Biology Overview Quiz
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Questions and Answers

Why is replication faster in prokaryotes compared to eukaryotes?

  • Eukaryotes utilize more complex replication proteins.
  • Prokaryotes have larger genomes that replicate more quickly.
  • Eukaryotes replicate in the cytoplasm instead of the nucleus.
  • Prokaryotes have a simpler structure with circular DNA. (correct)

    • What role do telomeres play in eukaryotic DNA replication?

  • They are involved in the proofreading mechanism.
  • They speed up the replication process.
  • They allow replication to occur at multiple origins.
  • They protect the ends of chromosomes from degradation. (correct)

    • What is a key difference in the replication machinery between eukaryotes and prokaryotes?

  • Prokaryotes have multiple origins of replication.
  • Eukaryotes require histones and complex proteins for chromatin remodeling. (correct)
  • Prokaryotes need telomerase for their chromosomes.
  • Eukaryotes employ circular DNA for replication.

    • Which of the following statements is true regarding eukaryotic DNA replication?

    <p>It involves multiple origins and occurs in the nucleus.</p> Signup and view all the answers

    In what way is the structure of DNA in prokaryotes significant during replication?

    <p>Prokaryotic DNA is circular, allowing for a faster replication process.</p> Signup and view all the answers

    What is the correct sequence of processes in the Central Dogma of Molecular Biology?

    <p>Replication → Transcription → Translation</p> Signup and view all the answers

    Which property of life specifically describes the ability of an organism to maintain stable internal conditions?

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

    What distinguishes prokaryotic cells from eukaryotic cells regarding their DNA structure?

    <p>Eukaryotes contain multiple chromosomes while prokaryotes contain one circular chromosome.</p> Signup and view all the answers

    Which statement about viruses is true?

    <p>Viruses require a host cell to reproduce.</p> Signup and view all the answers

    Which of the following is NOT a property of life?

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

    What is the main mode of reproduction for Paramecium?

    <p>Binary fission</p> Signup and view all the answers

    What size range differentiates prokaryotic cells from eukaryotic cells?

    <p>Prokaryotic cells range from 0.5-10 µm in size.</p> Signup and view all the answers

    Which of the following cellular structures is found in eukaryotic cells but absent in prokaryotic cells?

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

    What primarily determines the host specificity of a virus?

    <p>The affinity of capsid proteins to host cell receptors</p> Signup and view all the answers

    Which of the following correctly describes prions?

    <p>They are infectious proteins that cause other proteins to misfold.</p> Signup and view all the answers

    How does mitochondrial DNA (mtDNA) differ from nuclear DNA (nDNA)?

    <p>mtDNA is circular and varies in copy number with cell function.</p> Signup and view all the answers

    What key characteristic differentiates eukaryotic somatic cells from germ cells?

    <p>Somatic cells have two copies of genetic information, while germ cells have one.</p> Signup and view all the answers

    Which nitrogenous base is found in RNA but not in DNA?

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

    What role does the major groove of DNA play?

    <p>It binds to proteins that are essential for DNA replication.</p> Signup and view all the answers

    Which type of RNA is primarily responsible for the actual synthesis of proteins?

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

    What structural feature characterizes both DNA and RNA?

    <p>Both are made of nucleotides consisting of a sugar, phosphate, and base.</p> Signup and view all the answers

    How do plasmids contribute to bacterial genetic diversity?

    <p>Plasmids can transfer genetic material between different bacteria.</p> Signup and view all the answers

    What is a primary function of ribosomal RNA (rRNA)?

    <p>Forming part of the ribosome and catalyzing peptide bonds.</p> Signup and view all the answers

    What is the composition of a nucleotide?

    <p>A pentose sugar, a phosphate group, and a nitrogenous base.</p> Signup and view all the answers

    Which type of cell lacks a cell wall and has a liquid-like structure?

    <p>Animal cells</p> Signup and view all the answers

    The double-stranded nature of DNA allows for what primary function?

    <p>Stabilization of genetic information.</p> Signup and view all the answers

    What is one of the roles of non-coding RNAs in cells?

    <p>They regulate gene expression and epigenetics.</p> Signup and view all the answers

    What enzyme is responsible for unwinding the DNA double helix during replication?

