Respiration Flashcards
What is ATP made up of?
- 3 phosphate groups
- nucleotide adenine
- ribose sugar
What is ATP synthesised from?
ADP + Pi- Adenosine diphosphate and an inorganic phosphate
Define Phosphorylation
The addition of Phosphate to a molecule
-can be bonded onto different compounds
What is the point of phosphorylation
-make the molecule more reactive
-happens to glucose at the start of glycolysis
Define Hydrolysis
The breaking of ATP involves splitting the splitting of a molecule using water- the reaction is catalysed using the enzyme ATPase.
-a small amount of energy is released
-ATP- immediate energy source- only one bond has to be hydrolysed to release energy
Can ATP be stored
Cells don’t store large amounts of ATP at one time- can be rapidly built up from ADP + Pi- there is a continual cycle between ADP + Pi and ATP.
What are the 2 main forms of phosphorylation
- Photophosphorylation- occurs during the light-dependant reaction in chlorophyll
- Oxidative Phosphorylation- occurs in cellular respiration in aerobic cells.
What makes ATP so suitable as an immediate energy source?
- The hydrolysis of an ATP molecule releases a small amount of energy
- Involves a single reaction to release energy using one enzyme (ATPase). Breaking one bond releases energy immediately and allows the cell to have control over its energy budget.
- Can be transported easily from the mitochondria to any part of the cell as it is SMALL and SOLUBLE.
- RELEASES ENERGY QUICKLY- instant access to energy compared to breaking down a glucose molecule.
What are the uses of ATP in a cell
- Anabolic reactions- build up molecues from their component units, eg polysaccharides from monosaccharides, proteins from amino acids
- Movement- provide energy required for cellular movement, eg muscle contractions.
- Active Transport- move materials against a concentration gradient, eg ion pumps- absorption of amino acids in PCT
- Secretion- formation of vesicles necessary in secretion of cellular products, eg exocytosis, endocytosis
- Activation of chemicals- makes chemicals more reactive, enabling them to react more readily, eg Glycolysis- glucose is phosphorylated
- Respiration- and cell cycles
What are the three main points about Glycolysis
-occurs in the cytoplasm
-common to both aerobic and anaerobic
-doesn’t require oxygen
Describe the steps involved in Glycolysis
-Involves the activation of glucose by phosphorylation- makes glucose more reactive
-the two required phosphates come from the hydrolysis of two ATP molecules
-the phosphorylation of glucose converts it to fructose bisphosphate
-the 6-carbon fructose bisphosphate splits into two 3-carbon triose phosphate.
Draw the process of glycolysis
Define a coenzyme
A molecule loosely associated with an enzyme
What is dehydrogenation
NAD (coenzyme) picks up hydrogen from triose phosphate (reduced)
-triose phosphate becomes oxidised- loses hydrogen and gives it to NAD
-the removal of oxygen involves the enzyme dehydrogenases in a process called dehydrogenation
What is NAD
-Nicotinamine Adenine Dinucleotide
-a coenzyme which assists an enzyme
NAD accepts hydrogen removed by dehydrogenases to become oxidised during respiration
What are the important points about the Link Reaction
-Only when oxygen is available
-No ATP made
-occurs twice for every glucose molecule
Describe the steps in the Link Reaction
-The Pyruvate produced during Glycolysis is transpored into the Matrix of the mitochondrium (diffuses across the inner and outer membranes of the mitochondrium) in the presence of oxygen.
-Pyruvate is decarboxylated (removal of CO2)- to form Acetate
-Dehydrogenation occurs- removal of hydrogen- NAD carries it away- becomes reduced (NADH)
-The 2-carbon acetate combines with coenzyme A- form acetyl coenzyme A (acetyl CoA).
Draw the process of Link Reaction
What is the purpose of acetyl Coenzyme A
Bring acetate into the cycle
Where does the Krebs cycle occur?
Mitochondrial Matrix
Draw the process of the Krebs cycle
Describe the process of the krebs cycle
-The 2-carbon acetyl coenzyme A from the link reaction combines with the 4-carbon acid- this releases coenzyme A whose purpose was the bring acetate into the cycle- can be reused in the link reaction
-this produces 6-carbon citrate- which enters the cycle
-Decarboxylation of the 6-carbon citrate, results in the formation of the 5-carbon, oxoglutarate, with the loss of a CO2 molecule.
-Decarboxylation of the 5-carbon molecule, oxoglutarate, reults in the formation of the 4-carbon acid, oxaloacetate, with the loss of a CO2 molecule and the cycle continues.
-The cycle involves dehydrogenation, which is carried out by a dehydrogenase enzyme. At 3 points in the cycle, hydrogen is released, reducing NAD- reduced NAD (NADH).
Hydrogen is picked up by another hydrogen carrier FAD- reduced FAD (FADH).
-The krebs cycle involves a series of Redox (Oxidation/ Reduction Reactions).
Where does the Electron Transport Chain occur?
Inner Mitochondrial membrane (cristae)
Describe the process of the Electron Transport Chain
NAD, FAD and other coenzymes and carriers in the ETC are highly organised and arranged in a sequence of decreasing potential energy
-each carrier downstream has a slightly stronger reducing power than the one immediately before
-the hydrogens/ electrons, pass along the chain with the carriers being successively reduced/ oxidised as hydrogens/ electrons pass along the chain in a series of oxidation/ reduction REDOX reactions
-Nad and FAD function as hydrogen carriers- both function to bring hydrogen into the chain
-Initially hydrogen atoms are passed along but later split after coenzyme Q into hydrogen ions, and electrons, and only the electrons pass from carrier to carrier
