Biology Central Dogma and Protein Structure
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Questions and Answers

What is the correct order of the processes in the central dogma of molecular biology?

  • Protein -- RNA -- DNA
  • DNA -- Protein -- RNA
  • RNA -- Protein -- DNA
  • DNA -- RNA -- Protein (correct)
  • During protein synthesis, what is the main function of a ribosome?

  • To translate mRNA into a polypeptide (correct)
  • To replicate DNA
  • To synthesize RNA from DNA
  • To attach amino acids to tRNA
  • What molecule is produced as a result of translation?

  • mRNA
  • tRNA
  • DNA
  • Proteins (correct)
  • What is a key characteristic of an exergonic reaction?

    <p>It releases energy to its surroundings</p> Signup and view all the answers

    Which of the following is true regarding autotrophs?

    <p>They can produce their own food through photosynthesis.</p> Signup and view all the answers

    What occurs during the light reactions of photosynthesis?

    <p>ATP and NADPH are produced.</p> Signup and view all the answers

    What is the role of amino acyl tRNA synthetase during protein synthesis?

    <p>To bind amino acids to tRNA</p> Signup and view all the answers

    What is a catabolic reaction?

    <p>A reaction that releases energy through the breakdown of molecules.</p> Signup and view all the answers

    Study Notes

    Central Dogma

    • DNA is transcribed into RNA, then translated into proteins.
    • DNA uses the nitrogenous bases adenine (A), guanine (G), cytosine (C), and thymine (T).
    • RNA uses the nitrogenous bases A, G, C, and uracil (U).
    • Proteins are made up of amino acids.

    Transcription

    • Transcription produces messenger RNA (mRNA) from DNA.
    • This mRNA serves as the template for translation.

    Protein Conformation

    • Refers to the 3-dimensional structure of a protein.
    • The four levels of protein structures are:
      • Primary: The linear sequence of amino acids.
      • Secondary: Local folding patterns, like alpha-helices and beta-sheets.
      • Tertiary: The overall 3D shape of a single polypeptide chain.
      • Quaternary: The arrangement of multiple polypeptide chains in a protein complex.

    Codons and Anticodons

    • A codon is a three-nucleotide sequence in mRNA that codes for a specific amino acid.
    • An anticodon is a three-nucleotide sequence on tRNA that is complementary to a codon.

    Translation

    • The process of synthesizing a protein from mRNA.
    • tRNA molecules bring specific amino acids to the ribosome.
    • Ribosomes read the mRNA codons, and match them with the correct tRNA anticodons.
    • This process continues, forming a chain of amino acids, until a stop codon is reached.

    Ribosomes

    • Molecular machines that synthesize proteins.
    • They have three sites:
      • A Site (Aminoacyl site): Where tRNA brings in the next amino acid.
      • P Site (Peptidyl site): Where the growing polypeptide chain is held.
      • E Site (Exit site): Where the tRNA exits the ribosome after releasing the amino acid..

    tRNA

    • Transfer RNA: Small RNA molecule that carries a specific amino acid to the ribosome during translation.

    Aminoacyl tRNA Synthetase

    • An enzyme that attaches the correct amino acid to a specific tRNA molecule.

    Translation Products

    • Translation produces polypeptide chains (proteins).

    Start and Stop Codons

    • Start codon: AUG (methionine), initiates translation.
    • Stop codon: UAA, UAG, or UGA, signals the termination of translation.

    Catabolic Reactions

    • Break down complex molecules into simpler ones, releasing energy.

    Anabolic Reactions

    • Build complex molecules from simpler ones, requiring energy.

    Exergonic Reactions

    • Reactions that release energy into the surroundings; negative change in free energy (ΔG).

    Endergonic Reactions

    • Reactions that require energy from the surroundings; positive change in free energy (ΔG).

    Free Energy

    • The energy available to do work.
    • Exergonic reactions have negative free energy changes, meaning they release energy.
    • Endergonic reactions have positive free energy changes, meaning they require energy input.

    Enzymes

    • Biological catalysts that speed up chemical reactions by lowering the activation energy (the energy needed to start a reaction).

    ATP

    • Adenosine triphosphate: Molecule used as the primary energy currency in cells.
    • Made of adenine, ribose, and three phosphate groups.
    • Energy is released when a phosphate group is removed.

    Laws of Thermodynamics

    • First Law: Energy cannot be created or destroyed, only transferred or transformed.
    • Second Law: Every energy transfer or transformation increases the entropy (disorder) of the universe.

    Enzyme Inhibitors

    • Competitive inhibitors: Bind to the active site of an enzyme, competing with the substrate (the molecule the enzyme acts on).
    • Noncompetitive inhibitors: Bind to a site on the enzyme other than the active site, changing its shape and reducing its activity.

    Autotrophs

    • Organisms that can produce their own food through photosynthesis, using sunlight as an energy source.

    Heterotrophs

    • Organisms that obtain food by consuming other organisms.

    Cellular Respiration

    • The process of breaking down glucose to produce ATP, using oxygen.
    • Four main stages:
      • Glycolysis: Glucose is broken down into pyruvate; occurs in the cytoplasm.
      • Pyruvate oxidation: Pyruvate is converted to acetyl-CoA; occurs in the mitochondrial matrix.
      • Krebs cycle: Acetyl-CoA is oxidized, producing electron carriers (NADH and FADH2); occurs in the mitochondrial matrix.
      • Electron Transport Chain: Electron carriers transfer electrons, generating a proton gradient across the inner mitochondrial membrane, driving ATP synthesis through oxidative phosphorylation; occurs in the inner mitochondrial membrane.

    Electron Transport Chain

    • A series of protein complexes embedded in the inner mitochondrial membrane.
    • Electrons from NADH and FADH2 are passed from one complex to another.
    • This movement of electrons releases energy, which is used to pump protons across the membrane, generating a proton gradient.
    • Oxygen is the final electron acceptor, forming water.

    Photosynthesis

    • The process by which plants and other organisms convert light energy into chemical energy (glucose).
    • Two main stages:
      • Light reactions: Light energy is captured by chlorophyll and used to produce ATP and NADPH.
      • Calvin cycle: ATP and NADPH are used to fix carbon dioxide, producing glucose; occurs in the stroma of chloroplasts.

    Chlorophyll

    • A pigment that absorbs light energy, mainly in the blue and red wavelengths.
    • Located in the thylakoid membranes of chloroplasts.

    Light Reactions

    • Occur in the thylakoid membranes of chloroplasts.
    • Light energy is absorbed by chlorophyll, exciting electrons.
    • This energy is used to split water, releasing oxygen.
    • Electrons are passed through an electron transport chain, generating ATP and NADPH.

    Calvin Cycle

    • Occurs in the stroma of chloroplasts..
    • Carbon dioxide is fixed using ATP and NADPH produced in the light reactions.
    • This process generates glucose.

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    Description

    This quiz covers the central dogma of molecular biology, focusing on the processes of transcription and translation. It also delves into protein conformation, detailing the different levels of protein structure and the role of codons and anticodons. Test your understanding of these fundamental biological concepts!

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