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NUCLEIC ACIDS

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Title: NUCLEIC ACIDS


1
BIOTEC 013
  • NUCLEIC ACIDS

Introduction to Biotechnology
2
Nucleic Acids
  • fundamental constituents of living cells
  • act as repositories and transmitters of genetic
    information for every cell, tissue and organism
  • it is where the blueprint of an organism is
    encoded
  • exist as polymeric chain (macromolecule) or
    polynucleotides made up of bases, sugar and
    phosphate groups

3
Nucleic Acids in Cells
4
Bases in Nucleic Acids
pyrimidines
5
Bases in Nucleic Acids
purines
6
Sugars in Nucleic Acids
7
Nucleosides Nucleotides
  • Nucleoside Base Sugar
  • ex adenosine, guanosine, cytidine, thymidine,
    uridine
  • Nucleotide Base Sugar Phosphate
  • ex Adenylic acid or adenosine monophosphate

8
Nucleosides Nucleotides
9
Polynucleotides Nucleic Acids
  • nucleotide linked to one another in 3, 5-
    phosphosdiester bond
  • phosphoric acid is connected to 3 OH of one
    sugar to 5 carbon of another sugar

10
DNA
  • DNA (Deoxyribonucleic acid)
  • stores the genetic information of individuals
  • dictates the type and structure of proteins
  • contains the sugar deoxyribose
  • the base content of DNA
  • A G T C
  • A T
  • G C
  • strands held by H bond
  • double stranded

Chargaffs Rule
11
H-bonding in DNA Bases

cytosine guanine
12
RNA
  • RNA (Ribonucleic acid)
  • responsible for observable traits
  • transmits information to make proteins
  • the base content of RNA is the same as DNA except
    T is replaced by U
  • single stranded

13
Comparison DNA and RNA
14
Properties of Nucleotides
  • Tautomerism
  • interconversion of bases

15
Properties of Nucleotides
  • Syn and Anti

syn
anti
16
Properties of Nucleotides
  • Stability Formation of Phosphodiester Linkage

17
Primary Structure
  • The primary structure is the sequence of
    nucleoside monophosphates (usually written as the
    sequence of bases they contain)
  • The Nature and Significance of Primary Structure
  • - Directionality of polynucleotide chain
  • - Individuality of polynucleotide chain
    determined by sequence of nucleotides

18
Primary Structure
Adenine (A)
Guanine (G)
pdApdGpdTpdC or AGTC
Thymine (T)
Guanine (G)
19
Secondary Structure
  • The secondary structure refers to the shape a
    nucleic acid assumes as a result of the primary
    structure.
  • B-DNA, A-DNA, and Z-DNA are forms of secondary
    structure

20
Secondary Structure
21
B-DNA
  • Also B-form DNA, beta DNA, ß-DNA
  • The most common structural conformation of the
    DNA double helix in living cells, which exists as
    a right-handed helix.
  • Narrower, more elongated helix than A.
  • Wide major groove easily accessible to proteins
  • Narrow minor groove
  • Favored conformation at high water concentrations
    (hydration of minor groove seems to favor B-form)
  • Base pairs nearly perpendicular to helix axis

22
A-DNA
  • Stable in dehydrated conditions.
  • This form is also assumed by DNA-RNA hybrid
    helices and by regions of double-stranded RNA. It
    is a right-handed helix and is more compact than
    B-DNA.
  • Most RNA and RNA-DNA duplex in this form
  • Shorter, wider helix than B.
  • Deep, narrow major groove not easily accessible
    to proteins
  • Wide, shallow minor groove accessible to
    proteins, but lower information content than
    major groove.
  • Favored conformation at low water concentrations
  • Base pairs tilted to helix axis and displaced
    from axis

23
Secondary Structure
24
Z-DNA
  • A "zig-zag" conformation that can be assumed by
    the DNA double helix. This form is less common
    than B-DNA
  • Is a left-handed helix
  • Narrower, more elongated helix than A or B.
  • Major "groove" not really groove
  • Narrow minor groove
  • Conformation favored by high salt concentrations,
    some base substitutions, but requires alternating
    purine-pyrimidine sequence.
  • Base pairs nearly perpendicular to helix axis
  • Zigzag backbone

25
Tertiary Structure
  • Tertiary structure refers to large-scale folding
    in a linear polymer that is at a higher order
    than secondary structure. The tertiary structure
    is the specific three-dimensional shape into
    which an entire chain is folded.

26
1?, 2? and 3? Structures
27
1?, 2? and 3? Structures
28
END
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