Bellringer-Write down 3

interesting things about DNA that you

didn’t know before. On page 15.

You should have learned at least 3 things.

Protein SynthesisProtein Synthesis

What is protein synthesis?Is protein synthesis important?

What is RNA?

Where is RNA found?Is RNA similar to DNA?

What is translation?

What is Protein Synthesis?

*Protein synthesis is the building

of proteins following the instructions of DNA.

*The instructions of DNA are written by the order of the bases.

Example of instructions on DNA:

A - G - A - T - C - T - A - G

Why is protein synthesis important?

*Proteins make up the structure of an organism AND control all of the organism’s chemical reactions to keep it alive.

Examples of proteins:Walls of arteries, ligaments, hair, nails, muscles , bones and antibodies.

Protein Structure

A protein is made up of a chain of AMINO ACIDS in a particular order, held together by PEPTIDE BONDS.

Example of Protein:*a chain of Amino Acids

Alanine Phenylalanine Glutamine Valine Proline Lysine

NAMES OF AMINO ACIDS

Actual Sequence and names

of AMINO ACIDS

In Blood (Hemoglobin)

Shapes of Proteins

*the shape of a protein depends on its function & its order of amino acids.

Where does protein synthesis occur?

*The DNA never leaves the nucleus.

*RNA copies the DNA in the nucleus.

*RNA carries the instructions from DNA out to the ribosome.

*The protein is built on the ribosome in the cytoplasm.

DNA in the nucleus is safe !!

DNA in the cytoplasm can be

destroyed

What is RNA?

RNA (ribonucleic acid)

*It is the nucleic acid responsible for

three things in protein synthesis:

1 – copying instructions from DNA

2 – carrying the instructions for

making proteins to the ribosome,

3 – putting the protein together on

the ribosome.

What makes up RNA?

Bases in RNASugar in RNA

Ribose

Strands in RNA

“ONE”

3 Types of RNA1. Messenger RNA (mRNA)2. Transfer RNA (tRNA)3. Ribosomal RNA (rRNA)

mRNA tRNA rRNA

Messenger RNA (mRNA)

Function: 1. Goes into the nucleus and makes a copy of DNA using

RNA bases. 2. Takes the copy to the ribosomes.3. Contains the “CODON” (group of 3 bases on mRNA)

Transfer RNA (tRNA)

Function:- carries amino acids to mRNA at the ribosome to (make) the protein.- contains “ANTICODON” (3 bases that match up w/codon on mRNA)

Ribosomal RNA(rRNA)*ribosomal RNA

major structural part of the ribosome where protein synthesis occurs.

Comparison of Comparison of DNA and RNADNA and RNA

*DNA* * RNA*

Strands: 2 1

Sugar: deoxyribose ribose

A, G, C, T A, G, C, UBases: *Thymine *Uracil

(A – T) (A – U)

Steps in Protein Synthesis

Part I – Transcription

Part II – Translation:

Step 1: TranscriptionStep 1: Transcription

Location: in the nucleusPurpose: to copy the DNA code (order of bases) onto mRNA.Events:1.) DNA is unwound and DNA helicase unzips DNA strand.2.) RNA polymerase reads the complementary base and adds the new

nucleotides along the DNA strand.3.) mRNA is made, leaves the nucleus to go to ribosome.

Step 1: TranscriptonStep 1: Transcripton

Location: in the nucleus

Main Event: mRNA comes into

the nucleus and makes

a copy of the order of

thebases on DNA.

RNA polymerase

Function:

Enzyme that recognizes

the complementary base

of RNA to DNA, and glues

them together.

Examples:

Guanine with Cytosine

Adenine with Thymine

*Uracil with Adenine

Step 2: TranslationStep 2: Translation

Location: in the cytoplasm, on the ribosome.Purpose: to convert the instructions of RNA (order of bases) into

amino acids, to make proteins.

Step 2: TranslationStep 2: Translation

Events of translation:1.) The first three bases of mRNA (codon) join the ribosome.

Usually (AUG – considered the start codon).2.) tRNA brings the “amino acid” down to the ribosome. The three

bases on tRNA (anticodon) match the complementary bases on mRNA.

Step 2: Translation … (final Step 2: Translation … (final stage)stage)

Events of translation:3.) Each tRNA has an AMINOACID, that is determined byits anticodon.

Ex: codon (AUG)Amino Acid - methionine

4.) The amino acids arejoined by polypeptide bonds.5.) The resulting chain of amino acids are called aPROTEIN.

Codons & Anticodons

Codon – def: three nucleotides of mRNA.

STOP codons - UAA, UAG, UGA - all three of these codons signal the end of a polypeptide chain

Codons - *C U A - *G G C - *A A C - *U U AAmino Acids Leucine - Glycine - Asparagine - Leucine

ANTICODON - segment of three bases on tRNA that are complementary to the mRNA codon.

Start codon - AUG codons signals the start of a polypeptide chain

TRANSLATION

& tRNA

in pictures

Closeup of translation…(mRNA, codons)

tRNA, amino acids, peptide bonds

Protein Synthesis, summary…

Protein Synthesis, summary…

Animations

• DNA Replication review

• Transcription & Translation

Practice with Amino Acids

• What is the Amino Acid for : – AUG – CCU – UGG – AGU