Energy and Cell Communication

Glycolysis

Glucose

Glucose 6-phosphate

Fructose 6 phosphate

Fructose 1,6-biphosphate

2 pyruvate

Pyruvate Oxidation

2 Acetyl Coenzyme A

Citric Acid Cycle

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Oxidative Phosphorylation

Electron Transport Chain

Protein Complex I

The electrons from NADH are
transferred to a molecule of
Flavoprotein.

Flavoprotein (FMN)

A redox reaction occurs and
Flavoprotein passes the electrons
to an Iron-Sulfur Protein.

Iron-Sulfur Protien (Fe-S)

A redox reaction occurs and
the electrons are passed to
Ubiquinone.

Protein Complex II

The electrons from
FADH2 are transferred
to a lower level of the
electron chain at
Complex II resulting in
about 1/3 the energy
for ATP synthesis
compared to NADH.

Iron-Sulfur Protein (Fe-S)

A redox reaction occurs and
the electrons are passed to
Ubiquinone.

Chemiosmosis

Chemiosmosis is the process
in which H+ is converted to
ATP. This begins when H+
interacts with an enzyme
called ATP synthase.

ATP Synthase

Part 1

Part 2

Part 3

Part 4

Part 5

TYPES OF FIRST MESENGER RECEPTORS

G-PROTEIN COUPLED (GCPR)

FIRST: Signal molecule actives the receptor when it binds to the G-protein

SECOND: This binding slightly changes the shape of of the GCPR and this allows the G-protein to bind to it

NEXT: GDP gets replaced with GTP activating it and it slides down the membrane to active enzyme and its GTP becomes GDP again

TYROSINE KINASE

consist of 2 polypeptides that dimerize when a signal molecule binds to them.

the polypeptides become kinases (they add phosphates to proteins)

Once all 6 get phosphate groups they become ACTIVE

ION CHANNEL

signal molecule binds to litigated protein causing it to open

Signaling Molecule/Signal/Ligand

Molecule released by a cell which is received by another cell. The signaling molecules that use intracellular signaling are small nonpolar molecules such as hormones that can pass through the hydrophobic region of the phospholipid bilayer that makes up cell membranes.

Receptor

Present in a target cell that receives the signal molecule. Intracellular signaling receptors are located in the cytoplasm.

Reception

The binding of a signaling molecule to a receptor protein

Steps

Step 1: A small nonpolar signaling molecule such as a hormone passes through the cell (plasma) membrane.

Step 2: The signaling molecule binds to a receptor protein in the cytoplasm, activating it. This forms a hormone-receptor complex.

Step 3: The hormone-receptor complex has the right configuration to enter the nucleus through a nuclear pore and binds to specific genes.

Step 4: The bound protein acts as a transcription factor, stimulating the transcription of the gene into mRNA.

Step 5: The mRNA is translated by ribosomes into a specific protein. This process brings about gene expression.

6 CO2 + 6H2O + LIGHT -> C6H12O6 + 6O2

Located in the CHLOROPLAST

STAGE 1: Light Reaction (thylakoid membrane)

Photosystem II

photon of light is absorbed by chlorophyll, this absorbed energy causes electrons to jump to excited state

then go back down to the ground state releasing the energy

energy is transferred from one pigment molecule to the other, eventually reaching the main pair of chlorophyll a molecules (P680)

the electrons are grabbed by an acceptor molecule

The electron hole in the main chlorophyll a molecules is constantly fed by electrons released when water is split. O2 is released

Electrons from the primary electron acceptor then go down an electron transport chain eventually reaching chlorophyll a molecules of PS1

Photosystem I

photon of light absorbed by one pigment molecule causing electrons to be excited

as they go back to the ground state energy is released which eventually reaches the main chlorophyll a molecules (P700).

Electrons of these chlorophyll a molecules jump to the excited state and are grabbed by a primary electron acceptor.

electrons go to Ferridoxin (Fd) then on to NADP+ to form NADPH

The electron hole in P700 chlorophyll molecules is supplied from electrons coming down the electron transport chain

This transfer of electrons down the electron transport chain lead to formation of ATP by photophosphorylation.

