BTEC Applied Science - Unit 3 - Flashcards in BTEC National Applied Science

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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Get Revising

BTEC Applied Science - Unit 3

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