DNA Structure and Function Chapter 8 We love this stuff So ? ? What is DNA? DNA is Information It is how your parents “made” you. It is how every cell in your body - was made by other cells Structure of the Hereditary Material
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DNA Structure and Function
Fig. 4-14, p.58
A binds to T and
G binds to C
2-nanometer diameter overall
0.34-nanometer distance between each pair of bases
3.4-nanometer length of each full twist of the double helix
In all respects shown here, the Watson–Crick model for DNA structure is consistent with the known biochemical and x-ray diffraction data.
The pattern of base pairing (A only with T, and G only with C) is consistent with the known composition of DNA (A = T, and G = C).
Fig. 13-6, p.211
Each parent strand remains intact
Every DNA molecule is half “old” and half “new”
Fig. 13-7, p.212
aA parent DNA molecule with two complementary strands of base-paired nucleotides.
bReplication starts; the strands unwind and move apart from each other at specific sites along the molecule’s length.
cEach “old” strand is a structural pattern (template) for attaching new bases, according to the base-pairing rule.
dBases positioned on each old strand are joined together as a “new” strand. Each half-old, half-new DNA molecule is like the parent molecule.
Fig. 13-8a, p.213
1 A microneedle
2 The microneedle has emptied the sheep egg of its own nucleus.
3 DNA from a donor cell is about to be deposited in the enucleated egg.
4 An electric spark will stimulate the egg to enter mitotic cell division.
the first cloned sheep
Fig. 13-9, p.214
. . . . . the moral issues rather than protect mankind. As such, cloning embryonic human life under any circumstance crosses an ethical line, takes an irrevocable step, from which science can never turn back."
Liberal position: "Therapeutic cloning will in time allow scientists to create organs that are a perfect match for those in need of a transplant.
Therapeutic cloning represents the ideal in organ transplantation, as it would provide an unlimited source of organs to anyone who needs them. The need for these organs is dire."