Question

when dna is heated, the double strands unwind and separate into single strands due to the breaking of hydrogen bonds between the bases. this process is called denaturation. an experiment was performed where two molecules of dna were placed in a solution and heated. both sets of dna contained 40 base pairs, but each dna molecule was modified such that one dna molecule contained only adenine and thymine bases and the other contained only cytosine and guanine bases. examine the data in the chart below. 13. describe the effect that temperature had on each dna molecule. 14. propose an explanation for the results in the table above by discussing how changes in structure affect functionality. 15. using the image to the right, create a list of similarities and differences between the two nucleic acids.

Explanation:

13.

As temperature increases, the percentage of single - strand DNA increases for both types. The DNA with only A/T bases has a higher percentage of single - strands at each temperature compared to the DNA with only C/G bases. This is because A/T base pairs are held together by 2 hydrogen bonds while C/G base pairs are held together by 3 hydrogen bonds, making the C/G - rich DNA more stable at higher temperatures.

The structure of DNA is related to its stability. A/T base pairs have 2 hydrogen bonds and C/G base pairs have 3 hydrogen bonds. Higher temperature provides energy to break these hydrogen bonds. The more hydrogen bonds, the more energy (higher temperature) is required to break them and denature the DNA. Functionally, denatured DNA cannot perform normal processes like replication and transcription until it renatures. The A/T - rich DNA denatures more easily, which may affect these processes at lower temperatures compared to C/G - rich DNA.

Similarities: Both are nucleic acids, composed of nucleotides, have a sugar - phosphate backbone, and are involved in genetic information storage or transfer. Differences: DNA is double - stranded (usually) while RNA is usually single - stranded, DNA has deoxyribose sugar and RNA has ribose sugar, DNA has thymine and RNA has uracil.

Answer:

For DNA with only A/T bases, as temperature rises from 37°C to 57°C, the percentage of single - strand increases from 0% to 52%. For DNA with only C/G bases, as temperature rises from 37°C to 57°C, the percentage of single - strand increases from 0% to 17%. The A/T - rich DNA denatures more readily with increasing temperature compared to the C/G - rich DNA.

14.