B3 | genetics

Question 1

what is DNA made up of?

Answer 1

twisting, repeating nucleotides consisting of:

• a sugar
• a phosphate
• a base

Question 2

what are the bases in DNA held together by?

Answer 2

weak hydrogen bonds

Question 3

what are the 4 types of bases? what are their complementary base pairs?

Answer 3

A, C, T and G
A pairs up with T (or U)
C pairs up with G

Question 4

genetic modification steps

Answer 4

1. identify DNA of desired trait
2. cut open vector using restriction enzymes
3. cut out desired DNA using same restriction enzymes at the recognition site
4. join DNA and vector together at exposed sticky ends using ligase enzymes
5. combinant DNA is formed

Question 5

what shape is the phosphate in DNA?

Answer 5

circle

Question 6

what shape is the sugar in DNA?

Answer 6

pentagon

Question 7

what shape is the base in DNA?

Answer 7

rectangle

Question 8

what is a genome?

Answer 8

the entire DNA of an organism

Question 9

what is a gene?

Answer 9

a section of DNA on a chromosome that codes for a particular protein

Question 10

how to extract DNA from fruit:

Answer 10

• make extraction buffer using water, sodium chloride and detergent, then stir it slowly to prevent frothing
• wash fruit and cut into small pieces
• add to a ziplock bag
• add extraction buffer (contains lipase which breaks down fatty membranes of the cell, breaks open nuclear membrane to release DNA) and protease solution
• seal the bag tightly and crush the fruit to break open cells and release DNA into the solution
• place ziplock back in water bath for 10mins
• place funnel and gauze filter into boiling tube
• carefully pour mixture into the funnel; filtration removes any insoluble material
• using a pipette add cold ethanol to the filtrate (DNA is insoluble in alcohol, so it precipitates/becomes visible)
• use inoculating loop to collect DNA and look at it under a microscope