Biology Paper 1

• Genetic Engineering


  The process of modifying the genetic makeup of an organism
• Genetic Engineering


  1. Find one organism with a desirable characteristic

  2. Take the gene and transfer to another organism

  3. So that the organism develops the same trait

  4. This organism has now been genetically modified
• Crops genetically modified to become

  • Resistant to diseases
  • Resistant to insects
  • Resistant to herbicides
• Gene therapy


  Giving a person the healthy version of a gene to fix a problem
• Gene therapy is difficult to get to work
• You would have to transfer the new gene to every cell in the body
• If the transfer of the gene was made at an early stage of development (egg or embryo) as they develop the new gene would be passed on to all other cells
• How to carry out genetic modification

  1. Find the gene that you want

  2. Cut the gene out using enzymes

  3. Insert the gene into a vector (either as virus or bacterial plasmid)

  4. Introduce the vector to the organism that we want to have the gene

  5. The organism's cells will take up the vector and start producing a protein that the gene codes for
• Genetic engineering can be carried out between completely different species
• Bacteria has been genetically engineered to produce

  • Human insulin
• Steps of genetic engineering for human insulin

  1. Isolate the insulin gene from human DNA using restriction enzymes, forming sticky ends

  2. Use the same restriction enzymes to cut open a bacterial plasmid, forming complementary sticky ends

  3. Insert the insulin gene into the plasmid using the enzyme DNA ligase to form a recombinant plasmid

  4. Insert the recombinant plasmid into the best bacteria

  5. Let the bacteria divide and then produce the insulin protein
• Neurones are long, thin and have lots of branched connections to other nerve cells
• Central nervous system


  Made up of our brain and spinal chord
• Central nervous system


  Sends signals to the rest of the body
• Synapse


  The connection between nerve cells
• Impulse reaching a synapse

  Chemicals are released which diffuse across the gap to the next cell where they trigger another electrical impulse
• When the CNS has decided what to do, it sends impulses back out to the body via motor neurones
• Reflex arcs are nerve pathways that respond automatically to danger
• Relay neurones pass the impulse from the sensory neurone to the motor neurone
• Neurones


  Carry electrical impulses from one place to another
• Sensory neurones


  Carry information from receptors all over our body to the CNS
• The nervous system and reflex arc are related
• There is no information provided about the 3D shape of molecules
• Enzymes are proteins that act as biological catalysts to speed up the rate of a chemical

  reaction without being changed or used up in the reaction

  They are biological because they are made in living cells

  Enzymes are necessary to all living organisms as they allow all metabolic reactions to occur

  at a rate that can sustain life

  For example, if we did not produce digestive enzymes, it would take around 2 -3weeks

  to digest one meal; with enzymes, it takes around 4 hours
• increasing of characteristics each time to form a better outcome
• MITOSIS VS MEIOSIS
• The products of meiosis are four genetically different haploid daughter cells
• Meiosis occurs in the testes for men ovaries for women
• Alfred Russel Wallace


  A scientist that came up with the idea of natural selection , independently of Darwin . Although his proposed mechanism differed , his observations provided further evidence to support the theory .
• Antibiotic - resistant bacteria


  Bacteria that mutate to become resistant to an antibiotic , survive and reproduce very rapidly , passing on their antibiotic resistance .
• Archaea


  One of the three domains . It consists of primitive bacteria existing in extreme environments .
• Ardi


  A 4.4 - million - year - old female hominid fossil that shows phenotypic traits encompassing characteristics of both humans and apes .
• Bacillus thuringiensis


  A soil - borne bacterium which secretes a toxin that kills insect larvae . The gene for toxin production in Bt can be introduced into the DNA of crop plants to provide insect resistance .
• Bacteria


  One of the three domains that consists of true bacteria .
• Biological control


  The introduction of a new organism ( often a predator ) into an ecosystem to control a pest or pathogen .
• Carbon - 14 dating


  Estimating the age of carbon - containing material that is found in or alongside archeological remains in order to determine their age .
• Charles Darwin


  The scientist who developed the theory of evolution by natural selection .
• Classification


  The organisation of organisms into groups based on their characteristics and structure .
• Competition


  When different organisms compete for the same resources ( e.g. light , water , mates , territory ) in an ecosystem . This limits population size and stimulates evolutionary change .
• Eukarya


  One of the three domains that consists of all eukaryotic organisms .