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

    Which DNA polymerase is primarily responsible for synthesizing the leading strand in eukaryotic cells?

    <p>DNA polymerase ε</p> Signup and view all the answers

    What problem arises during the replication of the lagging strand?

    <p>Lack of free 3' OH group</p> Signup and view all the answers

    Which of the following enzymes is responsible for sealing the gaps between Okazaki fragments?

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

    During the termination phase of DNA replication, what occurs to telomeres with each cell division in eukaryotes?

    <p>They shorten</p> Signup and view all the answers

    What type of RNA component is part of the telomerase enzyme?

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

    How do eukaryotic cells differ from prokaryotic cells in terms of origins of replication?

    <p>Prokaryotes have a single origin, eukaryotes have multiple.</p> Signup and view all the answers

    What specific role does RNase H perform during DNA replication?

    <p>Removes RNA primers</p> Signup and view all the answers

    Which strand of DNA is synthesized continuously during replication?

    <p>Leading strand</p> Signup and view all the answers

    Which of the following best describes the main difference in DNA structure between eukaryotes and prokaryotes?

    <p>Eukaryotes have linear DNA complexed with histones, while prokaryotes have circular DNA.</p> Signup and view all the answers

    What is the primary energy source for the polymerization of DNA during replication?

    <p>Pyrophosphate hydrolysis</p> Signup and view all the answers

    What is the direction of synthesis for all newly added nucleotides during DNA replication?

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

    During DNA replication, what is the role of topoisomerase?

    <p>To prevent supercoiling of the DNA</p> Signup and view all the answers

    What defines the semi-conservative nature of DNA replication?

    <p>Each new DNA molecule contains one old and one new strand.</p> Signup and view all the answers

    The flow of genetic information follows the order DNA → RNA → ______.

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

    Paramecia are surrounded by small hairs called ______ that allow them to move.

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

    Eukaryotes have a ______ and membrane-bound organelles, unlike prokaryotes.

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

    Viruses must infect a ______ to grow and reproduce.

    <p>host-cell</p> Signup and view all the answers

    Life is organized into ______, which are the basic units of life.

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

    The primary reproduction method for Paramecium is ______.

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

    Prokaryotes are generally ______ in size compared to eukaryotes.

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

    Both eukaryotes and prokaryotes contain ______ as their genetic material.

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

    Eukaryotes have ______ DNA, while prokaryotes have circular DNA.

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

    In eukaryotes, replication occurs in the ______.

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

    Eukaryotic cells need the enzyme ______ to maintain telomeres.

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

    Eukaryotes require a more complex set of replication ______ due to the chromatin structure.

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

    Prokaryotes replicate their DNA ______ than eukaryotes due to their simpler structure.

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

    The infectious particles made of nucleic acids are surrounded by a protein coat called a ______.

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

    Bacteriophages specifically infect ______.

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

    Prions can cause neuro-degenerative disorders by misfolding ______ proteins.

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

    In prokaryotes, DNA is typically ______ and located in a structure called the nucleoid.

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

    Plasmids are small, circular ______ that can provide advantages like antibiotic resistance.

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

    Nuclear DNA (nDNA) is linear and ______-stranded.

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

    Chloroplast DNA (cpDNA) is typically ______ and involved in photosynthesis.

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

    Animal cells lack a cell wall, whereas plant cells have cell walls made of ______.

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

    MRNA delivers copied information to the ______ for protein synthesis.

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

    Transfer RNA (tRNA) binds activated amino acids and delivers them to ______.

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

    In DNA, A pairs with T and G pairs with ______.

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

    RNA is typically ______-stranded and can form loops and folds.

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

    The ______ groove of DNA binds to specific proteins and is crucial for transcription initiation.

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

    Non-coding RNA molecules are involved in ______ regulation, influencing cellular processes.

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

    Viruses and proviruses consist of nucleic acid molecules; they have ______ structure.

    <p>no cell</p> Signup and view all the answers

    RRNA forms the core of ______, catalyzing peptide bonds in proteins.

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

    In eukaryotic cells, DNA replication occurs in the ______ phase of the cell cycle.

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

    During DNA replication, helicase uncoils the double-helix by breaking ______ bonds.

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

    The leading strand is synthesized in the ______ direction.

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

    The RNA component of telomerase serves as a ______ to synthesize the single-stranded telomere cap.

