TAMU BIOL 111 - LAB EXAM #2 WITH VERIFIED CORRECT ANSWERS ALREADY GRADED A+

In the DNA isolation procedure, why did we add chelex-resin to the tube? The chelex-resin absorbs ions that inhibit the function of Taq Polymerase. Write down the components of the master mix that were use in the PCR amplification of STRs. - Buffer - Loading Dye - Deoxynucleotides - 3 pairs of primers - Taq polymerase - Water Brainpower Read More Previous Play Next Rewind 10 seconds Move forward 10 seconds Unmute 0:01 / 0:15 Full screen What are the 3 main steps in PCR? Explain each step briefly. 1. Denaturing - melt DNA from double-stranded helix to 2 single strands (breaks H-Bonds) 2. Annealing - temperature is lowered to enable the DNA primers to attach to the template DNA. 3. Extension - temperature is raised again and Taq polymerase creates the new strand of DNA. How do forensic scientists use non-coding DNA in criminal investigation? Inside non-coding DNA are Short Tandem Repeats (STRs) that can be amplified with PCR, separated through gel electrophoresis, and used to differentiate between multiple people. How can you tell which lanes in a gel image are homozygous or heterozygous homozygous = 1 band matches M heterozygous = more than 1 band matches What is the purpose of the DNA ladder in gel electrophoresis? The DNA ladder is a solution of double-stranded DNA fragments whose molecule weights (and number of base pairs) are known and standardized. The ladder is used to calibrate electrophoresis gels so that samples of unknown DNA that have been introduced into the gel can be measured. Why can you see banding patterns when you observe your gel over to the UV transilluminator? Due to the SYBR Green dye, which binds to DNA and fluoresces under UV illumination. When you switched on the electrophoresis chamber, why does DNA always migrate from negative to positive? Because DNA molecules have a negative charge due to the phosphate groups in the backbone Fill in the Blank: β‐Galactosidase (β-Gal) is an enzyme produced by the bacteria ________________________, is able to cleave _____________________________________ into galactose and ortho-nitrophenol. E. Coli; ortho-nitrophenyl-β-galactoside (ONPG) Fill in the Blank: β‐Galactosidase expression is regulated by sugars at the level of transcription, which leads to how much protein can be synthesized during translation. Therefore, can investigate the regulation of __________________________ by measuring enzyme activity of the ______________________. LacZ Transcription; β-Gal Protein What are the components of the Lac Operon - RNA Polymerase - Promoter - Operator - Repressor - 3 lactose utilization genes (lac Z, lac Y, and lac A) Briefly describe the function of promoter and the operator, which is involved in the lac operon. Promoter - binding site for RNA polymerase Operator - negative regulatory site bound by the lac repressor protein. Fill in the Blank: The cell cycle has two major phases: __________________________ and the mitotic phase. During interphase, the cell _________________________________. During the mitotic phase, the replicated DNA and cytoplasmic contents are separated, and the cell cytoplasm is typically partitioned by a third process of the cell cycle called ____________________________. Interphase; grows & DNA is replicated; cytokinesis In which phase were most of the cells in? Why? Interphase; Because a typical cells spends most of its life in interphase. During interphase the cell replicates its DNA and prepares itself for mitosis. What is the difference between interphase & prophase? The cell spends a lot of time in interphase undergoing protein synthesis, DNA replication, and growth while the cell spends a short time in prophase by undergoing condensation of chromatin, pairing of homologous chromosomes and spindle fiber formation What is the basic chromosome number of onions? 2n = 16 What does the acronym BLAST stand for? Basic Local Alignment Search Tool In animals, what type of sequence is commonly used to construct a phylogeny and determine ancestry? Mitochondrial DNA What are the uses of BLAST? - Identifying species - Locating domains - Establishing phylogeny - DNA mapping Fill in the Blank: Interactions between proteins can be predicted computationally by looking for sets of genes that occur as a _________________________________. single gene in at least one genome. What are the main reasons for why scientists use Arabidopsis plants for experiment purposes? - Easy to grow in Lab - Short generation times - model organism What are the 3 principles of Mendelian genetics? 1. Law of Dominance 2. Law of Segregation 3. Law of Independent Assortment