The document discusses chemical tests for biological molecules like carbohydrates, proteins, lipids, and nucleic acids. It describes the basic structure of DNA as a double helix consisting of nucleotides with phosphate, sugar, and nitrogenous base components. DNA contains the genetic instructions for life and encodes hereditary information through its sequence of nucleotide base pairs between strands. RNA is similar to DNA but is usually single-stranded and found in the nucleus.

1. Chemical tests and Nucleic acids
Jorge Melo

2.  Monosaccharides
 Disaccharides
 Polysaccharides

6.  What name is given to the carbohydrate in which n
is
 6
 5
 3
 State 2 different functions of the carbohydrates
 Simple carbohydrates are combined to form
disaccharides, what else is produced?

7.  This is a hydrolysis reaction.

11.  List different types of biological tests
 Describe the basic structure of DNA
 List DNA properties
 Distinguish between RNA and DNA
 Explain why DNA is so important

12.  Chemical tests
 DNA History
 DNA properties
 RNA
 DNA polymerase

14.  Test to detect
proteins
 A positive test will
show a purple ring
 Peptide bond

15.  Test for reducing sugars
 A positive for reducing
sugars is a brick-red
precipitate
 Reducing sugars
 Non reducing sugars
(sucrose)

16.  Test for starch
 A positive test for
amylose (starch) is a
blue-black colour

17.  Test for
lipids
 Cloudy
white
emulsion is
formed
 Ethanol
(alcohol)

19.  What is DNA after all??
 Is it so Important?
 And RNA?

20.  Early scientists thought protein was the cell’s
hereditary material because it was more complex
than DNA
 Proteins were composed of 20 different amino
acids in long polypeptide chains

21.  Fred Griffith worked with virulent S
and nonvirulent R strain
Pneumoccocus bacteria
 He found that R strain could become
virulent when it took in DNA from
heat-killed S strain
 Study suggested that DNA was
probably the genetic material

22. copyright cmassengale 22

23. Rosalind Franklin - X-ray photo of DNA (1952)
 She was able to deduce that
the phosphate groups of
DNA must be positioned on
the outside of the molecule
 This work was of vital
importance to the later
discovery of the double
helix.

24. Watson and Crick - described the DNA molecule from
Franklin’s X-ray (1953)
They built the first DNA model using Franklin’s X-rays

25.  Stands for:
 Deoxyribonucleic acid
 Made up of subunits called nucleotides
 Nucleotide:
 1. phosphate group
 2. 5-carbon sugar
 3. Nitrogenous base

26. Phosphate
Group
O 5
O=P-O CH2
O
O
N
Nitrogenous base
C4 C1 (A, G, C, or T)
Sugar
(deoxyribose)
C3 C2

27.  Two strands coiled
called a double helix
 Sides made of a
pentose sugar
Deoxyribose bonded to
phosphate (PO4)
groups by
phosphodiester bonds
 Center made of
nitrogen bases bonded
together by weak
hydrogen bonds

28. •DNA had specific pairing
between the nitrogen bases:
ADENINE – THYMINE
CYTOSINE - GUANINE
•DNA was made of 2 long
stands of nucleotides arranged
in a specific way called the
“Complementary Rule”

29. “Rungs of ladder”
Nitrogenous
Base (A,T,G or C)
“Legs of ladder”
Phosphate &
Sugar Backbone

30.  One strand of
DNA goes from 5’
to 3’ (sugars)
 The other strand
is opposite in
direction going 3’
to 5’ (sugars)
copyright cmassengale 30

31. 5 O 3
3 O
P 5 P
5 O
1 G C 3
2
4 4
2 1
3 5
O
P P
5
T A 3
O
O
5
P 3 P

32.  PURINES
1. Adenine (A)
2. Guanine (G)
A or G
 PYRIMIDINES
3. Thymine (T)
4. Cytosine (C)
T or C

33.  Adenine must pair with Thymine
 Guanine must pair with Cytosine
 Their amounts in a given DNA molecule will
be about the same.
T A G C

34. H-bonds
G C
T A

35.  What is meant by:
 complementary rule
 Antiparallel
 Chargaff's rule
 What is the sequence of:
 AGTCCAATGCTAGGCTAA

36.  Different
arrangements of
NUCLEOTIDES in a
nucleic acid (DNA)
provides the key to
DIVERSITY among
living organisms.

37.  Stands for:
 Ribonucleic acid
 Polynucleotide
 Usually single
stranded

38.  Made up of
nucleotides
containing the
base pairs
A, U, C, G

40.  Idea presented by Watson & Crick
 The two strands of the parental molecule
separate, and each acts as a template for a new
complementary strand
 New DNA consists of 1 PARENTAL (original)
and 1 NEW strand of DNA
DNA Template
Parental DNA
New DNA

41.  Helicase
 DNA polymerase

47.  Name given to some stretches of DNA and
RNA that encode for a peptide
Stands for:
Ribonucleic acid