Test 3 Review Flashcards
-where does substrate level phosphorylation occur
A smaller amount
of ATP is formed directly in a few reactions of glycolysis and
the citric acid cycle by this mechanism
This mode of ATP synthesis
occurs when an enzyme transfers a phosphate group from a
substrate molecule to ADP, rather than adding an inorganic
phosphate to ADP as in oxidative phosphorylation.
What are the end products for glycolysis
2 pyruvate, 2 net gain ATP (4 total), and 2 NADH
How many molecule of ATP produced from 1 glucose
molecule
For each molecule of glucose degraded to CO2
and water by respiration, the cell makes up to 32
molecules of ATP
Which parts of cellular respiration/photosynthesis occurs in
the cytosol
glycolysis
glycolysis
Glycolysis (“sugar splitting”) breaks down glucose
into two molecules of pyruvate and two molecules of water
Glycolysis occurs in the cytoplasm and has two
major phases
Energy investment phase
Energy payoff phase
Glycolysis occurs whether or not O2 is present
fermentation
catabolic partial degra-
dation of sugars or other organic fuel that occurs without the
use of oxygen
anaerobic
occurs without the use of oxygen as a reactant (fermentation)
aerobic
catabolic process that occurs with oxygen as a reactant
What type of reaction is the breakdown of glucose?
Exergonic (it can happen spontaneously and doesn’t require the input of energy)
It has a negative free energy change because the products store less energy than the reactants
redox reactions
transfer of one electron from one reactant to another
oxidized
the first reactant becomes oxidized and transfers to the first product
loses electrons
C6H12O6 is oxidized to become 6CO2
Reduced
The second reactant becomes reduced to become the second product
addition of electrons (number of protons are reduced)
6O2 is reduced to 6H2O
oxidizing agent
the second reactant is the oxidizing agent because it oxidizes the first reactant
6O2
Reducing agent
is the first reactant
C6H12O6
what role does oxygen play in cellular respiration
it’s the oxidizing agent
and it serves as the final electron acceptor in the Electron Transport Chain
What are the reactants in glycolysis
C6H12O6, 2NAD+,2ADP+2pi
What are the products of the Krebs Cycle?
ATP, CO2, FADH2, NADH
What are the reactants of the Krebs Cycle?
Acetyl CO.A, NAD+, FAD+, ADP+Pi
Roles of NADPH/NAD- what do they carry and how are
they used in the metabolic processes
electrons
facultative anaerobes
Yeast and many bacteria
they can survive
using either fermentation or cellular respiration
pyruvate can lead to cellular respiration via O2 or ethanol lactate or other products without O2 (fermentation)
Athletes and scarce O2
Human muscle cells use lactic acid fermentation to
generate ATP when O2 is scarce
Energy released by the electron transport chain is used to
pump H+ into which location in eukaryotic cells
from the mitochondrial matrix into the intermembrane space
The synthesis of ATP by oxidative phosphorylation, using
the energy released by movement of protons across the
membrane down their electrochemical gradient, is an
example of ?
chemiosmosis
During aerobic respiration, H2O is formed. Where does the
oxygen atom for the formation of the water come from?
Oxygen from the air we breathe (from photosynthesis) and food
Where are the proteins of the electron transport chain
located?
in the mitochondrial membrane (cristae)
In the presence of oxygen, the three-carbon compound pyruvate
can be catabolized in the citric acid cycle. First, however, the
pyruvate (1) loses a carbon, which is given off as a molecule of
CO2, (2) is oxidized to form a two-carbon compound called
acetate, and (3) is bonded to coenzyme A. The three listed steps
result in the formation of ?
Acetyl CoA`
When a glucose molecule loses a hydrogen atom as the result
of an oxidation-reduction reaction, the molecule becomes ?
CO2
Most of the CO2 from the catabolism of glucose is released
during ?
