I have a grid in xaml that has two columns with widths 4.5* and 5.5*

In column 1 i have a textblock. When this textblock has text that is very long it is making the textblock column very wide and my second column is getting smaller.

I need the textblock column to stay the wide that is set and wrap the text instead.

Here is the xaml:

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="25"  />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="4.5*"/>
        <ColumnDefinition Width="5.5*"/>
    </Grid.ColumnDefinitions>
    <TextBlock x:Name="lblCheck" Text="{Binding Path=Text}"  Grid.Column="0"  Grid.Row="0" TextWrapping="Wrap" Margin="5,0,0,0"/>
    <CheckBox x:Name="chkOption" Grid.Column="1" IsChecked="{Binding Path=Checked}" Grid.Row="0"  IsEnabled="True"/>
</Grid>

Thanks