We have just looked at the structure of DNA by colouring and cutting and pasting a model of DNA in the classroom. Now, I would like you to explore how DNA makes copies of itself - which it needs to do in order for a cell to divide. This process is called DNA replication.
Watch this animation to see the steps of DNA replication in action.
DNA replication
Remember how long each DNA molecule was and how many base pairs it possesses? Although there are proofreading enzymes, mistakes in base pairing during replication can occur, which are called mutations. Mostly, mutations have a negative effect on the cells ability to perform it's function, but there is a possibility that a mutation can be advantageous.
Although we are all humans with 46 chromosomes, we each have distinct traits that we have inherited from the DNA of our parents. A key factor in evolution is that there is diversity in life forms and variation in these traits within a population.
Next we are going to look at the variation of some unimportant physical traits within our class, collect data, and see if there are any extreme phenotype (what we look like) variations - how might that benefit an organism?
Working in partners, measure the following physical characteristics:
a) Height (without shoes, in cm)
b) Cubit (bend arm at elbow, measure from tip of elbow to end of fingers)
c) Hand span (tip of thumb to tip of pinky finger, hand spread wide)
d) Eye width (stare straight ahead, partner measures center of one eye to center of other eye)
e) Foot length (stand on ruler)
Enter info into shared google spreadsheet that you can access here:
Data
Once everyone has inputed their data, you are to plot a frequency graph for each characteristic - so that you can see how often each characteristic occurs. Plot the measured characteristic on the x-axis, and the number of people having the characteristic on the y-axis. One graph / characteristic...
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