Nucleic Acids and DNA Structure
30 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What sugar is found in the nucleotides of DNA?

  • Deoxyribose (correct)
  • Fructose
  • Glucose
  • Ribose

    • Which nitrogenous base replaces thymine in RNA?

  • Uracil (correct)
  • Guanine
  • Adenine
  • Cytosine

    • What is the structural shape of DNA called?

  • Circular loop
  • Single strand
  • Beta-pleated sheet
  • Double helix (correct)

    • How do DNA strands run relative to each other?

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

    What enzyme unwinds the DNA during replication?

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

    What direction does DNA polymerase read the template strand during replication?

    <p>3’ -&gt; 5’ (C)</p> Signup and view all the answers

    Which strand of DNA is replicated continuously during DNA replication?

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

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

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

    What is the primary role of messenger RNA (mRNA)?

    <p>To transcribe genes and carry genetic messages (D)</p> Signup and view all the answers

    What is the role of transfer RNA (tRNA) in gene expression?

    <p>To translate genetic information from RNA to proteins (C)</p> Signup and view all the answers

    How does gene expression affect phenotype?

    <p>It controls the proteins made by regulating gene expression. (A)</p> Signup and view all the answers

    What initiates the transcription process in eukaryotic cells?

    <p>RNA polymerase binding to a promoter with the help of transcription factors (A)</p> Signup and view all the answers

    What happens to mRNA after transcription during the editing process?

    <p>Introns are removed and exons are spliced together. (D)</p> Signup and view all the answers

    What is the significance of alternative RNA splicing?

    <p>It allows for multiple proteins to be produced from a single gene. (D)</p> Signup and view all the answers

    How is mRNA regulated after transcription?

    <p>It may be degraded if a protein is needed only occasionally. (B)</p> Signup and view all the answers

    What characterizes proteins that have both inactive and active forms?

    <p>Only the active form can perform their functions. (D)</p> Signup and view all the answers

    What is the role of DNA ligase in DNA replication?

    <p>It joins Okazaki fragments on the lagging strand. (D)</p> Signup and view all the answers

    What is the first step of transcription?

    <p>DNA helicase unwinds the DNA. (C)</p> Signup and view all the answers

    Why are Okazaki fragments formed during DNA replication?

    <p>Because DNA polymerase can only move in the 5' to 3' direction. (D)</p> Signup and view all the answers

    What happens during the termination phase of transcription?

    <p>The DNA double helix rewinds and the RNA polymerase detaches. (C)</p> Signup and view all the answers

    What is the end product of transcription?

    <p>A strand of messenger RNA (mRNA). (D)</p> Signup and view all the answers

    During translation, what sequence of nucleotides is recognized as a START codon?

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

    Which component of the tRNA corresponds to the mRNA codon?

    <p>Anticodon. (C)</p> Signup and view all the answers

    What does the cap and tail of mRNA do?

    <p>Protect mRNA from enzymatic degradation. (A)</p> Signup and view all the answers

    In protein synthesis, what role do codons play?

    <p>They are sequences of nucleotides that specify amino acids. (A)</p> Signup and view all the answers

    What is the purpose of alternative RNA splicing?

    <p>To produce multiple proteins from a single gene. (C)</p> Signup and view all the answers

    How does gene regulation affect gene expression?

    <p>It controls when genes are turned on or off. (C)</p> Signup and view all the answers

    What differentiates the leading strand from the lagging strand during DNA replication?

    <p>The leading strand has no Okazaki fragments, while the lagging strand does. (A)</p> Signup and view all the answers

    Which of the following correctly signifies an error in transcription?

    <p>A mismatch in codon and anticodon pairing. (B)</p> Signup and view all the answers

    What is the role of transfer RNA (tRNA) in translation?

    <p>To carry amino acids to the ribosome. (D)</p> Signup and view all the answers

    Flashcards

    Gene Expression

    The process of converting genetic information from DNA to proteins.

    mRNA

    Messenger RNA that transcribes genes and carries the message to ribosomes for protein synthesis.

    tRNA

    Transfer RNA that translates mRNA codons into amino acids during translation.

    Alternative RNA Splicing

    A process where introns are removed and exons are spliced to create mature mRNA.

