1. Topic 24 – DNA Replication
Day 1 of 3
Topic 24 – DNA Replication

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Get Student Exploration: Building DNA Worksheet
Quietly read first page
Answer Prior Knowledge Questions.
Be prepared to share your answers

3. DNA Replication
Structure of DNA

4. THINK – PAIR – SHARE Where is DNA located in the cell?
Students pair up and combine their best answer
Teacher ask question
Students think individually
Where is DNA located in the cell?
What type of macromolecule is DNA?
What happens during DNA replication?
When does the cell replicate its DNA?
Students share their new and improved answer with the class.

5. What are we learning today?
Benchmark
Objectives
SC.912.L.16.3 – Describe the basic process of DNA replication and how it relates to the transmission and conservation of the genetic information.
Students will describe the structure of DNA.
To the Teacher:
Introduce today’s benchmark.
Read or have a student read the day’s objectives.

6. What is the essential question?
DNA holds our hereditary information. How does the structure of this macromolecule help it perform its function?

7. What is the essential vocabulary?
Double helix – the shape of DNA, resembling a twisted ladder.
Nucleotide – a subunit of a nucleic acid molecule that consists of a sugar, a phosphate, and a nitrogenous base.
Nucleoside – a subunit of a nucleic acid molecule that consists of a sugar and a nitrogenous base.

8. What are the components of DNA?
The backbone of a DNA chain is formed by sugar and phosphate groups of each nucleotide.
The nitrogenous bases stick out sideways from the chain.
The nucleotides can be joined together in any order, meaning that any sequence of bases is possible.

9. What are the components of DNA?
DNA is a long molecule made up of units called nucleotides.
Each nucleotide is made up of three basic components:
A 5-carbon sugar called deoxyribose.
A phosphate group.
A nitrogenous base.
There are four kinds of nitrogenous bases in DNA:
Purines: Adenine and guanine
Pyrimidines: Cytosine and thymine.

10. Gizmos – Building DNA Learning Objectives: Students will …
Build a molecule of DNA from a set of components.
Observe how nitrogenous bases bond to form the central “rungs” of the DNA molecule.

11. Home Learning Gizmos: Activity A
“The same people who never did their homework in high school are still doing that to this very day out in the real world.“
by Jules Shear
A Canine Family Tree

12. Topic 24 – DNA Replication
Day 2 of 3
Topic 24 – DNA Replication

13. Bell Ringer (10 minutes)
Grab a Biology EOC Exam Preparation Bell Ringer
Provide a GIST of the Question.
Bubble your answer.
Explain why you believe is the correct answer.
BE PREPARED TO PARTICIPATE IN CLASS DISCUSSION.
After correcting, reflect on our answer.

14. DNA Replication
Duplication of DNA

15. What is the essential question?
How does replication ensure that identical copies of DNA are made?

16. What is the essential vocabulary?
Replication – the process of DNA duplication.
Replication fork – Site where DNA strands separate and replication occurs.
Enzyme – a protein that facilitates a specific chemical reaction in the body.
Leading strand – DNA strand that forms as a continuous strand during DNA replication.
Lagging strand – DNA strand that forms as a series of short segments, called Okazaki fragments, which are then connected together.

17. What is DNA replication?
During DNA replication, the DNA molecule produces two new complementary strands.
Each strand of DNA serves as a template for the new strand.
Described as semiconservative because each DNA molecule has one new strand and one original strand.

18. How does DNA replication work?
A very complex process requiring the assistance of several enzymes and regulatory molecules.
DNA helicases bind to the double stranded DNA and stimulate the separation of the two strands.
Primase initiates replication by adding a short RNA fragment called a primer to the old strands
DNA polymerases join individual nucleotides to produce a new strand of DNA using the old strand as a template. They also carry out DNA proofreading and repair.
Ligase binds the DNA fragments together by addition of phosphates in the gaps that remain in the phophate-ribose sugar backbone.
These enzymes are the crucial parts of replication assembly line. The precision with which every single segment of the complementary strand is aligned is mind-boggling. No man-made assembly line can match the efficiency, detailing and brilliance of the DNA replication mechanism that makes biological inheritance possible.
Helicase DNA replication begins at places called origins, within the DNA molecule and the creation of replication forks. The process of strand separation is made possible because of the enzyme Helicase which separates the two strands using the energy that is derived from ATP hydrolysis. DNA Primase One of the most crucial enzymes is DNA Primase. After the DNA strands are separated, to begin the creation of new DNA molecules, through addition of complementary bases to the templates, a short RNA segment, called a 'primer' is required. These primers are synthesized by DNA primase enzymes, thus initiating the DNA replication process. That is why DNA Primase is one of the most important DNA replication enzyme. DNA Polymerase The most important enzymes, that carry out the main task of aligning the complementary bases with template strands of 'unzipped' DNA, are the DNA polymerases. They are a large family of enzymes that carry out the task of adding complementary base nucleotides by reading the template strands. Besides the task of elongating the DNA molecule, they also carry out DNA proofreading and repair. DNA Ligase While Helicase works to unwind the DNA molecule, DNA Ligase is the DNA replication enzyme that binds the DNA fragments together by addition of phosphates in the gaps that remain in the phophate-ribose sugar backbone.

19. Gizmos – Building DNA Learning Objectives: Students will …
Explain how DNA replication occurs.
Observe that the result of DNA replication is two identical molecules of DNA.

