Nucleic Acids and the Origin of Life
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Questions and Answers

What is unique about RNA compared to DNA?

  • RNA contains thymine.
  • RNA has uracil instead of thymine. (correct)
  • RNA cannot form 3-D structures.
  • RNA is double-stranded.

    • DNA can reproduce itself through a process known as translation.

    False

    What is the term for the complete set of DNA in an organism?

    genome

    The process of copying DNA sequences into RNA is known as ______.

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

    Match the following terms with their definitions:

    <p>Replication = Process by which DNA makes a copy of itself Transcription = Process of copying DNA into RNA Translation = Process of converting RNA into a polypeptide Gene = Sequence of DNA that is transcribed into RNA</p> Signup and view all the answers

    What is the function of ATP in biochemical reactions?

    <p>Energy transfer</p> Signup and view all the answers

    Francesco Redi proved that spontaneous generation does not occur.

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

    Name one gas that was used in the Miller and Urey experiments to simulate early Earth conditions.

    <p>H2 (hydrogen)</p> Signup and view all the answers

    GTP is primarily an energy source in __________ synthesis.

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

    What did Louis Pasteur's experiments demonstrate?

    <p>Microorganisms arise only from other microorganisms.</p> Signup and view all the answers

    Match the following experiments with their contributors:

    <p>Redi's Experiment = Disproved spontaneous generation Pasteur's Experiment = Demonstrated that microorganisms arise from other microorganisms Miller and Urey Experiment = Simulated conditions of early Earth to form organic molecules</p> Signup and view all the answers

    The Miller and Urey experiments concluded that life forms on Earth originated through spontaneous generation.

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

    Chemical evolution theorizes that life began through the formation of __________ molecules under specific conditions.

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

    What molecule is suggested to have originated from meteorites according to the given information?

    <p>Purines and pyrimidines</p> Signup and view all the answers

    It is widely accepted that organisms can survive in meteorites.

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

    What is RNA proposed to have acted as in early life forms?

    <p>A catalyst</p> Signup and view all the answers

    The process of chemically testing Martian soil involves exposing it to nutrients labeled with __________.

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

    Match the following concepts related to the origin of life:

    <p>Catalysts = Proteins called enzymes Meteorites = Source of organic molecules RNA = Possible first catalyst Polymers = Formed from small molecules</p> Signup and view all the answers

    Which hypothesis was tested by the Mars Viking landers?

    <p>Martian soil can show signs of life.</p> Signup and view all the answers

    DNA evolved from RNA.

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

    Which of the following correctly identifies the two types of nucleic acids?

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

    The next stage in chemical evolution theory involves explaining how __________ formed.

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

    DNA contains ribose as its sugar component.

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

    What are the monomers that make up nucleic acids?

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

    In nucleic acids, nucleotides are linked by __________ bonds.

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

    Match the following nitrogenous bases with their classifications:

    <p>Adenine = Purine Cytosine = Pyrimidine Guanine = Purine Thymine = Pyrimidine</p> Signup and view all the answers

    Which of these statements about complementary base pairing is true?

    <p>Purines pair with pyrimidines.</p> Signup and view all the answers

    The growth direction of nucleic acids is from 3' to 5'.

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

    What are the two types of nitrogenous bases found in nucleic acids?

    <p>Purines and Pyrimidines</p> Signup and view all the answers

    What type of bacteria was identified in 3.5 billion-year-old rocks in Australia?

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

    Photosynthesis contributes to the specific ratio of carbon isotopes found in fossils.

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

    How many years did it likely take for the first cells to appear after Earth's formation?

    <p>500 million to 1 billion years</p> Signup and view all the answers

    NASA's primary goal includes finding evidence of life on ______.

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

    Which of the following missions aims to bring Martian soil samples back to Earth?

    <p>Mars Sample Return mission</p> Signup and view all the answers

    The Curiosity rover found complex organic compounds on Mars soil in 2018.

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

    Match the following moons with their associated missions:

    <p>Europa = Jupiter's moon being investigated for potential life Enceladus = Saturn's moon being explored Titan = Saturn's largest moon with a thick atmosphere Bennu = Asteroid from which soil samples are planned to be returned</p> Signup and view all the answers

    Evidence for current or past life on Mars is a primary goal of ______.

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

    What does the 'RNA world' hypothesis primarily suggest about the origin of life?

    <p>RNA was the first molecule to evolve.</p> Signup and view all the answers

    Ribozymes can catalyze peptide linkages.

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

    What must the compounds involved in the origin of life have been concentrated in?

    <p>A compartment</p> Signup and view all the answers

    If short nucleic acid strands capable of self-replication are placed inside protocells, nucleotides can pass through the bilayer and be incorporated into __________ chains.

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

    What role does reverse transcriptase play in retroviruses?

    <p>It catalyzes the synthesis of DNA from RNA.</p> Signup and view all the answers

    Protocells are not capable of replication.

