Nucleic Acid Structure & Function. Biomedical Importance Genetic information is coded along the...
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Nucleic Acid Structure & Function. Biomedical Importance Genetic information is coded along the length of a polymeric molecule composed of only four types
Biomedical Importance Genetic information is coded along the
length of a polymeric molecule composed of only four types of
monomeric units This polymeric molecule, DNA, is the chemical basis
of heredity and is organized into genes, the fundamental units of
genetic information. The basic information pathway DNA directs the
synthesis of RNA, which in turn directs protein synthesis Genes do
not function autonomously; their replication and function are
controlled by various gene products, often in collaboration with
components of various signal transduction pathways.
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Biomedical Importance Knowledge of the structure and function
of nucleic acids is essential in Understanding genetics and many
aspects of pathophysiology as well as the genetic basis of
disease.
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The interrelationship of DNA,RNA & Protein
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DNA CONTAINS THE GENETIC INFORMATION DNA can Transform Cells
DNA Contains Four Deoxynucleotides deoxyadenylate, deoxyguanylate,
deoxycytidylate, and thymidylate Monomeric units of DNA are held in
polymeric form by 3,5-phosphodiester bridges constituting a single
strand The informational content of DNA (the genetic code) resides
in the sequence in which these monomers are ordered.
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Polynucleotides Are Directional Macromolecules The polymer
possesses a polarity one end has a 5-hydroxyl or phosphate terminal
the other has a 3-phosphate or hydroxyl terminal. 5' -terminus
& 3' terminus
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Polynucleotide representation The base sequence or primary
structure of a polynucleotide can be represented as The
phosphodiester bond is represented by P or p, bases by a single
letter, and pentoses by a vertical line.
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Polynucleotide representation More compact notation
pGpGpApTpCpA The most compact representation shows only the base
sequence GGATCA 5- end is at the left, and all phosphodiester bonds
are 3 5.
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Oligonucleotides, Nucleic acids containing 50 nucleotides
Polynucleotides those that are longer Mononucleotides (nucleoside
monophosphates) linked by 3 5- phosphodiester bonds Polynucleotides
may be RNA Contain Ribonucleosides & uridine (U) DNA
Deoxyribonucleosides & deoxythymidine (dT)
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Polynucleotides may be Single strand Double strand Linear or
circular
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a single-stranded DNA sequence held together by a
phosphodiester backbone between 2- deoxyribosyl moieties attached
to the nucleobases by an N- glycosidic bond. the backbone has a
polarity (ie, a direction)
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STRUCTURE OF DNA DNA is a double-stranded helix The two strands
held together by hydrogen bonds Each strand of which possesses a
polarity, antiparallel; one strand runs in the 5 to 3 direction and
the other in the 3 to 5 direction. The pairings between the purine
and pyrimidine nucleotides on the opposite strands are very
specific and are dependent upon hydrogen bonding of A with T and G
with C
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the concentration of deoxyadenosine (A) nucleotides equals that
of thymidine (T) nucleotides (A = T), while the concentration of
deoxyguanosine (G) nucleotides equals that of deoxycytidine (C)
nucleotides (G = C)
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Double-Helical DNA
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The structure of a G-quartet. The four coplanar guanines form a
tetrameric structure by formation of Hoogsteen hydrogen bonds. The
cavity in the cenrer of [he quartet can accommodate a sodium or
potassium ion with coordination by the four 0-6 oxygens.
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extent of DNA packaging in metaphase chromosomes
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Types of sequences in the human genome.
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Requirements for DNA Replication
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Classes of proteins involved in replication
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DNA provides a template for Replication &
transcription
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DNA replication is semiconservative
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Steps involved in DNA replication in eukaryotes
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DNA polymerase III
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The initiation of DNA synthesis upon a primer of RNA
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A comparison of prokaryotic and eukaryotic DNA polymerases
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The telomere replication problem
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Cell cycle
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Bacterial promoters
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Promoter structure
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Bacterial promoters
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Eukaryotic Promoters Are More Complex
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the transcription control regions
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Structure of a typical eukaryotic mRNA showing elements that
are involved in regulating mRNA stability
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Classes of eukaryotic RNA.
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Nomenclature and properties of mammalian nuclear DNA-dependent
RNA polymerases.
