DNA: Discovery & Replication

DNA is in the nucleus

DNA is in the nucleus of all species looked ateach species has it’s own ‘amount’ of DNA

Somatic cells have twice the DNA as gametes

Does DNA = genes?

Rosalind Franklin: July 25, 1920 – April 16, 1958

Maurice Wilkins: December 15, 1916 – October 5, 2004

Figure 10.3C

Twist

Figure 10.3D_2

Hydrogen bond

Partial chemicalstructure

G C

T A

A T

C G

Figure 10.5B

1

5 end 3 end

54

32

1

23

45

P

P P

PP

HO

A T

C G

G C

P P

P

AT

OH

5 end3 end

5C

3C

5C3C

http://cm3.missiondata.com/uploads/43/Image/dna%20101/dna-pairs.jpg

Figure 10.4A_s1

A parentalmoleculeof DNA

G C

A T

T A

A T

C G

Figure 10.4A_s2

A parentalmoleculeof DNA

A

C

G C

A T

T A

The parental strandsseparate and serve

as templates

Freenucleotides

T A T

T

A

A

T

AG

G GC

C

A T

C G

C

Figure 10.4A_s3

A parentalmoleculeof DNA

A

C

G C

A T

T A

The parental strandsseparate and serve

as templates

Freenucleotides

T A T

T

A

A

T

AG

G GC

C

A T

C G

C

Two identicaldaughter moleculesof DNA are formed

A T A T

A TA T

T A T A

C G C G

G C G C

Figure 10.5C

Overall direction of replication

DNA ligase

Replication fork

Parental DNA

DNA polymerasemolecule This daughter

strand is synthesizedcontinuously

This daughterstrand is synthesizedin pieces

35

35

3

5

35

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