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Flashcards in Biology Lab 2 Deck (31):
1

4 main macromolecules

Carbohydrates (sugars),
Lipids (fats),
Proteins,
Nucleic Acids

2

Reducing sugar

Has an Aldehyde group on it.

Can reduce copper ions (at proper pH)

3

Copper ions react with glucose to form a precipitate of ?

Copper oxide

4

Which precipitate has more sugar? Green or brownish red?

Brownish red

5

Benedict's solution is used to test for ?

Presence of simple sugars (in food, blood, urine)

6

Reducing sugars are either monosaccharides or?

Disaccharides

7

If Benedict's reagent is added to a solution and it turns blue, is there a reducing sugar?

No

8

If Benedict's reagent is added to a solution and it turns orangish brown, is reducing sugar present?

Yes

9

A single or simple sugar is called a

Monosaccharide (mono=1) (saccharine=sugar)

10

2 or more monosaccharides bonded together are called?

Oligosaccharides (oligo=few)

11

Barfoed's reagent is used to

Distinguish between monosaccharides and oligosaccharides.

12

Benedict's reagent and Barfoed's reagent both contain?

Copper ions

13

Which reagent is more acidic? Benedict's or Barfoed's?

Barfoed's

14

If Barfoed's reagent is added to a solution and a reddish precipitate forms at the bottom of the test tube, are monosaccharides present?

Yes

15

List 3 monosaccharides.

Glucose, Fructose, Sprite

16

________is a polysaccharide used for storing energy in plants

Starch

17

Starch reacts w/ Lugol's iodine (IKI) to produce what color?

Dark blue/black

18

List 2 characteristics of LIPIDS (oils, fats, waxes, steroids)

Do not dissolve well in water

Do not all have similar chemical structures (like carbohydrates do)

19

Name 2 types of tests for lipids

Brown paper test

Sudan IV test

20

Sudan IV is a ______________ that dissolves in_____________ but not in water.

Red powder

Lipids

21

Biuret is prepared from?

Urea

22

Biuret contains 2?

Peptide bonds

23

When Biuret reacts with copper sulfate, what color forms?

Purple

24

A reaction between copper ions and peptide bonds causes what color?

Purple

25

Proteins give a strong reaction to Biuret because?

Proteins contain many peptide bonds, which link individual amino acids in the polypeptide chain.

26

Name something that reacted with Biuret.

Albumin solution.

27

If a sample tests positive with Benedict's reagent but not with Barfoed's reagent, what can you tell about that sample?

That it contains a reducing sugar, but it is not a monosaccharide, it is an oligosaccharide.

28

Benedict's reagent and Barfoed's reagent are both blue because?

They both contain copper ions

29

Draw 2 different isomers of the chemical C2H6O

Draw

30

List 2 foods that would react with Benedict's reagent but not with IKI

Soda (Sprite), Apple?

31

Macromolecules

Latin -> macro = large

Large molecules that make up important parts of the cell