Chapter 3: Nutrients Flashcards

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1
Q

What are the 3 types of nutrients?

A

-Carbohydrates
-Fats
-Proteins

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2
Q

Why do we need nutrients in food?

A

-Provide energy for vital activities
-Supply raw materials to make new protoplasm for cell growth, reproduction and repair of worn-out tissues

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3
Q

Carbohydrates are organic compounds made of…?

A

-Carbon
-Hydrogen
-Oxygen
Where Hydrogen:Oxygen=2:1

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4
Q

What are the three main groups of carbohydrates? (+examples)

A

Monosaccharides
- Glucose
- Fructose
- Galactose

Disaccharides
- Maltose (Glu-Glu)
- Sucrose (Glu-Fru)
- Lactose (Glu-Gal)

Polysaccharides
- Starch
- Cellulose
- Glycogen

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5
Q

Which monosaccharide/ disaccharide is NOT a reducing sugar?

A

Sucrose!
(Everything else is a reducing sugar)

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6
Q

Name the (main) properties of monosaccharides.

A
  1. Basic unit of carbs, cannot be further digested into smaller molecules
  2. [Of those in syllabus] Small enough to pass through cell membranes (and other ppms)
  3. [Of those in syllabus] Same chemical formula (C6 H12 O6), but diff. arrangements, giving them diff. properties
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7
Q

Name the (main) properties of disaccharides.

A
  1. Formed when 2 monosaccharides join tgt in a condensation reaction
  2. [Of those in syllabus] Same chemical formula (C12 H22 O11), but in diff. arrangements, giving them diff. properties
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8
Q

What is a Condensation Reaction?

A

A chemical reaction in which 2 monosaccharides are joined tgt to form a disaccharide +water
(e.g. glucose+glucose-> maltose+ water)

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9
Q

What is Hydrolysis [of disaccharides] (/hydrolytic reaction)?

A

A chemical reaction in which water is needed to break up disaccharide into 2 monosaccharides
(e.g. water+ maltose—> glucose+glucose [catalysed by maltase])

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10
Q

What is the test for reducing sugars?

A

Benedict’s test

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11
Q

[Describe Procedure]
Procedure of Benedict’s test?
(+Solid food sample modifications & result indication)

{glucose, fructose, galactose, maltose, lactose}

A
  1. Add 2cm^3of Benedict’s solution to 2cm^3 of food sample in a test tube
  2. Shake the mixture
  3. Heat contents in a boiling water bath for 2-3 mins

Solid food sample modification:
1. Crush food w/ mortar & pestle
2. Add water to the crushed food to dissolve the nutrients
3. Decant the mixture to a new test tube
[Proceed w/ og step 1]

Blue- No reducing sugar
Green colouration- Traces of reducing sugar
Yellow/orange colouration- Moderate amnt of reducing sugar
Brick-red precipitate- Large amnt of reducing sugar

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12
Q

Examples of polysaccharides?

A

Starch
Cellulose
Glycogen

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13
Q

Structure, role and occurrence of starch?

A

Structure: Several thousand glucose molecules joined tgt

Role: Storage form of carbs in plants

Occurrence: Storage organs of plants (e.g. potato tubers/tapioca)

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14
Q

Structure, role and occurrence of cellulose?

A

Structure: Many glucose molecules joined tgt, but bonded diff. from starch

Role: Cellulose cell walls protect plant cells, also serves as dietary fibres to prevent constipation

Occurrence: Cell walls of plants

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15
Q

Structure, role and occurrence of glycogen?

A

Structure: Branched molecule of many glucose molecules joined tgt

Role: Storage form of carbs in animals

Occurrence: Stored in liver & muscles of mammals

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16
Q

[Application]
How are glycogen and starch suitable as stores of glucose?

A

-Insoluble in water
-Large molecules that cannot diffuse thru ppm
-Easily hydrolysed to glucose when needed
-Have compact shapes, so they occupy less space

17
Q

[Application]
Describe the hydrolysis of starch.

A
  1. Starch is broken down into maltose by amylase
  2. Maltose is broken down into glucose by maltase
18
Q

What is the test for starch?

A

Iodine test

19
Q

[Describe Procedure]
Procedure of Iodine test?
(+Solid food sample modifications & result indication)

A
  1. Add 2cm^3 of food sample to a clean test tube
  2. Add a few drops of iodine solution to the test tube

Solid food sample modification:
1. Crush food w/ mortar & pestle
2. Add a few drops of iodine solution directly onto the crushed food

Blue-black colouration observed- +ve result
Sol. remains yellowish-brown- -ve result

20
Q

Why do we need carbohydrates?

A

1. Provide an immediate source of energy
2. Form supporting structures (e.g. cell walls in plants)
3. For conversion into other organic compounds (e.g. amino acids in plants & fats in plants and animals)
4. To form nucleic acids (in DNA & RNA)

21
Q

Fats are organic compounds made of…?

A

Carbon
Hydrogen
Oxygen

With less oxygen in proportion to hydrogen, but with no fixed proportions

22
Q

What is a fat MOLECULE made up of?

A

3 fatty acids
1 glycerol

23
Q

What is the difference between saturated and unsaturated fats?

A

Saturated- Unhealthy
Unsaturated- Healthier

Saturated- Straight fatty acid chain
Unsaturated- Fatty acid chain has kinks

24
Q

Describe hydrolysis of fats.

A

Fats are broken down into fatty acids and glycerol by hydrolysis.

25
Q

Why do we need fats?

A

-As a source of energy
-As an insulating material that prevents excessive heat loss
-Surround organs for protection
-Help reduce water loss from skin surface

26
Q

What is the test for fats?

A

Ethanol emulsion test

27
Q

[Describe Procedure]
Procedure of ethanol emulsion test?
(+Solid food sample modifications & result indication)

A
  1. Add 2cm^3 of ethanol to 2cm^3 of food sample in a test tube
  2. Shake the contents of the tube vigorously
  3. Add 2cm^3 of water into the test tube and shake the mixture

Solid food sample modification:
1. Crush food w/ mortar & pestle
2. Add ethanol to the crushed food to dissolve the nutrients
3. Shake and decant the mixture to a new test tube
4. Proceed w/ step 3

Cloudy white emulsion is observed- +ve result
Sol. remains clear- -ve result

28
Q

Proteins are organic compounds made of…?

A

Carbon
Hydrogen
Oxygen
Nitrogen
(sometimes + sulfur)

29
Q

Amino acids are made up of…?

A

-Amino group
-Acid group
-Side chain

30
Q

Relationship betw. amino acid and protein?

A

Amino acids (held tgt by peptide bonds)
->Polypeptide
->Protein

31
Q

Why do we need proteins?

A

-Synthesis of new protoplasm for growth and repair of cells
-Synthesis of enzymes and some hormones
-Synthesis of antibodies

32
Q

What is the test for proteins?

A

Biuret test

33
Q

[Describe Procedure]
Procedure of biuret test?
(+Solid food sample modifications & result indication)

A
  1. Add 2cm^3 of biuret solution to 2cm^3 of food sample in a test tube
  2. Shake the contents of the tube thoroughly
  3. Wait for a few minutes

Solid food sample modification:
1. Crush food w/ mortar & pestle
2. Add water to the crushed food to dissolve the nutrients
3. Decant the mixture to a new test tube
4. Proceed w/ step 1

Purple/violet colouration observed- +ve result
Sol. remains blue- -ve result