Can anyone explain to me please why the following words do not follow the consonant harmony word mutation rule and if there is an exception to apply the rule, if so when?

saç + -e = saça and not saca

top + e = topa and not toba

kek + e = keke and not keðe

at + e = ata and not ada

thank you for your help.

I think it´s because they are one syllable words and/or of foreign origin. 

because rule doesn´t apply to one syllable words.

Thank you guys for your reply.

I think this  should be noted in the lesson. The exceptions to the rule were not mentioned!

thanks again

Oops, It was mentioned and I didnt see it!! duh how stupid of me.

thanks again