Central Dogma of Genetics

•Genetic information flows in one direction for

gene expression

•DNA🡪 RNA🡪 Protein

How does DNA tell the cell to make

a specific kind of protein?

* First: Transcription

* Second: Translation

* Called PROTEIN SYNTHESIS

* There are 2 major steps in this process

How does DNA tell the cell to make

a specific kind of protein?

Transcription : Process in which mRNA is

synthesized from the DNA template.

Major Player: mRNA(messenger RNA) transfers the recipe for
making proteins from the DNA to to the ribosome

Remember that RNA replaces the T in DNA with a U!

The correct answer is
DNA: TAGCGA
RNA: AUCGCU

Why is Transcription Necessary?

•DNA cannot leave the nucleus
•DNA must remain secure!
•DNA is used repeatedly as a template
•DNA cannot not bind to ribosomes for translation (second step of protein synthesis)

translation (second step of protein
synthesis)

to be added to the growing
RNA chain

•Termination

•The enzyme reaches the

stop codon and falls off the
DNA chain, allowing the
double helix to return back
to shape

Now What?...Translation!

Translation: Process in which mRNA attaches to

the ribosome and a protein is
assembled/made.

* Codon: 3 base code in DNA or RNA

Words to know:

ACG ATA CGG CTT

Now What?...Translation!

Translation: Process in which mRNA attaches to

the ribosome and a protein is
assembled/made.

* Codon: 3 base code in DNA or RNA

Words to know:

* Amino Acid: Small monomer subunits joined together

to build proteins

There are 20 different Amino Acids.

Different combination of Amino Acids make

different kinds of proteins.

#1. AUG GCA UCC UGA

Methionine, Alanine, Serine, Stop

#2. AUG CCC GGU UAG

Methionine, Proline, Glycine, Stop

#3. AUG AAG GUG UGA

Methionine, Lysine, Valine, Stop

Translating mRNA codes into amino
acids to create polypeptide chains

(protein chains)

What is the amino acid for the

following codons?

AAU

Asparagine

(Asn)

GUG

Valine
(Val)

UGG

Tryptophan

(Trp)

Now What?...Translation!

Translation: Process in which mRNA attaches to

the ribosome and a protein is
assembled/made.

* Codon: 3 base code in DNA or RNA

Words to know:

* Amino Acid: Compounds joined by peptide bonds

to build proteins

* Ribosome: “Reads” mRNA recipes so it can

synthesize/make proteins

Now What?...Translation!

* tRNA: (transfer RNA) Type of RNA that

transports amino acids to the ribosome

More Words to know:

tRNA

Now What?...Translation!

More Words to know:

* Anticodon: Complementary codons on tRNA that can pair that with the codons on the mRNA

tRNA

What happens during

translation?

Ribosome

Peptide chain/

Protein Chain

tRNA

Amino
Acid

Anticodon

Codon

Steps of Translation