Instructor’s Name:  Christina Stewart-Jordan

Subject:  Biology I- Genetics

Date:  June 18, 2008

Period:  4th Period

Time: 50 Minutes

Objective(s):

The Student Will:

    1.  Compare the different components and functions of DNA and RNA, as they relate to

    the replication process; (DOK 2, Biology 5.a);

    2.  Summarize the replication process (DOK 2, Biology 5.a).

.

Materials: 

Textbook, 3-ring binder with 5 tabs, pen and/or pencil, loose leaf paper, and colored pencils.

Do Now: 

1.  Define, in your notes:

a.  Origin of Replication, DNA Polymerase, & Okazaki Fragments

Set:

Fill out your “Traits” chart, identifying which traits you possess. 

[Name the traits.]:

a. Hitch-hikers thumb: thumb turns about 90 degrees,

b.  Attached earlobe:  Earlobe is either hanging or attached,

c.  Ability to Roll Tongue:  Ability to make a bowl with your tongue,

d.  Widow’s Peak:  Hairline makes a “V” at the top of forehead.

Put a check mark if you do possess the trait, and put an “X” if you don’t.  When done, I will call you one by one to put your answers on the board.  Where do you think these traits come from?

(5 minutes)

Procedure: 

1.  Begin teacher-led discussion (see above Set).

2.  Continue lesson on replication, reviewing:

    i. The difference between DNA & RNA [show chart on overhead and allow students to

    fill in verbally].

3.  Activity:  Show first video of DNA replication.

4.  Give second handout: 

    i.  Form groups of two, and label the model of DNA replication together. 

    ii.  Allow students to verbalize their findings from left to right on each strand.   

5.  Activity:  Show second video of DNA replication.

    i.  Notice how the process is carried out in a very mechanic, machine-like manner.

6.  a.  DNA Replication: (to be put in their notes, from overhead)

    i.  Origin of Replication:  Region where DNA denatures into single strands, signaling the

    start of replication at that site.

    ii.  Replication Fork:  “Y” shaped structure, that is created as a result of the DNA    

    unwinding; moves in the direction of the unwinding DNA.

    iii.  DNA helicase: prevents DNA from recoiling by holding it in place, as replication

    occurs.

    iiii.  DNA primase makes the enzyme, RNA primer, which starts replicating the lagging    

    strand, through complementary base pairing.

    b.  Leading strand:  DNA strand being produced in the 5’ to 3’ direction/ same direction

    as the replication fork.

    i.  DNA Polymerase:  Makes DNA on the leading strand, through complementary base

    pairing.

    c.  Lagging strand:  DNA strand being produced in the opposite, 3’ to 5’ direction.

    i.  Okazaki Fragments:  fragments of DNA, created by the lagging strand.

    ii.  DNA ligase:  Joins/ glues the Okazaki fragments together to form complete its

    complementary strand.

• Then, the RNA primer is removed by DNA Polymerase, as it replaces the RNA primers with DNA;

• DNA ligase follows behind DNA Polymerase to glue the strands together, again, completing the lagging strand.

[Why does DNA Polymerase replace the RNA primer & re-glue the lagging strand?]  RNA codes for base pair A-U, instead of A-T, which is found in DNA.

[Which strand do you think has a better chance of error?] lagging strand

7.  Instruct students to complete quiz on second handout, to be turned in for a grade.

8.  Review (See Closure)

(30 minutes)

Closure:

So, DNA is produced by a process called replication, in which RNA primers and DNA Polymerase create new DNA strands through complementary base pairing of unwound DNA.  The newly formed strands are glued together by DNA ligase.  These new DNA strands make up our chromosomes, which have those hereditary traits that we discussed at the beginning of class.  Tomorrow we will discuss how those genes are expressed, when we talk about the process of transcription.  Class dismissed!

(5 minutes)

Assessment/ Evaluation:

Objectives: 

•  Compare the different components and functions of DNA and RNA, as they relate to the replication process (DOK 2, Biology 5.a).

Informal:  The teacher will listen to students (M) recall the different components of DNA and RNA (C).

Formal:  The teacher will collect the students’ quizzes, consisting of base pairing rules for DNA and RNA, (C) and record the grades in the grade book (D).

• Summarize the replication process  (DOK 2, Biology 5.a).

Informal:  The teacher will listen to students (M) discuss the replication process as a group, while completing their group-assessment work on labeling the parts of the replication process (C).

Formal:  The teacher will collect the students’ group-assessment quizzes, consisting of the students’ group activities and a summary of the replication process, (C) and record the grades in the grade book (D).