STAAR Notebook 2

DNA

DNA stands for Deoxyribose Nucleic Acid. Nucleic acids like DNA are long chains of nucleotides. Every nucleotide has 3 parts. Phosphate Group Nitrogenous base Sugar (Deoxyribose) The sugar-phosphate backbone provides shape and structure DNA contains 4 different nucleotides that each have a different nitrogenous base. Nitrogenous bases pair up along the middle of the DNA Hydrogen bonds hold the strands together 1. Adenine 2. Thymine 3. Guanine 4. Cytosine

DNA A pairs with T G pairs with C The double-helix shape makes DNA look like a twisted ladder! This X-ray photograph taken by Rosalind Franklin gave scientists evidence that DNA was in the shape of a double-helix. Because of the way bases pair, DNA always contains the same amounts of A & T, and the same amounts of G & C. The instructions for specific traits are carried by the sequence of nucleotides. The order of nitrogenous bases determines the order of amino acids in a protein!

STAAR Questions DNA

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The Genetic Code

Organisms pass inherited traits to their offspring through genetic material. ALL living things contain genetic material in the form of DNA. The genes of ALL living things are made from the same building blocks: the nucleotides A, T, G, and C! ALL living things are made from the same building blocks: the nucleotides A, T, G, and C! ALL living things share a common genetic code! This means that all living things use the information in DNA to make proteins in the same way.

STAAR Questions The Genetic Code

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Transcription and Translation

TRANSCRIPTION Information in the DNA is transcribed so that it can be used by the cell. Base Pairing: RNA is very similar to DNA, but it contains Uracil (U) instead of Thymine (T)! Product: Messenger RNA (mRNA)

TRANSLATION Product: Protein The genetic code is translated into a specific sequence of amino acids. Product: Protein (Amino Acid Sequence) Ribosomes direct the translation of proteins. Proteins are just long sequences of amino acids!

Using a Codon Chart Starting with DNA Translating mRNA Step 1: Transcribe the DNA into mRNA Step 2: Put a line after every 3rd nucleotide Step 3: Use the mRNA codon chart to translate each 3 letter codon into an amino acid Translating mRNA Step 1: Put a line after every 3 nucleotides to define the reading frame. Step 2: Use the mRNA codon chart to translate each 3 letter codon into an amino acid

Transcription and Translation STAAR Questions Transcription and Translation

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Gene Expression

Genes for fur color can be regulated by temperature. Expressed Gene expression describes how genes are used to determine traits. Gene expression is a regulated process that is controlled by the cell. This means cells can turn genes ON or OFF! Every cell in your body contains a complete set of DNA. Cells become specialized by regulating gene expression! Genes for fur color can be regulated by temperature. Gene expression can be influenced by environmental factors.

STAAR Questions Gene Expression

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Mutations

Insertion Substitution Deletion A mutation is a change to the sequence of nucleotides in DNA Insertion Nucleotides are added to the DNA Deletion Nucleotides are removed from the DNA Substitution A single nucleotide is replaced

Mutations can cause codon sequences to be incorrect. This can change the amino acids in the protein being made! Silent mutations are changes to DNA that do NOT change the amino acids in a protein. Frame shifts are when insertions or deletions change the reading frame. This can change EVERY codon!

Only mutations to gamete cells are inherited by offspring. Inherited diseases are the result of changes to the DNA. Mutations are also a source of genetic variations. The differences in these species of finch are the result of mutations.

STAAR Questions Mutations

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Quiz Next Class!!!!!!!!!!!!!! Study STAAR 2 for Quiz next class! Will count double in the gradebook!