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Study Guide for Biology 120: DNA Profiling, Mendelian Genetics, and Microscopy

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Q1. Review each of the transformation plates — why was each plate used?

Background

Topic: Bacterial Transformation & Experimental Controls

This question tests your understanding of why different plates are used in a transformation experiment, including controls and selective media.

Key Terms:

  • Transformation: Introduction of foreign DNA into a cell.

  • LB (Luria Broth): Nutrient-rich medium for bacterial growth.

  • Ampicillin: Antibiotic used for selection.

  • Arabinose: Sugar used to induce gene expression.

Step-by-Step Guidance

  1. Identify the purpose of each plate (e.g., LB, LB/amp, LB/amp/ara) in the experiment.

  2. Consider which plates serve as controls and which are used for selection or induction.

  3. Think about what you expect to see on each plate based on the presence of antibiotics or arabinose.

  4. Relate the expected results to the transformation process and gene expression.

Try solving on your own before revealing the answer!

Q2. Understand the basis of operon theory and the significance of adding arabinose to the LB/amp/ara plate

Background

Topic: Operon Theory & Gene Regulation

This question focuses on how operons work and why arabinose is important for gene expression in certain transformation experiments.

Key Terms:

  • Operon: Cluster of genes under control of a single promoter.

  • Inducer: Molecule that activates gene expression (e.g., arabinose).

  • Promoter: DNA sequence where RNA polymerase binds.

Step-by-Step Guidance

  1. Review the concept of operons and how gene expression is regulated in bacteria.

  2. Understand the role of arabinose as an inducer in the experiment.

  3. Connect the addition of arabinose to the activation of the target gene on the LB/amp/ara plate.

  4. Consider how this relates to the results observed on the plate.

Try solving on your own before revealing the answer!

Q3. What is PCR? Where and why do scientists use it?

Background

Topic: Polymerase Chain Reaction (PCR)

This question tests your understanding of PCR, its purpose, and its applications in science.

Key Terms:

  • PCR: Technique to amplify DNA.

  • DNA amplification: Making many copies of a DNA segment.

Step-by-Step Guidance

  1. Define PCR and its basic function.

  2. List common applications of PCR in research, medicine, and forensics.

  3. Explain why scientists need to amplify DNA.

Try solving on your own before revealing the answer!

Q4. What are the three basic steps in a PCR reaction? How has it revolutionized science?

Background

Topic: PCR Mechanism & Impact

This question asks you to identify the steps of PCR and discuss its significance.

Key Terms:

  • Denaturation: Separation of DNA strands.

  • Annealing: Binding of primers to DNA.

  • Extension: DNA synthesis by polymerase.

Step-by-Step Guidance

  1. List the three main steps of PCR: denaturation, annealing, and extension.

  2. Describe what happens in each step.

  3. Discuss how PCR has enabled rapid DNA analysis and its impact on fields like genetics and forensics.

Try solving on your own before revealing the answer!

Q5. What is the “Master Mix” used in PCR? Be specific.

Background

Topic: PCR Reagents

This question tests your knowledge of the components required for PCR.

Key Terms:

  • Master Mix: Pre-mixed solution containing PCR reagents.

  • Components: DNA polymerase, dNTPs, buffer, MgCl2, primers.

Step-by-Step Guidance

  1. Identify the essential components of a PCR Master Mix.

  2. Explain the function of each component in the reaction.

  3. Discuss why using a Master Mix improves consistency and efficiency.

Try solving on your own before revealing the answer!

Q6. What components are essential for PCR?

Background

Topic: PCR Requirements

This question focuses on the necessary ingredients for a successful PCR reaction.

Key Terms:

  • DNA template: The DNA to be amplified.

  • Primers: Short DNA sequences that initiate replication.

  • dNTPs: Nucleotide building blocks.

  • DNA polymerase: Enzyme for DNA synthesis.

  • Buffer: Maintains optimal conditions.

Step-by-Step Guidance

  1. List all essential PCR components.

  2. Describe the role of each component in the reaction.

  3. Explain why each is necessary for DNA amplification.

Try solving on your own before revealing the answer!

Q7. What is Taq Polymerase and why is it important?

Background

Topic: Enzymes in PCR

This question tests your understanding of Taq polymerase and its significance in PCR.

Key Terms:

  • Taq Polymerase: Heat-stable DNA polymerase from Thermus aquaticus.

Step-by-Step Guidance

  1. Explain what Taq polymerase is and where it comes from.

  2. Discuss why heat stability is important for PCR.

  3. Describe how Taq polymerase enables repeated cycles of DNA synthesis.

Try solving on your own before revealing the answer!

