annoying questions

• onion microscope question : part 2

  microscope steps

  1. Carefully place the slide onto the stage and clip it in place.
  2. Select the objective lens with the lowest power and therefore lowest magnification.
  3. While looking down the eyepiece, move the stage up and down using the coarse adjustment knob until the image becomes more focused.
  4. Use the fine-adjustment knob to further focus the image until it is clear. 
  5. Switch to a higher powered objective lens and refocus if greater magnification is required.
• onion microscope question - part 1

  get the stage ready

  1. Add a drop of water to a clean slide.
  2. Carefully extract the cells of interest and place them on the slide, in the water – common choices are human cheek cells (animal) and onion epidermal cells (plant).
  3. Highlight the cells using an appropriate stain (Iodine for onion cells and methylene blue for cheek cells).
  4. Finally, place a cover slip over the top of the specimen.
• describe the lytic pathway of a virus and how this causes the spread and infection through a population - part 1

  lytic pathways :

  • viruses cannot replicate outside a host

  • virus binds to host cells

  • inserts genetic material into the host cell

  • use the cells machinery to produce viral proteins

  • use the cells machinery to produce nucleic acids

  • components assemble into new viral particles

  • viruses exit the cell through the host cell membrane 

  • or causes lysis of the host cell

  • allows production of many virus particles
• describe the lytic pathway of a virus and how this causes the spread and infection through a population - part 2

  spread of infection :

  • virus particles leave the host• virus released into body fluids• spread through airborne droplets/contact • allowing spread to another host
• Myxopyronin inhibits bacterial RNA polymerase.

  Explain why the antibiotic myxopyronin can be used to treat bacterial infections in humans ?

  • antibiotics destroy bacteria / prevent them reproducing (1)
  • doesn’t affect {eukaryotic cells/host cells/human cells/human RNA polymerase} (1)
  • prevents production of mRNA /prevents RNA polymerase binding (1)
  • during transcription /prevents transcription (1)
  • prevents proteins being produced /no protein synthesis (1)
• In 2003, the first complete human genome was sequenced.

  The genomes of different people have small changes in the sequence of the DNA bases.

  Describe how these changes in DNA sequence can affect the individuals and how sequencing a person’s genome could influence their medical treatments. - part 1

  
  

  DNA sequences :

  • DNA has 4 different bases
  • changes in the DNA are mutations
  • results in different alleles for these genes
  • affects the phenotype / produces variation
• In 2003, the first complete human genome was sequenced.

  The genomes of different people have small changes in the sequence of the DNA bases.

  Describe how these changes in DNA sequence can affect the individuals and how sequencing a person’s genome could influence their medical treatments. - part 2

  
  

  Outcome of DNA sequencing for the individual :

  1. identify genetic diseases
  2. identify the risk of developing diseases
  3. impact of knowing that a disease could develop
  4. allow the individual to modify their lifestyle to reduce risk
• In 2003, the first complete human genome was sequenced.

  The genomes of different people have small changes in the sequence of the DNA bases.

  Describe how these changes in DNA sequence can affect the individuals and how sequencing a person’s genome could influence their medical treatments. - part 3

  Impact on medical treatment :

  1. HGP has determined the location of genes/determined the function of proteins
  2. we have a better understanding of some diseases
  3. take preventative medicine
  4. provide tailor-made medical treatments /personalised medicines
• Yeast cells can be genetically modified to produce a painkiller. This painkiller is usually obtained from opium poppies.

  One method for genetically modifying a yeast cell uses a plasmid containing the desired gene.

  Discuss the possible benefits and risks of producing painkillers from genetically modified yeast cells rather than extracting the painkillers from poppies.

  BENEFITS -

  • (yeast grows rapidly) increasing yield (1)
  • it can be produced in a shorter time period (1)

  RISKS -

  • the painkillers may not be identical/as effective (1)
  • concerns over GM organisms entering environment (1)
• Describe the reasons why the anatomy of the pentadactyl limb suggests that bats and cats evolved from a common ancestor.

  • same structure of bones (1)
  • the structure is unlikely to have occurred more than once during evolution, common ancestor had similar pentadactyl limb structure/simple limb structures (1)