Pre-Class Reading Guide

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900

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Biology

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Oct 30, 2023

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LS7C Week 8 Pre-Class Reading Guide Fill out this worksheet as you complete your pre-class assignments. Bring your completed worksheet to class to use as a reference for in-class activities. After completing your pre-class assignments, you should be able to: • Define the terms genome, genome sequencing, sequence assembly, and genome annotation • Differentiate between small-scale and large-scale genome mutations • Describe the process of sequencing used to generate genome sequences • Determine whether mutations in DNA alter an amino acid sequence and the structure and function of a protein. 1. As you complete your pre-class assignments, define the following terms. a. Genome: originally the term referred to teh complete set of chromosomes present in a reproductive cell– sperm or egg- which in the human genome is 23 chromosomes … now defined as the genetic material transmitted from parent to offspring– embraces all known cellular forms of life b. Genome sequencing: a laboratory method that is used to determine the entire genetic makeup of a specific organism or cell type– this can be used to find changes in areas of the genome c. Sequence assembly: The process in which short nucleotide sequences of a long DNA molecule are arranged in the correct order to generate the complete sequence d. Genome annotation: the process by which researchers identify the various types of sequence present in genomes 2. Watch the video “How to sequence the human genome.” The video describes one of the most common processes used to sequence the human genome. Outline the key steps involved in this process and describe any special molecules or reagents used during the process. - How do you sequence someone’s genome (all genes plus some extra– genes are made of DNA) - Genome– tells your cell how to behave - You aim to find the individual sequence (the letters of DNA- A, G, T, C) that makes your own genome - First must break DNA into smaller pieces - The pieces are separated and sequenced individually - Two pieces of DNA must be exact opposites (complements) to stick together - Enzymes make thousands of copies of each genome piece (all with the same sequence) - We make a batch of special colored letters, which are added to the genome– at each spot, the letters will bind to form a complementary strand of DNA - Scientists take pictures, and the order of colors allows us to read the sequence - The sequences are stitched together to form teh entire genome - Next, we must decipher what the sequence means - The sum of differences is responsible for differences in how we look, act … and much more - Disparities between genes can become very important in medicine and life in general 3. Refer to Figure 13.10 in your textbook. What percentage of the human genome is protein-coding? What else is found in the human genome besides protein-coding sequences? - Only about 2.5% of the human genome actually codes for proteins - 97.5% of the genome includes introns, noncoding DNA, and other repetitive sequences - There are transposable elements which are DNA sequences that replicate and insert themselves into new positions in the genome– there are DNA transposons and retrotransposons which are a template to synthesize complementary strands of DNA

4. The diagram below shows four different types of large-scale chromosomal mutations. Label each mutation and briefly describe what is happening to the chromosome. - Deletion: a missing region of a gene or chromosome - Duplication: a region of a chromosome that is present twice instead of once - Inversion: the reversal of the normal order of a block of genes - Reciprocal Translocation: interchange of parts between nonhomologous chromosomes 5. D efine each of the following protein-coding mutations. You may find it helpful to review your notes from LS7A or review section 14.2 in your textbook. a. Missense (nonsynonymous) mutation: A genetic alteration in which a single base pair substitution alters the genetic code in a way that produces an amino acid that is different from the usual amino acid at that position. b. Silent (synonymous) mutation: Silent mutations occur when the change of a single DNA nucleotide within a protein-coding portion of a gene does not affect the sequence of amino acids that make up the gene's protein. c. Nonsense mutation: A nonsense mutation, or its synonym, a stop mutation, is a change in DNA that causes a protein to terminate or end its translation earlier than expected

Pre-Class Reading Guide

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