Q8. What is a STR and how is it used in forensic science?

Background

Topic: DNA Profiling & Forensics

This question focuses on short tandem repeats (STRs) and their application in forensic identification.

Key Terms:

  • STR: Short, repetitive DNA sequences.

  • Forensic science: Application of science to legal investigations.

Step-by-Step Guidance

  1. Define STRs and their characteristics.

  2. Explain how STRs vary between individuals.

  3. Describe how STR analysis is used to match DNA samples in forensic cases.

Try solving on your own before revealing the answer!

Q9. What is gel electrophoresis? How does it work?

Background

Topic: DNA Separation Techniques

This question tests your understanding of gel electrophoresis and its mechanism.

Key Terms:

  • Gel electrophoresis: Technique to separate DNA fragments by size.

  • Agarose gel: Medium for DNA separation.

Step-by-Step Guidance

  1. Describe the basic setup of gel electrophoresis.

  2. Explain how DNA fragments move through the gel under an electric field.

  3. Discuss how fragment size affects migration distance.

Try solving on your own before revealing the answer!

Q10. What is an allele ladder?

Background

Topic: DNA Analysis Tools

This question focuses on the use of allele ladders in DNA profiling.

Key Terms:

  • Allele ladder: Standard reference for DNA fragment sizes.

Step-by-Step Guidance

  1. Define what an allele ladder is.

  2. Explain how it is used to interpret gel electrophoresis results.

  3. Discuss its importance in identifying specific alleles.

Try solving on your own before revealing the answer!

Q11. How is DNA visualized on an agarose gel?

Background

Topic: DNA Visualization Methods

This question tests your knowledge of how DNA bands are made visible after electrophoresis.

Key Terms:

  • Staining: Use of dyes (e.g., ethidium bromide) to visualize DNA.

  • UV light: Used to detect stained DNA bands.

Step-by-Step Guidance

  1. Describe the process of staining DNA in the gel.

  2. Explain how UV light is used to visualize the bands.

  3. Discuss safety considerations for handling stains and UV light.

Try solving on your own before revealing the answer!

Q12. Can you interpret the results of an agarose gel using an allele ladder?

Background

Topic: DNA Interpretation

This question tests your ability to analyze gel results using an allele ladder for comparison.

Key Terms:

  • Interpretation: Matching sample bands to allele ladder bands.

Step-by-Step Guidance

  1. Review how to compare sample bands to the allele ladder.

  2. Explain how to determine the allele present based on band position.

  3. Discuss how this information is used in DNA profiling.

Try solving on your own before revealing the answer!

Q13. Review Prelab questions and basic genetics vocabulary

Background

Topic: Mendelian Genetics

This question tests your understanding of key genetics terms and concepts.

Key Terms:

  • Genotype: Genetic makeup.

  • Phenotype: Observable traits.

  • Allele: Variant form of a gene.

Step-by-Step Guidance

  1. Review definitions of basic genetics vocabulary.

  2. Understand how these terms relate to inheritance patterns.

  3. Apply these concepts to sample problems.

Try solving on your own before revealing the answer!

Q14. Review sample problems in Activity 1

Background

Topic: Genetics Problem Solving

This question focuses on applying genetics concepts to solve inheritance problems.

Key Terms:

  • Monohybrid cross: Single gene inheritance.

  • Dihybrid cross: Two gene inheritance.

Step-by-Step Guidance

  1. Identify the type of cross in the sample problem.

  2. Set up Punnett squares for the cross.

  3. Predict genotypic and phenotypic ratios.

Try solving on your own before revealing the answer!

Q15. Review genetic problems and examples of crosses (monohybrid, dihybrid, blood, sex-linked, etc.)

Background

Topic: Types of Genetic Crosses

This question tests your ability to solve different types of genetic crosses.

Key Terms:

  • Monohybrid: One gene.

  • Dihybrid: Two genes.

  • Sex-linked: Genes on sex chromosomes.

Step-by-Step Guidance

  1. Identify the type of cross and relevant genes.

  2. Set up the appropriate Punnett square.

  3. Calculate expected ratios for each cross.

Try solving on your own before revealing the answer!

Q16. What was the purpose of Activity 2 in this experiment?

Background

Topic: Experimental Design

This question asks you to explain the rationale behind a specific activity in the genetics experiment.

Key Terms:

  • Experimental purpose: Reason for conducting an activity.

Step-by-Step Guidance

  1. Review the objectives of Activity 2.

  2. Connect the activity to the overall experiment goals.

  3. Explain how the activity helps answer a scientific question.

Try solving on your own before revealing the answer!

