Biological Molecules Flashcards

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1
Q

What chemicals is the human body made up of?

A

65% oxygen
18% carbon
10% hydrogen
7% other elements

These elements combine to form all the compounds in the body

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2
Q

What 3 groups do most molecules found in living organisms fall into?

A

Carbohydrates
Proteins
Lipids

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3
Q

What are carbohydrates made up of?

A

Simple sugars

Formed from carbon, oxygen and hydrogen

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4
Q

Give an example of a simple sugar carbohydrate.

A

Glucose

Sucrose

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5
Q

Give an example of a larger moleculed carbohydrate.

A

Starch

Glycogen

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6
Q

What are proteins made up of?

A

Chains of amino acids linked together.

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7
Q

What are lipids?

A

What we often call fats.
Made up from fatty acids and glycerol
There are 3 fatty acids and glycerol in each lipid
Lipids contain carbon, hydrogen and oxygen atoms

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8
Q

What is the test for glucose (and other reducing sugars)?

A

Benedict’s reagent test
Blue Benedict’s reagent is added to samples and heated.
Green = small amount of reducing sugars
Yellow = medium amount of reducing sugars
Orange/red = large amount of reducing sugars

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9
Q

What is the test for starch?

A

Iodine solution is added to food sample.

If it changes from brown to blue black starch is present.

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10
Q

What is a catalyst?

A

A substance that helps to speed up a reaction.

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11
Q

What are catalysts that cause metabolic reactions inside cells in living organisms called?

A

Enzymes or biological enzymes

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12
Q

What would happen if we did not have enzymes?

A

Metabolic reactions would happen too slowly for life to carry on.

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13
Q

What are biological enzymes made of?

A

Proteins

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14
Q

Are enzymes general or specific?

A

Specific - they only work with one substance- substrate

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15
Q

What is amylase?

A

Type of carbohydrase enzyme
Produced in the mouth
Starts the digestion of starch in food into simple sugars

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16
Q

What is protease?

A

Digestive enzymes that break proteins into smaller units.

17
Q

What is lipase?

A

Digestive enzyme that breaks down lipids in food.

18
Q

What temperature do enzymes work best at?

A

At a particular temperature known as their optimum temperature
35-40*c for human enzymes
At a lower temperature they work more slowly as the molecules have less energy.
At temperatures that are too high the structure of the enzyme changes so will not work - it has become denatured.

19
Q

How can pH affect enzymes?

A

Very high or very low can slow down the rate of reaction and can in some case denature them.

20
Q

What is a test for protein?

A

Biuret Test
Prepare a sample of food and transfer 2cm3 to a test tube.
Add 2cm3 of biuret solution and gently shake.
If protein present solution changes colour from blue to pink/purple. If not present then remains blue.

21
Q

What is a test for lipids?

A

Sudan III test
Prepare a sample of food.
Transfer 5cm3 into a test tube
use a pipette to add 3 drops of Sudan III stain solution and gently shake
Sudan III stain solution stains lipids. If the sample has lipids it will separate into 2 layers. The top layer will be bright red. If there are no lipids then no separate red layer will form.