Chemical Evolution

1
Chemical Evolution

• Nucleic Acids

2
Nucleic Acids

• Composition Made up of nucleotides which each
  consist of three parts - a sugar, a base, and a
  phosphate group (from H3PO4)
• Structure polynucleotides which consist of bases
  attached to a backbone of sugar and phosphate
  groups

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General Composition of Nucleic Acids
Tro, 415
4
Sugar Components of Nucleotides
Hill/Kolb, "Chemistry for Changing Times",
7th,Prentice Hall, NJ, 1995, 473.
5
Base Components of Nucleotides
Hill/Kolb, "Chemistry for Changing Times",
7th,Prentice Hall, NJ, 1995, 473.
6
Base Components of Nucleotides
Hill/Kolb, "Chemistry for Changing Times",
7th,Prentice Hall, NJ, 1995, 473.
7
Abiotic Synthesis of Precursors to Bases

• CH4 NH3 gt HCN 3 H2
• 2 CH4 N2 gt C2N2 4 H2
• C2N2 2 OH- gt CN- NCO- H2O
• 6 CH4 N2 gt 2 HC?CC?N 11 H2

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Abiotic Synthesis of Purine Bases
Mason, Chemical Evolution,Oxford, UK, 1991, 240
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Abiotic Synthesis of the Pyrimidine Bases
Mason, Chemical Evolution,Oxford, UK, 1991, 240
10
A Nucleotide
A Specific Nucleotide
Hill/Kolb, "Chemistry for Changing Times",
7th,Prentice Hall, NJ, 1995, 473.
11
Nucleic Acid polynucleo-tide.Backbone chain
of de-oxyribose and phosphate groups.Bases
(attached to same side of backbone) are
DNA
Phosphate links C-5 of one sugar to C-3 of next
sugar
A Adenine T Thymine G Guanine C Cytosine
Brady/Holum, Fundamentals of Chemistry, 3rd,
Wiley, NY, 1988, 1039.
RNA has OH at C-2
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Base Pairing in DNA
Hydrogen bonds (dotted lines) can form between
bases on parallel nucleic acid chains
Brady/Holum, Fundamentals of Chemistry, 3rd,
Wiley, NY, 1988, 1041.
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DNA Double Helix
Hydrogen bonds that hold the two strands together
are indicated by dotted lines.
Brady/Holum, Fundamentals of Chemistry, 3rd,
Wiley, NY, 1988, 1040.
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Central Dogma of Genetics

• The function of DNA is to store information and
  pass it on to RNA so as to protect the integrity
  of DNA
• The function of RNA is to read, decode and use
  the information received from DNA to make proteins

http//www.ncc.gmu.edu/dna/nucleic.htm
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Contd

• The blueprint for making proteins occurs in the
  base sequence of the double helix of DNA
• Three consecutive bases comprise one base triplet
  that becomes a codon when transcribed to RNA
• A portion of RNA that contains the sequence of
  codons that specify a single protein is called a
  gene

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Functions of Nucleic Acids
Replication is the process by which a replica, or
identical copy, of DNA is made. Replication
occurs every time a cell divides so that
information can be preserved and handed down to
offspring.
Transcription is the process by which the genetic
messages contained in DNA are "read" or
transcribed. The product of transcription, known
as messenger RNA (mRNA), leaves the cell nucleus
and carries the message to the sites of protein
synthesis.
Translation is the process by which the genetic
messages carried by mRNA are decoded and used to
build proteins.
http//www.ncc.gmu.edu/dna/nucleic.htm
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(Code is the same for all organisms)
Start codon Met AUG

Codon Letters A Adenine, U Uracil, G
Guanine, C Cytosine
http//www.scientificpsychic.com/fitness/aminoacid
s1.html
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Replication of DNA

• For multicellular organisms (like us) cell
  division allows an organism to grow and develop
  from a single cell to trillions of cells, to
  repair and replace cells worn out and used up by
  everyday life, and in some cases, to make
  specialized cells for reproduction
• Your body needs to make about 300 MILLION NEW
  CELLS/minute!

19
Contd

• These new cells can only come from one place
  OTHER CELLS - through the process of cell
  division, or mitosis
• When a cell divides, the DNA is duplicated
  exactly by a process called replication

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Transcription of DNA to Messenger RNA
http//www.brooklyn.cuny.edu/bc/ahp/BioInfo/graphi
cs/Transcription.01.GIF
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Comparison of DNA and m-RNA
http//www.phschool.com/science/biology_place/bioc
oach/images/transcription/polynuc.gif
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Transcription and Translation of Genetic
Information
c
o
Base triplet
d
o
n
Translation
Transcription
Mandelkern,L, An Introduction to Macromolecules,
2nd,Springer-Verlag,NY,1983,145
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NUCLEIC ACIDS

• Nucleic acids are polymers of nucleotides
• DNA and RNA serve as the blueprints for
  proteins
• They ultimately control the life of a cell

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• The monomers of nucleic acids are nucleotides

• Each nucleotide is composed of a sugar,
  phosphate, and nitrogenous base
• The sugar and phosphate form the backbone for the
  nucleic acid

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(No Transcript)
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• DNA is double stranded two polynucleotides
  twisted into a double helix

• Consists of four types of nucleotides
• Adenine pairs to Thymine
• Cytosine pairs with Guanine
• The sequence of nitrogenous bases carries genetic
  information

Basepair
Nitrogenousbase (A)
Figure 3.20C
27
NUCLEIC ACIDS

• Nucleic acids are polymers of nucleotides
• DNA and RNA serve as the blueprints for
  proteins
• They ultimately control the life of a cell

28

• The monomers of nucleic acids are nucleotides

• Each nucleotide is composed of a sugar,
  phosphate, and nitrogenous base
• The sugar and phosphate form the backbone for the
  nucleic acid

29
(No Transcript)
30

• DNA is double stranded two polynucleotides
  twisted into a double helix

• Consists of four types of nucleotides
• Adenine pairs to Thymine
• Cytosine pairs with Guanine
• The sequence of nitrogenous bases carries genetic
  information

Basepair
Nitrogenousbase (A)
Figure 3.20C
31
RNA

• Usually single strands
• Four types of nucleotides A, C, G, and U
• Unlike DNA, contains the base uracil in place of
  thymine
• Three types of RNA that are key players in
  protein formation

messenger, transfer, and ribosomal
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The sugars in nucleic acid
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Comparison - nucleic acids
DNA
RNA

• Double stranded
• Thymine base
• Deoxyribose sugar

• Single stranded
• Uracil base
• Ribose sugar

34

• DNA /RNA action

• Stretches of a DNA molecule called genes
  program the amino acid sequences of
  proteins
• DNA information is transcribed into RNA
• RNA is then translated into the primary
  structure of proteins