Proteins are the molecules that DO stuff in our body.

In the cell membrane:

They facilitate molecule movement.

​Inside cells:

They are enzymes that do reactions.

​DNA is awesome, but... WE NEED PROTEINS!!! Why?

DNA holds the code to create proteins. DNA has to be copied then translated into a new molecule sequence. (Remember: C before L!!)

TRANSCRIPTION:

• Process of making mRNA from DNA

​TRANSLATION:

• Process of reading mRNA to construct a protein

​So how do we MAKE proteins???

"Transcribe" means to rewrite (you are "transcribing" this text right now...)

When you transcribe something, you are writing it in the same language. But it might be in handwriting versus typed text.

SIMMILARLY:

Transcription is when DNA is copied into mRNA. It is slightly different (single strand, and U instead of A) but it is the same language --> NUCLEOTIDES!!!!

​TRANSCRIPTION

"Translate" means to convert one language into another.

In language class (and maybe at home!) You are translating English into Spanish, sign-language, French, or what ever the new language is.

SIMMILARLY:

Translation is when mRNA is read to create an amino acid sequence. This is a whole new language of molecules --> NUCLEOTIDES to AMINO ACIDS!!!!

​TRANSLATION

By reading mRNA we can code the mRNA sequence. There are 2 types of charts you may use. The first, read left-top-right. The wheel is read from the center out.

.

Example: A-U-G --> Methionine amino acid.

.

Practice on your paper:

AUG CCG UAU AGA

.

When you hit "stop" a tRNA not carrying an amino acid breaks the chain.

​How do we code a sequence?

Mutations occur in transcription, translation, or even meiosis (crossing over).

.

SUBSTITUTION:

• One mRNA base is replaced by another: AUG --> AAG

INSERTION:

• 1 or more bases are added: AUGCCG --> AUCAGCCG

DELETION:

• 1 or more bases are deleted: AUGCCG --> AUCG

Substitutions MAY change the amino acids, but insertions and deletions create "frame shifts" that move the whole sequence and WILL change the sequence.

What about mistakes?? Uh-oh!

Time for independent practice!