DNA Structure
DNA: The Genetic Material Genes: The instructions for inherited traits; made up of DNA. DNA: Deoxyribonucleic acid, contains the information that determines inherited characteristics.
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.}
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
Nucleotides Phosphate Nitrogenous Base Pentose Sugar
Nucleotides The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”.
The 4 Nitrogenous Bases A Adenine T Thymine C Cytosine G Guanine
Complementary Base pair: each base has a match
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.
Hydrogen Bonds C N O Hydrogen bonds hold them together!
Watson and Crick
DNA Replication
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
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.
RNA In RNA Thymine is replaced by Uracil A-U (RNA) A-T (DNA)
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).
Translation Translation – Takes the three-letter codons of mRNA code for an amino acid.
A codon is a three-base word that codes for one amino acid.
Mutation A change in the structure or amount of the genetic material of an organism.
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.