Biology Exam 4 Flashcards
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Questions and Answers

Which of these is a difference between a DNA and an RNA molecule?

  • DNA contains nitrogenous bases, whereas RNA contains phosphate groups.
  • DNA contains five-carbon sugars, whereas RNA contains six-carbon sugars.
  • DNA contains uracil, whereas RNA contains thymine.
  • DNA is usually double-stranded, whereas RNA is usually single-stranded. (correct)

    • Which of these nitrogenous bases is found in DNA but not in RNA?

  • Adenine
  • Uracil
  • Cytosine
  • Thymine (correct)

    • In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.

    2'... 5'

    Nucleic acids are assembled in the _____ direction.

    <p>5' to 3'</p> Signup and view all the answers

    In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand.

    <p>thymine</p> Signup and view all the answers

    What is the difference between heterozygous and homozygous individuals?

    <p>All of the gametes from a homozygote carry the same version of the gene while those of a heterozygote will differ.</p> Signup and view all the answers

    When constructing a Punnett square, the symbols on the outside of the boxes represent _______, while those inside the boxes represent _______.

    <p>gametes, progeny</p> Signup and view all the answers

    The same phenotype can be produced by more than one genotype.

    <p>True</p> Signup and view all the answers

    In diploid organisms, a dominant phenotype will only be expressed if the individual is homozygous dominant for that trait.

    <p>False</p> Signup and view all the answers

    Two mice are heterozygous for albinism (Aa). The dominant allele (A) codes for normal pigmentation, and the recessive allele (a) codes for no pigmentation. What percentage of their offspring would have an albino phenotype?

    <p>50</p> Signup and view all the answers

    According to Mendel's law of segregation, a gamete

    <p>always receives only one of the parent's alleles for each gene.</p> Signup and view all the answers

    According to Mendel's law of segregation,

    <p>alleles segregate into gametes with equal frequency.</p> Signup and view all the answers

    Which statement correctly explains how to determine the frequencies of the F2 progeny?

    <p>The progeny frequencies are determined by the multiplication rule (multiplying the gamete frequencies together).</p> Signup and view all the answers

    What process is responsible for the independent assortment of alleles?

    <p>Meiosis.</p> Signup and view all the answers

    How do cells acquire homologous chromosome pairs that carry the alleles that are independently assorted?

    <p>Fusion of gametes.</p> Signup and view all the answers

    Which of the following statements most accurately describes the process of independent assortment?

    <p>Alleles of different genes segregate from one another in a random manner.</p> Signup and view all the answers

    The principle of independent assortment is best illustrated by events that take place during metaphase II, during which sister chromatids segregate independently of each other.

    <p>False</p> Signup and view all the answers

    How many genetically unique types of gametes could be produced by an individual with the genotype RrYY?

    <p>Two.</p> Signup and view all the answers

    Which of the following parental genotypes would yield a 1:1:1:1 phenotypic ratio in the offspring?

    <p>AaBb, aabb.</p> Signup and view all the answers

    DNA possesses many negative charges because of the presence of _________.

    <p>phosphate groups</p> Signup and view all the answers

    DNA contains ________, which distinguish DNA from RNA and help form the backbone of each DNA strand.

    <p>deoxiribose sugars</p> Signup and view all the answers

    Adenine and thymine are examples of _______, which pair with each other in the double helix.

    <p>nitrogenous base</p> Signup and view all the answers

    The complementary DNA strands of a double helix are held together by _______ between their nitrogenous bases.

    <p>hydrogen bonds</p> Signup and view all the answers

    In bacteria, DNA polymerase III is the enzyme that adds new nucleotides to a primer or growing strand of DNA. Which of the following statements correctly describes the formation of the bond between a new nucleotide and the primer?

    <p>The newly added nucleotide forms a bond with the hydroxyl (-OH) group on the 3' end of the primer.</p> Signup and view all the answers

    After DNA replication is completed, _____.

    <p>each new DNA double helix consists of one old DNA strand and one new DNA strand</p> Signup and view all the answers

    The first step in the replication of DNA is catalyzed by _____.

    <p>helicase</p> Signup and view all the answers

    The action of helicase creates _____

    <p>replication forks and replication bubbles.</p> Signup and view all the answers

    Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?

    <p>DNA polymerase can assemble DNA only in the 5' to 3' direction.</p> Signup and view all the answers

    The synthesis of a new strand begins with the synthesis of a(n) _____.

    <p>RNA primer complementary to a preexisting DNA strand</p> Signup and view all the answers

    An old DNA strand is used as a _____ for the assembly of a new DNA strand.

    <p>template</p> Signup and view all the answers

    What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA?

    <p>Transcription.</p> Signup and view all the answers

    What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?

    <p>Translation.</p> Signup and view all the answers

    What name is given to the process in which pre-mRNA is edited into mRNA?

    <p>RNA processing.</p> Signup and view all the answers

    Polypeptides are assembled from _____.

    <p>Amino acids.</p> Signup and view all the answers

    RNA processing converts the RNA transcript into _____.

    <p>mRNA.</p> Signup and view all the answers

    What is the process called that converts the genetic information stored in DNA to an RNA copy?

    <p>Transcription.</p> Signup and view all the answers

    DNA does not store the information to synthesize which of the following?

    <p>Organelles.</p> Signup and view all the answers

    Transcription begins at a promoter. What is a promoter?