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

    In prokaryotic cells, DNA replication occurs in the ______ since they lack a nucleus.

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

    Okazaki fragments are formed during the synthesis of the ______ strand.

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

    DNA polymerase β is responsible for filling in gaps left after the removal of ______ primers.

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

    The enzyme ______ connects newly added nucleotides by sealing the DNA backbone.

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

    The telomeres in humans consist of repeated nucleotide sequences known as ______.

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

    In eukaryotic DNA replication, multiple ______ of replication speed up the process along linear chromosomes.

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

    During the elongation phase, DNA polymerase epsilon (ε) synthesizes the ______ strand.

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

    DNA polymerase III primarily performs the bulk of DNA synthesis in ______ cells.

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

    The end-replication problem in eukaryotes is primarily associated with ______.

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

    Study Notes

    Central Dogma of Molecular Biology

    • Describes the flow of genetic information in organisms.
    • DNA replicates itself.
    • DNA is transcribed into RNA.
    • RNA is translated into proteins.
    • Information flows from DNA to RNA to protein.

    Properties of Life

    • Life is organized into cells.
    • Genetic information is stored in DNA and expressed through RNA.
    • Organisms synthesize proteins.
    • Metabolism involves chemical reactions for life maintenance.
    • Homeostasis maintains internal conditions.
    • Reproduction ensures the transmission of genetic material.

    Eukaryotes vs. Prokaryotes

    • Both have DNA, ribosomes, and plasma membranes.
    • Eukaryotes:
      • Have a nucleus, membrane-bound organelles, 80s ribosomes, and are larger (10-100 µm).
    • Prokaryotes:
      • Lack a nucleus (naked DNA), have a different cell wall composition (peptidoglycan), no membrane-bound organelles, 70s ribosomes, and are smaller (0.5-10 µm).

    Viruses and Prions

    • Disease-causing agents without cellular structure.
    • Cannot grow or self-reproduce, lack metabolism.
    • Require a host cell to grow and reproduce.
    • Viruses are cell (species) specific.
    • Viruses are infectious particles containing nucleic acids (DNA or RNA) encased in a protein coat (capsid).
    • Viruses require a host cell for replication.
    • Bacteriophages are viruses that infect bacteria.
    • Prions are infectious proteins that misfold normal proteins, causing diseases like Creutzfeldt-Jakob disease.
    • Prions lack nucleic acids and infect cells in the nervous system.

    Storage of Information in Cells

    • Prokaryotes:
      • DNA is circular and located in the nucleoid, a region with no surrounding membrane.
      • DNA is not attached to histone proteins.
      • Prokaryotes are haploid, having only one copy of genetic information.
      • Plasmids are small, circular DNA molecules containing extra genetic information.
    • Eukaryotes:
      • nDNA (nuclear DNA):
        • Linear and double-stranded.
        • Found in somatic (diploid) and germ (haploid) cells.
      • mtDNA (mitochondrial DNA):
        • Circular and double-stranded.
        • Contains information for mitochondrial function.
      • cpDNA (chloroplast DNA):
        • Circular and double-stranded.
        • Contains information for chloroplast function.

    Types of Eukaryotic Cells

    • Animal Cells:
      • Lack cell walls.
      • Have mitochondria.
      • Possess centrosomes for cell division.
    • Plant Cells:
      • Have cell walls composed of cellulose.
      • Contain chloroplasts for photosynthesis.
    • Fungal Cells:
      • Have cell walls containing chitin.
      • Lack chloroplasts.
    • Somatic Cells:
      • Form the body (tissues, organs).
      • Not involved in sexual reproduction.
      • Diploid, having two sets of genetic information.
    • Germ Cells:
      • Responsible for sexual reproduction.
      • Include primordial cells and mature gametes.
      • Haploid, having one set of genetic information.

    Chemical Composition of Nucleic Acids

    • Nucleic Acids are polymers of nucleotides (DNA and RNA).
    • They contain nitrogenous bases (adenine, guanine, cytosine, thymine in DNA, uracil in RNA), a pentose sugar (deoxyribose or ribose), and a phosphate group.

