Molecular Biology Quiz
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Questions and Answers

What is the primary focus of molecular biology?

  • The interactions between DNA, RNA, and protein biosynthesis (correct)
  • The structure and function of cells
  • The study of genetic information in prokaryotes
  • The evolution of unicellular organisms

    • What is the term for the total genetic information of an organism?

  • Genome (correct)
  • Gene
  • DNA
  • Protein

    • Where is DNA contained in a cell?

  • Mitochondria
  • Ribosome
  • Nucleus (correct)
  • Golgi apparatus

    • What percentage of DNA is identical between humans and chimpanzees?

    <p>98%</p> Signup and view all the answers

    What is the term for the basic units of inheritance?

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

    In which year was the term 'molecular biology' first coined?

    <p>1938</p> Signup and view all the answers

    What is the primary function of DNA?

    <p>Carrying the blueprint for life</p> Signup and view all the answers

    What are the essential components of a gene?

    <p>Exons, start site, stop site, and control region</p> Signup and view all the answers

    What is the role of ribosomal RNA (rRNA)?

    <p>Component of ribosomes, the protein-synthesizing complexes</p> Signup and view all the answers

    What is the purpose of messenger RNA (mRNA)?

    <p>Carrying information for protein synthesis from DNA to ribosomes</p> Signup and view all the answers

    How is DNA grouped into codons?

    <p>Into threes</p> Signup and view all the answers

    Where does translation occur?

    <p>In the ribosomes</p> Signup and view all the answers

    What is the proportion of proteins in a cell?

    <p>A huge proportion of the cell, after water</p> Signup and view all the answers

    What is the relationship between codons and amino acids during translation?

    <p>One codon corresponds to one amino acid</p> Signup and view all the answers

    What is the function of nucleotides in metabolic transactions?

    <p>Serve as energy currency</p> Signup and view all the answers

    What is the function of cAMP?

    <p>Serve as a second messenger of hormones</p> Signup and view all the answers

    What is the basic unit for the synthesis of DNA and RNA?

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

    What are the two major purine bases found in DNA and RNA?

    <p>Adenine and Guanine</p> Signup and view all the answers

    What is the term for the process of reusing nitrogenous bases resulting from normal cell turnover?

    <p>Salvage pathways</p> Signup and view all the answers

    What is the term for a nitrogenous base attached to a pentose sugar through a glycosidic bond?

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

    What is the function of nucleotides in carbohydrate synthesis?

    <p>Synthesize carbohydrates</p> Signup and view all the answers

    What is the term for the modified bases found in viral DNA and transfer RNA?

    <p>Unusual bases</p> Signup and view all the answers

    What is produced if the sugar is ribose?

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

    What is the prefix added to the names of deoxyribonucleosides of A, G, C, and T?

    <p>Deoxy-</p> Signup and view all the answers

    What type of pentose is found in the recurring deoxyribonucleotide units of DNA?

    <p>2'-deoxy-D-ribose</p> Signup and view all the answers

    What is formed when one phosphate group is attached to a nucleoside?

    <p>Nucleoside monophosphate</p> Signup and view all the answers

    What is the function of nucleic acids in cells?

    <p>Storage and expression of genetic information</p> Signup and view all the answers

    Where can DNA be found in plant cells?

    <p>In chromosomes, mitochondria, and chloroplasts</p> Signup and view all the answers

    What is the difference between ribonucleosides and deoxyribonucleosides?

    <p>Type of sugar molecule</p> Signup and view all the answers

    What is the name of the nucleotide formed when adenosine is attached to three phosphate groups?

    <p>Adenosine triphosphate</p> Signup and view all the answers

    Study Notes

    Molecular Biology

    • Molecular biology is the branch of biology that studies gene structure and function at the molecular level, overlapping with genetics and biochemistry.
    • The field primarily concerns interactions between DNA, RNA, and protein biosynthesis, as well as how these interactions are regulated.