    Signup and view all the flashcards

    Transcription Factors

    Proteins that assist RNA polymerase in binding to the promoter to initiate transcription.

    Signup and view all the flashcards

    Introns and Exons

    Introns are non-coding regions removed during RNA splicing, exons are coding regions that remain.

    Signup and view all the flashcards

    Regulation of Gene Expression

    Controlling when and how much protein is made from a gene.

    Signup and view all the flashcards

    Active vs Inactive Proteins

    Proteins can exist in active and inactive forms, only the active form performs functions.

    Signup and view all the flashcards

    Nucleic Acids

    Biological macromolecules composed of nucleotides, which include DNA and RNA.

    Signup and view all the flashcards

    Nucleotides

    Building blocks of nucleic acids; made of a phosphate group, sugar, and nitrogenous base.

    Signup and view all the flashcards

    DNA Bases

    Four nitrogenous bases in DNA: adenine, thymine, guanine, cytosine.

    Signup and view all the flashcards

    Complementary Bases

    Bases that pair together in DNA; A with T and G with C.

    Signup and view all the flashcards

    Semiconservative Replication

    DNA replication method where each new DNA strand contains one old and one new strand.

    Signup and view all the flashcards

    Antiparallel Strands

    In DNA, one strand runs 3’ to 5’ while the complementary strand runs 5’ to 3’.

    Signup and view all the flashcards

    Leading Strand

    The DNA strand replicated continuously in the same direction as helicase unwinds the DNA.

    Signup and view all the flashcards

    Lagging Strand

    The DNA strand replicated in fragments (Okazaki fragments) due to its antiparallel nature.

    Signup and view all the flashcards

    Antiparallel DNA

    DNA strands run in opposite directions (5’ to 3’ and 3’ to 5’).

    Signup and view all the flashcards

    Okazaki fragments

    Short DNA segments formed on the lagging strand during replication.

    Signup and view all the flashcards

    DNA ligase

    Enzyme that joins Okazaki fragments on the lagging strand.

    Signup and view all the flashcards

    Replication bubbles

    Sites where DNA replication begins, allowing for faster replication.

    Signup and view all the flashcards

    Transcription

    Process of copying DNA into RNA.

    Signup and view all the flashcards

    Promoter

    Region of DNA where RNA polymerase binds to start transcription.

    Signup and view all the flashcards

    Post-transcriptional modification

    Changes made to mRNA after transcription, including capping and tailing.

    Signup and view all the flashcards

    Translation

    Process of converting mRNA into a protein at the ribosome.

    Signup and view all the flashcards

    Codon

    A set of three nucleotides on mRNA that codes for an amino acid.

    Signup and view all the flashcards

    Gene regulation

    The process of turning genes on and off to control protein production.

    Signup and view all the flashcards

    Study Notes

    Nucleic Acids and DNA Structure

    • DNA and RNA are nucleic acids composed of nucleotides.
    • Nucleotides consist of a phosphate group, a sugar (deoxyribose in DNA, ribose in RNA), and a nitrogenous base.
    • DNA contains four nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C).
    • A always bonds with T, and G always bonds with C.
    • RNA has uracil (U) instead of thymine (T), which bonds with adenine (A).
    • Both DNA and RNA have a covalently bonded sugar-phosphate backbone.
    • DNA is double-stranded, forming a double helix. RNA is single-stranded.
    • The sugar-phosphate backbone forms the sides of the DNA "ladder," while the nitrogenous bases form the rungs, held together by hydrogen bonds.

    DNA Replication

    • DNA replicates during cell division, using each strand as a template to create a new strand.
    • The resulting DNA molecule contains one original (parent) strand and one new (daughter) strand (semiconservative replication).
    • DNA strands run antiparallel (3' to 5' and 5' to 3').
    • One end of a DNA strand has a phosphate group, and the other has a sugar.

    Leading Strand Replication

    • DNA helicase unwinds the DNA double helix.
    • RNA primase creates a short RNA primer.
    • DNA polymerase reads the template strand in the 3' to 5' direction and builds the new strand in the 5' to 3' direction.
    • This allows for continuous replication on the leading strand.

