DNA Structure and Replication Quiz
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Questions and Answers

What is the name of the enzyme responsible for unwinding the DNA double helix during replication?

  • Helicase (correct)
  • Ligase
  • DNA Polymerase
  • Primase

    • Which of the following accurately describes the role of Okazaki fragments in DNA replication?

  • Okazaki fragments are short segments of DNA that are synthesized on the leading strand.
  • Okazaki fragments are used to initiate DNA replication.
  • Okazaki fragments are long segments of DNA that are synthesized on the leading strand.
  • Okazaki fragments are short segments of DNA that are synthesized on the lagging strand. (correct)

    • What is the primary function of tRNA in protein synthesis?

  • tRNA acts as a template for mRNA synthesis.
  • tRNA catalyzes the formation of peptide bonds between amino acids.
  • tRNA carries genetic information from DNA to ribosomes.
  • tRNA carries amino acids to ribosomes. (correct)

    • Which of these is NOT a characteristic of a retrovirus?

    <p>Replicates using a lytic cycle. (D)</p> Signup and view all the answers

    What is the role of the promoter in gene expression?

    <p>The promoter initiates transcription by providing a binding site for RNA polymerase. (B)</p> Signup and view all the answers

    Which of the following correctly describes the process of translation?

    <p>Translation is the process of converting RNA into protein. (C)</p> Signup and view all the answers

    What is the function of the 5' cap and poly-A tail in eukaryotic mRNA?

    <p>They protect mRNA from degradation and facilitate its binding to ribosomes. (A)</p> Signup and view all the answers

    Which of the following is NOT a type of RNA?

    <p>dRNA (B)</p> Signup and view all the answers

    What is the name of the process in which a virus replicates its genome within a host cell, leading to the destruction of the host cell and the release of new viral particles?

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

    What is the role of telomerase in DNA replication?

    <p>Telomerase adds nucleotides to the end of chromosomes, preventing them from shortening during replication. (A)</p> Signup and view all the answers

    What is the difference between the leading and lagging strands in DNA replication?

    <p>The leading strand is synthesized continuously, while the lagging strand is synthesized discontinuously. (D)</p> Signup and view all the answers

    Which of the following is a characteristic of a nonsense mutation?

    <p>A nonsense mutation changes a codon for an amino acid into a stop codon. (C)</p> Signup and view all the answers

    Which of the following is NOT a key component of the translation initiation complex?

    <p>DNA (B)</p> Signup and view all the answers

    What is the function of a primer in DNA replication?

    <p>A primer is a short sequence of RNA that initiates DNA replication by providing a 3' hydroxyl group for DNA polymerase to add nucleotides. (C)</p> Signup and view all the answers

    What is the role of a release factor in protein synthesis?

    <p>A release factor binds to the stop codon, terminating translation. (C)</p> Signup and view all the answers

    What is the central dogma of molecular biology?

    <p>DNA is transcribed into RNA, which is translated into protein. (D)</p> Signup and view all the answers

    Flashcards

    DNA

    DNA carries genetic information in cells and controls structure and function.

    Genes

    Segments of DNA that determine physical characteristics.

    Chromosomes

    Structures made of DNA that organize genetic material in cells.

    DNA replication

    The process by which DNA copies itself before cell division.

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    Leading strand

    The DNA strand that is synthesized continuously during replication.

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    Lagging strand

    The DNA strand synthesized in short segments away from the replication fork.

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    Okazaki fragments

    Short segments of DNA formed on the lagging strand during replication.

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    Telomeres

    The ends of chromosomes that protect DNA from degradation.

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    RNA

    A nucleic acid that carries instructions from DNA for protein synthesis.

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    Transcription

    The process of copying a segment of DNA into mRNA.

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    Translation

    The process of decoding mRNA into a polypeptide chain (protein).

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    Mutation

    A change in the DNA sequence that can lead to different traits.

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    Virus

    A non-living infectious agent that requires a host cell to replicate.

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    Retrovirus

    A type of virus that uses RNA as its genetic material and reverse transcribes it to DNA.

