Molecular Biology: Nucleic Acids Quiz

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Questions and Answers

Which type of nucleic acid is responsible for carrying instructions for protein construction from the nucleus to the ribosomes?

  • Ribosomal RNA (rRNA)
  • Deoxyribonucleic Acid (DNA)
  • Transport RNA (tRNA)
  • Messenger RNA (mRNA) (correct)

What distinguishes DNA from RNA in terms of size and function?

  • RNA is larger and cannot replicate itself.
  • DNA is larger and remains in the nucleus. (correct)
  • DNA is smaller and mainly involved in protein synthesis.
  • RNA is larger and stores genetic information.

Which statement correctly describes the role of tRNA in protein synthesis?

  • tRNA codes for the genetic traits of an organism.
  • tRNA replicates the DNA molecule.
  • tRNA converts DNA into mRNA.
  • tRNA delivers amino acids to the ribosome. (correct)

What is meant by the term 'genome'?

<p>The total complement of genes present in a species. (D)</p> Signup and view all the answers

Which type of RNA forms a part of the structure of ribosomes?

<p>Ribosomal RNA (rRNA) (D)</p> Signup and view all the answers

What provides the structure of the sides of the DNA molecule?

<p>Alternating phosphate and deoxyribose sugars (C)</p> Signup and view all the answers

Which nitrogenous bases are complementary in DNA?

<p>Adenine and Thymine (D)</p> Signup and view all the answers

How are the nitrogenous bases connected to the deoxyribose sugar?

<p>By covalent bonds (A)</p> Signup and view all the answers

What are the components of a nucleotide in DNA?

<p>A deoxyribose sugar, a nitrogenous base, and a phosphate group (B)</p> Signup and view all the answers

What type of bond holds the two nitrogenous bases together in DNA?

<p>Hydrogen bonds (C)</p> Signup and view all the answers

What is the primary role of DNA Polymerase III during DNA replication?

<p>To add new nucleotides to the growing DNA strand (B)</p> Signup and view all the answers

What initiates the synthesis of the lagging strand during DNA replication?

<p>The attachment of an RNA primer by Primase (B)</p> Signup and view all the answers

What are Okazaki fragments?

<p>Discontinuous segments synthesized on the lagging strand (B)</p> Signup and view all the answers

What is the significance of the 3' to 5' direction in DNA replication?

<p>It helps to determine the direction of RNA primer attachment (C)</p> Signup and view all the answers

What role do Single-Strand Binding Proteins (SSB) play during DNA replication?

<p>They stabilize the separated strands of DNA (C)</p> Signup and view all the answers

Which of the following correctly describes Chargaff's rule?

<p>The amount of adenine equals the amount of thymine and the amount of cytosine equals the amount of guanine. (C)</p> Signup and view all the answers

What is the structural organization of DNA when a cell is not dividing?

<p>DNA is organized as a double helix within chromatin. (B)</p> Signup and view all the answers

What happens to chromatin during cell division?

<p>Chromatin condenses into a supercoil and forms chromosomes. (A)</p> Signup and view all the answers

Which statement accurately describes sister chromatids?

<p>They are two identical chromosomes connected by a centromere after DNA replication. (D)</p> Signup and view all the answers

During which phase of the cell cycle do chromosomes form?

<p>Chromosomes only form during cell division specifically. (C)</p> Signup and view all the answers

What is the purpose of helicase during DNA replication?

<p>To separate the DNA strands by unwinding the double helix (B)</p> Signup and view all the answers

What defines the 5' and 3' ends of a DNA strand?

<p>The orientation of carbon atoms in deoxyribose (B)</p> Signup and view all the answers

Which enzyme is responsible for unzipping the DNA strands during the initiation stage of replication?

<p>Helicase (A)</p> Signup and view all the answers

During DNA replication, where do the complementary nucleotides come from?

<p>Free-floating nucleotides present in the nucleus (B)</p> Signup and view all the answers

What occurs at the termination stage of DNA replication?