20. DNA Replication Overview
Right-click slide / select “Play”

21. DNA Replication Overview
Each strand of the DNA double helix has all the information needed to reconstruct the other half by the mechanism of base pairing.
Because each strand can be used to make the other strand, they are said to be complementary. A T C G T A A T G C
(a) Parent molecule

22. DNA Replication Overview
DNA helicase begins replication by separating the strands and exposing the nucleotide sequence.
Primase adds a primer to the DNA molecule to initiate replication
DNA polimerases move along the two strands, pairing complementary bases to the exposed nucleotides. A T A T C G C G T A T A A T A T G C G C
(a) Parent molecule
(b)
Separation of strands

23. DNA Replication OverviewG C G C G C G T A T A T A T A A T A T A T A T G C G C G C G C
(a) Parent molecule
(b)
Separation of strands
(c)
“Daughter” DNA molecules, each consisting of one parental strand and one new strand
DNA ligase seals up the fragments into one long continuous strand
Each original strand joins its complementary strand to form a DNA molecule, resulting in two identical DNA molecules.

24. DNA Replication Overview

25. What did we learned?
DNA, the genetic material of organisms, is composed of four kinds of nucleotides.
Each nucleotide consists of a sugar, a phosphate group and one of four bases.
Sugars and phosphates on the outside
Nitrogenous bases paired by hydrogen bonds (A with T, C with G) form the “rungs.”
The paired strands form a twisted-zipper shape called a double helix.
Before cell division, DNA copies itself in a process called replication.
During replication, DNA separates into two strands, and produces two new complementary strands following the rules of base pairing.

26. What is the essential question?
How does replication ensure that identical copies of DNA are made?

27. Home Learning Reinforcement: DNA Replication
“The same people who never did their homework in high school are still doing that to this very day out in the real world.“
by Jules Shear
A Canine Family Tree

28. Topic 24 – DNA Replication
Day 3 of 3
Topic 24 – DNA Replication

29. Bell Ringer (10 minutes)
Grab a Biology EOC Exam Preparation Bell Ringer
Provide a GIST of the Question.
Bubble your answer.
Explain why you believe is the correct answer.
BE PREPARED TO PARTICIPATE IN CLASS DISCUSSION.
After correcting, reflect on our answer.

30. DNA Replication
DNA Extraction Lab

31. What are we learning today?
Benchmark:
SC.912.L.16.9 – Explain how and why the genetic code is universal and is common to almost all organisms.
Objectives:
Explain that the basic components of DNA are universal in organisms.
Explain how similarities in the genetic codes of organisms are due to common ancestry and the process of inheritance.

32. What is the essential question?
Do you think you have ever eaten DNA? Where and when?

33. Lab – DNA Extraction
Purpose: To investigate if DNA is present in plants.
Problem Statement: Do you think you have ever eaten DNA? Where and when?
Safety: Handle breakable materials with care. Do not touch broken glassware. If you are allergic to certain plants, tell your teacher before doing activity. Wash your hands when you are finished with the activity. Flammable materials may be present. Make sure no flames, sparks, or exposed heat sources are present.
Vocabulary: decant

34. Lab – DNA Extraction Place two strawberries in a Ziploc baggie.
Kneed/mush the strawberries using your fist and fingers for 2 minutes. Careful not to break the bag!!!
Add the provided 10mL of extraction buffer solution to the bag.
Kneed/mush the strawberries/solution mix for an additional 1 minute.
Assemble your filtration apparatus as shown in your procedure.
Filter strawberry/solution mix through cheesecloth. Do not press it. Let gravity work!!!
Pour 2-3 mL (about 1 cm) of filtrate into a test tube.
Decant 4-6 mL (about 2 cm) of ice cold ethanol.
Stir gently with inoculation loop and spool DNA as it clumps at the ethanol/filtrate interface.

35. Lab – DNA Extraction
How is the appearance of your DNA similar or dissimilar to what you have learned about DNA structure?
A person cannot see a single strand of cotton thread from 30 meters away. But if thousands of threads are wound together into a rope, the rope can be seen at some distance. How is this statement an analogy to the DNA extraction you did?
DNA dissolves in water but not in ethanol. Explain what happened when the ethanol came in contact with the strawberry extract during the DNA extraction.

36. Lab – DNA Extraction PROCEDURE FUNCTION
Each step in the procedure aided in isolating the DNA from other cellular materials. Match the procedure with its function
PROCEDURE
FUNCTION
Filter strawberry slurry through cheesecloth.
Mush strawberry with salty/soapy solution
Initial smashing and grinding of strawberry.
Addition of ethanol to filtered extract.
___ To precipitate DNA from solution ___ Separate components of the cell ___ Break open the cells ___ Break up proteins and dissolve cell membranes

37. So, what’s the big deal about DNA?
The genetic code is the same in nearly all living organisms. (UNIVERSAL GENETIC CODE)
This supports the view that the code had originated at least by the time bacteria evolved, over 3.5 billion years ago.
It also provides evidence that all life on Earth evolved from a common origin.

38. What is the essential question?
Do you think you have ever eaten DNA? Where and when?

39. Complete Formal Lab Report for DNA Extraction Laboratory Home Learning
“The same people who never did their homework in high school are still doing that to this very day out in the real world.“
by Jules Shear
A Canine Family Tree