!!!Energy Transfer Of Organisms - Respiration Flashcards
What is respiration overall
Releasing energy from fats and sugars to make ATP which transfers energy to energy demanding reactions which are endergonic processes
What are the basic points on ATP regarding its role?
It’s an immediate source of energy that is released in small manageable quantities that can’t be stored so is constantly being regenerated
Give 5 uses of ATP
- anabolism ( making polymers)
- muscle contraction
- active transport
- activation/ phosphorylation
- maintaining body temperature
State and describe the 4 stages of respiration
- Glycolysis = the splitting of 6c glucose molecule into 2 3c pyruvate molecules
- link reaction = the 3c pyruvate molecule undergoes a series of reactions to lead to the production of COA 2c
- krebs cycle
- oxidative level phosphorylation
Where does glycolysis fit in the overall process of respiration?
It is the initial stage of aerobic and anaerobic respiration and occurs in the cytoplasm of all living cells
Describe glycolysis through its 4 stages
- Activation of glucose by phosphorylation - where adding 2 phosphate molecules to the glucose provided by the hydrolysis of ATP to form ADP make the glucose molecule highly reactive
- Splitting of the phosphorylated glucose- the glucose molecule splits into 2 3c molecules which are TP
- Oxidation of TP by dehydrogenation - where hydrogen is removed from each TP and transferred to NAD to form reduced NAD
- Substrate level phosphorylation - where enzyme controlled reactions convert each TP molecule into pyruvate (3c) by which 2 molecules of ATP are regenerated from 2 ADPs
What are the products of glycolysis?
- 2x ATP
- 2x red NAD
- 2x pyruvate
Where does the link reaction and the Krebs cycle take place?
In the matrix of the mitochondria
What happens in the link reaction?
- 3c pyruvate looses a co2 molecule and so 2 hydrogens so is oxidised forming acetate and the hydrogens are accepted by NAD to form reduced NAD
- The 2c acetate combines with CoA to produce acetyl CoA
What are the steps in the Krebs cycle?
- 2 carbon acetyl CoA combines with a 4c molecule to produce 6c citric acid
- The 6c molecule of citric acid is oxidised as it looses a hydrogen so nad+ is reduced and reduced nad is given off.
- 2 co2 molecules are also released
- FAD goes in and reduced FAD is released
- This releases a single molecule of ATP in substrate level phosphorylation to produce a 4 carbon molecule which can now combine with a new molecule of acetylCOA to repeat the cycle
What are the products of the link’s reaction and Krebs cycle overall?
- 6 co2
- 8 reduced NAD
- 2 reduced FAD
- 2 ATP
What do the coenzymes do in respiration and which is the most important?
They carry hydrogen atoms from one molecule to another. Most important being NAD as it works with dehydrogenase enzymes that catalyse the removal of hydrogen atoms from substrates and transfer them to the other molecules involved in oxidative phosphorylation
Where does oxidative phosphorylation take place?
In the inner membrane of the cristae of the mitochondria
Give four reasons why the Krebs cycle is so important
- breaks down macromolecules into smaller ones e.g. pyruvate broken into co2
- produces hydrogen atoms that are carried by the NAD to the etc to provide energy for oxidative phosphorylation leading to ATP production which provides cellular energy
- regenerates the 4c molecule so it can combine with acetylCOA otherwise it would accumulate
- source of immediate compounds used by cells in the manufacture of other important substances like fatty acids, amino acids and chlorophyll
Explain how ATP is synthesised in oxidative phosphorylation
- The hydrogen atoms produced in glycolysis and the Krebs cycle combine with coenzymes NAD and and FAD reducing them
- 2H -> 2e- + 2H+ as they undergo oxidation so they donate their electrons to the first electron carrier protein in the electron transfer chain
- The electrons pass along the electron transfer chain in a series of oxidation reduction reactions as they loose their energy which is transferred to the electron carrier proteins to provide energy to the proton pump which actively transports electrons across the inner mitochondrial membrane and into the inter-membrane space creating an electrochemical gradient
- The protons diffuse down their concentration gradient through chemiosmosis via ATP synthase which provides the energy to form ATP from the condensation of ADP and Pi
