BTEC Applied Science - Unit 3

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What are proteins made of?
Polypeptide chains - amino acids linked together by peptide bonds
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Condensation reaction
A chemical reaction in which two or more molecules (amino acids) combine to produce & lose water
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Dipeptide
2 amino acids bonded together by a peptide bond
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Polypeptide
A chain of many amino acids linked together by peptide bonds
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Enzymes
Proteins that act as biological catalysts
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Catalyst
A substance that speeds up the rate of a chemical reaction & is not used up
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What is an active site?
A region on an enzyme that binds to a protein or other substance during a reaction
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What does an active site consist of?
Small number of amino acids = form a specific shape
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Why are active sites made of amino acids?
Proteins secondary & tertiary structure
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Secondary structure
Regions of repetitive coiling (a helix) or folding (b-pleated sheet) in polypeptide chains due to hydrogen bonding between -NH & -C=O of two amino acids
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Tertiary structure
Three-dimensional due to interactions of the R groups of the amino acids making up the chain. Involves; hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.
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Substrate
A specific reactant acted upon by an enzyme
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Lock & Key Mechanism of Enzymes
1). The substrate molecule attaches itself to the Active Site of an enzyme with a shape complementary to its own.
2). This forms an Enzyme-Substrate complex, and the enzyme works on the substrate and catalyzes the reaction.
3). As a result of the reactio
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Collision theory
Particles must collide = gain enough to react
Energy of collision depends >>>> speed & angle
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Activation energy
The minimum amount of energy required to start a chemical reaction
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Measuring rate of reaction
- Decrease in substrate
- Increase in product
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Initial rate of reaction
The change in concentration of a reactant or product per unit time at the start of the reaction when t=0
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Enzymes and temperature
HIGH temperature denature enzymes and make them unable to bind to the substrate
- Substrate won't fit in the active site
- Enzymes goes through change in shape
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Optimum temperature
The temperature at which an enzyme is most active = 40C in humans
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Enzymes and pH
If pH is not the optimum = cause change charge of the active site
Change in charge = substrate unable to bind to it
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Optimum pH
The pH at which an enzyme achieves maximum activity
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Enzymes and concentration
Substrate & enzyme concentration = rate of collisions = reaction rate
Concentration of substrate = too high = no active sites to bind to = Concentration of enzyme = too high = too many active sites free compared to number of substrates = rate of reaction
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Other cards in this set

Card 2

Front

Condensation reaction

Back

A chemical reaction in which two or more molecules (amino acids) combine to produce & lose water

Card 3

Front

Dipeptide

Back

Preview of the front of card 3

Card 4

Front

Polypeptide

Back

Preview of the front of card 4

Card 5

Front

Enzymes

Back

Preview of the front of card 5
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