<p>Replication stops when the entire DNA strand has been copied (B)</p> Signup and view all the answers

What is the role of Primase in the lagging strand synthesis?

<p>To add an RNA primer for DNA Polymerase III (B)</p> Signup and view all the answers

How is the synthesis of the lagging strand characterized in relation to the leading strand?

<p>It synthesizes in the opposite direction to the leading strand (A)</p> Signup and view all the answers

What corrective mechanism occurs due to mismatched base pairs during replication?

<p>The action of enzymes to correct bulges (C)</p> Signup and view all the answers

Which enzyme is responsible for replacing RNA primers with DNA nucleotides on the lagging strand?

<p>DNA Polymerase I (C)</p> Signup and view all the answers

What describes the 'semi-conservative' nature of DNA replication?

<p>Each new DNA molecule contains one original strand and one newly synthesized strand (B)</p> Signup and view all the answers

Flashcards

Nucleic Acid

Macromolecules essential for reproduction and trait inheritance.

DNA

Large molecule carrying genetic instructions for protein synthesis.

RNA

Smaller nucleic acid involved in protein synthesis.

mRNA

Copies DNA's instructions for protein creation.

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Genome

The complete set of genes in an organism.

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DNA Structure

A double helix resembling a twisted ladder, with sugar-phosphate backbones and base pairs forming the rungs.

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Nucleotide

The building blocks of DNA, consisting of a sugar, a phosphate, and a base.

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DNA Base Pairing

Adenine pairs with Thymine, and Cytosine pairs with Guanine. These pairings are specific.

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Sugar-Phosphate Backbone

The alternating sugar and phosphate molecules forming the DNA's structural framework.

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Hydrogen Bonds

Weak bonds holding the DNA base pairs together.

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Base Pairing Rule

Adenine pairs with Thymine, and Guanine pairs with Cytosine in DNA.

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Chromatin Structure

DNA organized around histone proteins to condense and fit inside the cell nucleus.

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Chromosome Formation

Chromatin condenses into a supercoiled structure before cell division.

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Sister Chromatids

Two identical copies of a replicated chromosome connected by a centromere.

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DNA Replication before Mitosis

Before a cell divides, DNA makes a complete copy so the two new cells get identical DNA.

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DNA Replication

The process by which a DNA molecule creates an identical copy of itself.

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Leading Strand

The strand of DNA that is synthesized continuously during replication, running in the 5' to 3' direction.

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Lagging Strand

The strand of DNA that is synthesized discontinuously during replication, running in the 3' to 5' direction.

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Okazaki Fragments

Short segments of DNA synthesized on the lagging strand.

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What does Primase do?

Primase synthesizes RNA primers to initiate DNA synthesis on the lagging strand by providing a starting point for DNA Polymerase III.

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3' and 5' Ends

The ends of a DNA strand are identified by the positions of their phosphate groups and hydroxyl groups. The 5' end has a free phosphate group attached to the 5th carbon, while the 3' end has a free hydroxyl group attached to the 3rd carbon.

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Replication Origin

Specific regions on DNA molecules where replication starts. These sites have unique nucleotide sequences recognized by proteins involved in initiating the replication process.

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Helicase

An enzyme that unwinds the DNA double helix, separating the two strands. This is essential for replication, as it exposes the nucleotides for base pairing.

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Single-Strand Binding Proteins

Proteins that bind to and stabilize single-stranded DNA during replication. They prevent the separated strands from re-annealing, keeping them available for replication.

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DNA Replication Steps?

The replication process involves three major steps: initiation, elongation, and termination.

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DNA Ligase

An enzyme that connects Okazaki fragments on the lagging strand, creating a continuous DNA molecule.

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Semi-Conservative Replication

DNA replication creates two new DNA molecules, each with one original strand and one newly synthesized strand.

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Replication Error

An incorrect nucleotide base pairing during DNA replication, potentially resulting in a genetic mutation.

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