    Structure of DNA and RNA

    • DNA:
      • Double-helix structure with complementary base pairing (A-T, G-C).
      • Antiparallel strands running in opposite directions (5' to 3' and 3' to 5').
    • RNA:
      • Single-stranded, capable of forming loops and folds.
      • Contains uracil instead of thymine.
    • The double helix is stabilized by hydrogen bonds between bases and stacking interactions of aromatic rings.
    • DNA grooves (major and minor) allow protein binding and DNA unwinding.

    Biological Roles of DNA and RNA

    • DNA:
      • Stores genetic information.
    • RNA:
      • mRNA: Carries information for protein synthesis from DNA to ribosomes.
      • tRNA: Transfers amino acids to ribosomes during protein synthesis.
      • rRNA: Forms the core of ribosomes and catalyzes peptide bond formation.

    DNA Replication

    • Occurs in the S phase of the cell cycle in eukaryotes and during binary fission in prokaryotes.
    • DNA polymerase catalyzes the process.
    • Steps:
      • Initiation:
        • Starts at the origin of replication.
        • Requires initiation proteins.
        • Helicase unwinds the double helix.
        • Topoisomerase prevents supercoiling.
        • Single-strand binding proteins stabilize the separated strands.
        • Primase synthesizes RNA primers.
      • Elongation:
        • DNA polymerase adds nucleotides to the 3' end of the primer.
        • Synthesizes in the 5' to 3' direction.
        • Leading strand: Continuous synthesis.
        • Lagging strand: Discontinuous synthesis in Okazaki fragments.
        • RNase H removes RNA primers.
        • DNA polymerase fills gaps.
        • DNA ligase seals the DNA strands.
      • Termination:
        • Telomeres shorten with each replication in eukaryotes.
        • Telomerase adds telomere sequences to maintain telomere length.
    • Replication of Leading and Lagging Strands:
      • Leading strand: Continuous synthesis in the same direction as the replication fork movement.
      • Lagging strand: Discontinuous synthesis opposite to the replication fork movement, producing Okazaki fragments.

    Differences in DNA Replication between Eukaryotes and Prokaryotes

    • Location:
      • Eukaryotes: Nucleus.
      • Prokaryotes: Cytoplasm.
    • Origins of Replication:
      • Eukaryotes: Multiple origins.
      • Prokaryotes: Single origin.
    • DNA:
      • Eukaryotes: Linear and complexed with histones.
      • Prokaryotes: Circular and not complexed with histones.
    • DNA Polymerase:
      • Eukaryotes: Multiple DNA polymerases.
      • Prokaryotes: Primarily DNA polymerase III.
    • Speed:
      • Eukaryotes: Slower.
      • Prokaryotes: Faster.
    • Telomeres:
      • Eukaryotes: Have telomeres.
      • Prokaryotes: Lack telomeres.
    • Replication Machinery:
      • Eukaryotes: More complex.
      • Prokaryotes: Simpler.

    Central Dogma of Molecular Biology

    • Describes the flow of genetic information in living organisms
    • Information flows in this order: DNA → RNA → Protein
    • DNA replication: DNA makes an exact copy of itself
    • Transcription: DNA is transcribed into RNA
    • Translation: RNA is translated into a protein

    Properties of Life

    • Life is organized into cells
    • Life stores genetic information in DNA and realizes it through RNA
    • Life synthesizes proteins
    • Metabolism: Chemical reactions that maintain life (e.g., ATP production)
    • Homeostasis: Regulation of internal conditions (e.g., body temperature)
    • Reproduction: Life reproduces to pass on genetic material

    Paramecium Example

    • Paramecium is a heterotrophic, eukaryotic organism
    • Paramecia are surrounded by cilia, which allow them to move
    • Paramecia have a cytostome (feeding groove), through which they engulf food
    • Food particles are digested in vacuoles containing enzymes
    • Solid waste is removed through an anal pore, and liquid waste is pumped out through contractile vacuoles
    • Gases enter and exit the cell via diffusion
    • Paramecia divide asexually (fission), but can also share genetic information via conjugation

    Eukaryotes and Prokaryotes

    • Both have DNA, ribosomes, and plasma membranes
    • Eukaryotes have a nucleus, membrane-bound organelles, 80s ribosomes, and are larger (10-100 µm)
    • Prokaryotes lack a nucleus (have naked DNA, one circular chromosome), their cell walls are made of peptidoglycan, they lack membrane-bound organelles, have 70s ribosomes, and are smaller (0.5-10 µm)

