Energy and Cell Communication

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INTODUCTION TO PROKARYOTES

av faizatul aina zakariya

Cell Structure, Function and Organisation

av Gloria Ng Shu Yi

Organigrama arbol

av Harold shumager

Structure and Bonding

av Sam Bartlett

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

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.

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

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

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

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

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

photophosphorylation is making ATP by adding a phosphate group to ADP

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

Throughout complex III the electrons are passed through mainly cytochromes.

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

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.

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.

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.

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

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.

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.

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.

Citrate is dehydrated and through rehydration is converted into Isocitrate.

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

after signal molecule is received inside the cell Transduction takes place

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

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

Energy payoff

Energy investment

Net 2 NADH

Net of 2 ATP & 2 NADH

PHOTOSYNTHESIS

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

Located in the CHLOROPLAST

STAGE 2: Calvin Cycle (stroma)

3 PHASES

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.

PHASE 2

REDUCTION

Using 2 ATP and 6 NADPH, forms molecules of G3P

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.

STAGE 1: Light Reaction (thylakoid membrane)

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.

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

Intracellular Signaling

Reception

Steps

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

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

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

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

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

The binding of a signaling molecule to a receptor protein

Receptor

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

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.

Membrane Receptor Signaling

TYPES OF FIRST MESENGER RECEPTORS

ION CHANNEL

signal molecule binds to litigated protein causing it to open

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

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

Aerobic Cell Respiration

Oxidative Phosphorylation

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 5

Part 4

Part 3

Part 2

Part 1

Electron Transport Chain

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.

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.

Citric Acid Cycle

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Pyruvate Oxidation

2 Acetyl Coenzyme A

Glycolysis

Occurs outside the mitochondria in the cytosol and breaks down glucose into 2 pyruvate molecules through substrate-level ATP synthesizing.

Involves

energy investment
energy payoff

Glucose

Glucose 6-phosphate

Fructose 6 phosphate

Fructose 1,6-biphosphate

2 pyruvate