    Cells, Genome, Gene, and DNA

    • Almost all cells of a living organism contain genetic information in the form of DNA.
    • Cells from different parts of an organism have the same DNA.
    • Unicellular organisms are prokaryotes, while multicellular organisms are eukaryotes.
    • The genome refers to the total genetic information of an organism, encoded in DNA (or RNA for some viruses).
    • A gene is the basic unit of inheritance, a segment of DNA containing information required for the synthesis of a functional biological product (protein or RNA).

    DNA Structure and Function

    • DNA is contained in the nucleus, arranged in 22 chromosomes, plus two sex chromosomes, with two copies of each (total 46 chromosomes).
    • DNA is 99.9% identical to other humans and 98% to chimpanzees.
    • DNA is about 2 meters long, which is so long that it would stretch to the sun and back 600 times; it is tightly packed in the nucleus.
    • DNA carries the blueprint for life, duplicates for new cells, and makes proteins for biological functions.
    • The DNA molecule is composed of two complementary strands, 5' C-G-A-T-T-G-C-A-A-C-G-A-T-G-C 3' and 3' G-C-T-A-A-C-G-T-T-G-C-T-A-C-G 5'.

    Gene Structure

    • A gene is a segment of DNA with specific instructions for the production of one specific protein.
    • Genes are located on chromosomes at specific loci.
    • Genes must have exons, a start site, a stop site, and a control region.

    RNA and its Types

    • RNAs have a broader range of functions, including:
      • Ribosomal RNAs (rRNAs) as components of ribosomes, synthesizing proteins.
      • Messenger RNAs (mRNAs) as intermediaries, carrying information for protein synthesis.
      • Transfer RNAs (tRNAs) as adapter molecules, translating mRNA information into amino acid sequences.
      • Other RNAs with special functions (snRNA, snoRNA, etc.).

    Messenger RNA

    • mRNA is composed of codons, groups of three nucleotides.
    • Start and stop codons exist.
    • mRNA is modified and travels out of the nucleus.

    Translation

    • Translation uses mRNA as a template to make proteins in ribosomes.
    • One codon corresponds to one amino acid.

    Proteins

    • Proteins make up a huge proportion of cell components (after water).
    • Proteins have many functions:
      • Structural (e.g., collagen in bone)
      • Enzymatic
      • Transmembrane receptors
      • Hormonal
    • Proteins have four levels of structure.

    Nucleotides Functions

    • Serve as energy currency in metabolic transactions (ATP, GTP).
    • Serve as second messengers of hormones and other extracellular stimuli (cAMP).
    • Synthesize carbohydrates (UDP, CDP).
    • Serve as coenzymes (NAD, NADP, FADH2).
    • Store and transmit genetic information from one generation to the next.

    Nucleotide Structure

    • A nucleotide has three characteristic components:
      • A nitrogenous (nitrogen-containing) base
      • A pentose
      • One or more phosphates
    • The molecule without a phosphate group is called a nucleoside.

    Purines and Pyrimidines

    • Both DNA and RNA contain two major purine bases (adenine, guanine) and two major pyrimidines.
    • In DNA, the second common pyrimidine is thymine (T), while in RNA, it is uracil (U).

    Unusual Bases

    • Although nucleotides bearing major purines and pyrimidines are most common, both DNA and RNA contain some minor bases.
    • Found in viral DNA, transfer RNA, and modified bases include methylation, glycosylation, acetylation, and reduction.

    Nucleosides

    • The addition of a pentose sugar to a base through a glycosidic bond produces a nucleoside.
    • If the sugar is ribose, a ribonucleoside is produced; if the sugar is 2-deoxyribose, a deoxyribonucleoside is produced.
    • Examples include adenosine, guanosine, cytidine, and uridine.

    Nucleotides

    • The addition of one or more phosphate groups to a nucleoside produces a nucleotide.
    • Examples include nucleoside monophosphates (AMP), nucleoside diphosphates (ADP), and nucleoside triphosphates (ATP).

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    Test your knowledge of molecular biology, including gene structure and function, interactions between DNA, RNA and protein biosynthesis, and more.

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