5.7 - E - Respiration Flashcards
Define respiration
The release of chemical potential energy from organic molecules
inside mitochondria
What does ATP stand for?
Adenosine triphosphate
What are 7 uses of ATP?
Active Transport Endocytosis & exocytosis Synthesis of large molecules (collagen, enzymes, antibodies) DNA replication Cell division Movement Activation of chemicals
What type of molecule is ATP?
Phosphorylated nucleotide
How much energy is released when either the first or second phosphate group of ATP are removed?
How much energy is released when the third phosphate group of ATP is removed?
- 5 kJ
14. 2 kJ
What type of reaction occurs when a phosphate group is removed from ATP?
Hydrolysis - this requires water
List the full name of ATP when it has: 3 phosphate groups, 2 phosphate groups, 1 phosphate group, No phosphate groups
Adenosine triphosphate
Adenosine diphosphate
Adenosine monophosphate
Adenosine
What is adenosine monophosphate the same as?
RNA
What enzyme catalyses the removal of phosphate groups from ATP?
ATPase
Where does the energy that is released in the hydrolysis of ATP come from?
The chemical energy stored in glucose
Describe the role of coenzymes in respiration
They are enzymes needed to assist other enzymes in a reduction or oxidation reaction (because they can pick up and lose hydrogen atoms)
List the 3 coenzymes used in respiration
NAD - Nicotinamide Adenine Dinucleotide
CoA - Coenzyme A
FAD - Flavine Adenine Dinucleotide
What does RNA need to become ATP?
2 phosphate groups
Define energy
The capacity to do work
What is potential energy?
The energy that is stored in complex organic molecules.
Eg: fats, carbohydrates, and proteins.
State and explain the 2 types of metabolic reactions
Anabolic reactions - metabolic reactions where large molecules are synthesised from smaller molecules.
Catabolic reactions - metabolic reactions involving the hydrolysis of large molecules to smaller ones.
Why is ATP referred to as the universal currency of energy?
It occurs in all living cells and is a source of energy that can be used by cells in small amounts.
Why is all the chemical energy released during respiration not transferred to ATP?
It’s lost as heat
Why does each cell require the structures associated
with respiration?
ATP cannot cross the plasma membrane
What are the 4 main processes in aerobic respiration?
Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation
Define glycolysis
The first stage in respiration, a 10 stage metabolic biochemical pathway that occurs in the cytoplasm or all living things that respire that converts glucose to pyruvate.
What coenzyme helps some enzymes in glycolysis?
NAD - Nicotinamide Adenine Dinucleotide
What are the 3 main stages in glycolysis?
Phosphorylation of glucose to hexose bisphosphate.
Splitting each hexose bisphosphate molecule into 2 triose phosphate molecules.
Oxidation of triose phosphate to pyruvate.
When do enzymes require coenzymes?
When catalysing oxidation and reduction reactions as they accept hydrogen atoms removed during oxidation.
What is NAD and what does it do throughout glycolysis?
It’s a non-protein molecule that helps dehydrogenase enzymes to carry out oxidation reactions.
How is NAD synthesised?
In living cells from nicotinamide (vitamin B3), ribose, adenine and 2 phosphoryl groups.
What happens in the first main stage of glycolysis (phosphorylation)?
One molecule of ATP is hydrolysed the Pi is added to glucose to make hexose monophosphate.
Another molecule of ATP is hydrolysed and the Pi is added to the hexose phosphate to form a molecule of hexose bisphosphate.
The energy from the hydrolysed ATP molecules activated the hexose sugar and prevents it from being transported out of the cell.
Explain the structure of hexose bisphosphate
It’s a sugar that has one phosphate group at carbon atom number 1 and another at carbon atom number 6.
Explain the second main stage in glycolysis (the splitting of the hexose bisphosphate)
Each molecule of hexose bisphosphate is split into two 3-carbon molecules, triose phosphate, each with a phosphate group attached.
What happens in the third main stage in glycolysis (the oxidation of triose phosphate to pyruvate)?
Although this process is anaerobic, it involves oxidation, because it involves the removal of hydrogen atoms from substrate molecules:
Dehydrogenase enzymes, aided by the coenzyme NAD, remove hydrogens from triose phosphate.
The 2 molecule of NAD accept the hydrogen atoms (protons and electrons) and become reduced.
Describe the products at the end of glycolysis, in relation to the original glucose
At this stage of glycolysis, 2 molecules of NAD are reduced for every molecule of glucose undergoing this process. Also at this stage, four molecules of ATP are made for every 2 triose phosphate molecules undergoing oxidation.
For each molecule of glucose, at the end of glycolysis there are:
2 molecules of ATP; 4 have been made, but 2 were used to ‘kick start’ the process, so the net gain is 2 ATP molecules.
2 molecules of reduced NAD (NADH).
2 molecules of pyruvate.
What type of respiration includes the 4 stages of respiration?
Aerobic (glycolysis happens before the 2 types separate that require different stages)
How are the 4 ATPs made in the third stage of glycolysis?
Substrate level phosphorylation
What does the outer membrane of mitochondria contain? What are these used for?
Protein channels or carriers to allow pyruvate to pass through
Explain the inner membrane of mitochondria
Has a different membrane structure and is much less permeable to small ions (e.g. hydrogen ions)
Folded into cristae to give a large surface area
Contains electron carriers and ATP synthase enzymes
