D

• DNA replication


  The production of new strands of DNA with base sequences identical to existing strands
• DNA replication


  • Needed for reproduction and growth and tissue replacement in multicellular organisms
• Tissue


  A group of the same type of cells used to carry out a function
• Tissue


  • Larger organisms have more cells in each tissue
  • The cells in a tissue adhere to and communicate with each other and with other cells
• Nucleotide


  The building block of nucleic acids, like DNA and RNA, consisting of a nitrogenous base, a sugar, and a phosphate group
• Complementary


  The bases can only form hydrogen bonds in their complementary base pairings which are Adenine with Thymine, and Cytosine with Guanine
• Base pairing


  The bases can only pair in certain ways; cytosine with guanine, adenine with thymine in DNA, and adenine with uracil in RNA
• Nitrogenous bases used in DNA

  • Adenine
  • Thymine
  • Guanine
  • Cytosine
• Replisome


  The protein assemblies that replicate DNA, helicase and DNA polymerase are two essentials of it
• Helicase


  Ring shaped protein that separates the two strands of a DNA molecule so that they can act as templates to form new strands
• Replication fork


  The area where the DNA replication takes place
• DNA polymerase


  Assembles the new DNA strands by moving along the template and adding nucleotides one by one where they form hydrogen bonds and links the nucleotide to the end of the new strand
• Template


  The single strand from the original DNA strand after it has been separated is used to create a new strand by adding the complementary bases to the strand
• Semi-conservative


  DNA replication is referred to as semi-conservative as there are two DNA molecules when it is complete, both consisting of one original strand and one newly synthesized strand
• PCR (Polymerase Chain Reaction)


  An automated method of DNA replication that doubles the quantity of DNA with each cycle, only needing a single molecule from the beginning
• DNA amplification


  The process of producing more DNA with one specific base sequence
• Primer


  A short single strand of DNA designed to bind to the DNA at the point where the selected base sequence for replication begins
• Primer


  • The ideal length is 18-30 nucleotides
  • They select which sequences are copied
  • They are used to start the cycle of DNA amplification in PCR machines
• Denaturing


  When the forces between the side chains of the amino acids are broken due to factors like heat and pH, causing a protein to unfold or break and lose its shape and function
• Annealing


  The second step in the cycle of PCR. Cooling to 54 degrees for 30-60 seconds allowing primers to bind
• Elongation


  The third step in the cycle of PCR. Heating to 72 degrees providing the optimum working temperature for Taq DNA polymerase, which assembles the new DNA strand
• Taq DNA polymerase


  A heat resistant enzyme that allows for the production of large amounts of DNA copies in a short time
• Taq DNA polymerase


  • It binds to the single stranded DNA adjacent to the primer
  • In 30-60 seconds, it assembles the new DNA strands
• Gel electrophoresis


  A substance that can separate DNA molecules by length
• Gel electrophoresis


  1. A voltage is applied across a gel with DNA samples in wells

  2. The DNA molecules move across the gel at different rates depending on their size

  3. This allows the fragments to be separated according to their lengths
• Buffer


  A solution that resists changes in pH when acids or bases are added
• Electrode


  Metal pieces used to transmit electrical signals into or out of biological samples, like cells or tissues, for experiments and measurements
• Paternity testing


  A DNA sample is analysed to compare genetic markers such as STR
• Paternity testing


  1. They are copied and a pattern of bands is produced making an individual DNA profile

  2. The three DNA profiles are compared to see if the bands occur in either the mother or the father
• STR (Short Tandem Repeats)


  Sequences of 2-7 bases repeated consecutively, with different numbers of repeats in different people
• Test for coronavirus


  1. A swab taken from the patient is used to produce a liquid RNA sample

  2. The RNA is converted to DNA using reverse transcriptase

  3. PCR is used to amplify specific viral base sequences that are markers of the strain of coronavirus

  4. Fluorescent markers are attached to any DNA produced

  5. If it rises above a target level the test is positive
• Reverse transcriptase

  An enzyme used to convert RNA into DNA
• Fluorescent marker


  A molecule that glows when exposed to certain light, used to label and visualize specific molecules
• DNA


  A molecule with a double helix structure that stores and transmits the genetic information in an organism. It is made up of nucleotides that carry the genetic code.
• Protein synthesis


  1. DNA is transcribed into mRNA in the nucleus

  2. mRNA is transported to a ribosome

  3. mRNA is translated into a polypeptide with the help of tRNA

  4. Polypeptide is folded into a protein
• Transcription


  The synthesis of RNA, using DNA as a template. Since RNA is single stranded transcription only occurs along one of the two strands of DNA
• mRNA


  Messenger RNA, carries the genetic information of the DNA in the cell nucleus to the ribosomes, where it serves as a template for protein synthesis
• Ribosome


  An organelle responsible for protein synthesis. It reads the genetic information from mRNA and assembles amino acids into polypeptide chains according to the instructions encoded in the mRNA
• Translation


  1. mRNA is decoded by ribosomes to assemble amino acids into a polypeptide chain

  2. tRNA brings specific amino acids to the ribosome based on the codons on the mRNA

  3. As each codon on the mRNA is read, the corresponding amino acid is added to the growing polypeptide chain until a complete protein is formed
• tRNA


  Transfer RNA, carries amino acids to the ribosome during translation