DNA molecular techniques- lqc 18

Question 1

dna hybridisation

Answer 1

heat (95°c) double stranded dna samples from 2 different species, this denatures the dna and creates separate strands, mix the dna strands from both species together so that they complementary base pair to produce hybrid dna. hear the dna by slowly increasing temperature, the higher the temperature needed to denature the hybrids the more closely related the species

Question 2

dna profiling

Answer 2

use restriction enzymes to cut the dna at specific sequences different sized fragments are produced which can be visualised on a gel. mutations in sequences in different individuals in same species or different species will change the lengths of the fragments so different bands will be seen on the gel. the closer the match in the bands, the closer related the individuals or species

Question 3

dna and profiling sequences

Answer 3

comparing the sequence of bases in dna or amino acids in proteins between species the closer the sequence, the more closely related the species- they evolved from a common ancestor

Question 4

dna molecular clocks

Answer 4

as species evolved they accumulate random mutations at a regular rate becoming more genetically different. for given gene mutation rate is fairly constant, this can be used as a molecular clock. number of differences between species can be used to calculate how long ago they shared a common ancestor