Citric acid or krebs cycle
During aerobic respiration, electrons travel downhill in which
sequence, i.e from where to where?
when they’re being oxidized and pass the electrons down to their more electronegative neighbor (to the Iron Sulfur FeS protein in complex 1) which is in chemiosmosis
From the electron transport chain to ATP Synthase in chemiosmosis
This proton gradient that forms is called the proton motive force
The carrier protein downhill from oxygen to water
electron transport chain
a collection of molecules em-
bedded in the inner membrane of the mitochondrion in eu-
karyotic cells. (cristae)
If the the free energy for the oxidation of glucose to CO2 and
water is -686 kcal/mol and the free energy for the reduction
of NAD+ to NADH is +53 kcal/mol. Why are only two
molecules of NADH formed during glycolysis when it
appears that as many as a dozen could be formed?
Because we only use 34% of glucose for ATP; the rest is released as heat
alcohol fermentation
pyruvate is
converted to ethanol, releases CO2
lactic acid fermentation
pyru-
vate is reduced directly by NADH to form lactate as an end
product, with no release of CO2
beta oxidation
breaks
the fatty acids down to two-carbon fragments, which enter
the citric acid cycle as acetyl CoA. NADH and FADH2 are also
generated during beta oxidation
• Carbohydrates and fats are considered high-energy foods
because they___
They have high energy levels of electrons
A gram of fat oxidized by respiration produces
more than twice as much ATP as a gram of carbohydrate.
acetyl Coenzyme A
which links glycolysis to the citric acid cycle
joins the cycle by
combining with oxaloacetate, forming citrate
Allosteric regulation
uses an enzyme to keep the “pace” of cellular respiration
It monitors ATP and when ATP reaches a certain number, it stops glycolysis
it also monitors citrate, so it keeps each cycle consistent
Where is chlorophyll located
Green pigment that gives leaves their color and is found inside the thylakoid membrane of the chloroplast
When oxygen is released as a result of photosynthesis, it is a
direct by-product of ?
The chloroplast splits water into hydrogen and oxygen
It incorporates the electrons of hydrogen into sugar molecules and then releases oxygen as a byprouduct
The Oxygen comes from water
Difference between autotrophs and heterothrophs
autotrophs are self-feeders and sustain themselves without eating anything
heterotrophs are biosphere’s consumers because they consume compounds produced by other organisms
Engelman’s experiment
Used aerobic algae to test which wavelengths were the most suitable for photosynthesis
The wavelengths that were suitable to photosynthesis caused the algae to expel excess O2 and then the aerobic bacteria would congregate around it.
In What wavelength of light photosynthesis takes place
400-500 nm and 600-700 nm is the best for chlorophyll a
it can happen anywhere from 400-700
If the plant leaves appear reddish-yellow what wavelength
are being absorbed
everything except yellow, red
so orange, violet, blue, and green
What is the relationship between the wavelength of light and
the quantity of energy per photon?
The only photons absorbed are those whose energy is
exactly equal to the energy difference between the ground
state and an excited state, and this energy difference varies
from one kind of molecule to another. Thus, a particular
compound absorbs only photons corresponding to specific
wavelengths, which is why each pigment has a unique ab-
sorption spectrum.