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

    What are protocells proposed to help explain in terms of biological evolution?

    <p>The evolution of cells</p> Signup and view all the answers

    Study Notes

    Nucleic Acids and the Origin of Life

    • Nucleic acids are polymers specialized for storing, transmitting, and using genetic information
    • DNA = deoxyribonucleic acid
    • RNA = ribonucleic acid
    • Monomers of nucleic acids are nucleotides, composed of a pentose sugar, a nitrogenous base, and a phosphate group
    • DNA contains deoxyribose, while RNA contains ribose
    • Nucleosides consist of a pentose sugar and a nitrogenous base
    • Nitrogenous bases are divided into pyrimidines (single ring) and purines (fused double ring)
    • Pyrimidines include cytosine (C), thymine (T), and uracil (U)
    • Purines include adenine (A) and guanine (G)
    • Nucleotides are linked by phosphodiester bonds
    • Phosphate groups connect the 3' carbon of one sugar to the 5' carbon of another sugar
    • Nucleic acids grow in the 5' to 3' direction
    • DNA bases are: adenine (A), guanine (G), cytosine (C), and thymine (T)
    • The bases pair in a complementary manner: purines pair with pyrimidines through hydrogen bonds
    • RNA: single-stranded but can form 3-D structures through base pairing between different regions
    • RNA has uracil (U) instead of thymine (T)
    • RNA and DNA can also pair with each other in a complementary manner.
    • DNA forms a double helix
    • DNA sequences are copied into RNA (transcription)
    • RNA sequences specify the amino acid sequence in a polypeptide (translation)
    • Transcription + translation = gene expression
    • DNA replication and transcription rely on base-pairing properties
    • The complete DNA set in an organism is its genome
    • Genes are sequences of DNA transcribed into RNA
    • DNA carries hereditary information from one generation to the next
    • Closely related species have more similar base sequences
    • DNA sequencing tracks evolutionary relationships
    • Nucleotides have other roles (e.g ATP, GTP, cAMP) related to energy transfer, protein synthesis, and hormone action.
    • Early life forms were thought to arise from spontaneous generation
    • Francesco Redi disproved spontaneous generation in 1668
    • Louis Pasteur's experiments showed that microorganisms arise only from other microorganisms
    • Chemical evolution theory proposes that conditions on early Earth led to the formation of simple molecules (e.g. amino acids) which eventually led to life
    • Miller-Urey experiment simulated early Earth conditions to produce amino acids
    • Volcanoes can also contribute other gases such as CO2, N2, H2S and SO2 to the atmosphere
    • Some meteorites contain organic molecules like purines, pyrimidines and amino acids. This suggests life may have originated elsewhere and reached Earth
    • The Mars Viking landers sought evidence of life on Mars, but results were inconclusive
    • Current and planned missions to observe and sample Mars and its moons will look for signs of life on Mars.
    • RNA was likely the first catalyst, because some RNA molecules (ribozymes) have catalytic properties similar to enzymes.
    • Ribozymes can catalyze their own replication and protein synthesis.

    Investigating LIFE: Can We Find Evidence of Life on Mars?

    • A primary goal of NASA is finding evidence for current or past life on Mars
    • The Curiosity rover has found complex organic compounds on Mars.
    • Other rovers are planned by the European Space Agency and Russia.
    • A Mars Sample Return mission will collect Martian soil samples for analysis on Earth.
    • Future missions will investigate Jupiter's Europa and Saturn's Enceladus and Titan.
    • Another mission will bring samples of the asteroid Bennu.

    The Large Molecules of Life Originated from Small Molecules

    • The next stage of chemical evolution is explaining how polymers formed.
    • Models for this include powdered clays, hydrothermal vents, and hot pools.

    Cells Originated from Their Molecular Building Blocks

    • Compounds involved in the origin of life needed to be concentrated.
    • Today, living cells are separated from their environment by a membrane
    • Protocells can concentrate certain compounds and allow some molecules to pass through
    • Short nucleic acid strands that are capable of self-replication could be placed inside protocells
    • Nucleotides can pass through the protocell membrane. Newly formed nucleotides can be incorporated into polynucleotide chains
    • Protocells may have been a model for early cells due to their organized structure and ability to maintain a distinct interior environment.
    • Evidence of 3.5 billion-year-old cyanobacteria (blue-green bacteria) in Australian rocks shows their ability to perform photosynthesis using CO2 and yielding a specific carbon isotope ratio.
    • Several other bacteria may have been present.

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    Nucleic Acids and the Origin of Life PDF

    Description

    Explore the fundamental role of nucleic acids in storing and transmitting genetic information. This quiz covers the structures of DNA and RNA, their monomers (nucleotides), and the processes involved in their formation and function. Test your knowledge about nitrogenous bases, bonds, and the direction of nucleic acid growth.

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