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    Plasmid

    A small circular piece of DNA found in bacteria, often used in genetic engineering.

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    Study Notes

    DNA Structure and Replication

    • Deoxyribonucleic acid (DNA) is a large complex molecule that carries genetic information, determining human traits.
    • DNA is a polymer made of nucleotides (sugar, phosphate, and nitrogenous base).
    • DNA bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
    • Chargaff's rule: A pairs with T, and C pairs with G.
    • DNA is antiparallel, meaning the two strands run in opposite directions (5' to 3' and 3' to 5').
    • DNA replication ensures that each new cell receives a complete copy of the genetic information.
    • DNA replication is semiconservative; each new DNA molecule is composed of one original strand and one newly synthesized strand.
    • Leading strand: synthesized continuously in the 5' to 3' direction.
    • Lagging strand: synthesized discontinuously in short fragments (Okazaki fragments) and then joined by DNA ligase.
    • Enzymes involved in replication include helicase, single-strand binding proteins, topoisomerases, DNA polymerase, and primase.
    • Okazaki fragments are short segments of DNA synthesized discontinuously during replication of the lagging strand.

    DNA Replication - More Detail

    • Helicase unwinds the DNA double helix at replication origins.
    • Single-strand binding proteins stabilize the separated strands.
    • Topoisomerases relieve the strain created by unwinding.
    • DNA polymerase adds new nucleotides complementary to the template strand.
    • DNA polymerase works in one direction 5' to 3'
    • RNA primase creates RNA primers to initiate DNA synthesis (leading and lagging strands).
    • RNA primers are removed and replaced with DNA nucleotides.
    • DNA ligase joins the Okazaki fragments.
    • Mismatch repair corrects errors during replication.

    RNA and Protein Synthesis

    • Ribonucleic acid (RNA) carries genetic information from DNA to the ribosomes, where proteins are constructed
    • Types of RNA: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).
    • Transcription: synthesis of mRNA from a DNA template.
    • Stages of transcription: initiation, elongation, and termination.
    • RNA processing involves adding a 5' cap and a 3' poly-A tail to mRNA molecules and splicing out introns, leaving only exons.
    • Translation: conversion of mRNA to a polypeptide (protein).
    • Initiation: mRNA binds to ribosome; tRNA brings the first amino acid.
    • Elongation: codons on mRNA are read, tRNA brings amino acids, peptide chain grows.
    • Termination: stop codon signals the end of translation.

    Genetic Variation

    • Mutations are changes in DNA sequences.
    • Mutations can be silent, missense, or nonsense.
    • Mutations can be caused by various factors including errors in replication or exposure to mutagens.
    • Somatic mutations affect the cells of an organism, while germline mutations affect the sex cells and can be passed to future generations.
    • Frameshift mutations alter the reading frame of the genetic code.
    • Other mutations mentioned include insertion, deletion, and base substitutions.

    Genes and Viruses

    • Genes are segments of DNA that contain the code for proteins/traits.
    • A retrovirus contains RNA that is reversed transcribed to DNA
    • Viruses replicate using the host's cellular machinery and may lead to diseases.
    • Viruses can undergo two lifecycles: lytic (destructive) and lysogenic (dormant).
    • Bacteriophages are viruses that infect bacteria.
    • Transduction is when viruses acquire bits of bacterial DNA resulting in recombination.
    • Genetic recombination can occur during the process of sexual reproduction in eukaryotes.

    Bacterial Genetics

    • Bacteria have circular DNA in the nucleoid region.
    • Bacteria replicate DNA in both directions, mostly by binary fission.
    • Bacterial transformation: take in pieces of DNA from other places.
    • Plasmids: foreign circular pieces of DNA in bacteria.

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    DNA Notes Unit 5 PDF

    Description

    Test your understanding of the intricate details of DNA structure and its replication process. This quiz covers essential concepts including nucleotide composition, base pairing rules, and the mechanisms of leading and lagging strand synthesis. Dive into the world of genetic information and its preservation during cell division.

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