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DNA Structure
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DNA: The Genetic Material
Genes: The instructions for inherited traits; made up of DNA. DNA: Deoxyribonucleic acid, contains the information that determines inherited characteristics.
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The Shape of the Molecule
DNA is a very long molecule. The basic shape is like a twisted ladder or zipper. This is called a double helix. {Show students a model of the double helix. Explain what a spiral is and a helix is.}
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DNA Structure A molecule of DNA is made up of millions of tiny subunits called Nucleotides. A nucleotide consists of: Phosphate group Ribose sugar Nitrogenous base
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Nucleotides Phosphate Nitrogenous Base Pentose Sugar
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Nucleotides The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”.
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The 4 Nitrogenous Bases A Adenine T Thymine C Cytosine G Guanine
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Complementary Base pair: each base has a match
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Nucleotides Each base will only bond with one other specific base.
Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Form a base pair. Form a base pair.
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Hydrogen Bonds C N O Hydrogen bonds hold them together!
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Watson and Crick
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DNA Replication
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DNA Replication DNA is made up of 2 strands of complementary base pairs A –T and C – G If DNA are separated, it can serve as a pattern to make a new strand! DNA Replication: Process of making a new copy of DNA
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DNA Replication DNA Helicase – An enzyme that unwinds the DNA double helix during DNA replication. DNA Polymerase – An enzyme that helps in the formation of the DNA molecule.
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RNA In RNA Thymine is replaced by Uracil A-U (RNA) A-T (DNA)
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Transcription Transcription: RNA is made from the complementary DNA strand. This type of RNA is called messenger RNA or mRNA Copying (transcribing) notes from the board (DNA) to a notebook (RNA).
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Translation Translation – Takes the three-letter codons of mRNA code for an amino acid.
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A codon is a three-base word that codes for one amino acid.
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Mutation A change in the structure or amount of the genetic material of an organism.
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Deletion: a piece of a chromosome is lost.
Duplication: a piece remains attached to the chromosome after meiosis. Inversion: a piece reattaches to the original chromosome, but in a reverse direction. Translocation: When a chromosome piece ends up in a completely different chromosome.
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