Gene Expression
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Questions and Answers

What is the primary function of the central dogma?

  • To synthesize DNA from RNA
  • To transcribe proteins from RNA templates
  • To replicate DNA during cell division
  • To convert the instructions in DNA into a functional product (correct)

    • Who first proposed the concept of the central dogma in 1956?

  • Charles Darwin
  • James Watson
  • Rosalind Franklin
  • Francis Crick (correct)

    • What is the correct sequence of events in the central dogma?

  • Protein, Translation, Transcription
  • RNA, Translation, DNA
  • DNA, Transcription, Translation (correct)
  • Translation, Transcription, DNA

    • What is the end product of the central dogma?

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

    What is the role of RNA in the central dogma?

    <p>To intermediate the transfer of genetic information from DNA to proteins</p> Signup and view all the answers

    What is the process by which the instructions in DNA are copied into RNA?

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

    What is the primary molecule that carries genetic information from DNA to proteins?

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

    What is the connection between genes and proteins?

    <p>Genes carry genetic information to synthesize proteins</p> Signup and view all the answers

    What is the main function of RNA polymerase?

    <p>To synthesize RNA</p> Signup and view all the answers

    What is the difference between the sugar in DNA and RNA?

    <p>DNA has deoxyribose, RNA has ribose</p> Signup and view all the answers

    What is the function of mRNA?

    <p>To translate proteins</p> Signup and view all the answers

    What is the terminator sequence in bacteria?

    <p>The sequence signaling the end of transcription</p> Signup and view all the answers

    Which type of RNA polymerase is involved in transcription in eukaryotes?

    <p>RNA polymerase II</p> Signup and view all the answers

    What is the direction of RNA synthesis during transcription?

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

    What is the role of the promoter in transcription?

    <p>To bind RNA polymerase</p> Signup and view all the answers

    What is the difference between thymine and uracil?

    <p>Thymine is found in DNA, uracil is found in RNA</p> Signup and view all the answers

    What is the direction of RNA synthesis by RNA polymerase during transcription?

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

    What is the base pairing rule for Adenine?

    <p>A with T</p> Signup and view all the answers

    What is the role of the three codons UAA, UAG, and UGA in translation?

    <p>They are stop signals to end translation</p> Signup and view all the answers

    What is the characteristics of the genetic code?

    <p>It is non-ambiguous and redundant</p> Signup and view all the answers

    What is the result of not reading codons in the correct reading frame during translation?

    <p>A different polypeptide will be produced</p> Signup and view all the answers

    What is the significance of the genetic code being nearly universal?

    <p>It allows for genes to be transcribed and translated across species</p> Signup and view all the answers

    What is the purpose of genetically modifying bacteria?

    <p>To produce certain human proteins for medical use</p> Signup and view all the answers

    What is the difference between the DNA template strand and the DNA coding strand?

    <p>The DNA template strand is the 3'-5' strand and the DNA coding strand is the 5'-3' strand</p> Signup and view all the answers

    What is the direction of transcription in terms of the mRNA molecule?

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

    What is the function of the promoter in transcription?

    <p>To bind RNA polymerase</p> Signup and view all the answers

    In which direction is the DNA template read during transcription?

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

    What is the stage of transcription where the RNA polymerase unwinds the DNA and initiates RNA synthesis?

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

    What is the RNA polymerase responsible for during elongation?

    <p>Unwinding the DNA and synthesizing RNA</p> Signup and view all the answers

    What is the result of the termination stage of transcription?

    <p>The RNA transcript is released</p> Signup and view all the answers

    Which of the following is NOT a stage of transcription?

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

    What is the difference between the template strand and the non-template strand of DNA?

    <p>The template strand is used as a template for RNA synthesis</p> Signup and view all the answers

    What is the direction of the RNA strand elongation during transcription?

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

    What is the function of the polyadenylation signal in eukaryotes?

    <p>To terminate transcription</p> Signup and view all the answers

    What is the main difference between transcription in bacteria and eukaryotes?

    <p>The RNA processing that occurs after transcription</p> Signup and view all the answers

    What is the role of the 5' cap and poly-A tail in RNA?

    <p>To protect the RNA from degradation</p> Signup and view all the answers

    What is the function of RNA splicing?

    <p>To remove introns from the primary transcript</p> Signup and view all the answers

    How many adenine residues are typically found in a poly-A tail?

    <p>50-200</p> Signup and view all the answers

    What is the function of the polyribosome?

    <p>To translate RNA into protein</p> Signup and view all the answers

    What percentage of the genome encodes for proteins?

    <p>A small part of the genome</p> Signup and view all the answers

    What is the primary function of transcription in gene expression?