THIS IS THE NON-CYCLIC FLOW OF ELECTRONS

CYCLIC FLOW: when there is excess NADPH, only PSI is used. ATP is made by phosphorylation. No NADPH is formed.

STAGE 2: Calvin Cycle (stroma)

3 PHASES

PHASE 1

CARBON FIXATION

CO2 from the atmosphere is added to ribulose bisphosphate using RUBISCO. This forms a 6-carbon unstable intermediate.

The short intermediate then splits to 2 molecules of 3 carbon (3-phosphoglycerate). This is the first stable molecule.

PHASE 2

REDUCTION

Using 2 ATP and 6 NADPH, forms molecules of G3P

PHASE 3

REGENERATION OF CO2 RECEPTOR

5 of the G3P molecules go on to form more ribulose bis phosphate ( the carbon acceptor) and 1 molecule of G3P leaves the cycle to form glucose and other sugars.

Net of 2 ATP & 2 NADH

Net 2 NADH

Energy investment

Energy payoff

Large and polar signal molecules must be received by transmembrane receptor because they cannot easily go through the cellular membrane

after signal molecule is received inside the cell Transduction takes place

TRANSDUCTION: the sequential activation of KINASES, by getting phosphates from ATP

Citrate is produced through the
addition of Acetyl CoA's two carbon
group to oxaloacetate's four carbon
group.

Citrate is dehydrated and through
rehydration is converted into Isocitrate.

Through a redox reaction the isocitrate
is oxidized to become the five carbon a-Ketoglutarate. In this reaction a molecule of CO2 is released and NAD+ is reduced to NADH.

Another redox reaction occurs and
as a second molecule of CO2 is released another NAD+ is reduced to NADH. A CoA then binds with the resulting succiynl to form succinyl CoA.

The CoA unbinds and is replaced with a phosphate group. This process creates GTP or ATP depending on the type of cell. In most animal cells GTP is made and used to make ATP. In plant cells and some animal cells ATP is directly produced. When the CoA and phosphates are swapped Succinate is produced.

A redox reaction occurs and Succinate is oxidized, becoming Fumarate. FAD is reduced to FADH2 from this process as well.

A water molecule combines with the
Fumarate to form Malate.

Step 8

Since 2 Acetyl Coenzyme A are produced
in Pyruvate Oxidation the products of the Citric Acid Cycle per glucose are 6 NADH, 2FADH2, and 2 ATP.

The final redox reaction in the cycle
happens when Malate is oxidized and becomes oxaoacetate like at the beginning of the cycle. NAD+ is also reduced to NADH.

Ubiquinone (Q)

Protein Complex III

Cytochromes (Cyt)

Cyt b

Fe-S

Cyt c1

Cyt c

Protein Complex IV

Cyt a

Cyt a3

This is the last electron
carrier in the ETC. The
electrons are then passed
onto Oxygen in the
mitochondrial matrix.

Oxygen

Two Hydrogen Atoms
are then binded to
Oxygen to create H2O.

Ubiquinone is not a protein but
moves within the membrane and
transfers electrons from I and II
into protein complex III.

Throughout complex III
the electrons are passed
through mainly cytochromes.

Cytochromes are proteins
that differ by their heme
groups which carry electrons
down the chain.

photophosphorylation is making ATP by adding a phosphate group to ADP

These complexes pump
protons (H+) through
the mitochondrial membrane
into the intermembrane
space. These are used in
Chemiosmosis to produce
ATP.

The electrons from NADH/FADH2
move along four complexes in order
of increasing electronegativity whilst
releasing energy. This occurs on the
inner mitochondrial membrane.

Protons go down their gradient
and enter a channel of the stator part of ATP Synthase.

The protons are then entered into the
rotor which they connect to and do a full
rotation around.

After the rotation the protons enter the
stator again but through a different channel which deposits them into the mitochondrial matrix.

The rotor's spinning makes an internal rod
spin. This rod is connected to a knob that is only stopped from spinning by the stator which holds it in place.

The turning of the rod does activate
catalytic sites in the knob though. These make ATP from ADP and phosphate groups.