Assignment: The Scientific Evidence of DNA Replication Being Semiconservative Essay

As previously mentioned, Watson and Crick themselves had specific ideas about DNA replication, and these ideas were based on the structure of the DNA molecule. In particular, the duo hypothesized that replication occurs in a “semiconservative” fashion. According to the semiconservative replication model, which is illustrated in Figure 1, the two original DNA strands (i.e., the two complementary halves of the double helix) separate during replication; each strand then serves as a template for a new DNA strand, which means that each newly synthesized double helix is a combination of one old (or original) and one new DNA strand. Conceptually, semiconservative replication made sense in light of the double helix structural model of DNA, in particular its complementary nature and the fact that adenine always pairs with thymine and cytosine always pairs with guanine. Looking at this model, it is easy to imagine that during replication, each strand serves as a template for the synthesis of a new strand, with complementary bases being added in the order indicated.Semiconservative replication was not the only model of DNA replication proposed during the mid-1950s, however. In fact, two other prominent hypotheses were put also forth: conservative replication and dispersive replication. According to the conservative replication model, the entire original DNA double helix serves as a template for a new double helix, such that each round of cell division produces one daughter cell with a completely new DNA double helix and another daughter cell with a completely intact old (or original) DNA double helix. On the other hand, in the dispersive replication model, the original DNA double helix breaks apart into fragments, and each fragment then serves as a template for a new DNA fragment. As a result, every cell division produces two cells with varying amounts of old and new DNA (Figure 1).

When these three models were first proposed, scientists had few clues about what might be occurring at the molecular level during DNA replication. Fortunately, the models yielded different predictions about the distribution of old versus new DNA in newly divided cells, no matter what the underlying molecular mechanisms. These predictions were as follows:

• According to the semiconservative model, after one round of replication, every new DNA double helix would be a hybrid that consisted of one strand of old DNA bound to one strand of newly synthesized DNA. Then, during the second round of replication, the hybrids would separate, and each strand would pair with a newly synthesized strand. Afterward, only half of the new DNA double helices would be hybrids; the other half would be completely new. Every subsequent round of replication therefore would result in fewer hybrids and more completely new double helices.
• According to the conservative model, after one round of replication, half of the new DNA double helices would be composed of completely old, or original, DNA, and the other half would be completely new. Then, during the second round of replication, each double helix would be copied in its entirety. Afterward, one-quarter of the double helices would be completely old, and three-quarters would be completely new. Thus, each subsequent round of replication would result in a greater proportion of completely new DNA double helices, while the number of completely original DNA double helices would remain constant.
• According to the dispersive model, every round of replication would result in hybrids, or DNA double helices that are part original DNA and part new DNA. Each subsequent round of replication would then produce double helices with greater amounts of new DNA

Important information for writing discussion questions and participation

Welcome to class

Hello class and welcome to the class and I will be your instructor for this course. This is a -week course and requires a lot of time commitment, organization, and a high level of dedication. Please use the class syllabus to guide you through all the assignments required for the course. I have also attached the classroom policies to this announcement to know your expectations for this course. Please review this document carefully and ask me any questions if you do. You could email me at any time or send me a message via the “message” icon in halo if you need to contact me. I check my email regularly, so you should get a response within 24 hours. If you have not heard from me within 24 hours and need to contact me urgently, please send a follow up text to

I strongly encourage that you do not wait until the very last minute to complete your assignments. Your assignments in weeks 4 and 5 require early planning as you would need to present a teaching plan and interview a community health provider. I advise you look at the requirements for these assignments at the beginning of the course and plan accordingly. I have posted the YouTube link that explains all the class assignments in detail. It is required that you watch this 32-minute video as the assignments from week 3 through 5 require that you follow the instructions to the letter to succeed. Failure to complete these assignments according to instructions might lead to a zero. After watching the video, please schedule a one-on-one with me to discuss your topic for your project by the second week of class. Use this link to schedule a 15-minute session. Please, call me at the time of your appointment on my number. Please note that I will NOT call you.

Please, be advised I do NOT accept any assignments by email. If you are having technical issues with uploading an assignment, contact the technical department and inform me of the issue. If you have any issues that would prevent you from getting your assignments to me by the deadline, please inform me to request a possible extension. Note that working fulltime or overtime is no excuse for late assignments. There is a 5%-point deduction for every day your assignment is late. This only applies to approved extensions. Late assignments will not be accepted.

If you think you would be needing accommodations due to any reasons, please contact the appropriate department to request accommodations.

Plagiarism is highly prohibited. Please ensure you are citing your sources correctly using APA 7th edition. All assignments including discussion posts should be formatted in APA with the appropriate spacing, font, margin, and indents. Any papers not well formatted would be returned back to you, hence, I advise you review APA formatting style. I have attached a sample paper in APA format and will also post sample discussion responses in subsequent announcements.

Your initial discussion post should be a minimum of 200 words and response posts should be a minimum of 150 words. Be advised that I grade based on quality and not necessarily the number of words you post. A minimum of TWO references should be used for your initial post. For your response post, you do not need references as personal experiences would count as response posts. If you however cite anything from the literature for your response post, it is required that you cite your reference. You should include a minimum of THREE references for papers in this course. Please note that references should be no more than 5 years old except recommended as a resource for the class. Furthermore, for each discussion board question, you need ONE initial substantive response and TWO substantive responses to either your classmates or your instructor for a total of THREE responses. There are TWO discussion questions each week, hence, you need a total minimum of SIX discussion posts for each week. I usually post a discussion question each week. You could also respond to these as it would count towards your required SIX discussion posts for the week.

I understand this is a lot of information to cover in 5 weeks, however, the Bible says in Philippians 4:13 that we can do all things through Christ that strengthens us. Even in times like this, we are encouraged by God’s word that we have that ability in us to succeed with His strength. I pray that each and every one of you receives strength for this course and life generally as we navigate through this pandemic that is shaking our world today. Relax and enjoy the course!

Hi Class,

Please read through the following information on writing a Discussion question response and participation posts.

Contact me if you have any questions.

Important information on Writing a Discussion Question

• Your response needs to be a minimum of 150 words (not including your list of references)
• There needs to be at least TWO references with ONE being a peer reviewed professional journal article.
• Include in-text citations in your response
• Do not include quotes—instead summarize and paraphrase the information
• Follow APA-7th edition
• Points will be deducted if the above is not followed

Participation –replies to your classmates or instructor

• A minimum of 6 responses per week, on at least 3 days of the week.
• Each response needs at least ONE reference with citations—best if it is a peer reviewed journal article
• Each response needs to be at least 75 words in length (does not include your list of references)
• Responses need to be substantive by bringing information to the discussion or further enhance the discussion. Responses of “I agree” or “great post” does not count for the word count.
• Follow APA 7th edition
• Points will be deducted if the above is not followed

• Remember to use and follow APA-7th edition for all weekly assignments, discussion questions, and participation points.
• Here are some helpful links
• The is a great resource