    Lagging Strand Replication

    • DNA polymerase cannot continuously replicate the lagging strand (which runs 5' to 3'), so it moves in short fragments called Okazaki fragments.
    • RNA primase adds primers to initiate each Okazaki fragment.
    • DNA polymerase adds DNA nucleotides to each Okazaki fragment.
    • DNA ligase joins the Okazaki fragments to form a complete new strand.

    Replication Initiation Sites

    • Replication begins at multiple sites along the DNA molecule to increase speed. These sites create replication bubbles.

    Transcription

    • Genes contain the code for proteins.
    • DNA, which contains the genetic code, cannot leave the nucleus.
    • RNA carries the genetic code from the nucleus to the ribosomes.
    • Transcription analogous to copying architectural plans for a new construction.
    • The process is initiated, elongated, and terminated. These three phases are: Initiation, elongation, and termination.

    Transcription Initiation

    • DNA helicase unwinds the DNA helix.
    • RNA polymerase binds to the promoter (a region of DNA at the gene's start).

    Transcription Elongation

    • RNA polymerase moves along the template strand, building a complementary RNA strand.
    • RNA uses uracil (U) instead of thymine (T).

    Transcription Termination

    • RNA polymerase reaches the terminator sequence (end of the gene).
    • RNA polymerase detaches, and the DNA rewinds

    Post-transcriptional Modifications

    • mRNA capping: A modified guanine is added to the 5' end.
    • Polyadenylation: A poly-A tail (~250 adenine nucleotides) is added to the 3' end for protection from cellular enzymes.
    • Alternative splicing: Introns (non-coding regions) are removed from the mRNA, and exons (coding regions) are joined.

    Translation

    • RNA (mRNA) nucleotides are translated into amino acids.
    • mRNA, in sets of three nucleotides called codons, provides the instructions.
    • Transfer RNA (tRNA) carries amino acids to the ribosomes.
    • A codon is a sequence of three nucleotides specifying an amino acid. Each codon corresponds to a single amino acid
    • A codon wheel is used to determine the amino acid sequence
    • Translation occurs in ribosomes and involves three phases: Initiation, elongation, and termination.

    Translation Initiation

    • mRNA binds to a ribosome.
    • The start codon (usually AUG) initiates translation.
    • A tRNA molecule with the corresponding amino acid binds to the start codon.

    Translation Elongation

    • tRNA bringing the next amino acid binds to the A site of the ribosome
    • Peptide bonds form between the amino acids connected to the tRNA
    • The ribosome moves along the mRNA, adding amino acids to the growing polypeptide chain.

    Translation Termination

    • When a stop codon is reached, translation stops,
    • The polypeptide chain is released.

    Gene Regulation

    • Gene expression is the process of turning genes on or off to control protein production.
    • Gene regulation does not change DNA sequence (genotype).
    • It controls whether or not a protein is produced (phenotype).
    • Gene regulation is crucial and a precise control mechanism. Gene expression helps coordinate cellular activities and processes in many different organisms.

    Cell Differentiation

    • Cells differentiate to become specialized cell types during development.
    • All cells have the same DNA, but different genes are expressed in different cells.
    • Gene regulation is essential for differentiation.

    Eukaryotic Transcription Regulation

    • Transcription in eukaryotic cells relies on transcription factors which bind to the DNA enhancer sequence.
    • The DNA folds, locking RNA polymerase into position on the promoter to start transcription.

    Post-Transcriptional Gene Regulation

    • mRNA can be broken down or last for a while depending on how often that protein's gene needs to be expressed.
    • Some proteins have inactive and active forms changing how they function.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    This quiz explores the structure and functions of nucleic acids, focusing on DNA and RNA. Understand the composition of nucleotides, the complementary base pairing, and the processes of DNA replication. Test your knowledge on the differences between DNA and RNA and their structural properties.

    More Like This

    DNA and RNA Structure Quiz
    37 questions

    DNA and RNA Structure Quiz

    FieryCarnelian9965 avatar
    FieryCarnelian9965
    Nucleic Acids: DNA and RNA Structure
    30 questions

    Nucleic Acids: DNA and RNA Structure

    EventfulQuantum avatar
    EventfulQuantum
    Nucleic Acids: DNA & RNA Structure and Function
    6 questions

    Nucleic Acids: DNA & RNA Structure and Function

    HilariousNiobium6572 avatar
    HilariousNiobium6572
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser