Genetics and Molecular Biology Overview
46 Questions
0 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 are the characteristics of silent mutations?

  • They cause a frameshift in the genetic sequence.
  • They do not alter the amino acid sequence. (correct)
  • They result in a different amino acid being inserted.
  • They introduce a stop codon.

    • Which type of mutation is marked by the addition or deletion of nucleotide bases?

  • Frameshift mutation (correct)
  • Missense mutation
  • Silent mutation
  • Nonsense mutation

    • What role do mutations play in evolution?

  • They serve as stop signals in genetic coding.
  • They are the original source of genetic variation. (correct)
  • They are detrimental and hinder evolutionary processes.
  • They only cause lethal changes in species.

    • What is commonly a consequence of frameshift mutations?

    <p>Altered reading frame leading to an early stop codon. (C)</p> Signup and view all the answers

    Which of the following best describes nonsense mutations?

    <p>They lead to changes resulting in a stop codon. (D)</p> Signup and view all the answers

    In which direction is the RNA transcript synthesized?

    <p>5'-to-3' (A)</p> Signup and view all the answers

    What role does the promoter play in transcription?

    <p>It serves as a recognition and binding site for RNA polymerase. (D)</p> Signup and view all the answers

    What can vary between different genes regarding transcription?

    <p>The strand of DNA that is transcribed (A)</p> Signup and view all the answers

    What must happen for transcription to proceed according to the content?

    <p>Transcriptional activator proteins and RNA Pol II must interact with the mediator complex. (A)</p> Signup and view all the answers

    Where is the promoter located in relation to the transcription start site?

    <p>Upstream of the start site (A)</p> Signup and view all the answers

    What is the role of the large subunit in the ribosome during translation?

    <p>It contains binding sites for tRNAs. (A)</p> Signup and view all the answers

    What is the initiating amino acid in prokaryotic translation?

    <p>N-formylmethionine (D)</p> Signup and view all the answers

    Which factor is required for the binding of the second charged tRNA to the A site during elongation?

    <p>Elongation factor EF-Tu (C)</p> Signup and view all the answers

    During translation elongation, what happens to the ribosome after a peptide bond forms?

    <p>It moves one codon downstream. (D)</p> Signup and view all the answers

    What distinguishes the initiation process in eukaryotes from that in prokaryotes?

    <p>Eukaryotes lack a ribosomal binding site. (A)</p> Signup and view all the answers

    What does the peptidyl transferase do in the ribosome?

    <p>It forms peptide bonds between amino acids. (C)</p> Signup and view all the answers

    Where does the uncharged tRNA go after it has transferred its amino acid?

    <p>To the exit site (E) to be ejected. (A)</p> Signup and view all the answers

    Which site on the ribosome does the initiator tRNA bind to during the initiation of translation?

    <p>P site (A)</p> Signup and view all the answers

    What occurs when a ribosome encounters a stop codon during translation?

    <p>The polypeptide is released from the ribosome. (C)</p> Signup and view all the answers

    Which statement accurately describes prokaryotic gene expression compared to eukaryotic?

    <p>Eukaryotic genes usually contain introns. (D)</p> Signup and view all the answers

    What initiates the translation process in both prokaryotes and eukaryotes?

    <p>The AUG codon, preceded by a specific sequence or 5’ cap. (B)</p> Signup and view all the answers

    In eukaryotes, how does mRNA processing occur after transcription?

    <p>Multiple modifications occur, including splicing and 5’ capping. (A)</p> Signup and view all the answers

    What is the role of tRNA during the elongation stage of translation?

    <p>It brings amino acids to the A site of the ribosome. (A)</p> Signup and view all the answers

    What distinguishes prokaryotic transcription from eukaryotic transcription?

    <p>Eukaryotes undergo extensive mRNA processing before translation. (A)</p> Signup and view all the answers

    In the context of translation, what is the function of release factors?

    <p>They recognize stop codons to terminate translation. (A)</p> Signup and view all the answers

    How do several genes in prokaryotes often coordinate regulation?

    <p>By forming operons that express genes collectively. (A)</p> Signup and view all the answers

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

    <p>Codes for proteins (D)</p> Signup and view all the answers

    Which statement accurately describes the process of transcription?

    <p>Transcription synthesizes RNA from a DNA template (C)</p> Signup and view all the answers

    What is the significance of codons in the genetic code?

    <p>They correspond to amino acids during translation (D)</p> Signup and view all the answers

    Which component carries amino acids to the ribosomes during translation?

    <p>Transfer RNA (tRNA) (D)</p> Signup and view all the answers

    What is the function of stop codons in the translation process?

    <p>To terminate the translation process (D)</p> Signup and view all the answers

    What is one key difference between prokaryotic and eukaryotic transcription?

    <p>Eukaryotic transcription requires additional processing steps (C)</p> Signup and view all the answers

    What was the original hypothesis proposed by Beadle and Tatum regarding genes?

    <p>One-gene/one-enzyme hypothesis (C)</p> Signup and view all the answers

    During transcription, what replaces thymine (T) found in DNA?

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

    Which of the following is not a type of RNA found in eukaryotic cells?

    <p>Chloroplast RNA (cRNA) (A)</p> Signup and view all the answers

    What aspect of the genetic code is described as 'degenerate'?

    <p>Some amino acids can be specified by more than one codon (B)</p> Signup and view all the answers

    What direction does RNA grow during transcription?

    <p>5′ to 3′ direction (A)</p> Signup and view all the answers

    Which of the following RNA polymerases is responsible for transcribing mRNA in eukaryotes?

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

    Which process occurs before transcription is completed in prokaryotic cells?

    <p>Translation (D)</p> Signup and view all the answers

    What is the function of the 5′ cap added to eukaryotic mRNA transcripts?

    <p>To protect from degradation (A)</p> Signup and view all the answers

    What happens to the RNA-DNA hybrid within the transcription bubble at termination?

    <p>It dissociates (D)</p> Signup and view all the answers

    Which of the following is NOT a modification that occurs to primary mRNA transcripts in eukaryotes?

    <p>Addition of introns (D)</p> Signup and view all the answers

    What is the role of aminoacyl-tRNA synthetases in translation?

    <p>To charge uncharged tRNA (B)</p> Signup and view all the answers

    What is formed at the transcription termination site?

    <p>A sequence that signals 'stop' to polymerase (C)</p> Signup and view all the answers

    In eukaryotes, which enzyme is involved in the addition of the 3′ poly-A tail?

    <p>Poly-A polymerase (D)</p> Signup and view all the answers

    What structural feature characterizes the anticodon loop of tRNA?

    <p>It has 3 nucleotides complementary to mRNA codons (B)</p> Signup and view all the answers

    Flashcards

    Central Dogma

    The flow of genetic information from DNA to RNA to protein.

    Transcription

    The process of making RNA from a DNA template.

    RNA polymerase

    Enzyme that builds RNA during transcription.

    Codon

    Three-nucleotide sequence in mRNA that codes for a single amino acid.

    Signup and view all the flashcards

    mRNA

    Messenger RNA; carries the genetic code from DNA to ribosomes for protein synthesis.

    Signup and view all the flashcards

    tRNA

    Transfer RNA; carries amino acids to the ribosome during translation.

    Signup and view all the flashcards

    Translation

    The process of synthesizing a polypeptide chain from an mRNA template.

    Signup and view all the flashcards

    One-gene/one-polypeptide hypothesis

    The concept that each gene codes for a specific polypeptide chain.

    Signup and view all the flashcards

    Promoter (transcription)

    DNA sequence where RNA polymerase binds to initiate transcription

    Signup and view all the flashcards

    Stop codon

    A codon that signals the termination of translation.

    Signup and view all the flashcards

    Transcription direction

    RNA polymerase synthesizes RNA in a 5' to 3' direction.

    Signup and view all the flashcards

    Promoter region

    A region of DNA that signals the start of a gene and acts as a binding site for RNA polymerase.

    Signup and view all the flashcards

    Transcription initiation

    The process where RNA polymerase binds to the promoter region and begins the synthesis of RNA from DNA.

    Signup and view all the flashcards

    Enhancer sequence

    DNA sequence that can increase the rate of transcription of nearby genes through looping.

    Signup and view all the flashcards

    General transcription factors

    Proteins that are essential for RNA polymerase binding to the promoter. They form part of the complex that allows transcription to proceed.

    Signup and view all the flashcards

    RNA polymerase

    Enzyme that builds RNA molecules from DNA templates

    Signup and view all the flashcards

    Promoter region

    DNA sequence signaling the start of a gene

    Signup and view all the flashcards

    Transcription

    Process of creating RNA from DNA

    Signup and view all the flashcards

    Prokaryotic transcription

    Transcription coupled directly with translation

    Signup and view all the flashcards

    Eukaryotic RNA polymerase

    RNA polymerase comes in 3 kinds

    Signup and view all the flashcards

    mRNA modifications

    5' cap and 3' poly-A tail added to mRNA

    Signup and view all the flashcards

    Introns

    Non-coding sequences in DNA/RNA

    Signup and view all the flashcards

    Exons

    Coding sequences joined together during RNA processing

    Signup and view all the flashcards

    tRNA

    Transfers amino acids to ribosomes for protein synthesis

    Signup and view all the flashcards

    tRNA synthetase

    enzyme that attaches amino acids to tRNA

    Signup and view all the flashcards

    tRNA attachment

    Specific enzyme attaches amino acid to the 3' end of tRNA.

    Signup and view all the flashcards

    Ribosome binding sites

    Large ribosomal subunit has three sites (E, P, A) for tRNA.

    Signup and view all the flashcards

    Translation initiation (prokaryotes)

    Involves initiator tRNA (N-formylmethionine), small ribosomal subunit, and mRNA.

    Signup and view all the flashcards

    RBS (Ribosome Binding Site)

    mRNA sequence positioning small subunit.

    Signup and view all the flashcards

    Translation initiation (eukaryotes)

    Similar to prokaryotes, but uses methionine, more complex complex and binds to 5' cap of mRNA.

    Signup and view all the flashcards

    Elongation (translation)

    Adds amino acids one at a time via tRNA in the A site.

    Signup and view all the flashcards

    EF-Tu

    Elongation factor binding to tRNA to allow peptide bond formation.

    Signup and view all the flashcards

    Peptide bond formation

    Ribosome catalyzes the formation of peptide bonds between amino acids.

    Signup and view all the flashcards

    Point mutations

    Changes in a single DNA base pair.

    Signup and view all the flashcards

    Frameshift mutations

    Insertions or deletions of one or a few base pairs, altering the reading frame.

    Signup and view all the flashcards

    Silent mutation

    A point mutation that does not change the amino acid sequence.

    Signup and view all the flashcards

    mRNA processing

    Modifications to pre-mRNA, including splicing, capping, and tailing.

    Signup and view all the flashcards

    Mutations origin of variation

    Source of genetic diversity and the foundation of evolution.

    Signup and view all the flashcards

    Prokaryotic Gene Expression

    Prokaryotic gene expression involves coupled transcription and translation; multiple genes can be transcribed into a single mRNA molecule (operon)

    Signup and view all the flashcards

    Eukaryotic Gene Expression

    Eukaryotic gene expression involves separate transcription (in nucleus) and translation (in cytoplasm); mRNA is processed before translation (introns removal), and only one gene per mRNA molecule.

    Signup and view all the flashcards

    Stop Codon

    A codon that signals the end of translation, causing the release of the polypeptide.

    Signup and view all the flashcards

    Translation Elongation

    Building the polypeptide chain by adding amino acids in a step-by-step process to the growing chain.

    Signup and view all the flashcards

    tRNA Binding

    tRNA molecules bring amino acids to the ribosome, where they match with codons via hydrogen bonds.

    Signup and view all the flashcards

    Operon

    In prokaryotes, a group of genes with related functions organized and transcribed together.

    Signup and view all the flashcards

    Gene Expression Differences

    Prokaryotic and eukaryotic gene expression differ significantly in processes like RNA processing, site of transcription and translation, and initiation of translation.

    Signup and view all the flashcards

    Eukaryotic mRNA Modification

    Eukaryotic mRNA undergoes processing after transcription, including splicing and addition of a 5' cap and poly(A) tail, before it can be translated.

    Signup and view all the flashcards

    Study Notes

    Genes and How They Work

    • Genes' function was initially understood through the study of human diseases.
    • Early 1900s linked genes to enzymes.
    • Beadle and Tatum (1941) created mutations, tracked inheritance, and proposed the one-gene/one-enzyme hypothesis.
    • The current understanding is the one-gene/one-polypeptide hypothesis.

