DNA …… solving the puzzle of

life

Pieces of the Puzzle

Click on any picture to begin your journey

deep into the cell.

You will need to visit all legs of the trip and complete all tasks

to really investigate DNA and its mutations.

Choosing will bring you back here!

1. DNA Basics 2. DNA Replication

3. Mutations 4. Case Study

DNA – covering the basics

Today DNA is a term everyone uses but not so long ago, we did not really understand or know how our cells got their “instructions: to grow and develop.

An historical view of understanding DNA

Current understandings

DNA – covering the basicsThe structure of DNA is like a

twisted ladder – the outer structure supports the rungs where the information is coded.

What is DNA?What is a gene?

Build a DNA molecule

DNA Structure – review the first part of the animation by clicking on Start.

Task 1You have been given the basic

building blocks of DNA.Colored styrofoam balls (3 types /

phosphate, sugar and base), skewersBuild and draw part of a DNA

molecule that includes one codon.Identify the pairs and how they

match.

DNA ReplicationAs cells multiply, a new exact copy

of the genetic code must be created for each cell. This occurs through the process of replication.

The process is highly exact due to the pairs of bases that make up the code.

Replication (start the animation at Part 2 by clicking Replication Initiation and follow through to the end)

ReplicationReplication happens in the cell

rapidly, at over 1000 base pairs a second. This video will show you that process, even slowed down hundreds of times.

Replication Animation

Try it yourself – Click on play …. See how many pairs you can match while the cell matches thousands……

Task 2Replication is a very accurate

process with very few errors.What is the key to this accuracy?

Explain using a diagram.If there were many errors, what

would be the problem? (Remember that genes often make proteins).

How can we tell that an error has been made?

MutationA mutation is any change to the

“normal” pattern of the DNA of an organism.

There are many causes of this, including simple replication errors.

Overviews of mutation

Mutations …. good, bad, and

indifferentEach mutation results in a change

in the commands of the cell – they may stop production of a protein, produce an inactive enzyme so a reaction cannot occur, or actually make no difference at all.

Types of mutations

No real effect …. maybe

Mutations – specific examples

Today, many illnesses have been identified as genetic – having their cause in errors in an individual’s DNA.

Those errors can be passed on through the family or may occur due to environmental factors.Mutations – types and causes

Task 3 There are many human genetic traits, things

passed on through families. Doing your own research starting with the site

below, examine one type of mutation and a known medical problem associated with it. Identify the disease and its genetic cause. What are the effects? How are they caused in the

person’s cells and body? Prepare a report for the class that describes your

research and findings.

A detailed description of mutations

Case StudyThere are many genetic illnesses

that are caused by changes in the DNA code.

We will take a close look at one of these which is well known:

Sickle Cell AnaemiaSummary

Sickle Cell Anaemia

In this case, a single change has effects at many levels.

Sickle Cell - effects

Responding to the Environment

Most DNA changes come and go – often the organism dies or is unable to reproduce and does not pass on the change.

In cases where the change is retained in the population, it usually has a positive effect that outweighs the negatives.

Sickle Cell in West Africa

Evolution todayGenes are transmitted through each

generation. In organisms that have short lives, e.g. microorganisms, new mutations are occurring all the time. Today, swine flu, tuberculosis, and other infections are always in the news. Change is still happening, at the molecular level and in our lives.

Tuberculosis – still evolving

Task 4Today in the news swine flu is a

big deal. In other eras, it was the plague, pneumonia, measles, and other pandemics.Based on what you know about

mutation, why is it so important to understand DNA and mutations as we fight these diseases?

Will this change ever end?