BS 162 1nd Edition Lecture 4 Looking at Genetics MoreGene Structure- A small section of the DNA molecule – containing a specific nucleotide sequence- Can be as short as a few hundred pairs- Average human genes contain 3,000 bases, but vary in size- The largest known human gene is dystrophin at 2.4 million basesWhy is Genetic Information Transferred?- To make new somatic cells- Somatic cells allow to make gametes (eggs and sperm) to pass on to next generationMitosisProcess by which a cell duplicates the chromosomes in its cell nucleus, in order to generate two identical daughter cellsHow Do Organisms Grow/Repair?They must make new cells. Need to have same blueprint in all cells…therefore, DNA needs to replicate so that each daughter cell can have the entire blueprint in it. Cell Cycle Overview- G1: cells DNA is unduplicated (1 maternal & 1 paternal chromosome)- G2: cells DNA is duplicated (1 maternal & 1 paternal chromosome & 2 identical sisterchromatids attached in the middle by the centromere)- Metaphase: sister chromatids line up down the center- Anaphase: sister chromatids separate – 1 copy to each daughter cellGenes PurposeGenes code for proteins. These proteins affect how an organism looks and functions. They allow the cell to make identical daughter cells that will produce the same proteins (through mitosis).Information FlowThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Expression of a gene to form a protein involves 2 processes:-Transcription: copies information from gene to a sequence of RNA-Translation: converts RNA sequence to an amino acid sequenceMessenger RNA: (mRNA) forms as a complementary copy of DNA and carries information to the cytoplasm This is transcriptionTransfer RNA: (tRNA) molecules that carry amino acids line up on mRNA in proper sequence and form the polypeptide chain. This is translation.The Genetic Code: specifies which amino acids will be used to build a proteinCodon: a sequence of three bases. Each codon specifies a certain amino acid. Start Codon: AUG – initiation signal for translationStop Codon: stops translation and polypeptide is released**Each codon specifies only one amino acid****A change in a single nucleotide can cause a change in the amino acid and then result in a change in the protein. This is a single nucleotide polymorphism