Water and electron donation to photosystem II
H2O is split by enzymes and the electrons are transferred from the hydrogen atoms to P680+ thus reducing it to P680 (O2 is released as a byproduct)
Linear electron flow
Linear:
- Photon hits the pigment and the energy is passed from pigment molecules until it excites P680
- An excited electron from P680 is transferred via the primary electron transport (P680+)
- H2O is split by enzymes and the electrons are transferred from the hydrogen atoms to P680+ thus reducing it to P680 (O2 is released as a byproduct)
- Each electron “falls” down an electron transport chain to from the primary electron acceptor of PS 2 to PS 1
- Energy released by the fall drives the creation of a proton gradient across the thylakoid membrane (diffusion of H+ across the membrane drives ATP synthesis)
- In PS 1 transferred light energy excites P700 which loses an electron (P700+ accepts an electron passed down from PS 2 through the transport chain)
- Each electron falls down the chain from the primary electron acceptor in PS1 to ferredoxin (fd)
- The electrons are then transferred to NADP+ and reduced to NADPH
NADPH is then available for the Calvin cycle
This also removed H+ from the Stroma
Cyclic electron flow
Electrons cycle back from Fd to PS1 reaction center
Uses only PS 1 and produces ATP, but no NADPH
Don’t release O2
Ie purple bacteria which have PS1 but not PS2
Evolved before linear flow and may protect the plant from light damage
Where’s ATP synthase found
in the stroma? But it is kind of embedded in the thylakoid membrane
P680+
Photon hits the pigment in PS 2 and the energy is passed from pigment molecules until it excites P680 and becomes 680+
Calvin cycle/carbon cycle
Similar to the citric acid cycle because it regenerates its starting material after molecules enter and leave the molecule
It builds sugar from smaller molecules using ATP and reducing the power of electrons via NADPH
Carbon enters as CO2 and releases as glyceralhyde three phosphate G3P (has to go through Calvin cycle three times for this to occur
RuBp molecule and rubisco
Rubisco catalyzes carbon fixation in the calvin cycle and regenerates CO2 acceptor by RuBp
What compound provides the reducing power for Calvin
cycle reactions
ATP is involved, but it’s mostly NADPH
C3 plants
most plants
initial fixation of CO2,
via rubisco, forms a three-carbon compound
3-phosphoglycerate
C4 plants
minimize the cost of photorespiration by
incorporating CO2 into four-carbon compounds
two distinct types of cells in the leaves
of C4 plants:
Bundle-sheath cells
mesophyll cells
- The production of the four carbon precursors is
catalyzed by the enzyme PEP carboxylase in
the mesophyll cells
PEP carboxylase has a higher affinity for CO2
than rubisco does; it can fix CO2 even when CO2
concentrations are low - These four-carbon compounds are exported to
bundle-sheath cells - Within the bundle-sheath cells, they release CO2
that is then used in the Calvin cycle
CAM plants
what succulent plants use to fix carbon
open their stomata at night,
incorporating CO2 into organic acids
Stomata close during the day, and CO2 is released
from organic acids and used in the Calvin cycle
Photorespiration
rubisco adds O2 instead of
CO2 in the Calvin cycle, producing a two-carbon
compound
consumes O2 and organic fuel
and releases CO2 without producing ATP or sugar
In many plants, photorespiration is a problem
because on a hot, dry day it can drain as much
as 50% of the carbon fixed by the Calvin cycle
Cleavage furrow and cell plates
Cleavage furrow happens in cytokinesis of animal cells
Cell plates form in plant cells during cytokinesis
Centromeres
narrow “waist” of the
duplicated chromosome, where the two
chromatids are most closely attached
G1 phase
First gap - longest stage of interphase
G2 phase
second gap
shortest time in interphase
S phase
synthesis (where DNA is copied and synthesized) middle length stage of interphase
Mitotic phase
10 % of the total reproductive cycle of the cell and includes cytokinesis and PMAT and prometaphase between pro and meta
prophase
dna starts to condense
early mitotic spindle begins to form
become two sister chromatids
prometaphase
nuclear envelope begins to disassociate
kinetochores attach to the sister chromatids
kinetochore tubules attaches to kinetochores
non kinetochore microtubules also form
Kinetochores
Kinetochores are protein complexes associated
with centromeres
metaphase
sister chromatids line up along the metaphase plate
anaphase
The microtubules shorten by depolymerizing at
their kinetochore ends
telophase,
genetically identical daughter nuclei
form at opposite ends of the cell
density-dependent inhibition,
crowded cells
will stop dividing
anchorage dependence
to divide, they must be attached to a substratum
Cancer cells
don’t exhibit anchorage dependence or density-dependent inhibition
MPF
(maturation-promoting factor) is a cyclin-Cdk
complex that triggers a cell’s passage past the G2
checkpoint into the M phase
cyclins and cyclin-dependent
kinases (Cdks)
Two types of regulatory proteins are involved in
cell cycle control
checkpoints
in G1, G2 and m phases
G1 is most important, if it receives the go ahead from G1, it will usually continue to do the rest
M phase checkpoingt
without chromosomes being attached to microtubules, mitosis won’t proceed