    <p>To produce mRNA that carries genetic information from DNA to the ribosome</p> Signup and view all the answers

    What is the main difference between gene expression in prokaryotes and eukaryotes?

    <p>The presence or absence of a nuclear envelope</p> Signup and view all the answers

    What is the function of the genetic code in gene expression?

    <p>To encode instructions for assembling amino acids into proteins</p> Signup and view all the answers

    What is the result of gene expression in terms of the final product?

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

    What is the direction of the transcription process in terms of the DNA template?

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

    What is the intermediate molecule between genes and proteins in the central dogma?

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

    During which stage of transcription does the RNA polymerase unwind the DNA and initiate RNA synthesis?

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

    What is the purpose of RNA processing in eukaryotes?

    <p>To modify the primary transcript to produce mature mRNA</p> Signup and view all the answers

    What is the relationship between genotype and phenotype?

    <p>Genotype determines phenotype</p> Signup and view all the answers

    What is the role of the RNA polymerase during the elongation stage of transcription?

    <p>To add nucleotides to the growing RNA chain</p> Signup and view all the answers

    What is the central dogma of molecular biology?

    <p>The flow of genetic information from DNA to proteins</p> Signup and view all the answers

    Which strand of DNA is used as the template during transcription?

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

    What is the result of the termination stage of transcription?

    <p>The RNA transcript is released</p> Signup and view all the answers

    What is the direction of mRNA synthesis during transcription?

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

    What is the purpose of the promoter region in transcription?

    <p>To bind RNA polymerase</p> Signup and view all the answers

    What is the characteristic of transcription in terms of direction?

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

    What is the primary function of general transcription factors?

    <p>To recruit RNA polymerase II and bind it to the promoter</p> Signup and view all the answers

    What is the specific sequence within a promoter responsible for the assembly of the initiation complex?

    <p>TATA box</p> Signup and view all the answers

    What binds to the DNA before RNA polymerase II can bind to the promoter?

    <p>General transcription factors</p> Signup and view all the answers

    What is the complex formed by the binding of transcription factors and RNA polymerase II to a promoter?

    <p>Transcription initiation complex</p> Signup and view all the answers

    In which direction is the DNA template read during transcription?

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

    What is the role of the TATA box in eukaryotic promoters?

    <p>To recruit transcription factors</p> Signup and view all the answers

    What is the first step in the transcription initiation process?

    <p>General transcription factors bind to the TATA box</p> Signup and view all the answers

    What is the sequence of events in the transcription initiation process?

    <p>General transcription factors bind to the TATA box, then RNA polymerase II binds</p> Signup and view all the answers

    What is the direction of transcription in terms of the DNA template strand?

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

    What is the primary function of the codons in the genetic code?

    <p>To specify the sequence of amino acids in a polypeptide</p> Signup and view all the answers

    What is the significance of the genetic code being redundant?

    <p>It allows for more than one codon to encode for a specific amino acid</p> Signup and view all the answers

    What is the role of the ribosomes in translation?

    <p>To read the codons on the mRNA molecule</p> Signup and view all the answers

    What is the result of not reading the codons in the correct reading frame during translation?

    <p>A different polypeptide is produced</p> Signup and view all the answers

    What is the function of the base pairing rule in transcription?

    <p>To specify the complementary base pairing during RNA synthesis</p> Signup and view all the answers

    What is the role of the mRNA molecule in translation?

    <p>To carry the genetic information from DNA to the ribosomes</p> Signup and view all the answers

    What is the characteristic of the genetic code that allows it to be shared across different species?

    <p>It is universal</p> Signup and view all the answers

    What is the main function of rRNA?

    <p>To part of ribosome structure</p> Signup and view all the answers

    What is the difference between DNA and RNA in terms of their sugar component?

    <p>DNA has deoxyribose and RNA has ribose</p> Signup and view all the answers

    What is the function of tRNA?

    <p>To transfer amino acids to the growing polypeptide chain</p> Signup and view all the answers

    What is the role of RNA polymerase in transcription?

    <p>To synthesize RNA using a DNA template</p> Signup and view all the answers

    What is the correct sequence of events in transcription?

    <p>Initiation, elongation, termination</p> Signup and view all the answers

    What is the function of the promoter in transcription?

    <p>To bind RNA polymerase to DNA</p> Signup and view all the answers

    What is the difference between mRNA and tRNA?

    <p>mRNA carries genetic information, tRNA transfers amino acids</p> Signup and view all the answers

    Which type of RNA polymerase is involved in transcription in eukaryotes?

