manipulating genomes

Question 1

what is a genome?

Answer 1

• a genome is all of the genetic material of an organism

Question 2

what is an intron

Answer 2

• an intron is a large non-coding region of DNA that is removed from the mRNA before it is translated in to a polypeptide chain

Question 3

what is a satellite DNA

Answer 3

• sections of DNA that repeats itself multiple times

Question 4

what is a minisatellite DNA

Answer 4

• variable number tandem repeats , 20-50 base pairs long and repeated 50-100s times

Question 5

what is a microsatellite DNA

Answer 5

• short tandem repeats 2-4 base pairs long and repeated 5-15 times

Question 6

what does this have related to twins

Answer 6

• identical twins have identical satellite pattern due to near identical DNA

Question 7

what is the purpose of DNA profiling?

Answer 7

• to see the pattern of DNA

- used to identify individuals or family relationships

Question 8

what are the steps of producing a DNA profile

Answer 8

1. ) extracting the DNA
2. ) digesting the sample
3. ) separating the DNA fragments
4. ) hybridisation
5. ) seeing the evidence

Question 9

describe and explain the steps of producing a DNA profile?

Answer 9

1.) extracting the DNA

 - extract DNA and use PCR( polymerase chain reaction)  to amplify the sample and make lots of copies of it  2. )  Digesting the sample

   - the strands of DNA are cut into small fragments using restriction endonucleases
   - they cut DNA at specific sites known as restriction site or recognition sites 
    - make 2 cuts in each strand of DNA 

3. ) separating the DNA fragments
   - separate DNA fragments through electropherisis which is where charged DNA particles moving through gel medium under the influence of a electric current
   - gel is coated in alkali to separate the double DNA strands into a single strand
   - single stranded DNA is then transferred from gel to nylon membrane by southern blotting
4. ) hybridisation
   - excess radioactive or fluorescent DNA probes are added to the DNA fragments on the membrane
   - DNA probes are short DNA or RNA sequences that are complementary to a known DNA sequence
   - they bind uder particular conditions of pH and temperature
   - excess probes are washed off
5. ) seeing the evidence
   - if radioactive labels were added to the DNA probes, X-ray images are taken of the paper/membrane
   - if fluorescent labels were added to the DNA probes the paper is placed under UV light so the fluorescent tags glow
   - fragments can be seen by the pattern of bars known as the DNA profile

Question 10

what are DNA probes

Answer 10

• are short DNA or RNA sequences complementary to a known DNA sequence
• they bind to the complementary strands of DNA under pH and temperature conditions
• they identify the micro-satellite regions that are more varied than the larger micro-satellite regions

Question 11

describe and explain the steps of PCR - polymerase chain reaction

Answer 11

• allows to make lots of copies of DNA

1.) SEPARATING THE STRANDS
temperature in the PCR machine is increased to 90-95 for 30 seconds, this denatures the DNA by breaking the hydrogen bonds which hold the DNA strands together which separates the DNA strands

2. ) ANNEALING OF THE PRIMERS
   - the temperature is decreased to 55-60 and the primers bind to the ends of the DNA strands
   - they are needed for the replication of the strands to occur
3. ) SYNTHESIS OF DNA
   • the temp is increased to 72-75 for 1 min as this is the optimum temp of DNA polymerase to work the best
   • DNA polymerase adds bases to the primer building up complementary strands of DNA and so producing double stranded DNA identical to the original sequence
   • the enzyme taq polymerase is used which is obtained from thermophilic bacteria found in hot springs