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What is an enzyme?
- An enzyme is a protein molecule that acts as a biological catalyst.
- Their 3D structure is unique to each type of enzyme
What are the three characteristics of an enzyme?
- they increase the rate of a chemical reaction
- they act specifically with only one substrate (usually)
- they regulate from a state of low activity to high activity and visa versa
What is the name given to green plants?
What happens to ATP in the prescence of ATPase?
What is Metabolism?
- The sum total of all chemical reactions
- =Catabolism + Anabolism
What are catabolic reactions?
- Catabolic reactions involve the breakdown of molecules into simpler substances.
- Ex. Respiration or digestion
What are anabolic reactions?
- Anabolic reactions are the build up of simpler substances into more complex ones.
- Ex. Protein synthesis or photosymthesis
Role of NADP
- NADP carries hydrogen between the light dependant and light independant phase in photosynthesis where the hydrogen is then incorporated into the sugar production.
- In respiration, the NADP is used to carry hydrogen into the matrix of the mitochondria
What stage of photosynthesis is ATP produced?
- ATP is produced in the light dependant stage. The chlorophyll trap the light energy and transform it into chemical energy in the form of ATP. This is done by splitting water molecules into H+ and O2, producing ATP as a by-product.
- This ATP is then used in the light independant stage to produce sugars from CO2 and H+
What factors affect ENZYMES?
- Factors affecting enzymes are:
- Conc. of the enzyme
- Conc of the substrate
How do enzymes work?
- Enzymes generally work by binding to a substrate and decreasing the required activation energy, which effectively increases the reaction rate by increasing the number of particules which have the required energy in order for the reaction to occur.
- For a reaction to occur, the substrate needs to be raised to an unstable state (known as the transition state) in order to proceed
- Anaerobic respiration delays the production of pyruvate ions and allows the glucose breakdown to continue.
- It does not involve oxygen
- In terms of energy yield, this process is inefficient, only producing 2ATP
What are catalysts?
- Catalysts are substances which increase the reaction rate by providing an 'alternative pathway' with a lower activation energy.
- They are not used up in the reaction
- They generally take part in a reaction by binding to the reactant(s).
What is the active site?
- The active site is a function of the polypeptides complex tertiary structure.
- It is where the substrate is drawn to
- They are on ENZYMES
Where are active sites found?
- The cleft is a region which is made up of the active sites on an enzyme.
- This is where the substrate is drawn
What is the purpose of enzyme inhibitors?
- Enzyme inhibitors show that enzymes are flexible and are able to vary their shape
- The interact with the enzyme by modifying it
- The modification makes it unable to complete its duty by distorting the active site in some way. This can be reversible or irreversible.
What are the types of enzyme inhibitors?
- There are 4 types of enzyme inhibitors. These are:
- Competitive: which compete directly with the substrate for the active site, and can be overcome by increasing the conc. of the substrate.
- Non-competitive: which distorts the active site instead of competing with the substrate.
- These two types can further be classified into 2 more categories:
- Reversible: These can be displaced from the enzyme & they act as regulators in metabolic pathways
- Irreversible: which bind tightly to the enzyme (either on the active site or near it)
Cellular respiration briefly
- Splitting of glucose
- 1 glucose molecule is broken down to 2 pyruvate ions
- Net direct yield of 2ATP
- Occurs rapidly in the cytoplasm
Where is the major source of energy for cells and their functions?
In the chemical energy contained in the phosphate bonds of ATP
- also referred to as the citric acid cycle
- Aerobic process
- Occurs in the matrix of the mitochondria
- Pyruvate is oxidised
- 2ATP produced
- pyruvate is broken down into CO2 and H+Hydrogen acceptor molecules collect H atoms (now known as loaded acceptors) & takes them to the inner membranes of the mitochondria
- H is then exchanged for something useful
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