Molecular Biology: DNA and Replication
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Questions and Answers

What is the atomic mass of an element if it has 6 protons and 8 neutrons?

  • 8
  • 14 (correct)
  • 18
  • 6

    • Which of the following represents the correct relationship between atomic number and neutrons?

  • Atomic number = Atomic mass + Number of neutrons
  • Number of neutrons = Atomic mass - Atomic number (correct)
  • Atomic mass = Atomic number + Number of neutrons
  • Number of neutrons = Atomic number + Atomic mass

    • As you move down a group of non-metals in the periodic table, what trend occurs?

  • Reactivity increases
  • State of matter remains the same
  • Atomic size decreases
  • Reactivity decreases (correct)

    • What characterizes covalent bonds in compounds?

    <p>Electrons are shared between non-metal atoms</p> Signup and view all the answers

    What is the primary reason for increased reactivity in group 2 metals as you go down the group?

    <p>Increased number of electron shells</p> Signup and view all the answers

    What defines the periods in the periodic table?

    <p>Number of electron shells</p> Signup and view all the answers

    Which of the following elements is likely to have the same chemical properties as other elements in its group?

    <p>A metal sharing the same number of valence electrons</p> Signup and view all the answers

    What is the term for the electrostatic force that holds ionic compounds together?

    <p>Ionic bond</p> Signup and view all the answers

    What is the shape of DNA?

    <p>Double helix</p> Signup and view all the answers

    What term best describes a permanent change in the base sequence of DNA?

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

    Which of the following is a component of a nucleotide?

    <p>Phosphate group</p> Signup and view all the answers

    What role does DNA polymerase play in DNA replication?

    <p>Binds new base pairs</p> Signup and view all the answers

    Which of the following is not a potential effect of a mutation?

    <p>Immediate death</p> Signup and view all the answers

    What type of mutation involves the addition or deletion of a base?

    <p>Frameshift mutation</p> Signup and view all the answers

    In Mendel's experiments with pea plants, what trait was observed in the first generation?

    <p>Red plants</p> Signup and view all the answers

    How are dominant and recessive genes defined in the context of Mendel's experiments?

    <p>Dominant genes mask the expression of recessive genes.</p> Signup and view all the answers

    What is the primary function of B cells when they encounter an antigen?

    <p>To produce antibodies and memory cells specific to the antigen.</p> Signup and view all the answers

    How do B cells contribute to the secondary immune response?

    <p>They quickly generate Plasma B cells that produce previously encountered antibodies.</p> Signup and view all the answers

    What role do plasma B cells play in the immune response?

    <p>They are responsible for clumping together antigens and signaling phagocytes.</p> Signup and view all the answers

    What triggers the inflammatory response during an immune reaction?

    <p>Histamines released by immune cells.</p> Signup and view all the answers

    Which statement best describes the function of memory B cells?

    <p>They remain dormant until a previously encountered antigen re-enters the body.</p> Signup and view all the answers

    What is the role of fever in the immune response?

    <p>It makes the environment unfriendly for pathogens and enzymes.</p> Signup and view all the answers

    What is required for B cells to effectively bind to antigens?

    <p>Unique receptors specific to those antigens.</p> Signup and view all the answers

    What might happen during the primary immune response?

    <p>Inflammation and fever may occur as the immune system responds.</p> Signup and view all the answers

    What is the primary focus of the law of dominance in genetics?

    <p>Dominant traits overshadow recessive traits unless both recessive factors are inherited.</p> Signup and view all the answers

    Which best describes recombinant DNA technology?

    <p>Combining DNA from different organisms to create desired traits.</p> Signup and view all the answers

    What is a primary benefit of genetically modified organisms (GMOs) in agriculture?

    <p>Enhanced nutritional quality of crops.</p> Signup and view all the answers

    What is the significance of the Human Genome Project?

    <p>It determined the base sequence pairs of human DNA, aiding in understanding hereditary diseases.</p> Signup and view all the answers

    Which statement best defines biotechnology?

    <p>Using biological systems to develop products for human benefit.</p> Signup and view all the answers

    How are bacteria used in recombinant DNA technology for insulin production?

    <p>They are genetically modified to synthesize insulin when cultured.</p> Signup and view all the answers

    Which characteristic distinguishes embryonic stem cells from adult stem cells?

    <p>Embryonic stem cells can differentiate into all cell types in the body.</p> Signup and view all the answers

    What is one of the applications of cloning in biotechnology?

