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What are chromosomes made of?. DNA. Deoxyribonucleic Acid. DNA. A type of Nucleic Acid Genetic material in chromosomes. Monomer made of: Phosphate Sugar ( Deoxyribose ) Nitrogen Base Monomer= Nucleotide. DNA: Nitrogen Bases. Nitrogen Bases are the “steps” of the DNA “Ladder”
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DNA Deoxyribonucleic Acid
DNA • A type of Nucleic Acid • Genetic material in chromosomes. • Monomer made of: • Phosphate • Sugar (Deoxyribose) • Nitrogen Base • Monomer= Nucleotide
DNA: Nitrogen Bases • Nitrogen Bases are the “steps” of the DNA “Ladder” • Adenine == Thymine (A-T) • Cytosine == Guanine (C-G) • Held together by Hydrogen Bonds
DNA: History • 1950’s Rosalind Franklin & Maurice Wilkens • Xray photography • Spiral structure
DNA: History • 1950’s Watson & Crick • DNA consists of a double helix. • Two strands that are complements of each other. • Heredity is based on this chemical molecule!
The Functions of DNA • Replication • Occurs during interphase. • Split your model and make two replicated strands!
The Language of DNA • Sets of 3 nitrogen bases is a “word” called a codon. • Each segment of DNA that makes a protein is called a gene. ATCCGTACTAACGTACATTGC C0D0N GENE
The Functions of DNA • Protein Synthesis • One gene codes for one protein DNA --> mRNA --> Protein TranscriptionTranslation
How Proteins are Made • DNA can not leave the nucleus. • Messenger is needed to carry the information to the ribosome where the proteins are made.
Ribonucleic Acid • A nucleic acid. • Single strand • Sugar = Ribose • Nitrogen bases: Cytosine == Guanine Adenine == Uracil • Types • mRNA, tRNA, rRNA
Transcription • The synthesis of mRNA using DNA as the template. • DNA = T T C A T C • mRNA= A A G U A G
Transcription Please turn to page 209 in the blue book and record the steps from the picture in your notes.
How to Read a Codon Sheet Stop Codon Stop Start Codon
Translation: Let’s Try! • The process of building a protein at a ribosome where the mRNA determines the sequence of amino acids in the protein. • mRNA= A A G U A G • Amino Acids/Codons= Lysine, Stop Codon
Translation Animation http://www.concord.org/~btinker/workbench_web/models/DNAmsgON.swf
Translation • The ribosome reads the mRNA sequence and translates it into the amino acid sequence of the protein. • The ribosome starts at the sequence AUG, then reads three nucleotides at a time. • Each 3 nucleotide codon specifies a particular amino acid. • The stop codons (UAA, UAG, UGA) tell the ribosome that the protein is complete.
Mutations Mutation: Any change in the nucleotide sequence of DNA.
Mutation Types Point Mutation (Base Substitution) Replacement of one nitrogen base for another.
Mutation Types Silent Mutation: The change in the nitrogen base makes no difference in the coded amino acid.
Mutation Example • Sickle Cell Anemia Sickle cell anemia is the most common inherited blood disorder in the United States. • SCA is genetic disease caused by a point mutation in the hemoglobin beta gene.