Metabolism Flashcards
What is ATP?
Is used by cells of all living organisms as a source of energy
Name a few processes that involves ATP:
Active transport, endocytosis, exocytosis, DNA replication, protein synthesis, polysaccharides in cell division, muscle contraction 
Cells can’t get energy directly from glucose so?
In respiration, the energy released from glucose is used to make a molecule called ATP, which stores energy temporarily
How is ATP made?
When energy released from respiration is used to add a phosphate ion to adenosine diphosphate ADP by condensation. The energy is stored temporarily in bonds between the phosphate groups in ATP molecule.
What is the equation for ATP synthesis?
ADP + PI + energy = ATP
How is ATP broken down?
Energy is released when ATP is broken down into ADP and PI by hydrolysis of a phosphate bond
What is the equation for ATP breakdown?
ATP = ADP + pi + energy
ATP hydrolysis is catalysed by what?
The enzyme ATP hydrolase
What ensures that the energy released from ATP hydrolysis is used directly in the in a reaction, rather than being lost as heat
It can be coupled to other reactions in a cell, which require energy 
Why is ATP a good energy source?
Energy is released in a single reaction
Energy is released in small amounts to prevent cell damage
ATP is soluble
Why is rate of ATP production very high?
ATP is unstable
ATP cannot be stored because it is immediate source of energy
ATP only releases small amounts if energy at a time. The energy from ATP is needed for lots of biological processes, so ATP is in high demand. 
Why are enzymes called biological catalysts?
Because they speed up chemical reactions without being used up
Molecules used of an enzyme reactions are called
Substrates
Enzymes which catalyse reactions inside cells are called?
Intracellular enzymes
Enzyme is it to catalyse reactions outside of cells are called?
Extracellular enzymes
Enzymes are specific meaning what?
Each enzyme catalyses a reaction involving only one type of substrate
Enzymes specificity is directly related to enzyme 3-D tertiary structure, because?
Enzymes contain a small pocket called active site which has a very specific shape and only substrates with the correct complimentary shape to the active site can fit into the active site
What does the induced fit model suggest?
Enzymes active site is not fully complimentary until a substrate fits into it causing the enzyme to change shape so its active site wraps are on the substrate more closely
What do enzyme reactions involve?
Random collisions between enzymes in substrate to form enzyme substrate complex. Is it
What increases the rate of enzyme reactions?
Increase in enzyme concentration
Increase in substrate concentration
Increase in temperature 
How does an enzyme becomes a denatured?
High temperatures, extremes of pH and noncompetitive inhibitor‘s all change the 3D tertiary structure, so change the shape of an enzyme. If the shape of the enzymes active site site changes too much it stops working 
What are competitive inhibitors?
Molecules of a similar shape to an enzymes normal substrate. They slowdown enzyme catalysed reactions by binding to an enzymes active site, blocking the entry of a normal substrate.
What is an active site?
A small part of an enzyme is 3D tertiary structure into which is substrate molecule fits. It has a very specific shape and only substrates of the correct complimentary shape to the active site can fit into the active site
what is activation energy?
Is the level of energy required to enable reactions take place enzymes reduce the reaction activation energy needed for reactions take place so that the reactions can take place at much lower temperatures
What is the lock and key hypothesis?
Only straight to the correct complimentary shape to the active site can fit into an enzyme active site and a temporary enzyme substrate complex is formed in which the substrate of site is catalysed . The products of the reaction because their shape is different from the shape of the substrate .
What is the problem with the lock and key hypothesis?
it doesn’t explain how enzymes Enzymes lower activation energy
What is the induced fit hypothesis?
When is substrate binds to an enzymes active site? The enzymes, active site changes shape so that it fits around the substrate more closely causing the substate to change shape.
How does that explain lower activation energy?
The slowest activation energy by either holding substrate molecules closer together, so they react more easily, putting strains on the bonds in the substrate, say it breaks down more easily.
What are the four stages of aerobic respiration?
glycolysis, link reaction, Krebs cycle, and oxidative phosphorylation
What is a redox reaction?
Redox reactions involve oxidation of one substance, and reduction of another. Oxidation is loss of H atoms or electrons, reduction is gain.
Where does glycolysis take place?
In the cytoplasm
What is anaerobic respiration?
Respiration is the release of energy from glucose in the absence of oxygen. It involves glycolysis alone, which yields 2ATP +2 reduced NAD +2 pyruvate per glucose.
