Paper 2🍃

• DNA replication


  • To create identical copies of DNA needed for mitosis or meiosis (replace, repair or reproduce)
  • Allows for hereditary info to be passed on
  • Maintains correct chromosome number
• DNA replication


  1. Double helix unwinds

  2. DNA unzips/weak hydrogen bonds break into TWO SEPERATE strands

  3. BOTH strands act as a template

  4. Free floating DNA nucleotides from nucleoplasm join to their COMPLEMENTARY DNA base triplets OR A-T and G-C

  5. Hydrogen bonds reform

  6. DNA rewinds and rezips

  7. Forms TWO IDENTICAL strands
• ALWAYS mention the type of nucleotide (DNA or RNA)
• ALWAYS speak about BOTH strands acting as a template
• DNA profiling for paternity test

  • Determining the father of the child
  • Highlight all the markers (bands) that the child shares with the mother and any of the potential fathers
  • Only highlight the marks that line up EXACTLY in position and thickness
  • 50% of the markers match the mother and 50% of the rest of the markers match the father
• DNA profiling for forensics

  ALL the markers on the DNA profile must match
• DNA profiling may NOT be called DNA finger printing
• HOW TO ANSWER LONG QUESTIONS

  1. Describe the process

  2. Explain the process

  3. Explain/Describe the effects of a mutation
• The mutation had no affect on the type of amino acid
• Translation


  To transport code from DNA to ribosome to create proteins
• Translation


  1. Double helix unwinds

  2. DNA unzips/weak hydrogen bonds break into TWO SEPERATE strands

  3. ONE strand acts as a template

  4. Free floating RNA nucleotides from nucleoplasm join to their COMPLEMENTARY DNA base triplets OR A-U and G-C

  5. This produces mRNA

  6. mRNA now has the coded message for protein synthesis

  7. moves from nucleus to cytoplasm

  8. attaches to ribosome
• Species


  A basic unit of classification in biology that represents a group of living organisms that are similar to one another and are capable of interbreeding and producing fertile offspring
• Speciation


  The process by which new species form in the course of evolution
• Speciation occurs when populations of a single species become genetically distinct


  They can no longer interbreed and produce fertile offspring
• Hybridisation


  The interbreeding of two distinct species, leading to the formation of a new hybrid species
• Hybridization occurs when individuals from different species mate and produce offspring that possess a unique combination of genetic traits from both parent species
• Hybridization is most common in plants but can also occur in animals and birds
• Geographic isolation


  The physical separation of populations of a species by geographic barriers, such as mountains, rivers, or oceans
• Geographic isolation restricts gene flow between the separated populations and creates opportunities for genetic divergence and the formation of new species
• Geographic isolation example


  1. A river arises and splits the population into two separate populations

  2. Two populations evolve differently due to their different environments and selection pressures

  3. If the river dries up and the two populations meet, they will be unable to breed as they have now formed two distinct species
• Reproductive isolation


  The barriers that prevent individuals from different species from interbreeding or producing fertile offspring
• Types of reproductive isolation

  • Prezygotic
  • Postzygotic
• Types of prezygotic isolation

  • Ecological isolation
  • Temporal isolation
  • Behavioural isolation
  • Mechanical isolation
• Types of postzygotic isolation

  • Hybrid inviability
  • Gametic isolation
  • Hybrid infertility
• Evolution is an ongoing process that continues to shape life in modern times
• Organisms are adapting and evolving to survive and reproduce in changing environments
• Notable examples of evolution today

  • Antibiotic resistance in bacteria
  • HIV resistance to antiretrovirals
  • Pesticide resistance in insects
• Human activities, such as habitat destruction and climate change, exert selective pressures that drive evolutionary changes in many species
• Understanding and monitoring contemporary evolutionary processes are crucial for conservation efforts and managing the impacts of human activities on biodiversity
• Kinds of nucleic acids

  • DNA
  • RNA
• Nucleotides


  Building blocks (or monomers) of nucleic acids
• Nitrogenous bases of DNA

  • Adenine
  • Thymine
  • Guanine
  • Cytosine
• Nitrogenous bases of RNA

  • Adenine
  • Uracil
  • Guanine
  • Cytosine
• Adenine always pairs with

  Thymine
• Guanine always pairs with


  Cytosine
• DNA


  • Double-stranded molecule
  • Contains deoxyribose sugar
  • Contains thymine
• RNA


  • Single-stranded molecule
  • Contains ribose sugar
  • Contains uracil
• DNA replication


  1. Unwinds

  2. Unzips

  3. Template forms

  4. Complementary strand forms

  5. Two identical DNA molecules
• DNA replication takes place at interphase before mitosis or meiosis begins
• DNA replication is the process during which a DNA molecule makes an exact copy of itself