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Biology 3.1 > 3.1.2: Enzymes and the Digestive System > Flashcards

3.1.2: Enzymes and the Digestive System Flashcards

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0
Q

What is an enzyme?

A

A globular protein which acts as a catalyst altering the rate of a biochemical reaction.

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1
Q

What is digestion?

A

The process in which large molecules are hydrolysed by enzymes into small molecules which can be absorbed and assimilated.

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2
Q

What is the role of glands in the digestive system?

A

Glands produce enzymes which break down large molecules into small ones ready for absorption.

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3
Q

What is the role of the oesophagus?

A

Carries food from mouth to stomach. Adapted for transportation as food is forced down by peristalsis muscle as it creates a wave of circular muscular contraction and relaxation.

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4
Q

What is the role of the stomach?

A

Muscular sac with the inner layer producing enzymes. Stores and digests food, has glands that produce enzymes which digest proteins. Has mucas producing glands which prevent the enzymes from digesting the stomach.

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5
Q

What is the role of the small intestine?

A

Enzymes produced in the long muscular tube by glands. Inner wall is folded into villi giving a large surface area. Surface area is further increased as there is microvilli on the epithelial cell of each villus. Absorbs products of digestion into bloodstream.

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6
Q

What is the role of the large intestine?

A

Absorbs water, food becomes drier and faeces is formed.

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7
Q

What is the role of the rectum?

A

Faeces are stored here before being removed via the anus in a process called egestion.

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8
Q

What is the role of the salivary glands?

A

Situated near the mouth, produce enzyme amylase which breaks down starch into maltose.

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9
Q

What is role of the pancreas?

A

Situated below the stomach, produces pancreatic juice. Contains:
Proteases to digest proteins
Lipase to digest lipids
Amylase to digest starch

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10
Q

What is physical digestion?

A

Large molecules broken down into smaller molecules so it can be ingested. Provides a large surface area for chemical digestion to take place.

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11
Q

What is chemical digestion?

A

Carried out by enzymes, the break down of large insoluble molecules into smaller soluble molecules by hydrolysis.

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12
Q

What is hydrolysis?

A

Hydrolysis is the splitting up of molecules by adding water to the chemical bonds that hold them together.
Enzymes that do this are called hydrolases.

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13
Q

What are the three digestive enzymes?

A

Carbohydrates: breaks down carbohydrates to monosaccharides.
Lipases: breaks down lipids into glycerol and fatty acids.
Proteases: break down proteins into amino acids.

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14
Q

What is assimilation?

A

Once large molecules have been hydrolysed into small molecules, they are absorbed from the small intestine into the blood. They are carried to different parts of the body and are built up into large molecules again which are incorporated into body tissues or used in processes within the body.

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15
Q

What is absorption?

A

Taking soluble molecules into the body.

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16
Q

What are carbohydrates made up of?

A

Carbon molecules and water.

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17
Q

What is the name of an individual molecule?

A

Monomer.

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18
Q

What is a chain of repeating monomers called?

A

Polymers.

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19
Q

What part of the monomer joins to form a polymer?

A

The carbon atoms join.

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20
Q

What is the basic monomer unit in carbohydrates?

A

Sugar (saccharide).

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21
Q

What is a single carbohydrate monomer called?

A

Monosaccharide.

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22
Q

What is a pair of monosaccharides combined called?

A

Disaccharide.

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23
Q

What are a large number of monosaccharides combined called?

A

Polysaccharides.

