Protein Synthesis (to make Protein Synthesis (to make proteins)proteins)

What is Protein Synthesis?What is Protein Synthesis?

Flow of Genetic Information:Flow of Genetic Information:

DNA DNA RNA RNA ProteinProtein

DNA holds the code for protein DNA holds the code for protein synthesis but synthesis but cannotcannot leave the leave the nucleusnucleus

Protein Synthesis is performed at the Protein Synthesis is performed at the ribosomesribosomes in the in the cytoplasmcytoplasm

The cell uses The cell uses RNARNA to to copy copy the code the code from DNA and from DNA and bringbring it to the it to the ribosomesribosomes

RNA – Ribonucelic AcidRNA – Ribonucelic AcidI.I. Nitrogenous BasesNitrogenous Bases

a. Adeninea. Adenineb. Cytosineb. Cytosinec. Guaninec. Guanined. d. UracilUracil

I.I. Simple Sugar – a Simple Sugar – a riboseribose rather than a rather than a deoxyribosedeoxyribose

II.II. Phosphate GroupsPhosphate Groups

II. StructureII. Structure

a. A nucleic acid backbone

b. single strand of nucleotides

c. Sugar is ribose

d. Contains uracil base instead of thymine

Difference between DNA and RNADifference between DNA and RNA

DNADNA RNARNA Double strandDouble strand single strandsingle strand DeoxyriboseDeoxyribose riboseribose ThymineThymine uraciluracil

III. Types of RNAIII. Types of RNA

Three types of RNA are Three types of RNA are used to make used to make proteinsproteins

a. mRNA – messenger a. mRNA – messenger RNARNA

b. rRNA – ribosomal RNAb. rRNA – ribosomal RNA

c. tRNA – transfer RNAc. tRNA – transfer RNA

IV. mRNA FunctionIV. mRNA Function

A. transcribe DNA codeA. transcribe DNA code

B. take code outside of nucleus to ribosome B. take code outside of nucleus to ribosome

C. give instructions to ribosome on how to C. give instructions to ribosome on how to build proteinbuild protein

How does DNA transfer info to How does DNA transfer info to RNA?RNA?

A = U

G = C

T = A

No T’s in RNA

V. tRNA FunctionV. tRNA Function

To deliver amino To deliver amino acids to the acids to the ribosome as it is ribosome as it is building building (synthesizing) (synthesizing) protein protein

VI. rRNA FunctionVI. rRNA Function

where translation of RNA to protein where translation of RNA to protein takes placetakes place

Ribosomes are made up of protein Ribosomes are made up of protein and ribosomal RNA (rRNA)and ribosomal RNA (rRNA)

Remember:Remember:

How many different amino acids are How many different amino acids are there?there?

2020Look at your notes - What makes each Look at your notes - What makes each

amino acid different from one another?amino acid different from one another?

R groupsR groups

VIII. The CODE!! VIII. The CODE!!

A.A. James Watson and Francis Crick, with James Watson and Francis Crick, with the help of Rosalind Franklin’s X-ray the help of Rosalind Franklin’s X-ray crystallography images unraveled the crystallography images unraveled the structure of DNA:structure of DNA:

B. The fact that bases paired led directly B. The fact that bases paired led directly to a theory of how DNA codes for to a theory of how DNA codes for proteins. It took a few years to proteins. It took a few years to determine that the bases spell three-determine that the bases spell three-letter “words” called codonsletter “words” called codons

mRNA CodonsmRNA Codons

3 letters on mRNA are called codons. 3 letters on mRNA are called codons. These three letter codes are used to These three letter codes are used to determine which Amino Acid is to be determine which Amino Acid is to be placed on the protein. placed on the protein.

Ex: TACEx: TAC AUG = Start Codon (Methionine)AUG = Start Codon (Methionine)

This is where you begin translation of DNA’s This is where you begin translation of DNA’s code given to mRNAcode given to mRNA

See the mRNA codon chart (slime See the mRNA codon chart (slime green)green)

Write the codon for Proline here:Write the codon for Proline here:

Glycine?Glycine?

Which amino acid has the most codons?Which amino acid has the most codons?

