Genetics Exam Study Guide PDF
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New Mexico State University
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This genetics study guide covers key topics such as cell division, DNA structure, and replication. It outlines important concepts like the central dogma and key enzymes involved in transcription and translation. This guide is helpful for students learning genetic processes.
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**Genetics Exam Study Guide** **Section 1: Cell Division -- Mitosis & Meiosis** - **Mitosis**: Produces **2 genetically identical diploid (2n)** cells. Phases: Interphase (G1, S, G2), Prophase, Metaphase, Anaphase, Telophase, Cytokinesis. - **Meiosis**: Produces **4 genetically unique...
**Genetics Exam Study Guide** **Section 1: Cell Division -- Mitosis & Meiosis** - **Mitosis**: Produces **2 genetically identical diploid (2n)** cells. Phases: Interphase (G1, S, G2), Prophase, Metaphase, Anaphase, Telophase, Cytokinesis. - **Meiosis**: Produces **4 genetically unique haploid (n)** cells. Phases: Meiosis I (homologous chromosomes separate) and Meiosis II (sister chromatids separate). **Crossing over** and **independent assortment** during meiosis contribute to genetic diversity. **Section 2: Discovery of DNA -- Avery et al. Experiment** - **Griffith's Experiment**: Demonstrated that **DNA** was the material responsible for bacterial transformation. When heat-killed S strain (virulent) was mixed with live R strain (non-virulent), the mouse died, showing that DNA could transform bacteria. - **Avery, MacLeod, and McCarty**: Proved that **DNA** is the **transforming principle** in Griffith\'s experiment by showing that only DNA extract from the S strain could convert R strain into S strain. **Section 3: DNA & RNA Structure** - **Nucleotides**: Composed of a phosphate group, a pentose sugar, and a nitrogenous base. - **DNA**: **A** pairs with **T**, **C** pairs with **G**. - **RNA**: **A** pairs with **U** (uracil), **C** pairs with **G**. - **RNA vs. DNA**: RNA has **ribose** instead of deoxyribose, is **single-stranded**, and contains **uracil** instead of thymine. - **DNA structure**: **Double helix** with **antiparallel strands**; **A-T** and **G-C** base pairing. **Section 4: Genome Structure** - **Prokaryotic genome**: **Single, circular chromosome** in the nucleoid region. Some have **plasmids**. - **Eukaryotic genome**: **Multiple linear chromosomes** contained within the nucleus, with **histones** helping to package DNA into **chromatin**. - **Eukaryotic DNA** is more **complex**, with introns, repetitive sequences, and more regulation. **Section 5: Semiconservative DNA Replication (Meselson & Stahl)** - **Meselson & Stahl's experiment**: Proved that DNA replication is **semiconservative**, where each new DNA molecule consists of one old (parent) strand and one new (daughter) strand. - **Key enzymes**: - **Helicase** unwinds the DNA. - **DNA polymerase** adds new nucleotides. - **Ligase** seals the gaps between newly synthesized DNA strands. - **Okazaki fragments**: Short segments of DNA synthesized on the lagging strand. **Section 6: Transcription -- DNA to RNA** - **Transcription process**: 1. **Initiation**: RNA polymerase binds to the **promoter** and unwinds the DNA. 2. **Elongation**: RNA polymerase synthesizes mRNA in the 5' → 3' direction. 3. **Termination**: RNA polymerase reaches a termination signal, and the mRNA is released. - In eukaryotes, mRNA undergoes **5' capping**, **splicing** (removal of introns), and **poly-A tail** addition for stability. **Section 7: Translation -- RNA to Protein** - **Translation process**: 1. **Initiation**: Ribosome assembles around mRNA and tRNA carrying methionine binds to the start codon (**AUG**). 2. **Elongation**: tRNA brings amino acids to the A-site; peptide bonds form between amino acids. 3. **Termination**: When a stop codon (**UAA, UAG, UGA**) is reached, the protein is released. - **tRNA** carries amino acids and has an **anticodon** that matches the mRNA codons. **Key Concepts to Remember** - **Mitosis vs. Meiosis**: Mitosis produces identical diploid cells, while meiosis results in genetically diverse haploid cells. - **DNA is the Genetic Material**: Proven by Avery, MacLeod, and McCarty, and confirmed by Griffith's transformation experiment. - **Central Dogma**: DNA → mRNA → Protein. - **Genetic Code**: Each mRNA codon corresponds to one amino acid in the protein sequence. - **Post-Translational Modifications**: Proteins often undergo **folding**, **cleavage**, and **chemical modifications** (e.g., phosphorylation). **Important Enzymes to Remember** - **DNA polymerase**: Synthesizes DNA during replication. - **RNA polymerase**: Synthesizes RNA during transcription. - **Helicase**: Unwinds the DNA double helix. - **Ligase**: Seals breaks in the DNA strands. - **tRNA**: Transfers amino acids during translation.