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24
What are monosaccharides (glucose) and some disaccharides (maltose)?
Reducing sugars.
25
What is reduction?
Chemical reaction involving gain of electrons. | RIG (reduction is gain)
26
What is a reducing sugar?
Sugar that can donate electrons to reduce another chemical (in this case, Benedict's reagent).
27
What is the test for a reducing sugar?
Benedict's test.
28
What is Benedict's reagent?
Alkaline solution of copper(II)sulfate.
29
How is the Benedict's test carried out?
Add 2cm3 of food sample to be tested to a test tube. (It should be in liquid form, grind up in water). Add an equal volume of Benedict's reagent. Heat the mixture in a gently boiling water bath for 5 minutes.
30
What colour does the solution turn if a reducing sugar is present?
Brick red. (Orange-brown)
31
What colour does the Benedict's test turn if no reducing sugar is present?
Same colour- blue.
32
What does glucose linked to glucose form?
Maltose.
33
What does glucose linked to fructose form?
Sucrose.
34
What does glucose linked to galactose form?
Lactose.
35
What is a condensation reaction?
Chemical process where two molecules combine to form one by the removal of water. A glycosidic bond is created.
36
How can a non- reducing sugar be detected?
Following from Benedict's test (solution is blue)... Add 2cm3 food sample to 2cm3 of hydrochloric acid in a test tube. Place test tube in boiling water bath for 5 minutes. (HCL WILL HYDROLYSE ANY DISACCHARIDE PRESENT MAKING IT INTO MONOSACCHARIDES) Add sodium hydrogencarbonate solution to test tube to neutralise HCL (BENEDICTS REAGENT WILL NOT WORK IN ACIDIC CONDITIONS) Test with pH paper to check solution is alkaline. Redo Benedict's test IF NON REDUCING SUGAR WAS PRESENT, BENEDICTS REAGENT WILL NOW BE BRICK RED (Orange ️brown) DUE TO REDUCING SUGARS THAT WERE PRODUCED FROM HYDROLYSIS OF THE NON REDUCING SUGAR.
37
How do you test for starch?
Place 2cm3 of sample being tested into test tube. Add two drops of iodine. If starch is present, it turns iodine to a blue- black colour.
38
How is starch digested?
Mouth- physical digestion giving large surface area. Salivary amylase hydrolyses starch to maltose (disaccharide). Stomach- acidic conditions denature amylase. Passes into small intestine. Small intestine- pancreatic juice contains pancreatic amylase. Hydrolyses any remaining starch into maltose. Epithelial lining produces maltase which hydrolyses maltose into a-glucose.
38
How is sucrose digested?
Small intestine lining produces enzyme sucrase. Breaks down sucrose into glucose and fructose by hydrolysing glycosidic bond holding monosaccharides together.
39
How is lactose digested?
Epithelial lining in small intestine produces lactase enzyme. Hydrolyses the disaccharide lactose into glucose and galactose as glycosidic bond is broken.
40
Why is lactose intolerance a problem?
Not enough of the enzyme lactase is created and so when the lactose reaches the large intestine, the lactose is broken down by microorganisms releasing a large volume of gas causing bloating, cramps etc.
41
What monomer makes up proteins?
Amino acids.
42
What is a protein polymer called?
Polypeptide.
43
What are two amino acids called?
Dipeptide.
44
What links amino acids together?
Peptide bonds.
45
How is a polypeptide created?
Polymerisation.
46
What is the primary structure of proteins?
The sequence of amino acids present in the protein.
47
What is the secondary structure of a protein?
The twisting of the polypeptide chain into a 3D shape due to the weak hydrogen bonds created between amino acids.
48
What is the tertiary structure in a protein?
Further folding of the polypeptide chain to give it a 3D structure. Further twisting due to weak hydrogen bonds, ionic bonds and strong disulfide bonds.
49
What is the quaternary structure of proteins?
Protein consisting of more than one polypeptide and could consist of a combination of polypeptides and non protein groups.
50
How do you test for a protein?
Biuret test. Place sample of solution to be tested in test tube and add equal amount of sodium hydroxide solution at room temperature. Add dilute copper(II)sulfate solution and mix. Purple colour shows presence of peptide bonds hence a protein. Blue=no protein.
51
What is activation energy?
Energy required to bring about a reaction. The activation energy is lowered by using enzymes which act as catalysts and hence speed up reactions.
52
What is the active site on an enzyme?
Region of the enzyme in which the substrate fits into in order to catalyse a reaction.
53
What is a substrate?
Substance acted on or used up by another substance or process.
54
What is an enzyme-substrate complex?
When substrate is bound to the active site of an enzyme. Temporary bonds hold the substrate in.
55
For an enzyme to work, it must?
Come into physical contact with its substrate. | Have an active site which fits the substrate.
57
What is the lock and key model?
Enzyme has a rigid structure and substrate has a specific shape that fits the active site of the enzyme.
58
What is the induced fit model?
Enzyme is slightly flexible to fit the substrate. It moulds itself around the substrate. As the enzyme alters it's shape, it applies strain upon the substrate molecule distorting a particular bond and lowering the activation energy needed to break the bond.
61
What effect does a rise in temperature have on enzyme and substrate molecules?
Increases overall kinetic energy therefore the rate of reaction increases.
62
What is denaturation?
Permanent change to the enzymes tertiary structure resulting into the enzyme not being functional (as active site has altered its shape).
63
What does the optimum temperature result to?
The denaturing of enzymes so the tertiary structure is broken and enzyme activity is disrupted.
64
How is the pH of a solution measured?
It's hydrogen ion concentration is measured.
65
How does a change in pH alter the function of an enzyme?
Change in pH alters the charge on the amino acids that make up the active site of the enzyme. This means the enzyme is denatured.
66
What happens if the amount of enzyme is fixed but substrate is slowly added?
The rate of reaction increases until all substrates are bound to active sites. Once all active sites are occupied the rate of reaction is at its maximum. The addition of substrates will not effect the rate of reaction. The rate of reaction levels off.
67
What is a competitive inhibitor?
Binds to the active site of the enzyme, temporary and compete with the substrate. Blocks substrate therefore reducing rate of reaction.
68
What is a metabolic pathway?
Series of reactions in which each step is catalysed by an enzyme.
69
What is end-product inhibition?
When the end product inhibits the starting enzyme of a metabolic reaction. Non-competitive and allows the level of any chemical to be maintained at a constant level.
70
What is a non-competitive inhibitor?
Bind to anywhere but the active site, permanently alters the shape of the active site of an enzyme so a substrate cannot occupy it therefore the enzyme cannot function. An increase in substrate concentration does not decrease the effect of the inhibitor because the substrate and inhibitor are not competing for the same site.

Biology 3.1 (3 decks)

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