Biology - Energy and Respiration

What is ATP?

ATP is adenosine triphosphate which are packets of energy produced by the mitochondria.

Why is ATP regarded as the universal energy currency?

ATP is universal energy currency because it is easy to hydrolyze and can be done anywhere in a cell.

It is a perfect amount of energy inside it meaning once it’s hydroglyzed it’s neither wasted or too little for a reaction.

It is a stable molecule that can withstand different PH levels of a cell and only hydrolyzed when the enzyme ATPase is present

What is chemiosmosis?

The production of ATP from the energy released by hydrogen ions by moving down the concentration gradient across a mitrochondria membrane or chloroplast membrane.

Explain the link reaction.

After pyruvate is actively transported into the matrix of mitochondria, it is decarboxylated and dehydrogenated. The remainder is added to Coenzyme A which produces Acetyl Coenzyme A along with leftover hydrogen which is added to NAD to be produce reduced NAD.

Define Decarboxylation.

The removal of carbon dioxide from a substance.

Define dehydrogenation.

The removal of hydrogen from a substance.

Explain the Krebs cycle in detail.

The acetyl Coenzyme A (2C) in the link reaction is added to 4C oxaloacetate to form citrate (6C) the citrate during the cycle is decarboxylated and dehydrogenated until it’s got 4C left again and oxaloacetate is recovered from the cycle. During one cycle 3 NAD are reduced and 1 FAD is reduced. two carbon dioxide are produced and 1 ATP is produced by substrate linked phosphorylation.

Describe Ethanol fermentation in rice.

Rice can withstand being flooded due and other plants can’t due to not enough oxygen being produced, and co2 being unable to escape. But rice can as it has Aerenchyma which are loosely packed cells with air spaces allowing oxygen to better diffuse into the roots and stems that are submerged. But rice still need to undergo ethanol fermentation. Rice can handle a large amount of ethanol before toxicity and it also breaks down ethanol using ethanol dehydrogenase. All these allow rice to grow even though oxygen is scarcely available.

Compare energy values of the 3 substrates glucose, lipids, amino acids.

Glucose are used first then lipids then amino acids. Glucose are lowest energy density, amino acids are 2nd highest and lipids are the highest energy density due to large number of hydrogens.

the ratio of energy is roughly 4:4:9

What is an RQ value?

The RQ value of a respiratory reaction is the respiratory quotant which is the ratio of carbon dioxide produced to the ratio of Oxygen produced by a reaction given by RQ = mols of CO2/mols of O2. The higher the respiratory quotant the more likely alcohol fermentation is occurring and the lower the value the higher the chance the reaction is aerobic.

Typical RQ values for the substrates are 1.0 for glucose 0.7 for amino acids and 0.9 for lipids.

What is used to measure the rate of respiration of an organism?

A respirometer

What is ethanol fermentation?

This is a process where a cell produces energy where there is a lack of oxygen. This occurs in yeasts. The process involves glycolysis but after the glycolysis the pyruvate stays in the cell cytoplasm where it is decarboxylated to Ethanal then the ethanal is converted to ethanol by the addition of hydrogen by the enzyme Alcohol dehydrogenase which frees up more NAD to go produce ATP.

What is anearohic respiration in mammals?

Due to the lack of oxygen lactate fermentation happens because there is no oxygen to accept electrons at the electron transport chain therefore hydrogens cannot be released from NAD and therefore all NAD are reduced and cannot reduce more which stops the Krebs cycle and more glycolysis from taking place. To counter this mammals convert the pyruvate into Lactate by the enzyme lactate dehydrogenase which frees up NAD to further produce ATP. this lactate can be oxidized unlike alcohol in yeast which creates an oxygen debt as it builds up in muscle cells until it is broken down by liver. It can also be turned into glycogen.

Explain oxidative phosphorylation.

After the Krebs cycle when the NADH and FADH are produced an electron transport chain is started at the inner membrane of the mitochondria. This electron transport chain is a chain of carrier proteins at the inner membrane which splits the hydrogen from NADH and FADH into H+ ion and an electron, the electron contains energy and some of this is used to push H+ into the transmembrane space of the mitochondria. The electrons go across the transport chain by a series of redox reaction (oxidation by losing electron reduction by gaining electron) then the H+ ions come down from the channel protien via fascilitated diffusion by the enzyme ATP synthase. As they pass the channel protien thier energy is used to synthesize ATP in the process called chemiosmosis. Then oxygen is added to the 4 electrons and 4 hydrogen to produce 2 water molecules. Oxidative phosphorylation is the most ATP producer.

Compare the outer and inner membrane of the mitochondria.

Inner membrane has cristae which are folded membrane giving mitochondria a large surface area. The more active a cell the more folded a mitochondria inside of it. It is less permeable

Outer membrane is smooth and is more permeable so stuff can enter

What is ATP made of?

Adenine base, a ribose sugar and 3 phosphate groups.

What is an anabolic reaction?

An anabolic reaction is where larger more complex molecules are built from smaller less complex ones.

Explain the 5 steps of glycolysis in detail.

1) hexose glucose has a phosphate group donated to it by a ATP molecule giving it energy and making fructose phosphate.

2) Another ATP donates a phosphate group to the Fructose making 1,6 - fructose biphosphate. Meaning 2 total ATP worth of energy is used.

3) The fructose biphosphate is broken down into 2 molecules called triose phosphate.

4) NAD comes and oxidizes the triose phosphates by removing 1 hydrogen each making NADH+ then phosphates are added to each triose phosphate making triose biphosphate

5) Then 2 ATP is produced by substrate linked phosphorylation by the triose, then the triose is rearranged and further 2 ATP are produced. The end biproduct being pyruvate (C3H4O3) which is a high energy molecule.

What are the 4 stages of oxidative glucose breakdown?

1)Glycolysis

2) the link reaction

3)the Krebs cycle

4)oxidative phosphorylation.

What is phosphorylation?

When a phosphate group is added to a molecule.

What is Substrate - linked phosphorylation?

When a phosphate group is added directly to a ADP molecule to form ATP from a substrate due to the energy from another chemical reaction.