Transcript DNA …… solving the puzzle of life

DNA
…… solving the puzzle of life
Pieces of the Puzzle
1. DNA Basics
2. DNA Replication
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
3. Mutations
will bring you back here!
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 basics
The 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 1

You have been given the basic building
blocks of DNA.
Colored styrofoam balls (3 types / phosphate,
sugar and base), skewers
Build and draw part of a DNA molecule
that includes one codon.
 Identify the pairs and how they match.

DNA Replication
As 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)
Replication

Replication 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 2

Replication 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?

Mutation
A 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 indifferent

Each 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 Study
There 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 Anaemia
Summary
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 today

Genes 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 4

Today 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?