    <p>For therapeutic purposes, such as regenerative medicine.</p> Signup and view all the answers

    What defines a galaxy in the universe?

    <p>A massive group of stars, gas, and dark matter, bound by gravity.</p> Signup and view all the answers

    What unit of measurement is used for distances within our solar system?

    <p>Astronomical units</p> Signup and view all the answers

    What process is the primary source of energy in stars?

    <p>Nuclear fusion</p> Signup and view all the answers

    Which of the following describes a red giant?

    <p>A star that is larger and cooler than a main sequence star.</p> Signup and view all the answers

    What occurs when a star enters the white dwarf stage?

    <p>The star collapses due to gravitational forces overpowering expansive forces.</p> Signup and view all the answers

    What happens to a nebula as it evolves into a protostar?

    <p>Gravity causes it to become hot and dense, emitting light.</p> Signup and view all the answers

    Which statement best describes a black dwarf?

    <p>A cooling remnant that has ceased all nuclear reactions.</p> Signup and view all the answers

    How many kilometers are in one light year?

    <p>9.46 x 10^12 km</p> Signup and view all the answers

    Study Notes

    DNA

    • A polymer found in the nucleus of eukaryotic cells and cytoplasm of prokaryotic cells
    • Double helix shape
    • Sugar-phosphate backbone
    • Complementary base pairing: adenine, guanine, cytosine, thymine
    • Nucleotides: deoxyribose sugar, phosphate, nucleotide base
    • Hydrogen bonds between complementary bases

    DNA Replication

    • Occurs in the nucleus before cell division
    • Results in a polynucleotide chain with half of the original sequence
    • The two strands are separated as the hydrogen bonds between the bases breaks
    • The exposed nucleotides are attracted to the free complementary bases
    • The new pairs are bonded with DNA polymerase enzyme

    Mutations

    • Permanent change in the base sequence of DNA caused by mutagens or malfunctions during DNA replication
    • Point Mutation: A base sequence is changed
    • Frameshift Mutation: A base is added or deleted
    • Can have no effects, advantageous effects, disadvantageous effects
    • Environmental causes: Radiation: Cigarette smoke, UV radiation; Chemicals: Carcinogens, Processed foods; Infectious agents: Bacteria, Viruses.

    Mendel's Experiments

    • Crossbred red and white pea plants
    • First generation: Red plants
    • Second generation: Red and white plants
    • Crosspollinated plants based on different features to make discoveries on how traits are inherited
    • 7 characteristics were tested

    Gene and Allele

    • Gene: A small section of DNA that codes for a specific protein to produce characteristics
    • Allele: Variations of genes (dominant and recessive)

    Mendel's Laws

    • Law of segregation: One hereditary factor from each parent
    • Law of independent assortment: Different traits have equal opportunity of occurring together
    • Law of dominance: Offspring will inherit dominant characteristics, unless both recessive factors are inherited

    Biotechnology

    • The use of an organism to make or change a product to be of service to humans

    Recombinant DNA Technology

    • Combining DNA from different organisms to produce desired genetic traits
    • Example: Insulin production:
      • Insulin gene is isolated
      • Inserted into the plasmid acts as a vector
      • Introduced to the bacteria, bacteria that successfully take up the plasmid are selected by antibiotic resistant markers
      • Cultured in large fermentation tanks where they grow and reproduce, producing more insulin protein
      • Insulin protein is extracted and used for medical purposes

    Genetically Modified Organisms (GMOs)

    • Organisms whose genes have been altered
    • Reduced pesticides
    • Enhanced food quality
    • Form pharmaceuticals
    • Increase agricultural productivity
    • Crops: herbicide and pest resistance, nutritional advancement
    • Animals: Increased growth, disease resistance, improved production quality.

    Human Genome Project

    • International research project from 1990-2003
    • Determine the base sequence pairs of the genome of a man and a woman
    • Found the order of the base pair for all 46 chromosomes
    • Importance: Diagnosing and treating hereditary diseases and conditions

    The Periodic Table

    • Atomic number: Number of protons
    • Atomic Mass: Number of protons + Number of neutrons
    • Electron configuration: In energy levels around the nucleus.

    Determining the Number of Neutrons

    • Atomic mass- Atomic Number= Number of Neutrons
    • Groups: Horizontal rows in which depict the valence electrons/charge of the elements in each group
    • Periods: Vertical columns which show the number of shells for all the elements in each period.
    • Trends in physical and chemical properties:
      • All elements in each group have the same chemical properties as they take part in the same reactions since, they need to lose or gain the same number of electrons
      • Metals: Reactivity increases as you move down the group as the number of shells increases weakening the force of attraction between the nucleus and valence electron making it easy for the electrons to leave
      • Non-metals: Reactivity decreases as you move down the group as the number of shells increasing so the forces between the nuclei and valence electrons decrease making it hard to attract electrons
      • Non-metals: State of matter changes from gas to solid as you move down the group.

