4 LESSON_Q3

• DNA


  The molecule used by cells in the body to store the genetic instructions of life
• DNA Replication


  The process used to make two copies of DNA in preparation for cellular division
• Helicase


  The enzyme that splits the DNA into separate strands so they can be replicated
• Ribonucleic acid (RNA)


  Uses the sugar ribose in its backbone
• Uracil


  The nitrogenous base found in RNA but not in DNA
• Mutation


  A change in the instructions encoded in DNA
• Translation


  The second process of protein synthesis where mRNA is read by the ribosome to assemble amino acids into proteins
• Thymine


  The nitrogenous base that pairs with Adenine
• Trisomy 21 (Down Syndrome)


  Caused by a mutation at the chromosomal level
• Recombinant DNA


  A combination of DNA from two different species
• Protein Synthesis


  The process where DNA code is used to produce proteins
• Proteins


  Long chains of amino acids produced by ribosomes that become functional
• Semi-conservative


  The nature of DNA replication where one old strand and one new strand are produced
• Components of DNA and RNA nucleotides

  • Phosphate group
  • Sugar
  • Nitrogenous bases
• Recall also that in meiosis, this process is slightly more complicated because it involves two divisions (Meiosis I and Meiosis II) and requires homologous pairs to cross over during the first phase
• Mitosis is used for multiplying ordinary body cells. Therefore, it makes sense that the resulting cells should be identical to the parent cell and contain all the 46 chromosomes to maintain the same function
• Meiosis, on the other hand, is used for producing gametes (egg cell and sperm cell). Therefore, it must contain only half of the chromosomes because the other half will be provided by the other parent
• Remember that 23 chromosomes come from the father and 23 chromosomes come from the mother. The product of meiosis must also be NOT identical to promote variability among the offspring
• If the exchange of genetic materials between homologous chromosomes DID NOT happen during meiosis I, all sperm cells from your father would be identical and all egg cells from your mother would be identical. Therefore, siblings of the same parents would all be identical
• DNA


  Molecule that stores genetic information
• Nucleotides


  Components of DNA, made up of a phosphate group, a sugar, and a nitrogenous base
• Nitrogenous bases


  Adenine, Guanine, Cytosine, Thymine
• DNA replication


  Process of making two copies of DNA
• Mitosis


  Cell division process that produces two identical daughter cells
• Meiosis


  Cell division process that produces four genetically different daughter cells
• DNA replication


  1. Unzipping DNA strands

  2. DNA polymerase initiating base pairing

  3. Adenine pairing with Thymine

  4. Cytosine pairing with Guanine

  5. Semi-conservative replication
• When one DNA is replicated, the product is two DNA molecules
• DNA replication does not produce functional proteins like hormones, enzymes and components of the cell
• Physical traits or phenotypes and even some behavioral tendencies and mannerisms are a result of functional proteins in a person
• Protein


  Molecule composed of one or more long chains of amino acids, essential for all living organisms
• Protein synthesis


  Process where the instructions encoded in DNA result in the production of proteins
• DNA


  Double-stranded nucleic acid that stores genetic information
• RNA


  Single-stranded nucleic acid similar to DNA, used in protein synthesis
• Protein synthesis


  1. Transcription (DNA to mRNA)

  2. Translation (mRNA to protein)
• Transcription


  1. RNA polymerase binds and opens DNA

  2. RNA polymerase copies DNA sequence into mRNA

  3. mRNA leaves nucleus
• Translation


  1. mRNA binds to ribosome

  2. tRNA brings amino acids to ribosome

  3. Amino acids joined by peptide bonds

  4. Polypeptide chain released when stop codon reached
• Differences between DNA and RNA

  • DNA is double-stranded, RNA is single-stranded
  • DNA uses deoxyribose sugar, RNA uses ribose sugar
  • DNA uses Adenine, Guanine, Cytosine, Thymine, RNA uses Adenine, Guanine, Cytosine, Uracil
  • DNA is found in nucleus, RNA can be in nucleus and cytoplasm
• Genetic engineering enables scientists to alter the instructions for protein production in the DNA thereby changing its proteins and consequently its characteristics
• Protein synthesis


  1. DNA instructions transcribed into mRNA

  2. mRNA read by ribosome to string together amino acids into protein
• Transcription


  Process where DNA code is copied into mRNA