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Flashcards in CH-04 CHEMICALS OF LIFE Deck (20)
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1

What chemical elements do CARBOHYDRATE contain?

carbon
oxygen
hydrogen

2

What chemical elements do PROTEIN contain?

carbon
oxygen
hydrogen
nitrogen
some contain small elements such as sulfur.

3

What chemical elements do LIPIDS contain?

carbon
oxygen
hydrogen

4

What are the simplest kind of carbohydrates?

simple sugars/ monosaccharides

5

what does it make when two simple sugar molecules, makes a larger molecule called?

complex sugar/ disaccharide

6

What does it make when many complex sugars join together?

polysaccharide

7

what are proteins?

long chains of Amino acids

8

What is the test for glucose/ reducing sugar? also give the positive result.. and the process

Benedicts test
positive color change- blue to orange to brick red

process- Add Benedict’s solution into sample solution in test tube
Heat at 60 – 70 °c in water bath for 5 minutes
Take test tube out of water bath and observe the colour
A positive test will show a colour change from blue to orange or brick red

9

What is the test for Starch? also give the positive result..

Iodine test
positive color change- orange-brown to blue-black

process-
Add drops of iodine solution to the food sample
A positive test will show a colour change from orange-brown to blue-black

10

What is the test for protein? also give the positive result....

Biuret test
Positive color change- blue to violet/purple

process- Add drops of Biuret solution to the food sample
A positive test will show a colour change from blue to violet / purple

11

What is the test for Lipids? also give the positive result...

Ethanol test
Positive result- a cloudy emulsion

process- Food sample is mixed with 2cm3 of ethanol and shaken
The ethanol is added to an equal volume of cold water
A positive test will show a cloudy emulsion forming

12

What is the test for Vitamin C? also give the positive result...

DCIPIP test
positive color change- blue color of the DCIPIP SOLUTION disappearing

process-
Add 1cm3 of DCPIP solution to a test tube
Add a small amount of food sample (as a solution)
A positive test will show the blue colour of the dye disappearing

13

What is the full form of DNA?

deoxyribonucleic acid

14

What are the individual units of DNA called?

Nucleotides

15

Name 4 different bases in nucleotides.

A- adenine
C-cytosine
T-thymine
G-guanine

16

Write down the pairs of the bases in nucleotides.

A- T
C-G

17

Why is water important?

1. can easily transport substances dissolved in it
2.Toxic substances dissolved in water excreted as urea
3. ensures metabolic reactions can happen in cells

18

Give examples for proteins-

- enzymes- Biological catalysts - they only work with a specific site
- antibodies- released by phagocyte -WBC they only work if their active site perfectly fits the antigens on the pathogen molecule's membrane

19

Brief protein shape-

As amino acids have different sequences it causes the polypeptide chains to fold in different ways and giving rise to different shapes of proteins
In this following way every protein has a unique 3D shape that enables it to carry its function

20

Describe the structure of a DNA.

consists of two strands of DNA wound around each other in what is called a double helix
each strand contains chemicals called NUCLEOTIDES
the cross- links on the strand are formed by pair of bases