Without oxygen, what stage can’t occur?
Oxidative phosphorylation cannot occur, so the ETC stops and therefore reduced NAD a reduced FAD from Krebs cycle cannot be reoxidised. So NAD and FAD are not available, so the Krebs cycle and link reaction stop.
Why can glycolysis still occur?
Because pyruvate produced at the end of glycolysis is used to re oxidise the reduced NADs produced during glycolysis. NAD is recycled and use, except more heat on atoms from glucose. This allows glycolysis continue in the absence of oxygen.
When muscle cells use pyruvate reduced, NAD, the pyruvate is reduced to what?
Lactate
ATP comes from glycolysis, alone, meaning ATP yield in anaerobic respiration (2ATP per glucose) is much less than?
ATP yield in aerobic respiration (38ATP per glucose)
Increasing the concentration of Eva, enzyme substrate increases the rate of reaction. However, if the concentration of either the substrate is fixed rate of reaction does what?
Plateaus
What happens during glycolysis?
. One molecule of glucose (6C) is eventually split into two molecules of pyruvate (3C)
Glucose is made more reactive by adding what?
Hi adding phosphate ions released by the hydrolysis of two ATP molecules, this process is called phosphorylation.
adding one phosphate to glucose creates what?
Adding a second phosphate creates what ?
. Glucose phosphate.
. Hexose bisphosphate
4ATP molecules are made using energy released from compound process called?
Substrate level phosphorylation
Therefore, what is the ATP yield of glycolysis?
2ATP
What causes also involves removal of hydrogen atoms by a process called dehydrogenation what happens during this process?
. This process is catalysed by dehydrogenase enzyme is with the help of a coenzyme called NAD.
. NAD combines with hydrogen atoms to make reduced NAD
. Glucose oxidised during glycolysis because it loses hydrogen atoms.
. NAD is reduced during a glycolysis because it gains hydrogen atoms.
Where does link reaction take place?
In the mitochondrial matrix
What happens during link reaction?
. Pyruvate is actively transported from the cytoplasm into the mitochondria.
. Each pyruvate (3C) is converted to acetate (2C) by:
- Removal of one molecule of carbon dioxide (decarboxylation)
- Removal of two hydrogen atoms ( dehydrogenation)
- Addition of acetate to coenzyme A
. NAD combines with the H items to make reduced NAD.
. The final products or acetyl-coenzyme A, reduced NAD and carbon dioxide gas
Where does the Krebs cycle take place?
Is a mitochondrial matrix
What happens during the Krebs cycle?
. Acetyl-coenzyme A is used to transfer acetate to a 4C compound, making a 6C compound
. Coenzyme a is recycled to use again in the link reaction
. The 6C compound is decarboxylated to a 5C compound, then again to make the 4C compound. Two molecules of carbon dioxide released, and one molecule of ATP is made by substrate level phosphorylation.
. 8H atoms removed and are used to reduce coenzyme NAD and coenzyme FAD
. The final products or carbon dioxide gas, one molecule of ATP and reduced NAD and reduced FAD
Where does oxidative phosphorylation take place?
In the inner mitochondrial membrane
What happens during oxidative phosphorylation?
. Reduced NAD and reduce FAD, release, electrons and protons.
. Every oxidise any day and every day on our recycled and used again in glycolysis and link, reaction and Krebs cycle to combine with more hydrogen atoms.
. The electrons parcel of a chain of electron carriers called electron transport chain turn
. As electrons parcel of the electron transport, chain, redox reactions, release electrons
. This energy is used to pump protons are in the matrix into the inner membrane space
. The inner membrane is impermeable to a hydrogen plus ions so hundred and plus I was built up in the inter-membrane space which sets up a proton gradient.
. Hydrogen plus ions can diffuse down the proton gradient back into the matrix through channels in ATP synthase enzymes
. The flow of hydrogen plus ions is called oxidative phosphorylation.
. I was go through channels in ATP synthase the fourth of this flow, drives rotation of the head of the ATP synthase, which releases energy. This energy is used to combine ADP with Pi to make ATP
. Oxygen is the terminal electron receptor.
. Oxygen commands of electrons and protons to make H20
What are the final product of oxidative phosphorylation?
- Molecules of ATP.
Water
Oxidised, NAD and oxidised FAD
