NUCLEIC ACIDS

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BIOTEC 013

• NUCLEIC ACIDS

Introduction to Biotechnology
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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

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Nucleic Acids in Cells
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Bases in Nucleic Acids
pyrimidines
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Bases in Nucleic Acids
purines
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Sugars in Nucleic Acids
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Nucleosides Nucleotides

• Nucleoside Base Sugar
• ex adenosine, guanosine, cytidine, thymidine,
  uridine
• Nucleotide Base Sugar Phosphate
• ex Adenylic acid or adenosine monophosphate

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Nucleosides Nucleotides
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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

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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
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H-bonding in DNA Bases

cytosine guanine
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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

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Comparison DNA and RNA
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Properties of Nucleotides

• Tautomerism
• interconversion of bases

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Properties of Nucleotides

• Syn and Anti

syn
anti
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Properties of Nucleotides

• Stability Formation of Phosphodiester Linkage

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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

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Primary Structure
Adenine (A)
Guanine (G)
pdApdGpdTpdC or AGTC
Thymine (T)
Guanine (G)
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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

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Secondary Structure
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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

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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

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Secondary Structure
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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

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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.

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1?, 2? and 3? Structures
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1?, 2? and 3? Structures
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END