Answers for Transcription1. DNA acts as a template to make the RNA molecule.

2. Describe 3 ways RNA and DNA differ.1.) the sugar in RNA is ribose instead of

deoxyribose2.) RNA is generally single stranded3.) RNA contains uracil in place of Thymine

3. If the DNA molecule has the base adenine, the RNA molecule will have the base uracil.

4. If the DNA molecule has the base thymine, the RNA molecule will have the base adenine.

5. If the DNA molecule has the base cytosine, the RNA molecule will have the base guanine.

6. If the DNA molecule has the base guanine, the RNA molecule will have the base cytosine.

7. Transcription occurs in the nucleus of cells.

A

T

G

A

C

G

A

C

T

U

U

U

A

A

C

C

G

G

Original DNA

messenger RNA

Translation

• The decoding of an mRNA message into a polypeptide chain (protein) is known as translation

• Translation takes place on ribosomes

• To follow are the steps of translation

A.) Before translation occurs, mRNA is transcribed from DNA in the nucleus and released in the cytoplasm

B.) Translation begins when mRNA attaches to a ribosome. As each codon of mRNA moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA. The amino acid is transferred to the growing polypeptide chain

B.) Each tRNA carries one kind of amino acid. The tRNA molecule also has three unpaired bases. These bases are called anticodon and are complementary to one mRNA codon.

C.) This process works like an assembly line. The ribosome forms a bond between the amino acids. At the same time it breaks the bond held the first tRNA to its amino acid and releases the tRNA molecule. The ribomsome then moves to the next codon

D.) The polypeptide chain continues to grow until the ribosome reaches the stop codon on the mRNA molecule. It then releases the newly formed polypeptide and mRNA molecule

Review

• DNA and RNA are like two different plans that builders use.– DNA serves as the “master plan” that contains

all the information needed to build. The master plan can never be lost

– RNA serves as inexpensive, disposable copies of the master plan called “blue prints”

mRNA?

Amino Acids?

Single Strand of DNA

TACGCAATC

mRNA?

AUGCGUUAG

mRNA codons?

AUG-CGU-UAG

Amino Acids?

Met-Arg-Stop

On translation notes:Glue the copy of the

codon keys into your notes. Use the key for the following:

Identify the three amino acids being coded for

by the strand of mRNA. Copy the mRNA into your notebook and

answer.

A

U

G

A

C

G

C

G

U Isoleucine

Aspartic acid

Alanine

What is Your DNA Alias?Barton

DNA code:

(TAC) GCA GCT CGT AGT GAT GAC (ATC)

mRNA code:

(AUG) CGU-CGA-GCA-UCA-CUA-CUG (UAG)

Amino Acid Sequence:

(Met) Arg-Arg-Ala-Ser-Leu-Leu (Stop)