In a bulleted list you can opt to show all the bullet points at once and emphasize them afterwards in bold one by one. Or you can opt to show each bullet point one after the other separately and bold them. Here's an example of a list that will be used in a presentation.
Show all the bullet points at once and animate later.
The first option is the simplest, select the placeholder (click on the border) and click the 
Add
animation button on the 
Animation tab, choose the emphasis animation 
Bold reveal.
If you do not intervene each bullet point will be emphasized in bold when you press enter till all the bullets have been discussed. The bullets will stay in bold and will be animated by letter.
See this video:
If you want to remove the bold after an item has been discussed do the following. With all the bullet points still selected, right click an item and choose 
Effect options. On the 
Effect tab select 
All at once. On the 
timing tab next to 
Duration select 
Until next click.
This will give you this result:
Show the bullet points one by one and emphasize in bold afterwards. 
This has the advantage that the viewer cannot anticipate on the content and lose focus.
Select the placeholder (click on the border) and click the 
Add animation button on the 
Animation tab, choose the 
Fade animation.
Leave the selection and immediately apply the emphasis effect 
Bold reveal. Click next to 
start and choose 
With previous.
Drag the emphasize effects under the entrance animations:
Now apply the effect options 
All at once and 
Until next click as explained above.
See this video that illustrates the effect.