    Central Dogma

    • Crick first described the flow of information from DNA to RNA to protein.
    • DNA → Transcription → mRNA → Translation → Protein
    • Proteins carry out essential cellular activities.

    Transcription

    • One DNA strand (template strand) guides RNA synthesis.
    • DNA template is read 3' to 5', RNA is synthesized 5' to 3'.
    • Thymine (T) in DNA is replaced by uracil (U) in RNA.
    • New nucleic acid strands are always generated 5' to 3'.

    RNA

    • RNA is synthesized from a DNA template by transcription.
    • Found in all organisms.
    • mRNA codes for proteins.
    • rRNA forms ribosomes.
    • tRNA carries amino acids for translation.
    • Other types of RNA include snRNA, srpRNA, miRNA, and siRNA, only found in eukaryotes.

    Genetic Code

    • A codon is a block of three mRNA nucleotides corresponding to an amino acid.
    • The reading frame is crucial for correct protein synthesis.
    • The genetic code is practically universal, a strong indicator of common ancestry.
    • Stop codons terminate translation.
    • Start codon (AUG) signals translation start.

    Prokaryotic Transcription

    • Single RNA polymerase.
    • No primer needed.
    • Transcription unit includes a promoter, start site, and terminator.
    • The promoter is upstream of the start site; it's a recognition and binding site for RNA polymerase.
    • Transcription is initiated at a promoter sequence and ends at a terminator sequence.
    • mRNA translation can begin before transcription is complete.

    Eukaryotic Transcription

    • Three different RNA polymerases (I, II, III).
    • RNA polymerase I transcribes rRNA.
    • RNA polymerase II transcribes mRNA (and some snRNA).
    • RNA polymerase III transcribes tRNA (and other small RNAs).
    • More proteins are involved in initiation.
    • Termination is somewhat different from prokaryotes.

    Eukaryotic mRNA Modifications

    • Primary transcripts must be modified to become mature mRNA.
    • A 5' cap is added for translation initiation and protection from degradation.
    • A 3' poly-A tail is added for protection from degradation.
    • Non-coding sequences (introns) are removed by splicing.

    Eukaryotic Pre-mRNA Splicing

    • Introns are noncoding sequences.
    • Exons are coding sequences that will be translated.
    • Spliceosome removes introns and joins exons.

     

    tRNA and Ribosomes

    • tRNA molecules carry amino acids to ribosomes.
    • The anticodon loop of tRNA matches to mRNA codons.
    • Aminoacyl-tRNA synthetases "charge" tRNA with amino acids.

    Ribosomes

    • The large ribosomal subunit has three binding sites for tRNAs: E, P, and A.

    Translation Initiation (Prokaryotes)

    • Initiation complex includes initiator tRNA (with N-formylmethionine), small ribosomal subunit, and mRNA strand.

    Translation Initiation (Eukaryotes)

    • Similar to prokaryotes but with more complex initiation.
    • Methionine is the initiator amino acid.
    • Small subunit binds to the 5' cap of mRNA.

    Translation Elongation

    • Elongation adds amino acids to the growing polypeptide chain.
    • Elongation factor EF-Tu binds to tRNA and GTP.
    • A peptide bond forms aided by peptidyl transferase.
    • Ribosome moves one codon (3 bases).

    Translation Termination

    • Elongation continues until a stop codon is reached.
    • Release factors recognize stop codons, releasing the polypeptide.

    Mutations

    • Point mutations: alter a single base.
    • Silent mutations: same amino acid inserted.
    • Missense mutations: different amino acid inserted.
    • Nonsense mutations: change to a stop codon.
    • Frameshift mutations: addition or deletion of one or a few bases (not multiples of three), causing a major alteration in the reading frame.
    • Mutations are the raw material of evolution; however, too much change can be harmful. A balance between variation and health is essential for species survival.

    Studying That Suits You

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

    Quiz Team

    Related Documents

    Chapter 15 AMF - Transcription and Translation PDF

    Description

    Explore the fundamentals of genetics and molecular biology in this quiz. Understand the key principles, including gene function, the central dogma of molecular biology, and the process of transcription. Test your knowledge of how genes work and how they are expressed in proteins.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser