Aerobic Respiration- A2

The Mitochondria

This is a labelled Mitochondria. Mitochondria are where the link reaction (Matrix), the Krebs cycle (Matrix) and oxidative phosphorlyation (Inner Mitochondrial Membrane) take place.

Glycolysis

1. 
   
    Glucose (6 carbon) is made more reactive using 2ATP (Phosphorylation). Phosphate is added to it, as it lowers the activation energy for the reactions that follow.
2. 
   
   Each Phosphorylated glucose is split to form 2 Triphosphate molecules (3 carbon).
3. 
   
   The Triphosphates are oxidised by the removal of hydrogen to form PYRUVATE, the hydrogen is donated to an NAD co-enzyme, which makes red.NAD

Joining a phosphate to another molecule, e.g. ADP is phosphorlyation.

Substrate Level Phosphorylation: the phosphorylation of ADP + Pi = ATP using energy released from chemical reactions. So, the chemical energy used comes from the substrate, hence the name.

Link Reaction

PYRUVATE is oxidised by removing hydrogen. This is because of the DEHYDROGENASE enzyme.

PYRUVATE is DECARBOXYLATED. Decarboxylation is the removal of Carbon Dioxide (Decarboxylase Enzyme). Since a carbon has been removed, it goes from three carbons to two, an ACETYL group. This joins with a co-enzyme.

The Krebs Cycle

The Acetyl co-enzyme joins with a four carbon acceptor molecule to form a six carbon intermediate. The six carbon intermediate is then decarboxylated, and carbon dioxide is released, making it into a five carbon intermediate. At the same time, it is oxidised, loosing hydrogen. This hydrogen reduces an NAD co-enzyme, forming red.NAD which goes on to the electron transport chain.

The five carbon intermediate is decarboxylated, releasing carbon dioxide and making a four carbon intermediate. Enough energy is released to synthesise ATP by ADP+Pi = ATP. As well as this, the fout carbon intermediate is oxidised, donating a hydrogen to an FAD and 2NAD, reducing them too. The too move on to the electron transport chain. The four carbon acceptor goes back round in the cycle to join with an acetyl again.

Electron Transport Chain

In the electron transport chain, co-enzymes donate their electrons and protons (e- and H+). The electrons enter a chain of carriers, arranged in order of decreasing energy content, releasing energy, until they reach the final electron acceptor, molecular oxygen. Meanwhile, the H+ are actively transported through the ATP synthase enzyme, down a concentration gradient. The kinteic energy produced in the process gives enough energy to synthesis ADP + Pi => ATP. Also, the H+ joins on to the molecular oxygen with the electrons to form WATER.

Thoughts?
-Nin.

Respiration 1 - A2

Aerobic => Oxygen
Anaerobic => Turns glucose into lactate (when in animals), and into ethanol and CO2 (when in yeast, etc.)

Oxidation is the:

• Gain of Oxygen
• Loss of Electrons
• Loss of Hydrogen

Reduction is the:

• Loss of Oxygen
• Gain of Electrons
• Gain of Hydrogen

Reducing Agent means the thing that is oxidised, and that caused reduction by being an electron donator.
Oxidising Agent means the thing that is reduced, and that caused oxidation by being an electron acceptor.

Co-enzymes
NAD - Nicotamine Adenine Dinucleotide
FAD - Flavine Adenine Dinucleotide
Co-enzymes are a carrier of hydrogen molecules from one molecule to the other. They work in assistance with dehydrogenase enzymes which catalyse hydrogen removal.

When NAD picks up Hydrogen,
NAD + 2H+ => NADH2
The NADH2 is the reduced form as it has GAINED Hydrogen.


The stages of Aerobic respiration

1. Glycosis -> Takes place in the CYTOPLASM, Aerobic and Anaerobic.
2. Link Reaction -> Takes place in the Mitochondria (MATRIX), Aerobic.
3. Krebs Cycle -> Takes place in the Mitochondria (MATRIX), Aerobic.
4. Oxidative Phosphorylation -> Takes place in the Mitochondria (INNER MITOCHONDRIAL MEMBRANE), Aerobic.

ATP - A2

This topic is scary horrible. :P

Energy Supply

ATP => Adenine Triphosphate

Energy supply has two key processes: Photosynthesis and Respiration

Photosynthesis - transfers light energy into chemical energy in organic molecules
CO2+H2O => (with light energy) O2 + C6H12O

Respiration - releases energy from organic molecules, e.g. glucose.
C6H12O + O2 => CO2 + H2O + Energy

We only ever have 5g of ATP in the body at any one time, and use 40kg of it in a single day.

Why do organisms need energy?

• Growth and Repair
• Muscle Contraction
• Active Transport (changes the chape of the protein carrier)
• Metabolism
• Maintainence of body temperature in birds and mammals.
• Movement.
• Building up of large molecules.