    Chemical Formulae

    • Ionic compounds: Held together by ionic bonds which is the electrostatic force of attraction between oppositely charge particles of metal and non-metal atoms, in order to become stable
    • Covalent compounds: Held together by covalent bonds which is when electrons are shared between non-metal atoms in order to gain stability.

    The Human Immune System - General

    • First line of defence: Skin, mucus membranes, cilia in respiratory tract
    • Second line of defence: Phagocytosis, inflammation, fever

    Phagocytosis

    • Specialised white blood cells called phagocytes (neutrophils and macrophages)
    • Engulf pathogens, form their membrane around it, and release enzymes that breakdown the pathogens

    Inflammation

    • Caused by chemical signals called histamines that are sent to the brain, to increase blood-flow in the area where the pathogens detected
    • Increase blood flow results in more phagocytes reaching the pathogens and destroying it
    • The increased blood flow in a certain area causes, redness and swelling in that area known as inflammation

    Fever

    • The body releases chemical signals to the part of the brain known as hypothalamus that is responsible for controlling body temperature
    • Raises the body temperature, making it unfit for enzymes, pathogens to survive

    Role of B cells in the Immune System

    • B cells produced in the bone marrow
    • Unique receptors that bind to specific antigens
    • B cells divide into Plasma B cells and Memory B cells
    • Primary response: Plasma B cells create antibodies for the antigens, clumping them together and destroying them (neutralise the antigen, inactivating them) or signalling for phagocytes to do so.This process may take a few days and cause inflammation and fever
    • Secondary response: If the pathogen were to re-enter the body, the memory cells would divide into Plasma B cells.They remember the antibody for the specific antigen and produce it if the pathogen re-enters.This process is a lot faster than the first time an antigen enters the body

    Immunisation in Disease Prevention

    • Deliberately exposing the body to a weakened form of the antigen
    • Allows the body to produce antibodies and memory cells
    • If the individual encounters the actual harmful antigen, they will be able to fight it off before it can cause serious illness

    Astronomy

    • Galaxies: A massive group of stars, dust gas, stellar remnants and dark matter, bound together by gravity.
    • Stars: A colossal mass of gas and dust that is luminous and self-sufficient.It drives its energy from its internal energy sources.
    • Nebula: Interstellar nurseries made of gas and dust produced by supernova.It is where a star is born.
    • Solar systems: A system of planets, stars, and moons that is bound together by a gravitational field.

    Units of Stellar Distance

    • Astronomical Units: The average distance between the sun and the earth.It is used to measure distances within the earth.
      • 1 astronomical unit= 1.49 x 10^8km
    • Light years: The distance travelled by light within one year.It is used to measure distances beyond the solar system.
      • 1 light year = 9.46 x 10^12 km

    Stellar Energy Source - Nuclear Fusion

    • Atomic nuclei under extreme pressure and temperature fuses to form denser, heavier elements , releasing immense amount of energy
    • The source of energy in the star.

    Stellar Life Cycle

    • Nebula: Gravity pulls on the nebula closer making it hot and dense.
    • Protostar: The particles collide and slide by each other, creating friction.This emits light.The hydrogen nuclei gain enough energy to fuse into a helium nuclei.This process is known as nuclear fusion.
    • Main Sequence Star: The nuclear fusion releases thermal energy causing the star to expand.This is the most stable point in a star's life as the expansive forces= the gravitational pull.
    • Stars the same size as the sun:
      • Red giant: The star cools as it expands due to fusion and hence, appears redder.It is brighter than a main sequence star.
      • White Dwarf: As the hydrogen depletes, the fusion stops.The gravitational forces> expansive forces causing the star to collapse inwards.The outer layers of the star are expelled leaving a hot dense core known as the white dwarf.It is extremely bright due to the energy condensed into a small area.
      • Black Dwarf: All the energy is emitted into the surroundings.

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    Year 10 Science Task 4 Notification PDF

    Description

    Explore the essential concepts of DNA structure, replication, and mutations with this quiz. Delve into the intricacies of nucleotides, hydrogen bonds, and the role of enzymes during replication. Understand how mutations can impact the genetic code and their potential consequences.

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