Question

1. dna consists of a series of nitrogenous base molecules held together by weak hydrogen bonds. these base pairs are in turn bonded to a sugar - phosphate backbone. the four nitrogenous bases are adenine, thymine, guanine, and cytosine (a, t, g, and c). the base - pairing rule is a - t and g - c. the schematics below represent a very small section of dna from three different individuals. analysis of the three dna samples might help us detect similarities and differences in samples of dna from different people. in this representation of dna the symbol system is as follows:

backbone:
s = 5 - c sugar molecule known as deoxyribose
p = phosphate group
dna nucleotide bases:
a = adenine
c = cytosine
g = guanine
t = thymine
the structure of dna
(images of three dna molecules: plant, human, bacterial)

1. compare the \backbone\ of the sugar - phosphate arrangements in the side chains of all three figures. are there any differences? explain.
2. in the above figures, do all three samples contain the same bases? describe your observations.
3. are the bases paired in an identical manner in all three samples? describe the pattern of the base pair bonding.
4. in your attempt to analyze dna samples from three different individuals, what conclusions can you make about the similarities and differences of the dna samples?
5. what will you need to compare between these dna samples to determine if they are identical or non - identical?

Explanation:

Question 8

Step1: Analyze the backbone structure

Observe the symbols for the backbone (S for deoxyribose and P for phosphate group) in each of the three DNA molecule figures (Plant, Human, Bacterial).

Step2: Compare the arrangements

Check if the sequence or pattern of S and P in the side chains (backbone) is the same across all three figures. From the schematics, the backbone is made of alternating S (deoxyribose) and P (phosphate) groups. Visually, all three figures show the same alternating S - P - S - P... pattern in their side - chain backbones.

Step1: Identify the bases in each sample

Look at the DNA nucleotide bases (A, T, G, C) in each of the three DNA molecule figures (Plant, Human, Bacterial).

Step2: Compare the bases

In the plant DNA, human DNA, and bacterial DNA figures, we can see the presence of adenine (A), thymine (T), guanine (G), and cytosine (C). So all three samples contain the same set of bases (A, T, G, C).

Step1: Analyze base - pairing in each sample

Check the base - pairing (A - T or G - C) in each of the three DNA molecule figures (Plant, Human, Bacterial).

Step2: Describe the pattern

In all three samples, the base - pairing follows the rule A - T (adenine pairs with thymine) and G - C (guanine pairs with cytosine). So the bases are paired in an identical manner in terms of the pairing rules (A with T, G with C) across all three samples. The pattern of base - pair bonding is that adenine (A) always pairs with thymine (T) and guanine (G) always pairs with cytosine (C) via weak hydrogen bonds.

Answer:

There are no differences in the sugar - phosphate (backbone) arrangements in the side chains of the three figures. All three have an alternating pattern of the 5 - C sugar molecule (S, deoxyribose) and phosphate group (P) in their side - chain backbones.

Question 9