Skip to main content
Back

Microbiology Exam 2 & Practice Questions – Step-by-Step Study Guidance

NotesPracticeVideo lessons

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Q1. Which one of the following sequences best describes the flow of information from a gene to synthesis of a cellular component?

Background

Topic: Central Dogma of Molecular Biology

This question tests your understanding of how genetic information is transferred from DNA to functional proteins in cells.

Key Terms:

  • DNA (Deoxyribonucleic Acid): The molecule that stores genetic information.

  • RNA (Ribonucleic Acid): The intermediate molecule transcribed from DNA.

  • Protein: The functional product synthesized from RNA instructions.

  • Transcription: The process of copying DNA into RNA.

  • Translation: The process of synthesizing proteins from RNA.

Step-by-Step Guidance

  1. Recall the central dogma: information flows from DNA to RNA to protein.

  2. Identify which process (transcription or translation) occurs first and what each produces.

  3. Eliminate answer choices that do not follow this order.

  4. Consider the roles of tRNA and mRNA in translation, but focus on the main flow of information.

Try solving on your own before revealing the answer!

Q2. The sugar-phosphate backbone of DNA is held together by _______ bonds and the two strands of a double helix are held together by _____ bonds.

Background

Topic: DNA Structure

This question tests your knowledge of the types of chemical bonds that stabilize DNA's structure.

Key Terms:

  • Covalent Bonds: Strong bonds formed by sharing electrons, holding the backbone together.

  • Hydrogen Bonds: Weaker bonds between complementary bases, holding the two strands together.

Step-by-Step Guidance

  1. Recall what forms the backbone of DNA (sugar and phosphate groups).

  2. Identify the type of bond between sugar and phosphate groups.

  3. Consider what holds the two DNA strands together (between bases).

  4. Match the correct bond types to each part of the DNA structure.

Try solving on your own before revealing the answer!

Q3. Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. What percent of the nucleotides in this sample will be thymine?

Background

Topic: Chargaff's Rules and DNA Base Pairing

This question tests your understanding of base pairing in DNA and how to calculate nucleotide percentages.

Key Terms and Formulas:

  • Chargaff's Rule: In double-stranded DNA, %A = %T and %C = %G.

  • Base Pairing: C pairs with G, A pairs with T.

Step-by-Step Guidance

  1. Assign the percentage of cytosine (C) as given: 38%.

  2. Since %C = %G, determine the percentage of guanine (G).

  3. Add %C and %G to find the total percentage of these bases.

  4. Subtract this total from 100% to find the combined percentage of adenine (A) and thymine (T).

  5. Remember that %A = %T, so divide the remaining percentage by 2 to find %T.

Try solving on your own before revealing the answer!

Q4. What is the role of DNA gyrase in DNA replication?

Background

Topic: DNA Replication Enzymes

This question tests your knowledge of the specific functions of enzymes involved in DNA replication.

Key Terms:

  • DNA Gyrase: An enzyme that relieves supercoiling ahead of the replication fork.

  • Replication Fork: The area where the DNA double helix is unwound for replication.

Step-by-Step Guidance

  1. Recall the challenges faced during DNA replication, such as supercoiling.

  2. Identify which enzyme relieves tension caused by unwinding the DNA helix.

  3. Differentiate the roles of other enzymes like helicase, ligase, and primase.

  4. Match the correct function to DNA gyrase.

Try solving on your own before revealing the answer!

Q5. Where would you find an anticodon?

Background

Topic: Translation and RNA Types

This question tests your understanding of the structure and function of different types of RNA in protein synthesis.

Key Terms:

  • Anticodon: A sequence of three nucleotides in tRNA that pairs with the codon in mRNA during translation.

  • tRNA (Transfer RNA): Brings amino acids to the ribosome and matches them to the mRNA codon.

Step-by-Step Guidance

  1. Recall the role of tRNA in translation.

  2. Identify which RNA molecule contains the anticodon region.

  3. Eliminate other RNA types (mRNA, rRNA) and DNA as possible answers.

Try solving on your own before revealing the answer!

Final Answers

  1. B) DNA → RNA → protein This is the central dogma: DNA is transcribed to RNA, which is then translated into protein.

  2. C) covalent, hydrogen The sugar-phosphate backbone is held by covalent bonds; the two strands are held together by hydrogen bonds between bases.

  3. A) 12 If cytosine is 38%, guanine is also 38%. That leaves 24% for adenine and thymine together, so thymine is 12%.

  4. D) relieves tension in the DNA ahead of the replication fork DNA gyrase prevents supercoiling during replication.

  5. A) tRNA The anticodon is found on tRNA, which pairs with the mRNA codon during translation.

Pearson Logo

Study Prep