(1) Restriction enzymes differ in the recognition specificity: target sites are different (2) Restriction enzymes differ in the length they recognized and thus the frequencies differ ()Restriction enzymes differ in the nature of the dNa ends they generate bun/ flush ends(平末端) sticky/ staggered ends(粘性末端) (4)Restriction enzymes differ in the cleavage activity 22
22 (1) Restriction enzymes differ in the recognition specificity: target sites are different. (2) Restriction enzymes differ in the length they recognized, and thus the frequencies differ. (3) Restriction enzymes differ in the nature of the DNA ends they generate: blunt/flush ends (平末端), sticky/staggered ends (粘性末端). (4) Restriction enzymes differ in the cleavage activity
Fig 20-4 Recognition sequences and cut sites of various endonucleases Hpal blunt ends 53 G DIOA A C CA A 35 cut (平末端) ECORI 5 IGOAAI IC 3 3 5 cut HindIll sticky ends 5'CAOAGC 3 3 TT C G AOA 5 (粘性末端) cut P53 G 3 G 5 cut Copyright o 2004 Pearson Education, Inc, publishing as Benjamin Cummings
23 sticky ends (粘性末端) blunt ends (平末端) Fig 20-4 Recognition sequences and cut sites of various endonucleases
Fig 20-5 Cleavage of an EcoRI site. The 5 protruding ends are said to be sticky" because they readily anneal through base-pairing to DNA molecules cut with the same enzyme 5 GOA A 3 5′ cut sticky"end A 3 3 sticky"end Copyright o 2004 Pearson Education, Inc, publishing as Benjamin Cummings 24
24 Fig 20-5 Cleavage of an EcoRI site. The 5’ protruding ends are said to be “sticky” because they readily anneal through base-pairing to DNA molecules cut with the same enzyme
Nucleic acids- DNA hybridization 3. dNa hybridization can be used to identify specific DNA molecules Hybridization: the process of base-pairing between complementary ssDNA or RNA from two different sources 25
25 3. DNA hybridization can be used to identify specific DNA molecules Hybridization: the process of base-pairing between complementary ssDNA or RNA from two different sources. Nucleic acids- DNA hybridization
Probe(探针) A labeled, defined sequence used to search mixtures of nucleic acids for molecules containing a complementary sequence 26
26 A labeled, defined sequence used to search mixtures of nucleic acids for molecules containing a complementary sequence. Probe (探针)