    Viruses and Prions

    • Disease-causing agents without cell structure
    • Cannot grow or reproduce independently, they must infect a host cell
    • Viruses are cell (species) specific, some can infect multiple species
    • Viruses are composed of nucleic acids (DNA or RNA) surrounded by a protein coat called a capsid
    • Bacteriophages are viruses that specifically infect bacteria
    • Prions are infectious proteins that cause diseases by misfolding normal proteins
    • Prions lack nucleic acids
    • Prions infect cells in the nervous systems
    • A prion is a misfolded version of a normal protein found in nerve cells
    • When a prion infects a nerve cell, it promotes the misfolding of healthy proteins, leading to a self-propagating cascade of misfolded proteins

    Storage of Information in Cells

    • Prokaryotes: DNA is circular and located in a structure called the nucleoid
    • Nucleoid is a complex of DNA and RNA with nucleoproteins and lacks a membrane
    • Bacteria are haploid organisms, meaning they have one copy of genetic information
    • Prokaryotes often have plasmids: small, circular molecules containing a small part of genetic information
    • Plasmids can contribute to antibiotic resistance, and some are mobile, allowing them to transfer between bacteria
    • Eukaryotic cells store genetic information in nDNA, mtDNA, and cpDNA
    • Nuclear DNA (nDNA): linear and double-stranded, found in somatic cells (diploid) and germ cells (haploid), contains information for organism development
    • Mitochondrial DNA (mtDNA): circular and double-stranded, the number of copies varies depending on cell function, contains information essential for mitochondrial function
    • Chloroplast DNA (cpDNA): circular and double-stranded, contains information for chloroplast function

    Types of Eukaryotic Cells

    • Animal Cells: lack cell walls, have mitochondria, and centrosomes for cell division, are flexible
    • Plant Cells: have cell walls (cellulose), chloroplasts, and are immobile
    • Fungal Cells: have cell walls made of chitin, lack chloroplasts, and are immobile
    • Somatic Cells: form the body (tissues, organs), are not involved in sexual reproduction, are diploid
    • Germ Cells: responsible for sexual reproduction (include all stages from primordial cells to gametes), are haploid

    Chemical Composition of Nucleic Acids

    • Nucleic acids are polymers of nucleotides (DNA and RNA)
    • Nucleotide components:
      • Nitrogenous Base: purines (Adenine, Guanine) and pyrimidines (Cytosine, Thymine in DNA, Uracil in RNA)
      • Pentose Sugar: Deoxyribose (in DNA), Ribose (in RNA)
      • Phosphate Group: Forms the backbone of the nucleic acid

    Structure of DNA and RNA

    • DNA: double-helix structure formed by complementary base pairing (A-T, G-C), strands run antiparallel (5' to 3' and 3' to 5')
    • RNA: single-stranded, can form loops and folds (secondary structure), and complex tertiary structures, contains Uracil instead of Thymine
    • The DNA double-helix is stabilized by hydrogen bonds between the bases and by stacking interactions of the aromatic rings of the bases in the center of the helix

    Biological Roles of DNA and RNA

    • DNA: stores genetic information
    • RNA: realizes DNA information
      • mRNA: carries copied information for protein synthesis from DNA to ribosomes
      • tRNA: transfers amino acids to ribosomes during protein synthesis
      • rRNA: forms the core of ribosomes, catalyzes peptide bond formation in proteins
    • Regulatory RNAs:
      • snRNA: involved in RNA splicing
      • ncRNA: regulates gene expression
      • miRNA: regulates gene expression by binding mRNA and causing its breakdown
      • siRNA: regulates gene expression by binding mRNA and causing its breakdown
      • lncRNA: long non-coding RNA, involved in various functions
    • Key Mnemonic: "DNA Stores, RNA Realizes and Delivers"

    DNA Replication

    • DNA replication is the process of making a duplicate of the DNA molecule (semiconservative)

    • Replication is catalyzed by enzymes

    • Replication ensures that each daughter cell receives a complete set of chromosomes during cell division

    • In eukaryotic cells, replication occurs during the S phase of the cell cycle

    • In prokaryotes, replication starts with binary fission

    • Steps:

