Download Genetic Traits and Probabilities Excel Instructions Each box in an

Genetic Traits and Probabilities
Excel Instructions
Each box in an excel spreadsheet is called a cell, each cell is referred to by its coordinates starting
with the letters then the numbers the first cell is A1 the cell next to it is B1 and so on.
Cells can store information that you type into them directly or they can contain a formula that tells
excel to calculate the value that you will see in the cell. Excel knows that you are entering a formula
when you start with and equals sign ( = ) in that cell.
To start with we are going to enter the information that our formulae will use.
In Cell A1 write “Dominant”
In Cell B1 write “Recessive”
These are our headings for our dominant and recessive alleles we are going to put our pairs of alleles
in the rows below these headings, these can be changed later to match the traits that you are
looking for.
In Cell A2 write “White”
In Cell B2 write “black”
In Cell A3 write “Tall”
In Cell B3 write “short”
In Cell A4 write “Small”
In Cell B4 write “large”
This is the place that we will go back to if we need to change what our traits are.
We are now going to setup the system that will make it so that we do not need to write these traits
in ever again (unless we change them to something else)
Select Cell D2
Click on the Data tab at the top of the window
From the Data Tools section click on Data Validation
In the Allow: menu select List – another box called Source: will appear
Click in the Source: box
Click and hold in cell A2 and drag to cell B2 to select both cells – “=$A$2:$B$2” should now be
written for you in the Source: box
-orIn the Source: Box write “=$A$2:$B$2”
This needs to be repeated for cells D3 and D4
Select Cell D3
Click on the Data tab at the top of the window
From the Data Tools section click on Data
Validation
In the Allow: menu select List – another box
called Source: will appear
Click in the Source: box
Select Cell D4
Click on the Data tab at the top of the window
From the Data Tools section click on Data
Validation
In the Allow: menu select List – another box
called Source: will appear
Click in the Source: box
Genetic Traits and Probabilities
Excel Instructions
Click and hold in cell A3 and drag to cell B3 to
select both cells – “=$A$3:$B$3” should now be
written for you in the Source: box
-orIn the Source: Box write “=$A$3:$B$3”
Click and hold in cell A4 and drag to cell B4 to
select both cells – “=$A$4:$B$4” should now be
written for you in the Source: box
-orIn the Source: Box write “=$A$4:$B$4”
The dollar signs tell excel to always look at these cells even when you copy the cells and paste them
else where
Now since our organism always has two alleles we need to copy what we have just done.
Click in Cell D2 and hold down the mouse button
Drag down to select cells the cells D2, D3 and D4
Press Ctrl-C to copy
Click on cell E2
Press Ctrl-V to paste all three cells
Now we are going to use a formula to get excel to tell us what the phenotype of our sheep will be.
We know for the colour of the sheep black is recessive allele so the only way the sheep will be black
is IF both the first AND second allele are for black wool.
To do this we are going to use some excel functions, these are tools that can be used to complete
tasks in excel quickly. Functions in excel start with the function name and then an open bracket
followed by the arguments that the function needs to work.
The functions we are going to use are the if and the and functions.
=IF( What are we checking for, What to do if the check is right, What to do if the check is Wrong)
=AND( Check for one thing, Check for another)
In cell F2 write “=IF(AND(D2=B2,E2=B2),B2,A2)”
This will check to make sure that both the alleles match the recessive trait and tell you which trait is
expressed
This can now be copied down into the cells below by clicking on the small square in the bottom right
corner of the cell and dragging down.
You now need to copy the entire table so that you can compare the two parents.
Click and hold on cell D2 and drag to Cell F4
Press Ctrl-C to copy
Click on cell D7
Press Ctrl-V to paste all three cells
You will notice that the right column now shows 0’s rather than the traits you would have expected,
this is because when you copied the cells down they are now looking at empty cells. If you click on
cell F7 you can see that cells A7 and B7 are where it is looking for the alleles, to fix this;
Click on cell F7 and press delete to clear the cell
Genetic Traits and Probabilities
Excel Instructions
In cell F7 write “=IF(AND(D7=$B$2,E7=$B$2),$B$2,$A$2)”
The dollar signs will stop the cells from moving when you copy, you also need to replace F8 and F9.
In cell F8 write “=IF(AND(D8=$B$3,E8=$B$3),$B$3,$A$3)”
In cell F9 write “=IF(AND(D9=$B$4,E9=$B$4),$B$4,$A$4)”
Now you can copy the entire table again for the child and the trait column will still work.