Which amino acid has the fewest?Which amino acid has the fewest?

Start codon starts each proteinStart codon starts each protein

Three codons tell a ribosome to stop Three codons tell a ribosome to stop making a protein. List them here:making a protein. List them here:

Transcription?Transcription? - - Copying the portion of DNA that carries the Copying the portion of DNA that carries the

code for a protein.code for a protein.

http://www.youtube.com/watch?v=ztPkv7wc3yhttp://www.youtube.com/watch?v=ztPkv7wc3yU&feature=relatedU&feature=related

mRNA Synthesis (Transcription begins with a mRNA Synthesis (Transcription begins with a promoter on DNA, site RNA polymerase promoter on DNA, site RNA polymerase binds to on DNA to begin transcription).binds to on DNA to begin transcription).

- A mRNA is transcribed (built) using A mRNA is transcribed (built) using unwound DNA’s code as a template.unwound DNA’s code as a template.

- RNA nucleotides find their compliment.RNA nucleotides find their compliment.- RNA Polymerase is the enzyme that brings RNA Polymerase is the enzyme that brings

in the nucleotides in the nucleotides

- Completed when reaches terminator - Completed when reaches terminator sequence on DNA – ending transcriptionsequence on DNA – ending transcription

The original strand is used as the The original strand is used as the template.template.

Result:Result:The resulting mRNA looks exactly like the The resulting mRNA looks exactly like the

template strand of DNA, with one template strand of DNA, with one important distinction important distinction

each T is replace with a U.each T is replace with a U.

http://www.youtube.com/watch?v=Jqx4Y0OjWW4&feature=relhttp://www.youtube.com/watch?v=Jqx4Y0OjWW4&feature=relatedated

Where does it go?Where does it go?The RNA releases from DNA and is then The RNA releases from DNA and is then

edited before leaving the nucleusedited before leaving the nucleus

Practice TranscriptionPractice Transcription

3 ‘ T A C G A T G C A T C G 5’

5 ‘ A U G C U A C G U A G C 3’

DNA Strand

RNA Strand

http://www.youtube.com/watch?v=NjczQKjFcks&feature=related

TranslationTranslation- The process of The process of interpretinginterpreting mRNA to build mRNA to build

a chain of a chain of amino acidsamino acids that make up a that make up a proteinprotein. .

http://http://www.youtube.com/watch?vwww.youtube.com/watch?v=B6O6uRb1D38&feature=related=B6O6uRb1D38&feature=related

How does it work?How does it work?

i. mRNA leaves the nucleus and heads i. mRNA leaves the nucleus and heads to the cytoplasm where the to the cytoplasm where the ribosomesribosomes are located. are located.

Remember: Ribosomes are where Remember: Ribosomes are where translation will occurtranslation will occur

• Each sequence of nucleotides is a Each sequence of nucleotides is a codon (mRNA codon)codon (mRNA codon). Each codon . Each codon codes for a specific codes for a specific amino acidamino acid

ii. ii. Amino acids are brought to the ribosome by tRNAAmino acids are brought to the ribosome by tRNA..

• There are 20 different tRNA molecules, one for each type There are 20 different tRNA molecules, one for each type of amino acid.of amino acid.

• tRNA anticodon finds their complimentary codon on tRNA anticodon finds their complimentary codon on mRNA.mRNA.

Anticodon – Anticodon – 3 letters found to match the mRNA’s 3 letters found to match the mRNA’s codon.codon.

– mRNA codon: UAA CGA GGCmRNA codon: UAA CGA GGC– tRNA anticodon: AUU GCU CCGtRNA anticodon: AUU GCU CCG

iii. iii. Peptide bonds form between the Peptide bonds form between the amino acids forming a polypeptide. amino acids forming a polypeptide.

iV. Translation stops when a stop iV. Translation stops when a stop codon is reached.codon is reached.

Video: Video: http://http://www.youtube.com/watch?vwww.youtube.com/watch?v=41_Ne5mS2ls&feature=related=41_Ne5mS2ls&feature=related

Video: Video: http://http://www.youtube.com/watch?vwww.youtube.com/watch?v=983lhh20rGY&feature=related=983lhh20rGY&feature=related