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Nucleic Acids


The nucleic acids include the amazing DNA molecule. It is the source of constancy and variation among species, and is the foundation for the unity and diversity of ... – PowerPoint PPT presentation

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Title: Nucleic Acids

Nucleic Acids Structure and Function
The nucleic acids include the amazing DNA
molecule. It is the source of constancy and
variation among species, and is the foundation
for the unity and diversity of all life on Earth.
Nucleic Acids
  • Nucleic acids store and transmit hereditary
  • The amino acid sequence of a polypeptide is
    programmed by a unit of inheritance called a gene
  • Genes are made of DNA, a nucleic acid
  • Genes
  • Are the units of inheritance
  • Program the amino acid sequence of polypeptides
  • Are made of specific nucleotide sequences on DNA

The Roles of Nucleic Acids
  • There are two types of nucleic acids involved in
    inheritance and protein synthesis
  • Deoxyribonucleic acid (DNA)
  • Ribonucleic acid (RNA)
  • DNA
  • Stores information for the synthesis of specific
  • Found in the nucleus of cells
  • Directs RNA synthesis (transcription)
  • Directs protein synthesis through RNA
  • RNA
  • Single stranded nucleic acid which carries the
    code for protein synthesis
  • Found in nucleus, and outside of nucleus in
    association with ribosomes

The Structure of Nucleic Acids
  • Nucleic acids
  • Exist as polymers called polynucleotides
  • Each polynucleotide
  • Consists of monomers called nucleotides
  • Sugar phosphate nitrogen base
  • Nucleotide monomers
  • Are made up of nucleosides (sugar base) and
    phosphate groups
  • The portion of a nucleotide without the phosphate
    group is called a nucleoside

Nucleotide Monomers
  • Nucleoside nitrogenous base sugar
  • There are two families of nitrogenous bases
  • Pyrimidines (cytosine, thymine, and uracil) have
    a single six-membered ring
  • Purines (adenine and guanine) have a six-membered
    ring fused to a five-membered ring
  • In DNA, the sugar is deoxyribose in RNA, the
    sugar is ribose

Nucleotide Polymers
  • Nucleotide polymers are linked together to build
    a polynucleotide
  • Adjacent nucleotides are joined by covalent bonds
    that form between the OH group on the 3? carbon
    of one nucleotide and the phosphate on the 5?
    carbon on the next
  • These links create a backbone of sugar-phosphate
    units with nitrogenous bases as appendages
  • The sequence of bases along a DNA or mRNA polymer
    is unique for each gene

DNA Double Helix

DNA Structure
  • Antiparallel nature
  • Sometimes called complementary sugar/phosphate
    backbone runs in opposite directions
  • one strand runs 5 to 3, while the other runs
    3 to 5
  • One DNA molecule includes many genes

Scientists can use DNA and Proteins as Tape
Measures of Evolution
  • Molecular comparisons
  • Help biologists sort out the evolutionary
    connections among species
  • How similar are the sequences of nucleotides?
  • The closer the sequence, the closer the
  • Remember, all life, from the simplest prokaryote
    to the most complex eukaryote, contains the same
    four nitrogenous bases.

It is simply the sequence of base-pairs, and
amount of DNA that differs from organism to
Adenosine triphosphate is a common source of
activation energy for metabolic reactions. ATP is
essentially an RNA adenine (adenosine) nucleotide
with two additional phosphate groups.
The wavy lines between these two phosphate groups
indicate high energy bonds. When that last bond
is broken, and the ATP is converted to ADP
(adenosine diphosphate), energy is released, and
can be used to spur a reaction.
Conversely, a new ATP molecule can be built by
combining ADP and a phosphate through a process
known as phosphorylation using energy obtained
from glucose.
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