Enzymes and Digestion Flashcards

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1
Q

Enzyme

A

a biological catalyst.

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2
Q

Catalyst

A

it is a substance which increases the speed of a reaction, without being changed or used up in a reaction.

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3
Q

How does an enzyme work?

A

.Every enzyme has an active site with a unique shape that fits onto the substance involved in the reaction.
.For the enzyme to work, the substrate has to fit into the active site of the enzyme.
. The chemical reaction then takes place.
. The products are then released

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4
Q

Optimum conditions for enzymes: Temperature

A

.A higher temperature increases the rate at first.
.But if it gets too hot, some of the bonds holding the enzyme together break.
.This changes the shape of the active site, so the substrate won’t fit anymore.
.The enzyme is said to be denatured

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5
Q

What is the optimum temperature in a human body?

A

37 degrees Celsius

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6
Q

Optimum conditions for enzymes:
pH

A

.If the pH is too high or too low, it interferes with the bonds holding enzyme together.
.This changes the shape of the active site, so the substrate can no longer fit.
. The enzyme is now denatured

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7
Q

What is the optimum pH in many enzymes?

A

pH 7, but not for all enzymes

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8
Q

REQUIRED PRACTICAL:
Investigating the effect of pH on amylase

A
  1. Put a drop of iodine solution into every well of a spotting tile
  2. Place a Bunsen burner on a heat-proof mat, and a tripod and gauze over it.
  3. Put a beaker on top of the tripod and heat the water until it is 35°C
  4. Use a syringe to add 1cm^3 of amylase solution and 1cm^3 of buffer solution with a pH of 5 to a boiling tube.
  5. Using test tube holders, put the boiling tube into he beaker of water and wait for 5 minutes.
    6.Next, use a different syringe to dd 5cm^3 of a starch solution to the boiling tube
  6. Immediately, mix the contents of the boiling tube and start a stop clock.
  7. Continuously sample to record how long it takes for the amylase to break down all the starch. Use a dropping pipette to take a fresh sample from the boiling tube every 30 seconds and put a drop into a well.
  8. Repeat the whole experiment with buffer solutions of different pH values.
  9. When the iodine solution remains browny-orange, starch s no longer present.
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9
Q

Control variables for pH practical

A

. Concentration of amylase solution
. Volume of amylase solution

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10
Q

Rate of reaction

A

Rate = 1000/time

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11
Q

Rate of reaction change over time

A

change/time

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12
Q

Mechanical digestion

A

teeth grinding down food and stomach churning up food

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13
Q

Chemical digestion

A

Where enzymes help to break down food

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14
Q

What do carbohydrases break down into?

A

convert starch into maltose

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15
Q

Amylase

A

Where it is produced:
salivary glands, pancreas and small intestine
Where it works:
mouth and small intestine

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16
Q

What do proteases break down into?

A

convert proteins into amino acids

17
Q

Protease

A

Where it is produced:
stomach, pancreas, small intestine
Where it works:
stomach and small intestine

18
Q

What do lipases break down into?

A

convert lipids into fatty acids and glycerol

19
Q

Lipase

A

Where it is produced:
pancreas and small intestine
Where it works:
small intestine

20
Q

Bile

A

.produced in the liver
.stored in the gall bladder
.The hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly.
.Bile is alkaline - it neutralises the acid and makes conditions alkaline.
. It also emulsifies fats which means it breaks the fat into tiny droplets.
.This gives a much bigger surface area of fat for the enzyme lipase to work on - which makes digestion faster.

21
Q

REQUIRED PRACTICAL: Testing for sugars

A
  1. Prepare a food sample and transfer 5cm^3 to a test tube.
  2. Prepare a water bath so that it’s set to 75°C.
  3. Add some Benedict’ solution to the test tube ( about 10 drops ) using a pipette.
  4. Place the test tube in the water bath for 5 minutes.
22
Q

Results for Benedict’s solution

A

blue to brick red

23
Q

REQUIRED PRACTICAL: Testing for starch

A
  1. Add a few drops of iodine solution into a test tube along with 5cm^3 of your food sample.
  2. Mix the contents
24
Q

Results for Iodine solution

A

orange/brown to blue/black

25
Q

REQUIRED PRACTICAL: Testing for proteins

A
  1. Add 2cm^3 of biuret solution to 2cm^3 of your food sample
  2. Mix the contents by gently shaking it.
26
Q

Results for Biuret test

A

blue to purple

27
Q

REQUIRED PRACTICAL: Testing for lipids

A
  1. Use a pipette to add 3 drops of ethanol to the test tube with 5cm3 of food sample.
  2. Gently shake the tube
28
Q

Results for ethanol

A

colourless to milky white emulsion