Q17. What specific species was used in this experiment? Why?

Background

Topic: Model Organisms

This question tests your understanding of why certain species are chosen for genetics experiments.

Key Terms:

  • Model organism: Species used for research.

Step-by-Step Guidance

  1. Identify the species used in the experiment.

  2. Discuss characteristics that make it suitable for genetics studies.

  3. Explain the advantages of using this species.

Try solving on your own before revealing the answer!

Q18. What were the specific phenotypes of the wild type and mutant alleles used in this experiment?

Background

Topic: Alleles & Phenotypes

This question focuses on identifying and describing the traits associated with wild type and mutant alleles.

Key Terms:

  • Wild type: Normal phenotype.

  • Mutant: Altered phenotype.

Step-by-Step Guidance

  1. List the phenotypes for wild type and mutant alleles.

  2. Describe how these phenotypes are observed in the experiment.

  3. Connect the phenotypes to the underlying genotypes.

Try solving on your own before revealing the answer!

Q19. Be able to explain the results of the Fast Plants experiment in terms of the genotypes and phenotypes of the F1 and F2 generations.

Background

Topic: Mendelian Inheritance

This question tests your ability to interpret experimental results using genetics principles.

Key Terms:

  • F1 generation: First filial generation.

  • F2 generation: Second filial generation.

Step-by-Step Guidance

  1. Review the genotypes and phenotypes of the parental, F1, and F2 generations.

  2. Use Punnett squares to predict expected ratios.

  3. Compare predicted ratios to observed results.

Try solving on your own before revealing the answer!

Q20. What is chi-square test? How do you use it to interpret results?

Background

Topic: Statistical Analysis in Genetics

This question tests your understanding of the chi-square test and its application in genetics experiments.

Key Terms and Formula:

  • Chi-square test: Statistical method to compare observed and expected data.

  • O = Observed value

  • E = Expected value

Step-by-Step Guidance

  1. Calculate expected values based on genetic ratios.

  2. Compute the chi-square statistic using the formula above.

  3. Compare the calculated value to a critical value to determine significance.

Try solving on your own before revealing the answer!

Q21. Be able to predict the outcome of offspring in simple crosses (monohybrid and dihybrid).

Background

Topic: Genetic Prediction

This question tests your ability to use Punnett squares to predict offspring outcomes.

Key Terms:

  • Punnett square: Diagram for predicting genetic crosses.

Step-by-Step Guidance

  1. Set up a Punnett square for the cross.

  2. Fill in the possible genotypes for offspring.

  3. Determine the phenotypic ratios based on genotypes.

Try solving on your own before revealing the answer!

Q22. Know the parts and functions of the Light Microscope

Background

Topic: Microscopy

This question tests your knowledge of microscope anatomy and function.

Key Terms:

  • Objective lens: Magnifies specimen.

  • Eyepiece: Further magnifies image.

  • Stage: Holds specimen.

Step-by-Step Guidance

  1. Identify each part of the microscope.

  2. Describe the function of each part.

  3. Explain how the parts work together to produce a magnified image.

Try solving on your own before revealing the answer!

Q23. Know how to focus and care for the microscope

Background

Topic: Microscope Use & Maintenance

This question tests your understanding of proper microscope handling and focusing techniques.

Key Terms:

  • Coarse focus: Large adjustments.

  • Fine focus: Small adjustments.

Step-by-Step Guidance

  1. Describe the steps for focusing a microscope.

  2. Explain how to care for and clean the microscope.

  3. Discuss best practices for storage and handling.

Try solving on your own before revealing the answer!

Q24. Know how to calculate total magnification

Background

Topic: Magnification Calculation

This question tests your ability to calculate the total magnification of a microscope.

Key Formula:

Step-by-Step Guidance

  1. Identify the magnification of the objective lens.

  2. Identify the magnification of the eyepiece.

  3. Multiply the two values to get total magnification.

Try solving on your own before revealing the answer!

Q25. Know basic terms such as parfocal, magnification, resolution

Background

Topic: Microscopy Vocabulary

This question tests your understanding of key terms related to microscopy.

Key Terms:

  • Parfocal: Ability to stay in focus when switching objectives.

  • Magnification: Enlargement of image.

  • Resolution: Ability to distinguish two points as separate.

Step-by-Step Guidance

  1. Define each term clearly.

  2. Explain how each term relates to microscope function.

  3. Provide examples of how these terms are used in practice.

Try solving on your own before revealing the answer!

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