In this lesson you will learn about how cells make copies of their DNA molecules and examine in detail the basic principle of base pairing to a template strand. You will examine the three models proposed for DNA replication.
By the end of this lesson, students should be able to:
- explain the basic principle of base pairing to a DNA strand.
- describe the three models of DNA replication: conservative, semiconservative and disperse models.
- describe Meselson and Stahl’s experiment and rationalize why the semiconservative model is the most accepted model of replication of DNA
- describe the stages of DNA replication: initiation, elongation, termination.
- use appropriate terminology to describe DNA replication including terms as origin of replication, replication bubbles, replication fork, template strand, leading strand, lagging strand, Okazaki fragments,
- describe the roles of Helicase, Single Stranded Binding Proteins (SSBP), Toposiomerase, Primase, DNA polymerase III, DNA polymerase I and DNA Ligase.
- describe in detail the elongation of a growing DNA strand, proofreading and repair of DNA mismatches
- explain how telomeres protect important genes from erosion in eukaryotic cells and highlight the work of Dr. Elizabeth Blackburn in elucidating the role of telomeres and telomerase activity during cell ageing.
Let’s start with a closer look at the models of DNA replication and Meselson and Stahl’s experiment. Once again watch video lesson and
DNA Replication Activity.
Watch closely the animation on DNA replication and prepare a timeline for the series of events that occur when DNA is copied. Upload your narrative (description) of the events chronologically and use proper terminology
Assignment – DNA Replication Activity
Below is a second drescription of the process of DNA replication. This video lesson is in a more student-friendly format and catoonist-way. Watch it and answer all the questions on the DNA repliocation worksheet below
Watch the video lesson on elongation of DNA strand, proofreading and repair of DNA and Telomeres below.