2 Enzyme and digestion system

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  • Created by: Naana
  • Created on: 02-11-14 15:52
Enzymes
a protein or RNA that acts as a catalyst and speeds up the rate of a biochemical reaction
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Hydrolysis
the breaking down of large molecules into smaller ones by the addition of water molecules
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Monosaccharide
a single monomer
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Disaccharide
a pair of monosaccharide combined by a condensation reaction
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What do non-competitive inhibitors do?
They bind to the allosteric site away from the active site. The inhibitor then alters the shape of the enzymes active site so the that substrates can no longer bind to the active site so no enzyme substrate complex can be formed.
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Does increasing the substrate concentration decrease the effect of the inhibitor?
No because the substrate and the inhibitor are not competing for the same site
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What do competitive inhibitors do?
They have a similar shape to the substrate which allows them to occupy the active site. They compete with substrates for available active sites.
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What will happen to the effect of a competitive inhibitor if you increase the substrate concentration?
The effect of an inhibitor will reduce as the inhibitor is only temporarily bound to the active site and so when it leaves a substrate can take its place.
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What effect does a change of pH have on enzyme action?
A change in pH can alter the charges on the amino acids that make up the active site of the enzyme, so substrates can’t bind anymore. It can also cause bonds in the tertiary structure of the enzyme to break-changes shape and becomes denatured
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Why can even small changes in in pH change the arrangement of the active site?
The arrangement of the active site is partly determined by the hydrogen and ionic bonds between NH2 and COOH groups of the polypeptides. The change in H+ ions affects the bonding, causing active site to change shape.
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Why does an increase in temperature increase the enzyme activity?
Increase in temperature increased the kinetic energy of molecules resulting in the molecules moving more rapidly and colliding more frequently. As a result enzymes and substrate molecules come together more in given time
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What is denaturation?
A permanent change that occurs when the 3D structure of a protein unravels due to changes in temperature or pH
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What two monosaccharides make up maltose?
Glucose and glucose
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What two monosaccharides make up sucrose?
Glucose and fructose
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What two monosaccharides make up lactose?
Glucose and galactose
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If starch is present what will happen to the colour of the potassium iodine solution?
Starch will change the colour of the iodine from yellow to blue-black
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What is the role of the salivary amylase?
It hydrolyses any starch in the food into maltose.
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Why does saliva contain mineral salts?
To help maintain the pH at around neutral, which is the optimum pH for salivary amylase to work
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What does the acidic conditions of the stomach prevent?
It prevents further hydrolysis of the starch as the acid denatures the amylase
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What is the role of the pancreatic amylase?
To continue the hydrolysis of any remaining starch into maltose. It works best at pH 7
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What is the role of the enzyme maltase?
The maltase hydrolyses the maltose from starch into alpha glucose
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What is the primary structure of a protein, and what does it determine?
The sequence of amino acids that make up the polypeptides of a protein. The primary structure determines the protein’s shape and its function
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What is the secondary structure of a protein?
The folding of the long polypeptide chain into an alpha helix or beta pleated sheet due to the weak hydrogen bonds
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What is the tertiary structure of a protein?
The secondary structure can be further folded and twisted to give a 3D, complex and unique/specific shape. This structure is maintained by the disulphide, ionic and hydrogen bonds.
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What is the quaternary structure of a protein?
When a number of individual polypeptide chains linked to form a complex molecule.
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Explain the lock and key model
In the lock and key model, the shape of the substrate is complementary to the active site of the enzyme. The substrate binds to the enzyme to form an enzyme substrate complex
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Explain the induced fit theory
In the induced fit theory, a molecule binds to then allosteric site away from the active site, which breaks the bond in then tertiary structure of the enzyme and changes the shape. As a result the active site becomes complementary to the substrate
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What is the function of the nuclear envelope?
It controls the entry and exit of materials in and out of the nucleus, and contains the reactions that take place within it
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What do nuclear pores do?
They allow large molecules e.g. mRNA to pass out of the nucleus. There is usually around 3000 pores in each nucleus
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What is chromatin?
This is the DNA found within the nucleoplasm
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What is nucleolus?
It is the small spherical body within the nucleoplasm. It makes ribosomal RNA and collects the ribosomes
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What is the function of the nucleus?
It acts as a control centre of the cell- through mRNA, retains the genetic material of the cell (in the form of DNA/chromosomes), makes ribosomal RNA and ribosomes
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Why is the inner membrane of a mitochondrion folded into a cristae?
To provide a large surface area for the attachment of enzymes involved in aerobic respiration to produce ATP
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What does the matrix do?
It contains proteins, lipids and traces of DNA that allow the mitochondria to control the production of their own protein
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What is the function of a rough endoplasmic reticulum?
It provides a large surface area for synthesis of protein and glycoproteins, and provides a pathway for the transport of materials throughout the cell esp. proteins
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What is the function of a smooth endoplasmic reticulum?
It synthesises, stores and transports lipids and carbohydrates.
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Card 2

Front

Hydrolysis

Back

the breaking down of large molecules into smaller ones by the addition of water molecules

Card 3

Front

Monosaccharide

Back

Preview of the front of card 3

Card 4

Front

Disaccharide

Back

Preview of the front of card 4

Card 5

Front

What do non-competitive inhibitors do?

Back

Preview of the front of card 5
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