD+
from NAD+ and NADH, who is the oxidized form?
NAD+
NAD+ stands for
Nicotinamide adenine dinucleotide
metabolic pathways
Sequence of chemical reactions
cellular respiration is
the oxidation of glucose and other molecules in food
So how NADH enters in the concept of electron transport chain?
The electrons removed from glucose are shuttled by NADH to the "top", higher-energy end of the electron transport chain.
What process produces the most NADH during respiration?
the reduction of NAD+
In an uncontrolled reaction, the one-step exergonic reaction of hydrogen and oxygen to form water releases a large amount of energy in the form of heat and light: explosion. In the case of cellular respiration, what happens?
The same reaction occurs in stages: an electron transport chain breaks the "fall" of electrons in this reaction into a series of smaller steps and stores some of the released energy in a form that can be used to make ATP (the rest of the energy is released as heat).
Redox reactions
Transfer electrons from one reactant to another by oxidation and reduction
In cellular respiration formula, who of the reactants becomes oxidized?
glucose
which is the sugar that cells most often use in cellular respiration?
glucose
Cellular respiration can be seen as the process of ...
harvesting chemical energy
What the electron transportation chain allows to?
it allows for is gradual "fall" of electrons, and conversion of that energy to a usable form (proton gradient).
since oxygen is so electronegative
it is one of the most potent of all oxidizing agents
In metabolic pathways the products are_to build up
less likely
In respiration, the oxidation of glucose transfer electrons to a
lower energy state, liberating energy that becomes available for ATP synthesis
catabolic pathways
metabolic pathways that released stores energy by breaking down complex molecules
A way to remember that reduction consist of the gaining of electrons is by
molecules gain electrons, thus become negatively charged so it reduces the amount of positive charge of that atom. Also steal is bad so reduction is gain (steal) electrons
when the NAD+ receives 2 electrons and 1 proton, it charge becomes_and thus it changes to_
neutral NADH
the electron transport chain directly or not directly produces ATP?
not directly
what types of molecules are the excellent fuels? why?
organic molecules that have an abundance of hydrogen because their bonds are a source of "hilltop" electrons, whose energy may be released as these electrons "fall" down an energy gradient when they are transferred to oxygen.
As an electron aceptor, NAD+ functions as an_during respiration
oxidizing agent
Catabolic pathways yield energy by
oxidizing organic fuels
aerobic respiration consumes_as a reactant along with _
oxygen organic fuels
cellular respiration consumes
oxygen and organic molecules such as glucose
Phtotsynthesis generates _used by_of eukaryotes as _for cellular respiration
oxygen and other organic molecules mitochondria fuel
The hydrogen atoms are not transferred directly to oxygen, but instead are usually
passed first to an electron carrier, coenzyme called NAD+
anaerobic respiration is carry out by
prokaryotic cells
Each electrons travels with a_-thus as _
proton hydrogen atom
chemical elements essential to life are transformed or recycled?
recycled
chemical elements essential to life are...
recycled
Energy is not_it must be_
recycled transformed
energy is not_, it must be_
recylced transformed
an electron loses potential energy when it
shifts from a less electronegative atom toward a more electronegative one
Each NADH molecule formed during respiration represents
stored energy that can be tapped to make ATP when the electrons complete their "fall" down an energy gradient from NADH to oxygen
how does the catabolic pathways that descompose glucose and other organic fuels yield energy?
the answer is based on the transfer of electrons during the chemical reactions. Thus the relocation of electrons releases energy stored in organic molecules, and this energy ultimately is used to synthesize ATP
what happens in catabolic pathways? (transformation from what to what)
the cell systematically degrades complex organic molecules that are rich in potential energy to simpler waste products that have less energy
oxidizing agent
the electron acceptor, it oxidizes another molecules by removing the molecule's electrons.
Reducing agent
the electron donor, it reduces another molecules by donating electrons to the other reactant
what happens to one proton when dehydrogenases delivers the other 2 electrons with 1 proton?
the hydrogen ion is released into the surroundings
How does electrons that are extracted from glucose and stored as potential energy in NADH finally reach oxygen?
the mix of H2 and O2, provide a spark for activation energy, and the gases combine explosively. The explosion represents a release of energy as the electrons of hydrogen "fall" closer to the electronegative oxygen atoms. Cellular respiration also brings hydrogen and oxygen together to form water.
the more electronegative the atom
the more energy is required to take and electron away from it
cellular respiration is
the most prevalent and energetically efficient catabolic pathway
