Genetic Code and Properties
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Questions and Answers

What is the role of AUG in the genetic code?

  • It is the termination codon.
  • It codes for the amino acid serine.
  • It is the initiation codon that codes for methionine. (correct)
  • It serves as a repressor protein.

    • Which of the following statements correctly describes the degeneracy of the genetic code?

  • Each amino acid is coded by a unique codon.
  • One amino acid can be coded by multiple codons. (correct)
  • There are no degenerate codons in the genetic code.
  • One codon can correspond to multiple amino acids.

    • Which of the following is NOT a property of the genetic code?

  • Triplet nature
  • Universality
  • Ambiguity (correct)
  • Commaless

    • What is the significance of termination codons in the genetic code?

    <p>They do not code for any amino acid.</p> Signup and view all the answers

    What element of DNA is responsible for initiating transcription?

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

    How are genes within an operon typically regulated?

    <p>Underneath a single promoter controlling all genes.</p> Signup and view all the answers

    Which of the following statements best describes non-overlapping codons?

    <p>Codons are read independently of one another.</p> Signup and view all the answers

    Which statement correctly describes collinearity in the context of mRNA and polypeptide chains?

    <p>There is a direct linear relationship between codon order and amino acid sequence.</p> Signup and view all the answers

    What is the primary function of restriction enzymes in prokaryotes?

    <p>To cleave foreign DNA</p> Signup and view all the answers

    Which of the following best describes a palindromic sequence in DNA?

    <p>A sequence that matches itself when read in reverse on complementary strands</p> Signup and view all the answers

    How do modification enzymes protect prokaryotic DNA from restriction enzymes?

    <p>By modifying the prokaryotic DNA to block cleavage</p> Signup and view all the answers

    What is the significance of palindromic sequences in DNA replication?

    <p>They account for major deletions and insertions</p> Signup and view all the answers

    What effect do longer palindromic sequences have on DNA?

    <p>They make DNA more vulnerable to mutations</p> Signup and view all the answers

    How many different specificities do known restriction endonucleases represent?

    <p>More than 250</p> Signup and view all the answers

    What is polymorphism in genetics?

    <p>The occurrence of different forms within a species</p> Signup and view all the answers

    What is a primary use of restriction enzymes in laboratories?

    <p>For DNA modification and cloning</p> Signup and view all the answers

    What is the minimum frequency for two or more alleles at one locus to be considered as genetic polymorphism?

    <p>1%</p> Signup and view all the answers

    Which type of polymorphism is most commonly associated with genetic variation?

    <p>Single-nucleotide polymorphisms (SNPs)</p> Signup and view all the answers

    During which phase of the polymerase chain reaction (PCR) are the DNA strands separated?

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

    At what temperature does the annealing phase of PCR typically occur for optimal primer binding?

    <p>55-72 C</p> Signup and view all the answers

    What is the primary function of gel electrophoresis?

    <p>Separating DNA fragments based on size and charge</p> Signup and view all the answers

    What does a polymorphic population display that is too high to be explained by mutation?

    <p>Discontinuous forms</p> Signup and view all the answers

    What is the optimal temperature selected for enzyme-induced DNA replication during the elongation phase of PCR?

    <p>75-80 C</p> Signup and view all the answers

    Which of the following is an example of genetic polymorphism in humans?

    <p>Blood types</p> Signup and view all the answers

    Study Notes

    Genetic Code and Properties

    • Genetic code are sequences of nucleotides or nitrogenous bases in messenger RNA (mRNA)
    • mRNA sequences originate from DNA, their bases are complementary to DNA's segment.
    • There are 20 different amino acids in the body, but only four nitrogenous bases (A, U, G, and C) in mRNA.
    • 61 of the 64 triplet codons code for amino acids.
    • UAA, UAG, and UGA are termination codons.
    • AUG is the initiation codon, coding for methionine.

    Properties of Genetic Code

    • Triplet: Three nitrogenous bases form a genetic code in a specific sequence.
    • Commaless: No punctuation marks between adjacent genetic codes.
    • Non-overlapping: No codon overlaps with the next one.
    • Universality: Same genetic code applies to all organisms, including viruses.
    • Degeneracy: Multiple codons can code for the same amino acid.
    • Ambiguity: A codon only codes for one specific amino acid.
    • Collinearity: Linear arrangement of codons on mRNA corresponds to amino acid residues in the polypeptide chain.

    Transcriptional Regulation

    • A cell regulates the conversion of DNA to RNA (transcription).
    • Bacterial transcription is controlled by three main elements:
      • Promoters: DNA segments where RNA polymerase and other proteins bind, initiating transcription. Located upstream of the gene.
      • Operators: DNA segments that bind repressor proteins to inhibit gene transcription.
    • Positive control elements bind to DNA, increasing transcription rates.
    • Operons are functional units of DNA containing genes under a single promoter, transcribed together into mRNA.

    Genetic Engineering

    • Genetic engineering, or genetic modification, manipulates an organism's genes using technology.
    • It's used to change the genetic makeup, transfer genes between species, and produce improved organisms.
    • It replaces or corrects defective genes for biomedical applications.
    • It can introduce genetic changes to fix genetic disorders, create vaccines and other products, improving crop yields/nutrition, and resilience to environmental stresses.
    • Researchers isolate gene candidates.
    • Restriction enzymes cut DNA, or PCR amplifies the segment.
    • The gene is inserted into a plasmid that’s inserted into bacteria for replication.

    Recombinant DNA

    • Recombinant DNA (rDNA) combines genetic material from different sources.
    • DNA molecules can originate from any species.
    • Molecular cloning replicates a DNA sequence without altering it, inserting it in a vector for propagation.
    • Copies are generated for analysis/protein production by altering expression/function.
    • Cloning uses DNA from species to be cloned, and a host species for replication.
    • Recombinant DNA is vital in biotechnology, medicine, and research.

    Transgenic & Knockout Animals

    • Transgenic animals have altered or additional genetic material.
    • Knockout animals have deleted or modified genes.
    • Techniques like pronuclear microinjection introduce genetic material.
    • Gene targeting applies to mice, and is in development for other organisms.

    Reverse Transcription & cDNA

    • Reverse transcription synthesizes DNA from RNA using RNA-dependent DNA polymerases (reverse transcriptases).
    • cDNA is synthetic DNA transcribed from specific mRNA.
    • It has only coding sequences, and is a tool for gene cloning, and studying gene expression.
    • Widely used to express proteins in cells that don't naturally express them.

    Restriction Enzymes

    • Restriction enzymes cut DNA at specific sequences.
    • They're used, in part, to create rDNA.
    • They safeguard prokaryotes against invading viruses, cutting foreign DNA.

    DNA Sequencing

    • DNA sequencing determines the order of nucleotides in DNA.
    • The sequence reveals genetic information, including genes, regulatory instructions, and disease-causing mutations.
    • Sanger sequencing (chain termination) is a method to routinely sequence short DNA regions (up to about 900 base pairs).

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    Genetics PDF

    Description

    Explore the intricacies of the genetic code in this quiz focusing on its structure, properties, and significance. Learn about mRNA, codons, and how genetic information is translated into amino acids. This quiz covers essential concepts related to molecular biology and genetics.

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