Why is it an energy carrier?

It is small, soluble, and therefore, easily transported around the body.

ATP is a specialised compound. Reactions are coupled of transferring energy releasing reactions and those that require energy.

Why not just use Glucose?

Glucose is too slow to break down. It breaks down in several stages, and because of this, looses a lot of energy as heat energy. It is wasted.

How does ATP store energy?

• The bonds between the phosphate groups are unstable and have a LOW activation energy.
• This means the phosphate bonds are easilt broken to release energy.
• Usually only the terminal phosphate group is removed. Energy is released in small usable amounts when ATP is hydrolysed to ADP + Pi

ATP is RE-synthesised from ADP + Pi by Phosphorylation, which is a condensation reaction.

• ATP is broken down in a single reaction, rapidly releasing energy to cell reactions, unlike glucose which, as previously said, needs to be broken down by a long series of reactions.
• ATP releases smaller more useable quantities of energies than Glucose does. (Plus heat is released with Glucose.)

Summary: Advantage of ATP as an energy carrier (Universal)

1. It is an immediate source of energy (small reaction.)
2. The phosphate bonds are unstable, have a low activation energy and are easily broken.
3. ATP is a small molecule, and is highly soluble, meaning it is easily transported anywhere in the body.

Thoughts?

-Nin. Comments would be really nice by the way. (:

Predation -A2

Predators are animals that hunt and kill, then eat their prey.

In a predator-prey graph, there are two things to remember:

1. Predators numbers are always less then it's prey.
2. A little while after the preys populations increase, the predators does too.

As the prey population declines, there is increased competition between predators for they remaining prey. Eventually, their numbers begin to fall. When a predator population declines, prey population builds up. Predators have more food, so their population then rises again.

Competition -A2

Interspecific- When competition arises between two different species.
Intraspecific- When competition arises between the same species.

Plants compete for: Light, water, nutrients, growth space.

Interspecific Competition:

• Where two populations initially occupy the same niche, one will normally have a competitive advantage over the other.
• The population of this species will gradually INCREASE in size while the other will decrease. This is known as the 'comeptitve exclusion' principle.

'Competitive Advantage' is a better term to use then 'Dominant'. Avoid dominant.

Niche + Competition ->

• Do they feed in different areas/levels? (E.g. feed in water, whereas other feeds from shrubs. Or Feeding on the sea bed, as opposed to the water surface.)
• Where do they nest/settle? (Trees, bushes, ponds, underwater, underground.)

Recapping Rates of Reaction (Kinetics)

Factors that affect Rate of Reaction


1) Temperature: When the temperature increases, the particles have increased kinetic energy, and therefore, they collilde more, and there are more successful collisions, and, more particles exceeding the activation energy. (Increased rate of reaction.)

2) Pressure: When the pressure is increased, there are more particles per a smaller space, so their is a higher likelihood or them colliding, and a therefore, and higher chance that there will be a successful collision. (Increased rate of reaction.)

3) Concentration: When the concentration is increased, there are more particles within the
space, meaning that there is a higher likelihood of collision, and a higher chance of successful collision. (Increased rate of reaction.)

4) Catalyst: A catalyst provide an alternate reaction pathway, that has a lower activation energy, more particles can exceed this activation energy, therefore, the rate of reaction will be quicker.

5) Surface Area: The parger the surface area, the more space upon which there is to react, therefore, more collisions can occur, so there will be a high rate of successful collisions: i.e. a higher rate of reaction.




Activation Energy Diagrams




Shows the enthalpy change. (The difference between products and reactants.) They also show how a catalyst lowers activation energy.)

Maxwell Boltzmann Curves show the number of particles against the energy of them. It shows that there are less amounts of particles with the energy to exceed the activation energy, or Ea.


The A2 Bit.

How do we measure rate?

• Measure the time it takes
• Collect gas -> Turn into moles using pV=nRT
• Measure the change in mass and then convert into moles. (n= Mr/Ar)

Rate is measured in mol dm-3 s-1. This mean moles per decimeter cubed per second.

The set up for a rate equation is Rate = k[A]x[B]y

K is called the constant rate, or the fiddle factor.

In two experiments, if the value you are focusing on doesn't change, and the end value doesn't either: factor O, if it does the same, e.g., they both double, it's factor 1, and if it does different i.e. it doubles and the end value quadruples, it's factor 2.

Essentially:

Zero- Changing the amount of this reactant has no effect on the rate.
One- Changing the amount of this reactant does the same to the rate. (Doubles both.)
Two- Changing the reactant does different to the rate - doubling the reactant quadruples the rate.

Thoughts?
-Nin.

(And do remember, I'm only a student myself, sorry if I get bits wrong. (: )