    <p>A site in DNA that recruits the RNA polymerase.</p> Signup and view all the answers

    Which of the following statements best describes the promoter of a protein-coding gene?

    <p>The promoter is a nontranscribed region of a gene.</p> Signup and view all the answers

    What determines which base is to be added to an RNA strand during transcription?

    <p>Base pairing between the DNA template strand and the RNA nucleotides.</p> Signup and view all the answers

    Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?

    <p>Complementary.</p> Signup and view all the answers

    What happens to RNA polymerase II after it has completed transcription of a gene?

    <p>It is free to bind to another promoter and begin transcription.</p> Signup and view all the answers

    Which of these correctly illustrates the pairing of DNA and RNA nucleotides?

    <p>GTTACG CAAUGC.</p> Signup and view all the answers

    The direction of synthesis of an RNA transcript is _____.

    <p>5' —&gt; 3'.</p> Signup and view all the answers

    Which two statements correctly describe the template and/or coding strands?

    <p>During transcription, the DNA bases on the template strand are paired with their complementary RNA bases to form the RNA transcript.</p> Signup and view all the answers

    Does RNA polymerase move in a set direction along a strand of DNA during transcription?

    <p>True</p> Signup and view all the answers

    Regions of the RNA transcript that contain non-coding bases are called _____.

    <p>Introns.</p> Signup and view all the answers

    In a process called _____, non-coding regions of the RNA transcript are removed.

    <p>Splicing.</p> Signup and view all the answers

    Molecular complexes called _______ carry out RNA splicing in the nucleus.

    <p>Spliceosomes.</p> Signup and view all the answers

    The completed mRNA contains the gene's _____ joined together in the correct order.

    <p>Exons.</p> Signup and view all the answers

    During RNA processing a(n) _____ is added to the 5' end of the RNA.

    <p>modified guanine nucleotide</p> Signup and view all the answers

    During RNA processing a(n) _____ is added to the 3' end of the RNA.

    <p>a long string of adenine nucleotides</p> Signup and view all the answers

    Spliceosomes are composed of _____.

    <p>snRNPs and other proteins.</p> Signup and view all the answers

    The RNA segments joined to one another by spliceosomes are _____.

    <p>Exons.</p> Signup and view all the answers

    Translation occurs in the _____.

    <p>Cytoplasm.</p> Signup and view all the answers

    Viral DNA makes mRNA by the process of _____.

    <p>Transcription.</p> Signup and view all the answers

    The genetic material of HIV consists of _____.

    <p>Single-stranded RNA.</p> Signup and view all the answers

    What is the function of reverse transcriptase?

    <p>It catalyzes the formation of DNA from an RNA template.</p> Signup and view all the answers

    What is the source of a viral envelope?

    <p>Host cell membrane.</p> Signup and view all the answers

    Double-stranded viral DNA is incorporated into a host cell as a _____.

    <p>Provirus.</p> Signup and view all the answers

    _____ bind(s) to DNA enhancer regions.

    <p>Activators.</p> Signup and view all the answers

    Study Notes

    DNA vs. RNA

    • DNA contains thymine; RNA contains uracil.
    • DNA is typically double-stranded, while RNA is usually single-stranded.
    • DNA has deoxyribose sugar; RNA contains ribose sugar.
    • DNA is formed from nucleotides; RNA is a polymer of nucleic acids.
    • Specific base pairing occurs: adenine pairs with thymine, cytosine pairs with guanine.

    Nucleotide Structure

    • In a nucleotide, the nitrogenous base is attached to the sugar's 1' carbon.
    • The phosphate group connects to the sugar's 5' carbon.
    • Nucleic acids are assembled in the 5' to 3' direction.

    Genetic Variation

    • Heterozygous individuals have two different alleles for a trait; homozygous individuals have two identical alleles.
    • Phenotypic ratios may differ based on allele combinations in parents.

    Punnett Squares

    • Symbols outside Punnett squares represent gametes; symbols inside represent progeny.
    • Offspring phenotypic ratios can be predicted using genetic crosses (e.g., 1:1:1:1 indicates certain gametic combinations).

    Mendelian Genetics

    • Mendel's law of segregation states that gametes receive only one allele from each parent.
    • Independent assortment of alleles occurs during meiosis.
    • Gametes derive from the fusion of homologous chromosomes.

    RNA Structure and Synthesis

    • RNA processing converts RNA transcripts into mRNA, which involves splicing out introns.
    • Transcription is the process of synthesizing RNA from DNA.
    • RNA polymerase adds nucleotides to the growing RNA strand in the 5' to 3' direction.

    Transcription and Translation

    • A promoter is a DNA region where RNA polymerase binds to initiate transcription.
    • Introns are non-coding segments of RNA; exons are coding segments retained in mRNA.
    • Translation involves synthesizing polypeptides from mRNA in the cytoplasm.

    Viral Genetics

    • HIV contains single-stranded RNA as its genetic material.
    • Reverse transcriptase synthesizes DNA from an RNA template.
    • Viral envelopes originate from the host cell membrane.

    Additional Concepts

    • DNA polymerase III adds nucleotides during DNA replication.
    • Helicase unwinds the double helix, creating replication forks.
    • RNA transcripts undergo capping and polyadenylation for stability and structural integrity post-processing.

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    Test your knowledge with these flashcards for Biology Exam 4. This quiz focuses on key differences between DNA and RNA molecules among other essential concepts in biology. Perfect for revision and reinforcing your understanding of nucleic acids.

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