      • Initiation:
        • Starts at the origin of replication, a specific DNA sequence
        • Requires initiation proteins
        • Helicase unwinds the double-helix by breaking hydrogen bonds
        • Topoisomerase prevents supercoiling of the DNA
        • Single-strand binding proteins prevent the reformation of the double helix
        • Leading vs. Lagging Strand:
          • Leading strand: continuous synthesis of new DNA (5' to 3')
          • Lagging strand: discontinuous synthesis in short sections called Okazaki fragments (3' to 5')
        • Primers and Primase:
          • RNA primers (10-12 nucleotides long) are synthesized by primase
          • The polymerase complex starts working from the primer added
        • Polymerization:
          • DNA polymerase adds free dNTPs (deoxyribonucleotide triphosphates) to the 3' OH end of the primer
          • Synthesis always proceed in the 5' to 3' direction
          • Energy for Polymerization: the breaking of the bond between phosphate groups in dNTPs releases energy, driving the polymerization process.
      • Elongation:
        • DNA polymerase epsilon (ε) synthesizes the leading strand
        • DNA polymerase delta (δ) synthesizes the lagging strand
        • Both polymerases have repair activity to fix mistakes
        • RNA Primer Removal: RNase H recognizes and degrades RNA primers
        • Filling Gaps: DNA polymerase beta (β) fills in the gaps
        • Sealing the DNA: DNA ligase connects the newly added nucleotides
      • Termination:
        • The end of replication occurs at telomeres (ends of chromosomes)
        • Telomeres are made of repeated nucleotide sequences and are species-specific (TTAGGG repeats in humans)
        • The 3' end of the telomere is single-stranded and forms a protective cap
        • End-Replication Problem: due to the lagging strand, the ends of chromosomes can not be fully replicated
        • Telomerase: enzyme that adds telomere sequences to the end of DNA

    • Key Points:

      • Polymerase ε: Leading strand
      • Polymerase δ: Lagging strand
      • RNase H: Removes RNA primers
      • Polymerase β: Fills in gaps
      • Ligase: Seals the DNA strands

    Differences in Replication of Leading and Lagging Strands

    • DNA strands are antiparallel, meaning that one strand runs 5' to 3' and the other runs 3' to 5'
    • DNA polymerase can only synthesize new DNA in the 5' to 3' direction
    • Leading strand: synthesized continuously in the same direction as the replication fork moves
    • Lagging strand: synthesized discontinuously in short fragments called Okazaki fragments
      • Each Okazaki fragment is initiated by an RNA primer
      • The RNA primers are removed by RNase H
      • The gaps are filled by DNA polymerase
      • The fragments are sealed by DNA ligase

    Differences in DNA Replication between Eukaryotes and Prokaryotes

    • Eukaryotes:
      • Replication occurs in the nucleus
      • Multiple origins of replication on linear chromosomes
      • Linear DNA complexed with histones, resulting in telomere shortening
      • Multiple types of DNA polymerases (e.g., α, δ, ε) with specialized roles
      • Slower replication due to chromatin structure and larger genome size
      • Telomeres are maintained by telomerase
      • More complex replication machinery due to chromatin structure and larger genome size
    • Prokaryotes:
      • Replication occurs in the cytoplasm
      • Single origin of replication on circular DNA
      • Circular DNA, no telomeres
      • Primarily uses DNA polymerase III for synthesis and DNA polymerase I for primer removal and gap filling
      • Faster replication due to smaller genome and simpler structure
      • Lack telomeres
      • Simpler replication machinery due to absence of chromatin and smaller genome

    Memorization Tips:

    • Central Dogma: (DNA → RNA → Transcription)
    • Prokaryotes vs.Eukaryotes: "Euks have Nucs, Proks don't!"
    • Viruses and Prions
    • DNA vs. RNA: (DNA = Double-stranded, RNA = Single-stranded)
    • DNA Replication Process: "Helicase Opens, Polymerase Copies, Ligase Seals!"

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    Test your knowledge on key concepts in biology, including the Central Dogma of Molecular Biology, properties of life, and the differences between eukaryotes and prokaryotes. Additionally, explore the unique characteristics of viruses and prions. This quiz encompasses fundamental biological principles that are crucial for understanding life.

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