structure & function of dna
DESCRIPTION
Structure & Function of DNA. Understanding Growth & Development. 1. The Structure of DNA. DNA stands for: deoxyribonucleic acid DNA is: the molecule of life and is found in every organism DNA stores: information for proper cellular function. 2. The Structure of DNA, cont. - PowerPoint PPT PresentationTRANSCRIPT
The Structure of DNA • DNA stands for: deoxyribonucleic
acid• DNA is: the molecule of life and is
found in every organism• DNA stores: information for proper
cellular function
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The Structure of DNA, cont.• The complete DNA
molecule is arranged in a structure called a double helix
• Double helix – 2 coiled strands; twisted ladder
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The Structure of DNA, cont. • DNA is: a large polymer that
contains the elements C,H,O,N & P• Polymer structure is made of single
units (monomers) called nucleotides
• 3 components of a nucleotide:5-carbon sugarPhosphate groupNitrogen-containing base
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The Structure of DNA, cont.• Sides of ladder:
Deoxyribose a 5-carbon (pentose) sugar
Phosphate group• Rungs of ladder:
2 nitrogen-containing bases joined with 2 or 3 hydrogen bonds
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Nitrogen-containing Bases• Double ring PURINES
Adenine (A)Guanine (G)
• Single ring PYRIMIDINESThymine (T)Cytosine (C)
T or C
A or G
Base-Pairings• The DNA of all organisms follows
the rule of base-pairing:
Cytosine always bonds with Guanine andAdenine always bonds with Thymine
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Base-Pairings• Three hydrogen bonds required
to bond Guanine & Cytosine
• Two hydrogen bonds are required to bond Adenine & Thymine
CG
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1868-Switzerland
• Johann Friedrich Miescher• Found it when working with
white blood cells that he took from pus drained out of a surgical wound.
1920-London• Frederick Griffith• Found that bacteria could acquire
something from each other to turn harmless bacteria into deadly bacteria, though he wasn't sure what.
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1944-New York
• Oswald Avery • Led a team that assessed Griffith’s
work• Discovered the molecule DNA was
what had caused the change.
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1950-New York• Edwin Chargaff • Found that the amount of adenine
was almost equal to the amount of thymine, and that the amount of guanine was almost equal to the amount of cytosine.
• Thus you could say: A=T, and G=C. • This discovery later became Chargaff’s
Rule.
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1952-London• Rosalind Franklin and Maurice Wilkins • Were able to obtain an x-ray image of
crystalized DNA• It showed a ladder with rungs twisted
in an “X” shape indicating DNA had a helix shape.
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1953-London• James Watson and Francis Crick• Published their findings about the
structure of DNA• Watson, Crick and Wilkins received a
Nobel Prize for their work in 1962
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All about you and your chromosomes
• Humans- 46 chromosomes-23 pairs• 22 autosomal pairs or 44 body
chromosomes• 1 pair of sex chromosomes-2 sex
chromosomes• XX-girl XY- boys• X in eggs only• Sperm will have either an X or a Y
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DNA ReplicationDNA structure in :• Prokaryotes - single, circular piece;
found in cytoplasm• Eukaryotes - arranged in multiple
threads called chromosomes; found in nucleus
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DNA Replication, cont.• Number of chromosomes varies
depending on organism: Fruit Fly - 8 Humans – 46 Chimpanzees - 48 Aquatic Rat - 92
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DNA Replication, cont.• Genes: sections of DNA on the
chromosomes• Genes: code for certain proteins that
provide instructions for cellular activity
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DNA Replication, cont.• Each cell of any type of organism
must be able to make copies of its DNA to pass on to daughter cells
• Replication – when DNA makes a copy of itself
• Both strands of DNA are complementary to each other
• Each serve as a template to make a new strand
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