    <p>RNA polymerase II</p> Signup and view all the answers

    Study Notes

    Transcription and Translation

    Structure of RNA

    • Single-stranded molecule
    • Consists of ribonucleotides
    • Each ribonucleotide consists of:
      • A nitrogenous base (A, G, C, or U)
      • A pentose sugar (ribose)
      • A phosphate group

    Types of RNA

    • mRNA (messenger RNA): translated into proteins
    • rRNA (ribosomal RNA): part of ribosome structure
    • tRNA (transfer RNA): transfers amino acids to growing polypeptide chain during translation

    Transcription

    • DNA-directed synthesis of RNA
    • Catalyzed by RNA polymerase
    • RNA synthesis similar to DNA replication, except that uracil substitutes for thymine
    • Starts with binding of RNA polymerase to a DNA region called promoter
    • Molecular components of transcription:
      • Promoter: the DNA sequence where RNA polymerase attaches
      • Terminator: the sequence signaling the end of transcription in bacteria
      • Transcription unit: the stretch of DNA that is transcribed
    • Transcription stages:
      1. Initiation: RNA polymerase binds to promoter
      2. Elongation: RNA polymerase adds nucleotides to the growing RNA strand
      3. Termination: RNA transcript is released and RNA polymerase detaches from DNA

    Eukaryotic RNA Processing

    • Addition of 5' Cap: a modified nucleotide (m7G) at the 5' end
    • Addition of poly-A tail at the 3' end (50-200 adenine residues)
    • RNA splicing: removal of certain segments from the primary transcript
    • Function of RNA end modifications:
      • Facilitate export of mRNA from the nucleus
      • Protect mRNA from degradation by hydrolytic enzymes
      • Help ribosomes attach to the 5' end during translation

    The Genetic Code

    • 64 codons (triplets) in the genetic code
    • 61 codons code for amino acids
    • 3 codons (UAA, UAG, UGA) are "stop" signals to end translation
    • AUG = Methionine or Start Codon
    • Genetic code characteristics:
      • Redundant: more than 1 codon can encode for a specific amino acid
      • Not ambiguous: each codon specifies only 1 amino acid
    • Codons must be read in the correct reading frame (correct nucleotide groupings) to produce the specified polypeptide

    Evolution of the Genetic Code

    • Nearly universal: shared by simplest bacteria to most complex animals
    • Genes can be transcribed and translated after being transplanted from one species to another### RNA Structure and Function
    • RNA (Ribonucleic acid) is produced by transcription of DNA and is a single-stranded molecule.
    • RNA consists of ribonucleotides, which are composed of:
      • A nitrogenous base (A, G, C, or U)
      • A pentose sugar (ribose)
      • A phosphate group

    Differences between DNA and RNA

    • DNA is double-stranded, while RNA is single-stranded.
    • The sugar in DNA is deoxyribose, while the sugar in RNA is ribose.
    • In DNA, the nitrogenous bases are A, T, G, and C, while in RNA, the bases are A, U, G, and C.

    Types of RNA

    • mRNA (messenger RNA): translates into proteins.
    • rRNA (ribosomal RNA): part of the ribosome structure.
    • tRNA (transfer RNA): transfers amino acids to the growing polypeptide chain during translation.

    Transcription

    • Transcription is the DNA-directed synthesis of RNA, catalyzed by RNA polymerase.
    • It is the first stage of gene expression.
    • RNA synthesis is similar to DNA replication, except that uracil substitutes for thymine.

    Molecular Components of Transcription

    • Promoter: the DNA sequence where RNA polymerase attaches, located at the 5’ end (upstream) of the gene.
    • Terminator: the sequence signaling the end of transcription in bacteria.
    • Transcription unit: the stretch of DNA that is transcribed.

    RNA Polymerase

    • RNA polymerase synthesizes RNA using a DNA template strand.
    • It only transcribes one of the two DNA strands (the 3’-5’ template strand).
    • It adds nucleoside triphosphates (NTPs) only in the 5’ to 3’ direction.

    Eukaryotic RNA Polymerases

    • RNA polymerase I: responsible for rRNA synthesis.
    • RNA polymerase II: responsible for mRNA and snRNAs synthesis.
    • RNA polymerase III: responsible for tRNA and small RNAs synthesis.

    Transcription Stages

    • Initiation: RNA polymerase II binds to the promoter.
    • Elongation: adds NTPs in the 5’ to 3’ direction.
    • Termination: the RNA transcript is released from DNA when it reaches the termination of transcription.

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    Topic 4 Gene Expression Lecture Notes 2024 PDF

    Description

    Test your understanding of gene expression, including the structure and function of RNA, transcription, RNA processing, and translation. This quiz covers the connection between genes and proteins, and is based on Chapter 17 of the course material.

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