F214- Respiration

Notes on the respiration module using specification points

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Outline why plants, animals and microorganisms need to respire, with reference to active transport and metabolic
Metabolic processes that need energy include
Active transport- moving ions and molecules across a membrane against a concentration gradient. All
cell membranes have a sodium-potassium pumps and these maintain the resting potential. When this
pump momentarily stops in neurone membranes, sodium ions enter the neurone and an action
potential occurs
Secretion- large molecules made in some cells are exported by exocystosis
Endocytosis- bulk movement of large molecules into cells
Synthesis of large molecules from smaller ones e.g. proteins from amino acids, steroids from
cholesterol and cellulose from -glucose
Replication of DNA and synthesis of organelles before a cell divides
Movement- e.g. bacterial flagella, eukaryotic cilia and undulipodia, muscle contraction and microtubule
motors that move organelles around inside cells
Activation of chemicals- glucose is phosphorylated at the beginning of respiration so that more is
unstable and can be broken down to release energy
Describe, with the aid of diagrams, the structure of ATP;
State that ATP provides the immediate source of energy for biological processes;
Phosphorylated nucleotide
Found in both prokaryotic and eukaryotic cells
Each molecule consists of adenosine and three phosphate groups
It can be hydrolysed to ADP and Pi releasing 30.6kJ energy per mol.
It is known as the universal energy currency as energy is released in small manageable amounts for
powering chemical reactions in cells and it is found in all types of cells
Explain the importance of coenzymes in respiration, with reference to NAD and coenzyme A;
Organic, non protein molecule
Helps dehydrogenase enzymes to carry out oxidation reactions
Contains the ribose sugar, the nitrogenous base adenine and phosphate groups
When NAD accepts two hydrogen atoms with their electrons it becomes reduced. It then acts as a
reducing agent by donating electrons
NAD operates during Glycolysis, the link reaction, Krebs cycle and during the anaerobic ethanol and
lactate pathways
Coenzyme A
Carries ethanoate groups made from pyruvate during the link reaction onto the Kreb's cycle
It can also carry acetate groups that have been made from fatty acids or from some amino acids onto
Kreb's cycle
Acetate + CoA AcetylCoA
Living organisms don't have much NAD or CoA in their cells as they are recycled/ regenerated.
State that glycolysis takes place in the cytoplasm;
Outline the process of glycolysis

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One ATP molecule is hydrolysed and the phosphate group released is attached to the glucose molecule
at carbon 6
Glucose 6-phosphate is changed to fructose 6-phosphate
Another ATP is hydrolysed and the phosphate group released is attached to fructose 6-phosphate at
carbon 1 which activates the hexose sugar which becomes fructose 1,6-bisphosphate
The energy released from the hydrolysed ATP molecules activates the hexose sugar and prevents it
from being transported out of the cell.…read more

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Some of the electron carriers also have a coenzyme that pumps protons from the matrix to the
intermembrane space using energy released from the passage of electrons
ATP synthase enzymes
Are large and protrude from the inner membrane into the matrix
Are also known as stalked particles
Allow protons to pass through them
State that the link reaction takes place in the mitochondrial matrix;
Outline the link reaction, with reference to decarboxylation of pyruvate to acetate and the reduction of NAD;
Explain that acetate…read more

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The first electron carrier to accept the electrons from reduced NAD is a protein complex called
The protons go into solution in the matrix
Electron transport chain- the electrons are passed along a series of electron carriers and then donated to
molecular oxygen, the final electron acceptor
Outline the process of chemiosmosis, with reference to the electron transport chain, proton gradients and
As electrons flow along the electron transport chain, energy is released and used by the coenzymes
associated with some of…read more

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Alcoholic fermentation (under anaerobic respiration in yeast cells)
Each pyruvate molecule loses a carbon dioxide molecule; it is decarboxylated and becomes
This reaction is catalysed by the enzyme pyruvate decarboxylase which has a coenzyme bound to
Ethanal accepts a hydrogen atom from reduced NAD which becomes reoxidised as ethanal is
reduced to ethanol.…read more

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Excess amino acids, released after protein digestion, may be deaminated. This involves removal of the
amine group and its conversion to urea.…read more


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