Education Portal Video reviewing replication, transcription & translation

How Helicase Unwinds the DNA Double Helix in Preparation for Replication

How DNA Polymerase and RNA Primase Initiate DNA Replication

Watch the two short tutorials above and reflect on what was learned.  Education portal (education-portal.com) is a great resource for Biology and other classes!! :)

DNA Replication, Transcription & Translation

By the end of the block, you should be able to describe 

• DNA Replication
• Transcription
• Translation

These are sometimes referred to as the "Central Dogma" of molecular biology.

As always, you can demonstrate your learning in a multitude of ways.  You can do a scavenger hunt through the on-line resources you have at your disposal and put together a few paragraphs, a presentation or something else to show that you understand these concepts.  You can also go to the Mader website, go to Chapter 12, and go through ALL of the BioTutorial Animation Quizzes & the ScieCentral Video quizzes (on the left side of the window) and e-mail the results to yourself as well as to me.  You can do this work in pairs.

If you happen to complete that, then please go to the on-line textbook (Cengage) and complete the Review Quiz for Chapter 9 "From DNA to Protein" (you should also be able to complete the review quiz for Chapter 8)

From Gene to Protein: A Historical Perspective "Replication of DNA"

What were the three models of DNA replication under investigation in the 1950's?

You should be able to describe and define:
Conservative
Semiconservative
Dispersive

Watch the animation from the DNA learning center to learn more about the three models
http://www.dnalc.org/view/15880-Models-of-DNA-replication.html


How might you test to determine which model is the correct one?
Assume you have the following materials in your laboratory.  Design an experiment using these materials.  You must justify your choice of organism and isotopes.  You will share your information on a whiteboard with the group.

1. An experimental organism of your choice
2. Your choice of radioactive isotopes (e.g. ¹⁴C, ¹⁴N, ¹⁵N, ³²P)
3. Test Tubes
4. Food/Growth media for organisms
5. A Centrifuge

Meselson & Stahl did an experiment to determine which of the 

models for DNA replication was actually correct

Short animation (from McGrawHill)

DNA from the beginning, Module 20 all about DNA replication and the Meselson Stahl experiment.

Bill Nye Cloning

Today we are going to watch two episodes of Bill Nye "the eyes of science"

Clones

As you watch, please think about how the knowledge you gain might be useful in your "Genetic Screening of Newborns" project.
Take notes 
On the Block day we are going to focus on DNA replication and talk about the debate on Wed/Thurs.  

DNA Extraction

DNA

Today you will extract DNA from some of your cells and learn more about DNA.

Extracting DNA from Your Cells

Cells from the lining of your mouth come loose easily, so you will be able to collect cells containing your DNA by swishing a liquid around in your mouth. 

To extract DNA from your cells, you will need to separate the DNA from the other types of biological molecules in your cells.  You will be using the same basic steps that biologists use when they extract DNA (e.g. to clone DNA or to make a DNA fingerprint).  You will follow these 3 easy steps to extract the DNA:

  Detergent

eNzymes (meat tenderizer)

  Alcohol

 

Getting Your Sample of Cells

Obtain a cup with sports drink.  You will need to get thousands of your cheek cells in the sports drink in order to extract enough DNA to see.  Therefore you should swish the sports drink around in your mouth vigorously for at least one minute. Then spit the drink back into the cup.

Step 1: Detergent

Open the centrifuge tube (place the lid on a paper towel.  Why is this important?) Add a small amount of detergent to a centrifuge tube (about 0.25 mL).  Now carefully pour the drink containing your cheek cells into the test tube with detergent until the tube is half full. 

Step 2: Enzymes

Add a pinch of enzyme (meat tenderizer) to your centrifuge tube.  Replace the lid on the tube; gently invert the tube five times to mix.  Place the tube in the test tube rack.  Let the mixture sit for at least 10 minutes.  While you are waiting, answer the questions on the following pages. 

Why am I adding detergent?

Why am I adding enzymes? 

The protease in meat tenderizer comes from plants, but animals also make proteases.  What is one reason why humans and other animals need to have protein-cutting enzymes?

DNA Structure

DNA consists of two strands of nucleotides wound together in a spiral called a double helix.  Read the explanation in the figure before answering questions 1 and 2. 

 

(Figure from Biology -- A Guide to the Natural World by Krogh)

 

1.  The three components of each nucleotide are:

______________________

______________________

______________________

Draw a rectangle around a single nucleotide in the double helix.

2.  The complete name for DNA is deoxyribonucleic acid.  Which component of each nucleotide accounts for the "deoxyribo” part of this name?

3.  DNA has the same double helix structure in all living organisms.  However, we know that a plant, mammal and bacterium must have different genes in their DNA to result in the very different characteristics of these different organisms.  So, the question is: What is different in the DNA of these different organisms?  Complete the following table to identify what is different between the DNA of the plant, mammal and bacterium.

	Compare the plant and mammal DNA.	Compare the mammal and bacterium DNA.
Is the arrangement of the sugar and phosphate groups the same in each type of DNA?
Does each type of DNA contain the same four bases (A, C, G, T)?
Is the sequence of bases the same in each type of DNA?
Are the base-pairing rules the same in each type of DNA?

In your attempt to analyze DNA samples from three different species, what claims can you make about the similarities and differences of the DNA samples?

Step 3: Alcohol

Using a pipette, slowly add cold rubbing alcohol into the test tube; let the alcohol run down the side of the test tube so it forms a layer on top of the soapy liquid. Add alcohol until you have about 2 cm of alcohol in the tube.  Alcohol is less dense than water, so it floats on top.  Do not mix or bump the test tube for 10 minutes.  DNA molecules will clump together where the soapy water below meets the cold alcohol above, and you will be able to see these clumps of DNA as white strands. 

Why doesn’t the alcohol mix with the water?

Mid semester reflection

Please fill out the following form.  The responses are anonymous.  I look forward to your responses.
Thanks!! :)

Wednesday 3/5/14

Hi guys!  Sorry I am stuck in Kansas :(  I should be back late this evening, so I will be back in class tomorrow!

Please continue to work on the article from the block day.  You need to write a summary and reflection and post it to Canvas.  Also, the selective permeability lab is available for submission on Canvas.  Use the remainder of your time to work on your Genetic testing policy project.

See you tomorrow!

Summary/Reflection of Watson & Crick article

Write a paragraph describing what you learned and what you thought about reading the journal article from Watson & Crick (as well as anything you want to add from the "Secret of Photo 51" video). 
Be honest (but nice) about what you really thought about reading the article as well as what you learned from the reading. You can write the reflection in pairs or individually, but everyone needs to submit the assignment on Canvas individually (it is there now, as well as the selectively permeable membrane lab)
Also, check out a more recently published article and we will discuss the similarities and differences on Wednesday
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035159